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§ 9. Reflex regulation
1. What is part of the central nervous system, and what is part of the peripheral nervous system?
2. What is a reflex?
3. What is reflex arc?
Central and peripheral nervous system. The human nervous system is divided into central and peripheral based on its location in the body. TO central nervous system include head and spinal cord. Peripheral nervous system consist of nerves, nerve ganglia and nerve endings. The majority of all neurons are localized in the central nervous system. Their bodies, together with short processes - dendrites, form the gray matter of the brain. Depending on the manner and location of neurons, gray matter can be represented or bark on the surface of the brain (neurons are arranged in layers), or cores(accumulations within the white matter). Long processes of neurons, covered with protective membranes, form nerve fibers. In the central nervous system, collections of nerve fibers are called tracts or pathways. They form the white matter of the brain. At the periphery, bundles of nerve fibers form part of the nerves. There are sensory, executive and mixed nerves. Sensory nerves carry information from the senses to the central nervous system. Through the executive nerves, control commands from the brain go to the organs, causing a response from the body. Mixed nerves contain both executive and sensory fibers. Humans have 12 pairs of cranial (cranial) and 31 pairs of spinal nerves.
Nerve cells located on the periphery form special clusters - nerve nodes, or ganglia. Some nerve nodes, they are called sensitive, receive primary information, process it and then transmit it to the central nervous system. Other nerve nodes (vegetative) process signals coming from the central nervous system and transmit information to the internal organs.
Reflex and reflex arc. Reflex call the body's response to irritation, occurring with the participation of the central nervous system and under its control.
Humans, like animals, have many reflexes: food, defensive, orienting. Involuntarily we pull our hand away from the hot object and turn our heads in the direction of an unexpected sound. These are examples of congenital - unconditional– reflexes.
Unconditioned reflexes are the result of the evolution of the species and were preserved thanks to natural selection. They are the same in all people and in animals of the same sex and age belonging to the same species. Animal species differ not only in the structure and functions of their organs, but also in the set of innate reflexes, which is a species characteristic.
Reflexes acquired during life are called conditional. Depending on whether a result beneficial to the body is achieved or not, they remain, change or disappear.
The reflex begins with irritation of receptors. Receptors- these are the endings of sensory nerve fibers or special sensory cells that convert irritation into nerve impulses. Through the processes of sensory neurons, the impulses generated in the receptors reach the central nervous system. There this information is processed by interneurons. The latter are located within the central nervous system. After this, the signals are received by executive neurons, on which the response depends. They get excited and send signals, triggering the work of muscles, glands, and internal organs, thanks to which the desired effect is achieved. Clusters of neurons of the central nervous system that cause one or another reflex action, called reflex centers these reflexes. They are found in the spinal cord and in various parts of the brain.
As an example, consider the innate blink reflex. To do this, let's conduct a simple experiment. For those who wear glasses, we suggest taking them off during the experiment. The experiment can only be carried out with clean hands. The use of pencils and other objects to irritate the skin and eyelids is unacceptable.
Progress of experience. Gently touch the corner of the eye from the side of the nose, the side of the cheek, as well as the eyelashes and eyebrows with your hand. Mark those areas whose irritation causes involuntary blinking with a “+” sign.
The reflexogenic zone is the area where receptors are located that cause a given reflex when irritated, in our case blinking. Experience shows that there are many such receptors in the inner corner of the eye, in the skin of the eyelids and eyelashes, but almost none in the outer corner of the eye.
Irritation of the receptors causes excitation in sensory neurons. Their bodies are located in a sensitive nerve node, outside the central nervous system. The axons of these neurons go to the medulla oblongata, where the interneurons are located. Those, in turn, transmit information to the higher parts of the brain and to the areas of the medulla oblongata where the centers of the blink reflex are located. From the executive neurons the signal goes to the orbicularis oculi muscles, and both eyes a short time close (flashing).
Rice. 21. Scheme of the reflex arc of the blink reflex: 1 – receptor; 2 – sensitive neuron located in the nerve ganglion; 3 – interneuron; 4 – motor neuron; 5 – circular muscle of the eye, closing the eyelids
The path along which nerve impulses travel from the receptor to the working organ is called reflex arc(Fig. 21). The reflex arc is the simplest neural circuit. It includes a receptor, a sensory neuron, interneurons and executive neurons. Sensory neurons carry information to the brain. Interneurons process it within the brain, executive neurons activate working organs.
Feedback system. The presence of a reflex arc is a prerequisite for the implementation of any reflex. However, it would be wrong to assume that the reflex reaction ends with the response of the working organ. The body must evaluate how correctly and correctly this response was organized. During the response, the receptors of the working organ are excited, and from them information about the achieved result is received back to the central nervous system.
So, during the experiment, you feel a touch on the skin, blinking. Thus, the presence of feedback allows the reflex nerve center to control the accuracy of the execution of its commands and, if necessary, make urgent changes in the work of the executive organ.
CENTRAL AND PERIPHERAL NERVOUS SYSTEM, REFLEX, REFLECTOR ARC, RECEPTOR, WORKING ORGAN, REFLEXOGENIC ZONE, FEEDBACK.
Questions
1. What is a reflex and a reflex arc? Give an example of a reflex arc.
2. What is another name for congenital reflexes and reflexes acquired during life? Why do you think they got these names?
3. What properties do receptors have?
4. Where are the bodies of sensory neurons located?
5. What function do intercalary and executive neurons perform?
6. Explain the need for feedback in the nervous system.
Tasks
1. Using Figure 21, sketch the reflex arc of the blink reflex and indicate its parts.
2. Touch carefully inner corner eyes several times. Determine how many touches the blink reflex will slow down. Analyze this phenomenon and indicate it possible reasons. Suggest what processes in the synapses of the reflex arc can cause inhibition of the reflex reaction.
3. Check whether it is possible to inhibit the blink reflex using volitional effort. If you succeeded, explain why it happened.
4. Remember how the blink reflex manifests itself when a speck gets into the eye. Analyze your behavior from the point of view of the doctrine of direct and feedback.
5. Draw a conclusion about the meaning of the blink reflex.
The main provisions of Chapter 3
The human body consists of cells, cells form tissues, tissues form organs, organs form organ systems, and those form the body as a whole.
The environment in which the organism is located is called the external environment. internal environment name the environment in which body cells function. Cells are diverse in shape and structure, but similar in structure. Every cell has a cell membrane. The cell nucleus contains chromosomes, which contain all the hereditary information of the organism. Sections of DNA responsible for the synthesis of a specific protein and controlling certain hereditary traits are called genes. The cytoplasm of the cell contains organelles: ribosomes, mitochondria, Golgi apparatus, endoplasmic reticulum, centrioles. They ensure the vital activity of the cell. Thanks to metabolic and energy processes, a cell can perform its functions, grow, develop and divide. Significant role in metabolism enzymes play. Cells can be in a state of excitation or in a state of rest.
