Systemic organization of behavior
In response to episodic environmental changes, organisms react reflexively. All reflexive responses are divided into innate (simple and complex unconditioned reflexes) and acquired (conditioned reflexes).
However, living beings do not merely respond passively to stimuli; they build active behavior to master environmental factors and satisfy their leading needs. The units of such activity are behavioral system quanta. Human and animal life consists of a continuous succession of system quanta, each aimed at a specific result.
If a species inhabits a relatively stable "environmental niche" for many generations, its behavior is quantized predominantly in the innate manner. This is particularly evident in the early stages of ontogeny in higher animals. In such cases, system quanta unfold independently without requiring special training.
The nature of instincts
There are several views in science regarding the nature of instinctive behavior:
- I.P. Pavlov considered instincts to be complex unconditioned reflexes.
- D. Hebb described them as innate forms of the organism's basic drives (hunger, fear, aggression, sexual drive).
- Ethologists (K. Lorenz, N. Tinbergen) defined instincts as genetically determined forms of behavior.
From the standpoint of systemic physiology, an instinct represents a genetically rigidly fixed program. Absolutely all components of an instinctive system quantum — from the initial need and motivation to goal-directed activity and final reinforcement — are encoded in the genome.
An instinct includes an innate apparatus for anticipating and evaluating results. If an animal encounters a new environment or an obstacle on the path to satisfying metabolic needs, innate mechanisms of exploratory behavior are triggered.
Rigid programming and the example of the Sphex wasp
Any form of instinctive behavior is subordinated to a feedforward program determined by the final vital result. All stages are strictly subordinated. To proceed to the next step, the organism must receive full afferent information regarding the achievement of the previous stage result (feedback).
A classic example of the rigidity of such programs, described by J. Fabre, is the reproductive behavior of the yellow-winged Sphex wasp (Sphex occidentalis). Its activity is triggered by hormonal changes (internal need) and external factors (temperature, humidity).
The wasp's action algorithm:
- Digs a burrow of a specific shape.
- Hunts a field cricket.
- Paralyzes the prey with three stings into the nerve ganglia.
- Transports the cricket and leaves it at the entrance to the burrow.
- Descends into the empty burrow to inspect it.
- Drags the prey inside and lays an egg.
- Repeats the hunt 1–2 more times.
- Seals the entrance (final result).
If, at the burrow inspection stage (step 5), the experimenter moves the cricket away, the wasp will come out, find it, place it by the entrance again, and necessarily descend for a re-inspection. It cannot drag the prey in without completing the "leave at the entrance — inspect" cycle. This cycle will repeat indefinitely. At the same time, if the program is fully completed (the entrance is sealed), complete destruction of the nest no longer causes any reaction in the wasp — the algorithm has been executed.
Conditions for the formation of innate forms of behavior
For the instinctive program to launch and successfully complete, a strict coincidence of two global factors is required:
- Presence of an internal need (alimentary, defensive, sexual).
- Action of "key" environmental factors.
External stimuli play a releasing (triggering) role, directing the animal toward the final adaptive result. In some cases, instinctive system quanta can be initiated exclusively by metabolic shifts in the internal environment, while external factors merely accelerate or inhibit this endogenous process. However, if specific signaling factors are completely absent in the environment (e.g., the required soil type for nest building), the implementation of the genetic program becomes impossible. Even with an acute internal need, the animal will not be able to execute the chain of actions, which can ultimately lead to the extinction of the species in that area.
Briefly: answers to topical questions
By what criteria are unconditioned reflexes of mammals classified?
Unconditioned reflexes belong to innate, genetically determined reflexes. Sources indicate the following criteria for classifying reflexes:
- by formation — conditioned and unconditioned;
- by receptors — exteroceptive, interoceptive, proprioceptive;
- by effectors;
- by significance;
- by complexity — monosynaptic and polysynaptic;
- by effect — excitatory and inhibitory;
- by location — spinal and brain reflexes.
For complex unconditioned reflexes, the following are listed: alimentary, defensive, sexual, parental, exploratory, etc.
What are the physiological mechanisms of the exploratory reflex?
The exploratory reaction, according to I.P. Pavlov, is a reaction to novel stimuli, the "what is it?" reflex. In external unconditioned inhibition, a strong new external stimulus against the background of current conditioned-reflex activity causes exploratory activity. An interaction of two foci of excitation arises in the central nervous system: the excitation from the orienting reaction proves to be stronger and inhibits the weaker excitation from the current conditioned reflex. From systemic standpoints, a stronger functional system suppresses a weaker one.
Upon the disruption of the dynamic stereotype, if the stage or final result of automated activity is not achieved, exploratory activity is switched on and dynamic cortical mechanisms are activated.
To understand the rigidity of the Sphex wasp's instinct, imagine a computer program: the code cannot proceed to execute "Line 6" (drag the prey inside) until it receives a signal about the successful execution of "Line 5" (inspect the burrow). No signal — the cycle repeats from the beginning.
Class and exam questions
What is the main difference between instinctive behavior and acquired behavior?
Instinctive behavior unfolds according to a strictly determined genetic program without prior learning, whereas acquired behavior (conditioned reflexes) is formed on the basis of individual experience.
What will happen if the animal fails to achieve the intermediate result of the instinct?
Due to rigid programming, the animal will not be able to move to the next stage. It will repeat the exact same actions an infinite number of times, trying to complete the failed stage.
What factors trigger instinctive activity?
The instinct is triggered by a combination of a dominant internal need (e.g., hormonal or metabolic shifts) and specific "key" environmental factors acting as a trigger signal.
What else to study on this topic
- The role of the action result acceptor in the correction of behavioral acts
- Interaction of endogenous metabolic needs and exogenous stimuli
- Innate mechanisms of exploratory behavior
- Classification of instincts according to D. Hebb and I.P. Pavlov: a comparative analysis
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