General characteristics of the theory
According to P.K. Anokhin's theory, any behavioral act has a complex stage-by-stage composition that unfolds across the structures of the central nervous system. The most important property of this system is the principle of isomorphism. This means that the central architectonics is completely universal (isomorphic) for any behavioral reactions. It applies both to the simplest adaptive reactions and to the most complex higher mental activity of humans.
The entire process is built exclusively through the activity of the brain, driven by complex, rapidly changing dynamic relationships between the cortex and subcortical structures. Under natural conditions, the full cycle from stimulus to response in the brain is achieved incredibly quickly—the formation of the act's structure takes only a few milliseconds.
Stage 1: Afferent synthesis
The first and main initiating stage of a behavioral act is afferent synthesis. At this very stage, the brain gathers and analyzes all available information to lay the groundwork for future action.
Afferent synthesis consists of four mandatory components:
- Dominant motivation is the leading element of the entire stage. Motivation is built on the basis of various current metabolic needs of the body. Its physiological mechanism is continuous neurohumoral signaling.
- Memory — utilizing past experience to solve the current task.
- Situational afferentation — the totality of all incoming signals regarding the current environmental conditions in which the organism is located.
- Triggering afferentation — the direct stimulus that initiates the entire behavioral act.
Stages of goal and program formation
The integration of all components of afferent synthesis triggers the sequential dynamics of systemic organization formation. This process can be divided into several key steps:
- Decision-making. Once afferent synthesis is complete, the brain must make a choice. Out of a vast multitude of possible response options, only one—the most adequate action—is selected.
- Goal formation. At this stage, the apparatus for anticipating the required (desired) result operates.
- Creation of the action result acceptor (ARA). A neuronal model of this very anticipated result is formed. It is against this ideal model that the brain will subsequently compare the actual outcome.
Execution, comparison, and correction
Once the plan is ready, the behavioral act proceeds to the execution stage. The construction of efferent synthesis is completed, followed by the action itself. The action inevitably leads to the achievement of a certain result.
Next comes the most crucial moment — the comparison stage. The parameters of the actually obtained result are compared with the parameters pre-established in the action result acceptor (ARA).
Two scenarios are possible:
- Successful action. If the parameters of the real result fully correspond to the neuronal model in the ARA, the behavioral act is considered successfully completed.
- Mismatch (error). If the parameters of the achieved result do not correspond to the ARA, an orienting-investigatory reaction (OIR) occurs.
In the event of an error, the system does not stop. A correction mechanism is triggered: the brain restructures afferent synthesis (taking into account the unsuccessful experience), makes a completely new decision, refines the ARA parameters, and performs a new action. This cyclic process repeats over and over until the real result matches the ideal embedded in the ARA.
Briefly: answers to topical questions
Which specific brain structures are involved in the formation of the action result acceptor?
The provided sources do not list specific anatomical centers for ARA formation. The following structures and levels are indicated:
- The ARA is formed within the central architectonics of the functional systems of mental activity.
- It represents a complex of selectively excited cortico-subcortical apparatuses.
- During formation, the dominant motivation, via collaterals of the pyramidal tract, excites a network of brain neurons at various levels.
- Feedback afferentation from the parameters of the achieved result selectively propagates to the corresponding brain structures.
- During subsequent behavior, motivation proactively activates the previously reinforcement-formed neuronal ensemble.
What components (autonomic, motor) does the efferent synthesis stage include?
The efferent synthesis stage is a temporal organization within the CNS of excitation and inhibition processes directed at effectors: muscles, glands, and other tissues. Its result is the formation of a general effector integral.
Components of the effector integral:
- somatic;
- autonomic;
- endocrine.
Movements are an important component of executive programs: postural setup, body displacement in space, maintaining body parts in a fixed position, and manipulations. Motor acts are accompanied by autonomic and endocrine reactions. Efferent synthesis processes are constantly restructured under the control of feedback afferentation.
Into which groups are dominant motivations classified in a behavioral act?
In the sources, motivations are classified into two main groups: biological and social.
- Biological motivations: the sources mention innate biological motivations; examples by prevalence include nutritional, aggressive, defensive, sexual, and others.
- Social motivations: formed under the influence of the external environment, learning, and memory mechanisms, in the process of social upbringing; examples include the pursuit of education, profession, art, literature, and lifestyle.
In humans at the stage of afferent synthesis, biological motivations interact with socially determined situational afferentation and memory mechanisms; social motives alter the character of biological motives, giving them a "social coloring".
You can remember the components of afferent synthesis by the acronym SPMM: Stimulus afferentation (Triggering), Situational afferentation, Motivation, Memory.
Class and exam questions
What does the principle of isomorphism mean in the theory of functional systems?
The principle of isomorphism means that the architecture of a behavioral act is universal and identical for behavioral acts of absolutely any complexity, up to human mental activity.
Which component of afferent synthesis is leading, and what is it based on?
The leading component is dominant motivation. It is built on the basis of various metabolic needs of the body using mechanisms of neurohumoral signaling.
What happens when the actual result does not match the action result acceptor (ARA)?
An orienting-investigatory reaction occurs. After this, afferent synthesis is restructured, a new decision is made, the ARA is refined, and a new action is performed until the desired result is achieved.
What else to study on this topic
- Mechanisms of neurohumoral signaling during the formation of dominant motivation
- The role of memory in the structure of afferent synthesis
- Neurophysiological foundations of the action result acceptor (ARA)
- Differences between situational and triggering afferentation
- Physiology of the orienting-investigatory reaction (OIR)
Master the entire topic in the "Physiology" course
This is a summary. The course covers everything tested in classes and exams.
- Full study guide on "Systemic architectonics of a behavioral act" and 4,128 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 114 video lessons on the subject
Other topics in the section "Systemic architectonics of behavioral acts"
Free video lessons: PhysiologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.