There are four types of tissues in the body: epithelial, connective, muscle and nervous. Epithelial tissues participate in the formation of integument and glands, connective tissues - in the formation of bones, cartilage, blood, fat and other formations. Muscle tissue is capable of contracting. They are smooth and striated. Nervous tissue specializes in receiving, processing and transmitting information. Its main elements are neurons. They consist of a body and processes: dendrites and axon. Dendrites receive information and transmit it to the neuron body. The axon carries information to other cells. Synapses are formed at the points of contact of the axon with these cells.
The functioning of the nervous system is based on the reflex principle. A reflex is the body’s response to irritation, carried out with the participation of the nervous system. The path along which nerve impulse during a reflex reaction, is called a reflex arc. From an anatomical point of view, a reflex arc is a chain of nerve cells. The reflex arc begins with a sensitive structure - a receptor that perceives a certain irritation (mechanical or light, sound or temperature, etc.). The second part of the arc consists of structures that transmit signals to the central nervous system. And finally, the control signal from the central nervous system reaches the working organ (muscle or gland) through the processes of executive neurons. Reflexes are innate (unconditioned) and acquired during life (conditioned).
Reflex regulation involves the central nervous system - the spinal cord and brain and the peripheral nervous system - nerves, nerve endings and nerve ganglia.
Chapter 4. Musculoskeletal system
In this chapter you will learn
About the structure and functions of the skeleton and muscles;
On the adaptation of the body to work and upright walking;
About the nervous regulation of muscle function;
About the training effect and the dangers of physical inactivity.
You will learn
Reveal essential features musculoskeletal system;
Identify poor posture and the presence of flat feet;
Provide first aid for injuries to the musculoskeletal system.
§ 10. The importance of the musculoskeletal system, its composition. Bone structure
1. What qualities of bone ensure its lightness and strength?
2. Why is bone tissue classified as connective tissue?
Skeleton and muscles. The musculoskeletal system is often called the musculoskeletal system because the skeleton and muscles function together. They determine the shape of the body, provide support, protective and motor functions.
Support the function is manifested in the fact that the bones of the skeleton and muscles form a strong frame that determines the position of the internal organs and does not allow them to move.
Skeleton bones protect organs from injuries. Thus, the spinal cord and brain are in a bone “case”: the brain is protected by the skull, the spinal cord by the spine. The rib cage covers the heart and lungs, Airways, esophagus and large blood vessels. The abdominal organs are protected from the back by the spine, from below by the pelvic bones, and in front by the abdominal muscles.
Motor the function is possible only if the muscles and bones of the skeleton interact, since the muscles set the bone levers in motion.
Most of the bones of the skeleton are movably connected through joints. The muscle is attached at one end to one bone that forms the joint, and at the other end to another bone. When a muscle contracts, it moves the bones. Thanks to the muscles opposite action The bones can not only make certain movements, but also be fixed relative to each other.
Bones and muscles take part in metabolism, in particular in the metabolism of phosphorus and calcium.
Chemical composition of bones. If you burn a bone, it will turn black from the carbon left over from the combustion of organic matter. If the carbon also burns out, a white residue will be left, extremely hard but brittle. This is a bone mineral.
To determine the properties of organic bone substances, it is necessary to remove mineral substances using of hydrochloric acid. The bone will retain its shape. But the properties of the bone will change dramatically. It will become so flexible that you can tie it in a knot. Bone flexibility depends on the presence of organic substances, hardness - on inorganic substances.
A combination of hard yet brittle inorganic matter and elastic organic matter gives bones both strength and elasticity. Human bones are strongest in their mature age(from 20 to 40 years). In children, the proportion of organic substances in the bones is relatively large. Therefore, children's bones rarely break, but are easily deformed under the influence of incorrect posture or uneven load. In older people, the proportion of minerals in the bones increases. Therefore, their bones become more brittle.
Microscopic structure of bone. Under a microscope, it can be seen that the bone tissue is organized in the form of plates arranged in a certain way. They either intersect like metal beams of complex engineering structures, or form dense bone cylinders. This structure gives bones strength. Depending on the location of the bone plates, two types of bone substance are distinguished: compact and spongy (Fig. 22). Bone plates are the noncellular substance of bone.
Records compact substance form complex systems– osteons (Fig. 23). Osteons are several layers of thin bone plates arranged concentrically around a canal containing blood vessels and nerves. Between the bone plates are bone cells.
Rice. 22. Bone tissue: A – compact substance; B – spongy substance (micrographs)
IN spongy substance intersecting thin bone crossbars, consisting of bone plates, form many cells. The crossbars form vaulted structures oriented along compression and tension lines, which ensures uniform load distribution. The cells of the spongy substance contain red bone marrow.
Bone marrow is the tissue that fills the cavities of the bones in humans. There are two types of this fabric: red bone marrow(Fig. 24), the main function of which is the formation of blood cells, and yellow bone marrow rich in fat cells. There are no blood-forming elements in the yellow bone marrow. However, after large blood losses, hematopoietic tissue may form in place of the yellow bone marrow.
Rice. 23. Microscopic structure of compact bone substance: A – in a three-dimensional image: 1 – concentric cylinders formed by bone plates; 2 – bone cells; 3 – blood vessels passing in the bone cavities inside the cylinders; B – on a cross section
Rice. 24. Red bone marrow in the cells of the spongy substance (micrograph)
The ratio of compact and spongy substance in the bone depends on the place of the bone in the skeleton and its function.
Types of bones. Based on the type of structure, there are tubular, spongy, and flat bones.
Tubular bones They look like cylinders with thickened edge ends. The middle part of the tubular bone is called the body, the expanded ends are the heads (Fig. 25). On the outside, the body of the tubular bones is covered with a dense connective tissue plate - periosteum. It contains big number blood vessels and many nerve endings. The cells of the inner layer of the periosteum actively divide, ensuring the growth of the bone in thickness and its healing during a fracture. Under the periosteum there is a layer of compact substance. In the center of the bone there is a canal (medullary cavity) filled with yellow bone marrow. The walls of the medullary cavity contain cells that dissolve bone. Thanks to the complex and coordinated work of bone tissue cells, optimal bone strength is achieved with minimal weight and material consumption.
Rice. 25. Structure of the bones of the limb: A – tibia: 1 – periosteum (outer surface); 2 – compact bone substance; 3 – inner surface of the periosteum; 4 – articular cartilage; B – cut of the head of the femur: 1 – spongy substance; 2 – compact substance; 3 – bone marrow cavity; B – orientation of the spongy substance struts
The heads are formed by a spongy substance and covered with cartilage. The narrowed part between the body and the heads of the tubular bone is the neck. In childhood and adolescence, the neck consists of cartilaginous tissue. Cartilage cells actively divide, allowing bone to grow in length. With age, cartilage tissue is gradually replaced by bone. The final ossification of the necks of tubular bones ends in women by 16–18 years, and in men by 20–22 years. After this, bone growth in length stops.
