Physiology of large hemispheres of the brain and cerebellum

Author

ass.prof. N.M. Volkova

Neural Communication

Dopamine PathwaysSerotonin Pathways

Descending Pathways

• The direct pathways (corticobulbar and corticospinal) are indicated by the blue arrow.

• The indirect pathways and their interconnections are indicated by the red arrows.

Posterior Spinocerebellar Tract

• This tract transmits proprioceptive information from the thorax, upper limbs, and upper lumbar region to the cerebellum.

• Lines on the inset indicate levels of section.

Functional Regions of the Lateral Side of the Left Cerebral Cortex

Demonstration of Cortical Activities During Speech

• The figures show the pathway for reading and naming something that is seen, such as reading aloud.

• PET scans show the areas of the brain that are most active during various phases of speech. Red indicates the most active areas; blue indicates the least active areas.

Topography of the Somatic Sensory Cortex

• Cerebral cortex seen in coronal section on the left side of the brain. The figure of the body (homunculus) depicts the nerve distributions; the size of each body region shown indicates relative innervation.

• The cortex occurs on both sides of the brain but appears on only one side in this illustration. The inset shows the somatic sensory region of the left hemisphere (green).

Topography of the Primary Motor Cortex

• Cerebral cortex seen in coronal section on the left side of the brain.

• The figure of the body (homunculus) depicts the nerve distributions; the size of each body region shown indicates relative innervation.

Cerebral Medullary

Tracts

The (a) alpha and (b) beta rhythms of the EEG.

Effects of Aging on the Nervous System

• As a person ages, there’s a gradual decline in sensory function because the number of sensory neurons declines, the function of remaining neurons decreases, and CNS processing decreases.

• In the skin, free nerve endings and hair follicle receptors remain largely unchanged with age. Meissner’s corpuscles and pacinian corpuscles, however, decrease in number. The capsules of those that remain become thicker and structurally distorted and, therefore, exhibit reduced function. As a result of these changes in Meissner’s corpuscles and pacinian corpuscles, elderly people are less conscious of something touching or pressing on the skin, have a decreased sense of two-point discrimination, and have a more difficult time identifying objects by touch.

• These functional changes leave elderly people more prone to skin injuries and with a greater sense of isolation.