Transcript 04 Physiology of large hemispheres, cerebellum

Physiology of large
hemispheres of the brain and
cerebellum
FUNCTIONS OF THE BASAL
GANGLIA
These ganglia perform essentially all the motor
functions, even controlling the voluntary movements
in much the same manner that the motor cortex of
the human being controls voluntary movements.
Further more, in the cat, and to a lesser extent in the
dog, decortication removes only the discrete types of
motor functions and does not interfere with the
animal's ability to walk, eat, fight, develop rage,
have periodic sleep and wakefulness, and even
participate naturally in sexual activities.
Cycle of putamen
Provide an action of separate movement,
which need previous studying.
It starts from premotor and addition motor zones
of cortex go to putamen, than to globus pallidus.
After that can be two ways:
1) from globus pallidus impulses go to thalamus;
2) from globus pallidus impulses go to substantia
nigra and than to thalamus.
From thalamus impulses go to primary motor
zone.
Cycle of caudate nucleus
Regulate the moving behavior (the model
of movement).
It starts from associative zones of cortex go to
caudate nucleus.
After that can be two ways:
1) from caudate nucleus impulses go to globus
pallidus;
2) from caudate nucleus impulses go to putamen and
than to globus pallidus.
From globus pallidus impulses go to thalamus and
than to premotor and addition motor zones.
Neural Communication
Serotonin Pathways
Dopamine 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.
Cerebellum
Connected to brainstem by cerebellar peduncles
White matter (arbor vitae) visible in sagittal
section
Sits atop the 4th ventricle
FUNCTION OF CEREBELLUM
1. Regulation of posture and
equilibrium, and muscle tone
2. Coordination of posture and slow
determined movements
3. Coordination of fast determined
movements
Cerebellar Inputs and Outputs
The 3 deep nuclei are:
– (1) fastigial - concerned with balance; sends
information mainly to the vestibular and
reticular nuclei
– (2) dentate and (3) interposed - both concerned
with voluntary movement; send axons mainly to
the thalamus and red nucleus
All 3 receive inputs from sensory afferent tracts
and from the cerebellar cortex.
FUNCTIONAL AREAS OF CORTEX
SENSORY AREAS OF THE CORTEX
The somatic senses include sensations of touch,
pressure, temperature, body position, and similar
perceptions that do not require complex sensory organs.
The special senses include vision, hearing, and other
types of perception that require complex sensory
organs.
The postcentral gyrus serves as a primary area for the
general somatic senses. Under central gyrus presents
secondary somatic sensory area. It also has topic
structure.
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.