In the human skeleton, there are two types of tubular bones: long (bones of the shoulder and forearm, thigh and lower leg) and short (bones of the metatarsus, metacarpus and phalanges of the fingers).
Spongy bones have a rather thin compact substance on the surface, under which there is a spongy substance. Spongy bones include the bones of the vertebral bodies, sternum, carpal and tarsal bones. Basically, cancellous bones are located where it is necessary to combine strength and mobility.
Flat Bones located where increased strength is needed. They consist of two parallel plates of a compact substance, between which a spongy substance is located. Flat bones include the bones that form the cranial vault, shoulder blades, and pelvic bones.
SKELETON, MUSCLES, PERIOSTE, COMPACT AND SPONGEY BONE, RED BONE MARROW, YELLOW BONE MARROW; TYPES OF BONES: TUBULAR, SPONGEIOUS, FLAT.
Questions
1. Why are the skeleton and muscles classified as a single organ apparatus?
2. What are the supporting, protective and motor functions of the skeleton and muscles?
3. What is chemical composition bones? How can you find out the properties of its components?
4. Explain why bone curvatures occur more often in children, and fractures more often in older people.
Tasks
1. Look at Figure 25, A, B and C. Compare it with a preparation of a cut of natural bone. Find the periosteum, compact substance, spongy substance, medullary cavity.
2. Consider Figure 25, B and C. Explain why the crossbars of the cancellous substance are oriented in the direction of the forces of compression and tension of the bone.
Laboratory work
Microscopic structure of bone
Equipment: microscope, permanent preparation “Bone tissue”.
Progress
1. Examine bone tissue at low magnification using a microscope. Using Figure 23, A and B, determine whether you are considering a transverse or longitudinal section.
2. Find the tubules through which the vessels and nerves passed. In cross section they look like a transparent circle or oval.
3. Find the bone cells that are located between the rings and look like black spiders. They secrete intercellular substance, which is then impregnated with mineral salts.
4. Think about why a compact substance consists of numerous tubes with strong walls. How does this contribute to bone strength with the least amount of material and bone mass required? Why is the airframe made from durable duralumin tubular structures, and not from sheet metal?
§ 11. Human skeleton. Axial skeleton
1 . What is a skeleton?
2. What parts is it divided into?
3. Why are the skull and trunk skeleton classified as the axial skeleton?
4. How is the skeleton adapted to walking upright?
5. Why is it okay to nod and shake your head?
Skeleton called a collection of bones, cartilage and ligaments that strengthen them. They determine the shape of the body and serve as support soft parts, protect internal organs from mechanical damage.
Axial skeleton. In the human skeleton there are axial skeleton And accessory skeleton. The axial skeleton combines the skull and the trunk skeleton. The accessory skeleton consists of the bones of the limb girdles and the skeleton of the free limbs (Fig. 26).
Scull determines the shape of the head, protects the brain, organs of hearing, smell, taste, vision, and serves as an attachment point for muscles involved in facial expressions. In the skull there are cerebral And facial departments (Fig. 27). Top part The brain section is formed by unpaired frontal and occipital bones and paired parietal and temporal bones. They form the cranial vault. At the base of the brain section of the skull are the sphenoid bone and the pyramidal processes of the temporal bones. In the cavities of the temporal bones there are receptors for hearing and the organ of balance. The brain is located in the cerebral part of the skull.
Rice. 26. Human skeleton: 1 – skull; 2 – shoulder girdle; 3 – ribs, together with the sternum and thoracic spine forming the chest; 4 – humerus; 5 – radius; 6 – ulna; 7 – spine (lumbar); 8 – pelvis; 9 – sacrum; 10 – femur; 11 – tibia; 12 – fibula; 13 – bones of the foot; 14 – hand bones
Rice. 27. Human skull: A – profile view: 1 – frontal bone; 2 – parietal bone; 3 – occipital bone; 4 – temporal bone; 5 – lower jaw; 6 – upper jaw; 7 – zygomatic bone; 8 – eye socket; B – bottom of the brain part of the skull: 1 – scales frontal bone; 2 – ethmoid bone; 3 – sphenoid bone; 4 – pyramidal process of the temporal bone; 5 – occipital bone; 6 – foramen magnum
Rice. 28. Spine: A – sections of the spine: 1 – cervical; 2 – chest; 3 – lumbar; 4 – sacral; 5 – coccygeal. Vertebrae: B – cervical; B – thoracic region; G – lumbar region; 1 – spinous process; 2 – vertebral body; 3 – arc; 4 – transverse processes; 5 – superior articular process
The facial part of the skull consists of 15 bones, the largest of which are the upper and lower jaws, cheekbones and nasal bones. The shape and size of the nose is determined by the nasal bones. The fibers of the olfactory nerve pass through the openings of the unpaired ethmoid bone.
The bones of the brain and facial skull are immovably connected to each other, with the exception of the lower jaw. It can move not only up and down, but also left and right, forward and backward. This allows you to chew food and speak clearly. The lower jaw is equipped with a mental protuberance, to which the muscles involved in speech are attached.
Skeleton of the body. The basis of the skeleton of the body is spine(Fig. 28, A). It is formed by separate vertebrae(Fig. 28, B, C, D). Each vertebra has body, arc And shoots. The vertebral body and arch form a ring. The vertebrae are located one below the other so that their rings form spinal canal. It contains the spinal cord (Fig. 29).
Between the vertebral bodies lie intervertebral cartilaginous discs. They give the spinal column mobility, elasticity and soften shocks when running, walking, jumping.
The human spine has four curves: cervical, thoracic, lumbar, sacral(in mammals - only cervical and sacral). Thanks to the S-shape, the spine is able to spring and act as a spring, reducing shocks when moving. This is an adaptation to walking upright.
In the spine there are departments: cervical, thoracic, lumbar, sacral, coccygeal(see Fig. 28).
Like all mammals, cervical spine The human spine has seven vertebrae. The skull articulates with the first cervical vertebra using two condyles. Thanks to this joint, you can raise and lower your head. It is curious that the first cervical vertebra does not have a body: it has grown to the body of the second cervical vertebra and formed a tooth - an axis around which horizontal plane The first cervical vertebra rotates along with the head when we show negation with a gesture (Fig. 30). A ligament of connective tissue separates the tooth from the spinal cord. It is especially fragile in infants, therefore, when holding them in an upright position, their head must be supported to avoid injury.
