Three Functional Divisions
The classical concept of the analyzer structure implies a clear division of the signal pathway into three successive levels. Each of them performs a strictly defined task.
- Peripheral division. This is the initial link that directly contacts the stimulus. It includes receptors, an accessory (supplementary) apparatus that ensures optimal perception, and the primary afferent neuron that receives the generated signal.
- Conduction division. Acts as a transport highway. It includes sensory nerves and specific afferent pathways passing through the spinal cord and brainstem. Excitation is directed to higher centers along these pathways.
- Central division. The highest instance of the analyzer. It is represented by specific areas of the sensory cerebral cortex. It is these cortical zones that specialize in receiving and final processing of excitation of a specific modality (e.g., visual, auditory, or tactile).
Role of the Peripheral Division
The peripheral division is the gateway for any sensory information. Its most important and fundamental component is the receptor.
Physiologically, receptors are specialized nerve endings. Their main fundamental function is transduction—they convert the energy of an external physical or chemical stimulus into the energy of an electrical potential. Only in this form is the nervous system able to perceive, transmit, and decode information about the surrounding world.
Principles of Analyzer Functioning
Analyzers work not merely as passive receivers, but as active tracking systems. They are constantly tuned to search for and anticipate meaningful information from the external or internal environment.
During the functioning of analyzers, researchers distinguish two completely opposite functional tendencies:
- Maximization of data. The system constantly strives to extract the absolute maximum of information about the surrounding space and the state of the organism itself.
- Data limitation. Simultaneously, there is a mechanism protecting the central nervous system (CNS) from overload by excessive and irrelevant information.
The balance of these tendencies plays a critical role in the behavioral act. The obtained and filtered information is actively used by the nervous system both at the stage of preparation for an action and for constant control during the direct execution of that action.