Transcript Basal Ganglia-Their Motor Functions

Chapter 56: Contributions of the Cerebellum
And Basal Ganglia to Overall Motor Control
Guyton and Hall, Textbook of Medical Physiology, 12 edition
Cerebellum and Its Motor Functions
• The cerebellum plays major roles in the timing
of motor activities and in rapid, smooth
progression from one muscle movement
to the next.
• The basal ganglia help to plan and control complex
patterns of muscle movement
• Cerebellum helps to sequence motor activities
and monitors and makes corrective adjustments
during motor activities
Cerebellum and Its Motor Functions
• The cerebellum receives continuously updated
information from the brain motor control areas
• Aids the cerebral cortex in planning sequential
movements
Anatomical Functional Areas of the Cerebellum
Fig. 56.1 Anatomical lobes of the cerebellum
Fig. 56.2 Functional parts of the cerebellum
Anatomical Functional Areas of the Cerebellum
Fig. 56.3 Somatosensory projection areas in the cerebellar cortex
Fig. 56.4 Principle afferent tracts to the cerebellum
Anatomical Functional Areas of the Cerebellum
Fig. 56.5 Spinocerebellar tracts
Fig. 56.6 Principle efferent tracts from the cerebellum
Functional Unit of the Cerebellar Cortex
Fig. 56.7 The left side of this figure shows the basic neuronal circuit of the cerebellum,
with the excitatory neurons shown in red, and the inhibitory neuron (Purkinje
cell) shown in black.
Functional Unit of the Cerebellar Cortex
• Cerebellum has nearly 30 million nearly
identical functional units; a Purkinje cell
on a corresponding deep nuclear cell
• Three major layers
a. Molecular layer
b. Purkinje cell layer
c. Granule cell layer
Functional Unit of the Cerebellar Cortex
• Neuronal Circuit of the Functional Unit
a. Purkinje fibers and deep nuclear cells fire
continuously under normal resting conditions
b. Balance between excitation and inhibition at the
deep cerebellar nuclei
c. Other inhibitory cells
1. Basket cells
2. Stellate cells
Functional Unit of the Cerebellar Cortex
• Turn-On/Turn-Off and Turn-Off/Turn-On Output
Signals from the Cerebellum
• The Purkinje Cells Learn to Correct Motor ErrorsRole of the Climbing Fibers
Functional Unit of the Cerebellar Cortex
• Function of the Cerebellum in Overall Motor Control
a. Vestibulocerebellum functions in association with the
brain stem and spinal cord to control equilibrium and
postural movements
b. Spinocrebellum-feedback control of distal limb movements
1. Prevention of overshooting of movements and
to “damp” movements
2. Control of ballistic movements
Functional Unit of the Cerebellar Cortex
• Function of the Cerebellum in Overall Motor Control
c. Cerebrocerebellum-function of the large lateral zone
to plan, sequence, and time complex movements
1. Planning of sequential movements
2. Timing function
3. Extramotor predictive functions
Basal Ganglia-Their Motor Functions
Fig. 56.9 Anatomical relations of the basal ganglia to the cerebral cortex and thalamus
Basal Ganglia-Their Motor Functions
• Neuronal Circuitry
Fig. 56.10 Relation of the basal gangli circuitry to the
corticospinal-cerebellar system for movement
control
Basal Ganglia-Their Motor Functions
• Function of the Basal Ganglia in Executing Patterns
of Motor Activity—the Putamen Circuit
Fig. 56.11 Putamen circuit
Basal Ganglia-Their Motor Functions
• Neural Pathways of the Putamen Circuit
a. Abnormal function
1. Athetosis
2. Hemiballismus
3. Chorea
Basal Ganglia-Their Motor Functions
• Role of the Basal Ganglia for Cognitive Control of
Sequences of Motor Patterns—Caudate Circuit
Fig. 56.12 Caudate circuit through the basal ganglia
Basal Ganglia-Their Motor Functions
• Function of the Basal Ganglia to Change the Timing
and to Scale the Intensity of Movements
a. Brain must determine how rapidly the movement is
to be performed, and
b. Control how large the movement will be
Basal Ganglia-Their Motor Functions
• Functions of Specific Neurotransmitter Substances
in the Basal Ganglial System
Fig. 56.14
Integration of the Many Parts of the Total Motor Control System
• Spinal Level
• Hindbrain Level
• Motor Cortex Level
a. Associated functions of the cerebellum
b. Associated functions of the basal ganglia