Rice. 29. Plot spinal column(cartilaginous discs not shown): 1 – spinous process; 2 – vertebral body
Rice. 30. The first two cervical vertebrae: 1 – first cervical vertebra (without body); 2 – tooth of the second cervical vertebra, formed by fusion of the bodies of the first and second cervical vertebrae; 3 – ligament separating the bone tooth and the spinal cord; 4 – second cervical vertebra; 5 – articular fossa for articulation of the condyles of the skull with the first cervical vertebra
Rice. 31. Chest: 1 – thoracic spine; 2 – ribs; 3 – sternum
Rice. 32. Sacral and coccygeal sections of the spine: 1 – fifth lumbar vertebra; 2 – sacrum; 3 – coccyx
Thoracic region The spine consists of 12 vertebrae, to which are attached ribs Of these, 7 pairs of ribs are movably attached to the sternum, 3 pairs are connected through cartilage to the overlying ribs. The two lower pairs of ribs end freely. The thoracic spine, ribs and sternum form chest(Fig. 31).
Lumbar consists of 5 vertebrae, quite massive, since they have to withstand the main weight of the body.
The next section consists of 5 fused vertebrae that make up one bone - sacrum(Fig. 32). If the lumbar region has high mobility, then the sacral region is motionless and very strong. When the body is in a vertical position, a significant load falls on it.
Finally, the last section of the spine - coccyx. It consists of 4–5 fused small vertebrae.
AXIAL SKELETON, ACCESSORY SKELETON, BRAIN AND FACIAL DIVISIONS OF THE SKULL, VERTEBRATE, INTERVERTEBRAL DISC, DEPARTMENTS OF THE SPINE: CERVICAL, THORACIC, LUMBAR, SACRAL, COCCYCOUS; CHEST, RIBS, STERNUM.
Questions
1. Which parts of the skeleton are classified as the axial skeleton, and which are classified as the accessory skeleton?
2. What is the significance of intervertebral cartilaginous discs?
3. What is the importance of the fixed connection of the bones of the skull, with the exception of the lower jaw?
4. How is the skull attached to the spine? Why should a newborn's head be held?
Tasks
1. Explain the significance of the S-shaped curve of the human spine.
2. Explain the structure and functions chest.
3. Bend your head and feel the seventh cervical vertebra at the border of the cervical and thoracic regions.
4. Using material from previous biology courses, compare the shape of the chest of a human and other mammals, such as a dog. What are their differences? What do you think is the reason for this?
5. Prince of Vladimir Andrei Bogolyubsky, who lived in the 12th century, according to contemporaries, was a proud man: he did not bow his head to anyone and did not show honor to anyone. And only 800 years later, scientists, restoring the appearance of the prince from his skeletal remains, established something that those close to the prince had no idea about. Using additional sources of information, find out why Andrei Bogolyubsky always walked with his head held high.
>> Reflex regulation
§ 9. Reflex regulation
What is part of the central nervous system and what is part of the peripheral nervous system?
What is a reflex?
What is a reflex arc?
Central and peripheral nervous system.
Most neurons are found in the brain and spinal cord. They make up the central nervous system. Some of these neurons extend beyond the central nervous system: their long processes are united into bundles, which, as part of the nerves, go to all organs of the body. Some of them (sensitive nerve fibers) receive information from organs about events occurring in the external environment. Others (executive) transmit brain commands that control authorities and guiding their actions. Both information is transmitted (as you already know) in the form of electrochemical signals - nerve impulses.
In addition to nerves, outside the central nervous system there are clusters of neuron bodies - these are nerve ganglia. Nerves and ganglia constitute the peripheral part of the nervous system. Some nerve nodes here receive primary information, process it and then transmit it to the central nervous system. Other nerve ganglia process signals coming from the central nervous system to the internal organs.
Reflex and reflex arc.
A reflex is the body's response to stimulation, which occurs with the participation of the central nervous system and under its control.
The reflex arc is the path along which signals from the receptor go to executive body. The reflex arc includes receptors, sensory neurons, interneurons, executive neurons and the working organ.
As an example, consider the blink reflex. To do this, let's conduct a simple experiment. For those who wear glasses, we suggest taking them off during the experiment. The experiment can only be carried out with clean hands. The use of pencils and other objects to irritate the skin and eyelids is unacceptable.
Progress of experiment 1.
Gently touch the corner of the eye from the side of the nose, the side of the cheek, as well as the eyelashes and eyebrows with your hand. Mark those areas whose irritation causes involuntary blinking with a “+” sign.
The reflexogenic zone is the area where receptors are located that cause a given reflex when irritated, in our case blinking. Experience shows that there are many such receptors in the inner corner of the eye, in the skin of the eyelids and eyelashes, but almost none in the outer corner of the eye.
When the receptors are stimulated, sensory neurons are stimulated. Their bodies are located in a nerve ganglion, outside the central nervous system. The axons of these neurons go to the medulla oblongata, where the interneurons are located. They transmit information to the higher parts of the brain and to the areas of the medulla oblongata where the blink reflex centers are located. From the executive neurons, excitation goes to the orbicularis oculi muscles, and both eyes close (blink) for a short time.
The path along which nerve impulses travel from the receptor to the working organ is called a reflex arc (Fig. 17). The reflex arc is the simplest neural circuit. It includes a receptor, a sensory neuron, interneurons and executive neurons. Sensory neurons carry information into the brain. Interneurons process it within the brain, executive neurons activate working organs.
During the experiment, you feel a touch on the skin, blinking. This happens because, along with direct connections that force the organs to work (orders from the brain), information about the response goes to the brain through feedback channels.
1. Using Figure 17, sketch the reflex arc of the blink reflex and indicate its parts.
2. Gently touch the inner corner of the eye several times. Determine how many touches the blink reflex will slow down.
3. Analyze these phenomena and indicate their possible causes. Find out what processes could occur at the synapses of the reflex arc in the first and second cases.
4. Check the possibility of using volitional effort to slow down the blink reflex. Explain why this was successful.
5. Remember how the blink reflex manifests itself when a speck gets into the eye. Analyze your behavior from the point of view of the doctrine of forward and backward connections.
6. Draw a conclusion about the meaning of the blink reflex.
Central and peripheral parts of the nervous system, reflex, reflex arc, receptor, sensory neuron, interneuron, executive neuron, working organ, reflexogenic zone, direct and feedback connections.
1. What is a reflex and a reflex arc? Give an example of a reflex arc.
2. What are they called? innate reflexes and reflexes acquired during life?
3. What properties do receptors have?
4. What function do intercalary and executive neurons perform?
5. What are the properties of synapses?
6. Explain the action of forward and feedback connections in the nervous system.
The main provisions of Chapter 3
The human body is made up of cells, cells form fabrics, tissues are organs, organs are organ systems, and those are the body as a whole. The body is divided into the integument of the body, the musculoskeletal frame, the thoracic and abdominal cavities of the body and the internal organs located in them. The brain and spinal cord are protected by the bones of the skull and spine. The environment in which the body is located is called the external environment, and the internal environment is called the environment in which the cells of the body function. Cells are diverse in shape and structure, but similar in structure. Each cell is surrounded by a cell membrane. The cell nucleus contains chromosomes, which contain the hereditary apparatus of the cell. Sections of DNA responsible for the synthesis of a specific protein and controlling certain hereditary traits are called genes. The cytoplasm of the cell contains organelles: ribosomes, mitochondria, membranes of the endoplasmic reticulum, centrioles. They are involved in protein synthesis, biological oxidation of organic substances and other processes. Thanks to metabolic and energy processes, a cell can perform its functions, grow, develop and divide. Enzymes play a significant role in metabolism. Cells can be in a state of excitation or in a state of rest.
