Unformatted text preview: tor Pathways and Structures!
The basal ganglia acts as a gatekeeper to motor control and plays
a critical role in the initiation and inhibition of motor movement.!
Includes the following subcortical nuclei:!
Caudate Nucleus & Putamen together are called the striatum. All together, can modulate movement, but
thought as gate keepers to motor action. They are important for initiating an action, and keeping that action
going,substania nigra! action. Both excite or inhibit the motor cortex.
and also stopping an
43:00 Striatum has an inhibitory pathway with the globus pallidus, which in turn has an inhibitory pathway
to the thalamus which has an excitatory pathway to the cortex (Turning off the off switch, thus result in
increased excitation of the cortex. Very important in the initiation of a movement.
Other pathway: Striatum sends inhibitory signal to another portion of the globus pallidus. This inhibits the
subthalmic nuclei, which activates the other portion of the globus pallidus, thus increasing inhibitory action
of the thalamus, thus decreasing activity in the cortex. Both of these systems can be in conﬂict: Both
respond to DA from Substania nigra.. And its sort of which one wins out. The direct pathway from the striatum inhibits (black pathways) the output nuclei of the internal segment of the globus
pallidus (Gpi), which in turn inhibits the inhibitory pathway to the thalamus leading to increased excitation of the cortex
(this pathway is fast).!
The indirect pathway from the striatum inhibits the external segment of the globus pallidus (Gpe), which in turn inhibits
the inhibitory pathway to the subthalamic nuclei (STN), which in turn excites the excitatory pathway to the Gpi and thus
excites the inhibitory pathway to the thalamus leading to inhibition of the cortex (this pathway is slow).! Disorders of Motor Pathways and Structures!
A genetic degenerative disorder in which
the primary pathology, at least in the
early stages of the disease, is observed in
the striatum (caudate and putamen) of the
basal ganglia. Prominent symptoms
include clumsiness and involuntary
movements of the head and trunk.
Cognitive impairments are also seen and
become pronounced over time.! In HD, the inhibitory projection along the indirect pathway from the
striatum to the GPe is reduced. The net c...
View Full Document
This note was uploaded on 01/18/2014 for the course PSY 123 taught by Professor Staff during the Fall '11 term at UCSB.
- Fall '11