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Memory in Physiology

Q: Which brain structures are responsible for memory consolidation?

The hippocampus plays a critical role in memory consolidation — the transition from short-term to long-term memory. Furthermore, forgetting functions are closely tied to the activity of the hippocampus and the temporal neocortex: upon damage to these structures, acquired skills are lost very rapidly due to impaired memory consolidation. Hippocampus — plays a dominant role in declarative and conscious memory fixation.Temporal neocortex — involved in storage and retrieval processes alongside the hippocampus.

Q: What constitutes the phenomenon of habituation?

Habituation (habituation) is a form of non-associative memory where repeated exposure to a relatively neutral stimulus leads to a diminished and ultimately abolished behavioral response.

Memoria

For medical students2 min readUpdated 2026-10-10

Memory is the fundamental ability of living organisms to encode, store, and, when necessary, retrieve information about past events and stimuli. This process is inextricably linked with learning, and in humans and higher vertebrates, its realization relies entirely on the functions of the central nervous system.

Main OrganIn humans and higher animals, memory processes are inextricably linked with the activity of the brain.

Systemic NatureMemory is integrated into all stages of the systemic architecture of any behavioral act.

HabituationRepeated application of a neutral stimulus leads to a complete extinction of the response.

SensitizationAmplification of the response when stimuli are reinforced by biologically significant (appetitive or defensive) factors.

Systemic Organization of Memory

From the perspective of functional systems theory, memory is not an isolated process. It is intrinsic to absolutely all components of the systemic architecture of a behavioral act. To successfully execute any action, the organism draws upon past experience at the following stages:

Afferent synthesis stage (collection and analysis of information about the current situation).
Decision making (selection of the optimal response pathway).
Action result acceptor / Acceptor of action results (formation of an ideal model of the future result for comparison with reality).
Efferent synthesis (direct assembly of the motor or other command programs).

Note: Despite understanding the role of memory in behavior, the precise systemic mechanisms of its operation at the cellular level remain among the complex areas of neurophysiology.

Simple Forms of Memory: Habituation

The simplest forms of learning are found even in animals with primitive nervous systems, such as mollusks. One of the basic forms of simple learning is habituation (habituation).

Its mechanism involves the repeated application of a relatively neutral stimulus to the organism. The dynamics of the process unfold as follows:

Upon initial exposures to the stimulus, the organism demonstrates a clear response (the orienting response or response to novelty).
With continuous repetition of the same stimulus, the response gradually weakens.
Eventually, the response disappears entirely.

The essence of habituation is that the organism learns to ignore an insignificant stimulus, despite its continued presence.

Simple Forms of Memory: Sensitization

The physiological process opposite to habituation is sensitization (sensitization).

In this case, as stimulus exposure continues, the magnitude of the organism's response does not wane, but rather increases. The primary condition for prominent sensitization is reinforcement: it becomes particularly pronounced when the initial stimulus is repeatedly paired with subjectively important events for the organism. Such events include:

Appetitive stimuli (e.g., food reinforcement).
Aversive stimuli (e.g., defensive or noxious pain stimuli).

Mnemonic

To avoid confusing simple forms of memory, use this association: Habituation is a "minus" (the response decreases and disappears to a boring stimulus), while Sensitization is a "plus" (the response increases when the stimulus heralds food or danger).

Frequently asked questions

What components are included in the stage of afferent synthesis?

The stage of afferent synthesis includes motivation, situational afferentation, memory, and triggering afferentation (puskovaya afferentatsiya).

Motivation — internal drives, including biological ones; in humans, biological motivations interact with socially determined situational afferentation and memory mechanisms.
Situational afferentation — environmental influences continuously entering the CNS via numerous exteroceptors.
Memory — a core component of afferent synthesis; includes genetic and acquired memory that shapes behavioral organization.
Triggering afferentation — the specific stimulus that immediately initiates the selected behavioral act.

Which brain structures are responsible for memory consolidation?

The hippocampus plays a critical role in memory consolidation — the transition from short-term to long-term memory.

Furthermore, forgetting functions are closely tied to the activity of the hippocampus and the temporal neocortex: upon damage to these structures, acquired skills are lost very rapidly due to impaired memory consolidation.

Hippocampus — plays a dominant role in declarative and conscious memory fixation.
Temporal neocortex — involved in storage and retrieval processes alongside the hippocampus.

What is the action result acceptor in the theory of functional systems?

The action result acceptor (acceptor of action results) is a predictive and evaluative neural mechanism for future outcomes.

At the stage of intent formation, this apparatus generates an ideal mental model (template) of the future result. During goal-directed behavior, ongoing feedback (recurrent/feedback afferentation) allows continuous comparison between:

What was originally planned (the model in the action result acceptor).
What was actually achieved during the behavior.

If the achieved result matches the model, the behavior terminates; if not, the system readjusts.

What is memory from the standpoint of normal physiology?

It is the fundamental ability of living organisms to encode, store, and retrieve information about previously encountered events, closely intertwined with learning processes.

At which stages of a behavioral act does memory function?

Within the framework of functional systems theory, it is engaged during afferent synthesis, decision making, the action result acceptor stage, and efferent synthesis.

What constitutes the phenomenon of habituation?

Habituation (habituation) is a form of non-associative memory where repeated exposure to a relatively neutral stimulus leads to a diminished and ultimately abolished behavioral response.

What condition is required for the development of sensitization?

Sensitization (response augmentation) is most prominently expressed when a stimulus is repeatedly paired with biologically appetitive (food) or aversive (defensive) stimuli.

Go deeper

Functional systems theory and the role of memory during afferent synthesis
Formation and functions of the action result acceptor
Specifics of simple memory formation in organisms with primitive nervous systems (e.g., mollusks)
Neurophysiological differences between habituation and sensitization
Correlation between memory processes and higher brain functions in vertebrates