There are four types of tissue in the body: epithelial, connective, muscle and nervous. Epithelial is involved in the formation of integument and glands, connective in the formation of bones, cartilage, blood, fat and other formations. Muscle capable of contracting. It is divided into smooth and striated. Nervous tissue specializes in receiving and transmitting information. Its main elements are neurons. They consist of a body and processes: dendrites and axon. Dendrites receive information and transmit it to the neuron body. The axon transmits information to other cells. Synapses are formed at the points of contact of the axon with these cells. When a nerve impulse arrives, the axon releases substances into the synaptic cleft that cause excitation or inhibition of the cell. In the first case, the cell strengthens or begins activity, in the second it weakens or stops. Neurons form circuits. The simplest of them is called a reflex arc. It consists of a receptor that perceives information and transmits it to the brain via a sensory neuron; intercalary cells that process it, and executive neurons that activate the working organs; muscles, glands. This is how it works reflex regulation. It involves the central nervous system: the spinal cord and brain and the peripheral nervous system - nerves and nerve ganglia.
Kolosov D.V. Mash R.D., Belyaev I.N. Biology 8th grade
Submitted by readers from the website
Question: 2. Gently touch the inner corner of the eye several times. Determine how many touches the blink reflex will slow down. 3. Analyze these phenomena and indicate their possible causes. Find out what processes could occur at the synapses of the reflex arc in the first and second cases. 4. Check the possibility of using volitional effort to slow down the blink reflex. Explain why this was successful. 5. Remember how the blink reflex manifests itself when a speck gets into the eye. Analyze your behavior from the point of view of the doctrine of forward and backward connections. 6. Draw a conclusion about the meaning of the blink reflex.
2.Touch the inner corner of the eye several times. Determine how many touches the blink reflex will slow down. 3. Analyze these phenomena and indicate their possible causes. Find out what processes could occur at the synapses of the reflex arc in the first and second cases. 4. Check the possibility of using volitional effort to slow down the blink reflex. Explain why this was successful. 5. Remember how the blink reflex manifests itself when a speck gets into the eye. Analyze your behavior from the point of view of the doctrine of forward and backward connections. 6. Draw a conclusion about the meaning of the blink reflex.
Answers:
With the help of volitional effort, you can slow down the action of the blink reflex. A nerve impulse arises in the nerve center. The nerve impulse reaches the synapse, in which bubbles burst with biologically inhibitory active substances. The fluid flows into the synaptic cleft and affects cell membranes muscle cells. Inhibition of the blink reflex occurs.
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change the phrase "... red sun" so that the noun is in the instrumental case, singular. See if the form of the adjective changes. What morpheme is used to link words into a phrase? Draw a conclusion. People were among the first to talk about volitional effort as a specific mechanism of will at the beginning of the 20th century. G. Munsterberg, G. I. Chelpanov, A. F. Lazursky. G. Münsterberg, for example, wrote: “If I try to remember the name of some bird that I see, and it eventually comes to my mind, I feel its appearance as a result of my own volitional effort.” A.F. Lazursky considered volitional effort as a special psychophysiological process associated with a person’s reaction to an encountered obstacle. He posed the question: “Is there one volitional effort that can be directed in different directions at will by a person, or, on the contrary, are there several of its varieties, related to each other, but still not identical to each other?” . Unfortunately, the answer to this question has not yet been found, although it is known that in Everyday life
a person is faced with the manifestation of volitional efforts in two directions. On the one hand, these are efforts whose task is to suppress impulses that prevent the achievement of a goal. These motivations are associated with unfavorable conditions that arise during the activity (fear, fatigue, frustration), which push a person to stop this activity. On the other hand, these are volitional efforts that stimulate activity aimed at achieving a goal. These efforts are of great importance for the manifestation of such strong-willed qualities as patience, perseverance, attentiveness, and perseverance.
What is this volitional effort? There are two types of views on this matter in psychology.
According to one view, volitional effort is a combination of motor (mainly muscle) sensations. When performing any muscle movements, you have to experience a feeling of tension, which is nothing more than a combination of muscle sensations. It is this muscular tension that we perceive as a feeling of effort. But there are such volitional acts in which there is no, but there is either a delay in this reduction, or other more complex psychophysiological detections. To explain these phenomena, the theory of the so-called innervation sense was put forward. It was assumed that any kind of nerve impulse, even if it did not lead to muscle contraction, but would remain a purely central brain process, is nevertheless accompanied by a certain subjective experience reminiscent of a volitional effort. As evidence, cases were cited when we experience motor effort, despite the fact that the muscles themselves, to the contraction of which this motor effort is aimed, are completely absent. This happens after amputation, when a person tries to move, for example, the toes of a severed leg, then, despite the absence of muscles that he should have contracted, he still experiences a certain volitional tension. However, more thorough research by James showed that in these cases a person usually contracts at the same time some of his other remaining muscles, just like, for example, with very high voltage With our hands, we also unwittingly strain some other muscles of the body. And so the muscle sensations that arose due to the contraction of auxiliary muscles were mistakenly taken for an innervation feeling.
...Until now we have been talking mainly about those volitional efforts that are aimed at performing certain motor acts or at delaying them. However, along with this, there is a whole series of volitional acts aimed at the flow of ideas, feelings, etc. Here there are often almost no movements or motor delays, and yet volitional tension can reach large sizes. It is these kinds of processes that force us to pay attention to another theory, to some extent opposite to the one just outlined. According to this second theory, volitional effort cannot be reduced to any motor acts, but, on the contrary, is an independent, completely unique psychophysiological process. While the first explanation refers mainly to data from physiology and biology, the second explanation is based mainly on data from introspection - however, without at all excluding the possibility that some specific brain process or complex underlies the directly perceived feeling of volitional effort. such processes.
Turning to the data of self-observation, we must first of all note that volitional effort is an extremely characteristic element of any generally conscious act of will. In addition, it is always something homogeneous; no matter what this effort is directed at, it is always experienced by us more or less the same. Finally, for our consciousness it is something elementary, indecomposable into further, simpler elements.
It seems to me that both theories cannot be accepted in their entirety. On the one hand, we saw that it would be too one-sided to reduce all volitional processes only to movements or their delay, since there is a whole series of volitional and, moreover, very intense acts in which the psychomotor elements are extremely insignificant. On the other hand, it would be wrong, in my opinion, to overestimate volitional effort, extending it to all our mental experiences. In my opinion, one should sharply distinguish the volitional process with its central factor, volitional effort, from more general concept mental activity. Volitional effort is one of the main mental functions, which occupies its definite place in our mental life along with feelings and intellectual processes.
