Distribution of functions between hemispheres
Functional specialization of the brain directly depends on a person's motor asymmetry (right- or left-handedness). This determines the specifics of information processing by each hemisphere.
In right-handed individuals (right-handers), the physiological picture is as follows:
- The left hemisphere is inextricably linked with speech functions. It acts as the leading center that determines the processes of sequential analytical activity. It is here that the logical structure of an utterance is formed and step-by-step analysis of incoming information takes place.
- The right hemisphere specializes in spatiotemporal relationships. Its competence includes non-verbal data processing: recognition of human faces, identification of various objects by their shape, as well as the adequate perception of music and melodies.
In left-handed individuals (left-handers), physiologists observe the reverse relationship of functions. Speech and analytical centers predominantly shift to the right hemisphere, while the left takes over the tasks of spatiotemporal analysis and imaginal perception.
It is important to note: the strict demarcation of functions between the left and right hemispheres is relative. The brain works as a unified integrative system, and both hemispheres continuously exchange information during any complex activity.
Physiological mechanisms of thinking and speech
The process of speech formation and cognitive processes is based on complex feedback mechanisms. A key role in this system is played by reverse afferentation.
During speech activity, neural impulses (afferentation) from the involved effector organs do not simply disappear, but continuously flow back into the central nervous system—to the acceptor of action results. This physiological apparatus performs a matching function: it allows for the dynamic evaluation of how accurately a thought has been expressed in a specific verbal phrase.
It is precisely thanks to the continuous flow of reverse afferentation to the acceptor of action results that the phenomenon of inner speech becomes possible—the mental "rehearsal" of an idea in the mind before its actual vocalization. The brain assesses the correctness of verbal constructions in advance.
Dependence of the cognitive process on effector organs
The physiology of thinking is inextricably linked with the peripheral apparatus. The quality and dynamics of the cognitive process significantly depend on the current state of effector organs (e.g., the articulation apparatus involved in speech).
These effector organs are not isolated tools; they are organically integrated into individual systemquants of cognitive activity. This means that the act of thinking and the act of physical (or covert) execution represent a single, indivisible functional unit.
Furthermore, the process is strictly controlled by mechanisms of self-regulation. The interaction of the internal (cerebral) and external (peripheral, effector) links of this system is carried out on the basis of equivalent information processes, ensuring the coordination of thought and word.
Briefly: answers to topical questions
Specifically, which cortical speech centers (motor and sensory) are localized in the dominant hemisphere?
The sensory and motor speech centers are localized in the dominant cerebral hemisphere.
- Wernicke's area (planum temporale) is the sensory (auditory) speech center. It is located in the posterior parts of the first (superior) temporal gyrus. It is responsible for understanding spoken speech and creating the semantic structure of an utterance.
- Broca's area is the motor speech center. It is localized in the lower third (posterior part) of the frontal gyrus of the same hemisphere. It performs the function of forming a detailed vocalization program (the motor pattern of speech).
Through which anatomical structures is integrative information exchange carried out between the left and right hemispheres?
Integrative information exchange between the left and right hemispheres is carried out via commissural connections.
- The corpus callosum (corpus callosum) is the anatomical structure through which the primary and secondary sensorimotor areas of the symmetrical cerebral cortex hemispheres are connected; transection of the corpus callosum eliminates interhemispheric information exchange.
For quick memorization of functions in right-handers: LEFT hemisphere stands for Logic and Linguistics (speech, analysis). RIGHT hemisphere stands for Space and Songs (shapes, faces, music).
Class and exam questions
Is the division of functions between the left and right hemispheres absolute?
No, the strict demarcation of functions is relative. In real conditions, both hemispheres work together, complementing each other.
Which brain structure evaluates the expression of thought in a verbal phrase?
This function is performed by the acceptor of action results, which receives reverse afferentation from the effector organs.
How are functions distributed in left-handers?
Left-handers exhibit reverse relationships compared to right-handers: the right hemisphere more often assumes analytical activity and speech, while the left takes on spatial perception.
The state of which structures significantly affects the cognitive process?
The cognitive process significantly depends on the state of effector organs, which are part of individual systemquants of cognitive activity.
What else to study on this topic
- Functions of the acceptor of action results in the nervous system
- Mechanisms of formation and pathways of transmission of reverse afferentation
- The concept of "systemquant" in the physiology of cognitive activity
- Information processes of self-regulation: internal and external links
- Physiological foundations of inner speech
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