Farmasevtika instituti farmakologiya va klinik farmatsiya kafedrasi

 
Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory 
It is ironic that of all the arts of the brain, we know the least about the functions of the cerebral 
cortex, even though it is by far the largest portion of the nervous system. But we do know the effects of 
damage or specific stimulation in various portions of the cortex. In the first part of this chapter, the 
known cortical functions are discussed; then basic theories of neuronal mechanisms involved in 
thought processes, memory, analysis of sensory information, and so forth are presented briefly. 
 
Physiologic Anatomy of the Cerebral Cortex 
The functional part of the cerebral cortex is a thin layer of neurons covering the surface of all the 
convolutions of the cerebrum. This layer is only 2 to 5 millimeters thick, with a total area of about one 
quarter of a square meter. The total cerebral cortex contains about 100 
billion 
neurons. Figure 57-1 
shows the typical histological structure of the neuronal surface of the cerebral cortex, with its 
successive layers of different types of neurons. Most of the neurons are of three types: (1) 
granular 
(also called 
stellate
), (2) 
fusiform, 
and (3) 
pyramidal, 
the last named for their characteristic pyramidal 
shape.
 
Anatomical and Functional Relations of the Cerebral Cortex to the Thalamus and 
Other Lower Centers. 
All areas of the cerebral cortex have extensive to-and-fro efferent and 
afferent connections with deeper structures of the brain. It is important to emphasize the relation 
between the cerebral cortex and the thalamus. When the thalamus is damaged along with the cortex, 
the loss of cerebral function is far greater than when the cortex alone is damaged because thalamic 
excitation of the cortex is necessary for almost all cortical activity.