Lazursky A. F. 2001. P. 235-237, M. Ya. Basov considered volitional effort as a subjective expression of the regulatory function of the will, which he identified with attention. He believed that attention and volitional effort are one and the same thing, only denoted by different terms. Thus, M. Ya. Basov indirectly joined the first of A. F. Lazursky’s assumptions: the mechanism of volitional effort is the same for all cases.
K. N. Kornilov considered volitional effort the main sign of will, so he gave following definition will: this " mental process“, which is characterized by a kind of effort and is expressed in the conscious actions and actions of a person aimed at achieving set goals.” Recognition of the central position of the question of volitional effort in the problem of will is found in the works of V. I. Selivanov, V. K. Kalin and others. However, there is another point of view.
S. N. Chkhartishvili did not consider volitional effort a sign of volitional behavior. On this occasion, he wrote: “Many researchers understand that the definition of will through signs of intelligence is a misunderstanding and find a way out in introducing another side of behavior into the definition of will, namely, the moment of effort. The flow of volitional acts often encounters some obstacle, overcoming which requires internal effort, a kind of internal tension. This moment of effort, or the ability to overcome obstacles, is declared the second sign of will.
However internal tension“, continued Sh. N. Chkhartishvili, “and the ability to overcome obstacles is not alien to animals. It takes exceptional effort for birds to overcome the storm that rages on the open sea and reach ultimate goal of your flight. An animal caught in a trap makes a tremendous effort to break free. In short, the ability to make the effort necessary to overcome obstacles that arise on the life path, is inherent in all living beings, and it is not surprising that man, having acquired the ability of consciousness, retained this property. However, no one considers an animal, despite the fact that it no less has the ability to make effort and fight obstacles, to be a creature with a will.” Regarding the last statement, I can note - and in vain. Animals certainly have the rudiments of volitional behavior, and one of them is their manifestation of volitional effort, as P.V. Simonov also wrote about. Sh. N. Chkhartishvili’s mistake, it seems to me, is that instead of denying volitional effort as a sign of will, he needed to recognize the presence of the rudiments of will in animals.
The elimination of volitional effort from will leads Sh. N. Chkhartishvili to strange conclusions and in relation to human behavior. Thus, he wrote: “An alcoholic or drug addict, who is in captivity of an ingrained need for alcohol or morphine, is aware of this need, is aware of the ways and means necessary to acquire strong drink or morphine, and often resorts to maximum effort to overcome the obstacles that have arisen in his way.” ways to satisfy your needs. However, it would be a mistake to consider the awareness of needs and intense efforts manifested in such acts of behavior as phenomena derived from the will and to believe that the stronger and more persistent the desire to satisfy such indomitable needs, the stronger the will. A need can activate the work of consciousness in a certain direction and mobilize all the forces necessary to overcome an obstacle. But this may not be an act of will. Therefore, it cannot be considered that the indicated signs of behavior manifest a specific feature of the will” [ibid., p. 73-74].
One cannot help but see in this statement echoes of an ideological approach to assessing volitional behavior. Alcoholism and drug addiction are considered negative inclinations in society, so anyone who cannot overcome these inclinations is weak-willed. But, firstly, you need to ask the alcoholic or drug addict himself whether he wants to overcome them, and secondly, what is the difference in the effort shown by the student when solving a problem and the alcoholic getting alcohol? In both cases, behavior is motivated, and in both cases we observe voluntary control of effort (after all, one cannot assume that this effort is manifested involuntarily by an alcoholic).
Therefore, from the point of view of behavior control mechanisms, there is no difference in these cases. Consequently, both of them show willpower in achieving the intended goal.
V. A. Ivannikov writes: “Recognition of increased motivation main function will was noted in the works of the last century and today is contained in the works of a variety of authors. Various solutions have been proposed to explain this phenomenon of will, but greatest distribution received a hypothesis about the volitional effort emanating from the individual.” And further V.A. Ivannikov poses the question: “Isn’t the concept of volitional effort a remnant of the gradual offensive experimental research to clarify the nature and mechanisms of motivation of personal activity, a remainder that has not yet found its explanation and experimental research methods?... Attempts to justify the introduction of the concept of volitional effort emanating from the individual by the need to recognize the individual’s own activity, which does not arise from the current situation, are hardly valid ... The task is not to introduce another motivating principle, but to find, through the existing mechanisms, the possibility of explaining the free independent activity of the individual.”
Developing his doubts, V. A. Ivannikov writes that “along with the sphere of motivation, personality becomes the second source of motivation for activity, and, unlike motives, personality not only encourages, but also inhibits activity. The theoretical awkwardness that arises in this case, apparently, confuses few people, and in the end it turns out that both the motivational sphere of the personality and the personality itself motivate, arbitrarily creating a volitional effort” [ibid.].
It seems to me that in reality there is no awkwardness that V. A. Ivannikov talks about and cannot exist. After all, the awkwardness that arose in him was based on the incorrect opposition of personality to motive. This opposition appeared in the author, obviously, because he accepted as a motive, following A.N. Leontyev, the object of satisfying a need, which is, as it were, outside the personality. In reality there is a motive personal education and one of the components of voluntary control, i.e. will in the broad sense, and therefore contrasting the motive of a person is the same as contrasting a part with the whole. A person controls his behavior both with the help of motive and with the help of volitional effort, between which, as V.I. Selivanov noted, there really is a qualitative difference. If a motive is something for which an action is performed, then volitional effort is something by which an action is carried out in difficult conditions. No one acts, wrote V.I. Selivanov (1974), for the sake of volitional tension. Volitional effort is only one of the necessary means of realizing a motive.
Therefore, V.K. Kalin rightly emphasizes that if it is incorrect to separate motive from will or replace will with motive, then it is equally incorrect to replace motive with the concept of “will”.
Let us remember how Lyudmila behaved in the garden near Chernomor in Pushkin’s poem “Ruslan and Lyudmila”:
In heavy and deep despondency She came up - and in tears she looked at the noisy waters, hit her chest, sobbing, decided to drown in the waves - However, she did not jump into the waters and continued on her way.
...But secretly she thinks: “Away from my beloved, in captivity, Why should I live in the world anymore? O you, whose disastrous passion torments and cherishes me, I am not afraid of the villain’s power: Lyudmila knows how to die! I don’t need your tents, nor boring songs, nor feasts - I won’t eat, I won’t listen, I’ll die among your gardens!” I thought and began to eat.
But here is another, already real case. W. Speer, Minister of Armaments Hitler's Germany, wrote in his “Memoirs” about the days spent under arrest after the defeat of his state in World War II: “Sometimes the thought came to me to voluntarily die... In Kransberg, one of the chemist scientists told us that if you crush a cigar, then dissolve it in water and drink this mixture, then it is quite possible fatal outcome; I carried a crumbled cigar in my pocket for a long time, but, as you know, there is a huge distance between intention and action.”
These are those cases when “we are destined for good impulses, but we are not given anything to accomplish.” To accomplish this, a willful effort is required.
The phylogenetic prerequisite for the emergence of volitional effort is the ability of animals to mobilize efforts in order to overcome the obstacles encountered on the path to a biological goal. This is the so-called “barrier” behavior of animals (P.V. Simonov). If they didn't have this mechanism, the animals simply wouldn't survive. It should be noted that animals also have a mechanism for regulating such efforts and dosing them (remember a cat jumping on objects of different heights). But if in animals such use of effort is carried out involuntarily, then man acquires the ability to use these efforts consciously.
Locke showed in his experiments that increasing the difficulty of the chosen goal led to higher achievements; they were higher when the difficulty level of the goal was uncertain or when the subject was simply required to “perform as best as possible.” The author rightly believes that after accepting a difficult goal, the subjects were forced to mobilize all their forces to achieve this goal. However, as noted by Kukla and Mayer, who developed the “effort calculation” model, the maximum increase in effort occurs at a level of difficulty that the subject believes is still surmountable. This is the limit beyond which the level of effort drops sharply.
V.I. Selivanov wrote that volitional effort is one of the main means by which a person exercises power over his impulses, selectively putting into action one motivational system and inhibiting another. Regulation of behavior and activity is carried out not only indirectly - through motives - but also directly, through mobilization, i.e. through volitional efforts.
V.I. Selivanov, emphasizing the connection of volitional effort with the need to overcome obstacles and difficulties, believed that it manifests itself in all normal work, and not only in extreme situations, for example, when tired, as some psychologists believe. He argued that “with such a view of the role of volitional effort, it looks like an instrument of only unpleasant and harmful to the body despotic coercion, when there is no longer any strength to work, but it is necessary. Undoubtedly, such situations can occur in a person’s life, especially in extreme conditions. But this is only an exception to the rule." Indeed, volitional effort is used by a person not only when exhausted, but also at the initial stage of the development of fatigue (with so-called compensated fatigue), when a person maintains his performance at a given level without despotism and damage to health. And simply pressing the dynamometer is also a manifestation of volitional effort. Another question is whether any activity requires the use of volitional effort. Unlike V.I. Selivanov, I believe that not any.
As V.I. Selivanov notes, central place in the diagnosis of will (understood by him as the mobilization of mental and physical capabilities) occupies the measurement of volitional effort, which is more or less present in various volitional actions (what is actually measured - volitional effort or something else, will be discussed in the chapter 13).
Volitional effort is qualitatively different from the muscular effort that we observe, for example, when lifting weights, when running fast, and to a lesser extent when moving eyebrows, clenching jaws, etc. In volitional effort, movements are often minimal, but internal tension can be colossal . An example of this is the effort that a soldier has to make while remaining at his post under enemy fire, a parachutist jumping from an airplane, etc.
With volitional effort there is always muscle tension. When recalling a word or carefully examining something, we tense the muscles of the forehead, eyes, etc. Nevertheless, it would be completely wrong to identify volitional effort with muscle tension. This would mean depriving the volitional effort of its special content.
Kornilov K.N. 1948. P. 326-There are several definitions of volitional effort. K.K. Platonov defined it as the experience of effort, which is an obligatory subjective component of volitional action, B.N. Smirnov - as a conscious tension of mental and physical capabilities that mobilize and organize a person’s state and activity in order to overcome obstacles. Most often, volitional effort is understood as consciously and for the most part a consciously made internal effort on oneself, which is a push (impulse) to choose a goal, to concentrate attention on an object, to start and stop movement, etc.
V. K. Kalin considers volitional effort to be the main operational mechanism volitional regulation. He defines volitional effort as “a unidirectional regulatory manifestation of consciousness, leading to the establishment or maintenance of a necessary state functional organization psyche".
S.I. Ozhegov defines effort as the tension of forces. It is in this sense that I understand volitional effort: it is a conscious and deliberate tension of physical and intellectual forces by a person.
Based on this understanding, I distinguish it from a volitional impulse that triggers (initiates) voluntary actions.
One autumn night I couldn’t sleep: my thoughts were busy with how I would start this article. I imagined various versions of the first sentence, followed by two more. Then I thought about how to connect the sentences to the next paragraph and to the rest of the article. All the pros and cons of the invented options were spinning in my head, which did not allow me to fall asleep. Neurons were literally buzzing in my head. Undoubtedly, it is this neuronal activity that explains why I came up with all these options and wrote exactly these words. But it also explains why I have free will.
More and more, neuroscientists, psychologists, and other pundits are telling me I'm wrong. They argue, citing some widely cited research, that I am controlled by unconscious processes that cause me to choose the exact words I write. According to such views, conscious deliberation and decision-making occur after choices have been made at the unconscious level. For supporters of this point of view, the conclusion is this: since “our brains do everything for us” when making any choice, therefore, free will is nothing more than an illusion.
The most cited work showing that our brain secretly controls us was done back in the late 1980s. Benjamin Libet from the University of California at San Francisco. He placed electrodes on the surface of the subjects' heads and asked them to bend their wrists whenever they wanted. About half a second before the movement was made, a special electrical reaction of the brain was noted, called the readiness potential. However, the experiment participants themselves were aware of their intention to bend their arm approximately a quarter of a second before performing the action, i.e. the brain made a decision before the person himself realized it. It turned out that unconscious processes occurring in the brain play a leading role. More recent studies using functional magnetic resonance imaging (fMRI) have shown that the decision begins at an unconscious level even earlier. John-Dylan Haynes, researcher at the Center for Computational Neuroscience. Bernstein in Berlin, together with colleagues, published a paper in 2013 that assessed brain activity while a person was making a decision: to add two numbers or subtract one from another. It turned out that by changing brain activity it is possible to predict what the subject's decision will be four seconds before he realizes it. And this is a much larger time gap.
Naturally, both studies, along with other similar work, led to radical claims that we do not have free will. Haynes, in an interview with New Scientist, noted that “our decisions are predetermined by unconscious processes long before our consciousness recognizes them,” and “the brain appears to make decisions before a person’s personality.” Other researchers share this opinion. Evolutionary biologist Jerry Coyne writes that “all of our...choices are like this, none of them resulting from free and informed decision-making on our part.” Neuroscientist Sam Harris has concluded that we are “biochemical puppets.” According to him, the fact that we were able to detect activity in the brains of people that provides them conscious choice, seconds before they themselves knew it, raises serious questions about the status of man as conscious personality, controlling her inner life. However, has research really shown that all our conscious thinking and planning is just a byproduct of unconscious processes in the brain, which has no influence on our further actions? Not at all. Others, including the philosopher Alfred Mele of Florida State University and myself, believe for many reasons that scientists who insist that free will is a mirage are misleading us.
Key points:
- Decision neurons fire in our brains long before we are aware of the choice we have made.
- One of the major and widely debated questions in neuroscience and philosophy is whether we have free will. If it turns out that it does not exist, then many of our legal and moral principles will require serious revision.
- The doubt arose from a series of clever experiments that showed that our brains trigger at least some actions before we are aware of the decision. If this is true, does free will exist and what does it consist of?
- The human will may indeed be less free than we previously thought, but this does not mean that it does not exist at all. Several recent social psychological experiments have shown that our behavior is strongly influenced by both conscious reasons and intentions.
Let's not rush
One can be wary of the arguments of opponents of human free will for many reasons. First, neuroscience is not technically sophisticated enough to determine exactly how the neural activity that underlies the ability to make predictions and evaluate future choices relates to what we will do minutes, hours, or days later. And in studies widely discussed by antagonists of free will, on the contrary, it is impossible to clearly draw a line between conscious and unconscious activity.
Consider Libet's experiment. First of all, the subjects consciously prepared to perform several similar and unplanned actions. When the experiment began, they flexed their wrist whenever they wanted. It can be assumed that the neural activity that determines conscious planning influenced the subsequent unconscious initiation of hand movements. This indicates a close interaction between conscious and unconscious brain activity.
Likewise, Haynes's study, in which subjects had to make multiple choices (add two numbers or subtract one from another), does not provide us with reliable evidence of the absence of free will. Brain activity observed in the four seconds before a participant becomes aware of their choice may reflect an unconscious preference for one option over the other.
Moreover, this brain activity made it possible to predict choice with only 10% higher accuracy than using a coin toss. In general, neural activity cannot unambiguously determine our choice four seconds before the action itself, since we are able to react to some changes in the situation in much less time. If this were not so, we would have died in a car accident long ago! Neural activity at the unconscious level can prepare us for conscious control and adaptation of our behavior.
Scientists denying free will, cite a number of psychological studies showing that conscious control of our actions is much weaker than we think. And indeed it is. We are unwittingly influenced by our environment and our emotional or cognitive biases. Until we realize similar influences, we cannot stop them. This is one of the reasons why I believe that we have less free will than many people think. But you must admit, there is a big difference between “to have, but less” and “not to have at all.”
The work of Libet and Haynes examines the choices that people make without conscious thought while acting. We all perform repetitive or habitual, including very complex actions, without thinking, simply because we have already learned them well. You insert the key into the lock. Baseball player catches the ball. A pianist dives into a performance of Beethoven's Moonlight Sonata.
A reflexive turn of a key, throwing for a ball or pressing black and white keys depend on a certain type of mental activity. What I do on a sleepless night (consciously considering various options for writing an article) is radically different from performing well-learned routine actions. IN psychological research conscious and deliberate deliberation has been shown to actually influence what we do.
Evidence suggests that when intentions are formulated, we are more likely to complete the planned behavior. This effect is called the implementation of intentions. New York University psychologist Peter Gollwitzer and his colleagues conducted a scientific study that showed that dieters who consciously chose to ignore thoughts of tempting but forbidden foods ended up eating less of them. those who just wanted to lose weight.
Psychologist Roy Baumeister of Florida State University and his colleagues found that conscious reasoning improves logical and linguistic problem solving, as well as helping to learn from past mistakes and curb impulsive behavior. In addition, psychologist Walter Mischel from Columbia University showed that self-control has crucial the ability to resist temptations through willpower.
Every day we take actions that we ourselves have consciously planned. Of course, it is possible that the neural activity responsible for planning does not actually influence our actions, or that the brain is making up stories backdating to explain to us and others what we have already done. However, from an evolutionary point of view, this makes little sense. Our brain takes up only 2% of the weight of the entire body, but it consumes 20% of all energy. There must be strong selection pressures to prevent the emergence of neural processes that support complex conscious thoughts that have nothing to do with our behavior. It is more likely that it was the neural circuits that allowed me to imagine how best to write this article that led to it being written in the form that it turned out.
Free will in the brain?
It is a common belief that people who believe in free will must be dualists, convinced that our psyche exists separately from the brain as a non-physical substance. Neuroscientist Read Montague wrote in 2008 that “the essence of free will is that we think and make choices independently of anything even remotely resembling a physical process.” And Jerry Coyne also argued that "true free will... requires us to go beyond the brain to modify its workings from there."
Some people think of free will this way. In fact, there is absolutely no reason for this. In most philosophical theories, the concept of free will is consistent with scientific views of human nature. Yet most people, research shows, believe that we have free will, even if all our mental activity provided only by brain activity. A way to test the strength of human beliefs about free will is to describe the possibility of creating a technology that would make it possible to perfectly predict actions, guided only by observation of brain activity. Sam Harris suggested that such a story would "debunk the notion of free will, showing that it is in fact an illusion."
Jason Shepard of Emory University, Shane Reuter of Washington University in St. Louis, and I recently conducted a series of experiments. We wanted to test whether people's belief in free will would actually be shaken if they learned that behavior can be accurately predicted by observing how the brain processes unconscious information.
The subjects, hundreds of students from the University of Georgia, were given a detailed account of fantastic brain-scanning technologies in the future. The story was about a woman from the distant future named Jill who wore a special device on her head for a month that read all her brain activity. With this information, neuroscientists could predict all of her thoughts and actions, even when Jill was trying to game the system. The story ended with the conclusion: “These experiments confirm the idea that all mental activity of a person is nothing more than the activity of his brain, and, therefore, by changing it, one can predict everything that a person will think about or what he will do in the near future.”
More than 80% of subjects said they believed that similar technology could be created in the future, with 87% of them answering that Jill had free will. They were also asked whether the existence of such technology meant that people's will was less free. About 75% agreed with this. Further results showed that the vast majority of participants in the experiment believe that technology will not yet allow control human brain and controlled from the outside, people will have free will and bear moral responsibility for their behavior.
Apparently, most subjects assumed that the hypothetical brain scanner was merely recording the activity of Jill's neurons as she consciously thought and considered different options for making a decision. So, rather than seeing Jill's brain as an organ that makes her do something (in which case she would not have free will), they tended to think that the scanning device was revealing how free will was located in the brain.
So why do people who deny free will think otherwise? Perhaps this is due to the current level of development of human knowledge. Until the problem of consciousness is solved in neuroscience, the ideas of opponents of the will will be very attractive: if our brain does everything itself, then there is no work left for conscious thinking.
Advances in technology for recording brain activity will help us more accurately assess how conscious our actions are and the extent to which our behavior is driven by unconscious processes that we cannot control. Finding answers to questions about free will is extremely important. The legal system and the moral foundation of our society require a better understanding of in which situations a person is responsible for his actions and in which he is not.
