Basal Ganglia and Internal Capsule Flashcards
(35 cards)
what i sthe function of the motor loop (putamen circuit) in the basal ganglia
learned moment
what is the purpose of the movemnet modulation inhibition in the basal ganglia
to support or facilitate ongoing movements through this positive feedback to the cortex.
what is the function o fthe pars compacta
unknown
what do axons of the pars reticulata synapse with
upper motor neurons
describe the direct pathway of the movement modulation through disinhibition
striatopallidal and striatonigral neurons directly inhibit internal pallidal or pars reticulata neurons
this leads to disinhibition of target neurons including those of the motor thalamus.
The resulting increase in the activity of thalamic neurons causes excitation of the cells of the cerebral cortex.
The effect of activation of the direct pathway is therefore to support or facilitate ongoing movements through this positive feedback to the cortex.
what is the function of the basal ganglia
fine-tune voluntary movements and is involved in the generation of goal-directed voluntary movements (motor learning)
what are the 5 pairs of nuclei in the basal ganglia
caudate nucleus
putamen
globus pallidus
subthalamic nucleus
substantia nigra
what is the basal ganglia
defined masses of grey matter which are grouped together imbedded in the subcortical white matter of the telencephalon around the lateral ventricle.
what is lateral to the putamen
extrenal capsule
what divides the corpus striatum
by a band of white matter called the internal capsule.
what is the function of the cognitive loop (caudate circuit) in the basal ganglia
cognitive control of sequences of motor pattern
what is the function of the oculomotor loop in the basal ganglia
voluntary eye movement
what is the function of the limbic loop in the basal ganglia
gives motor expression to emotions like smiling, aggression
what do axons from the striatum synapse with
the globus pallidus or thepars reticulata od the substantia nigra
what fibres travel through the genu of the internal capsule
corticobulbar fibres (cortex to brainstem)
what is the function of the internal capsule
large number of motor and sensory fibres travel to and from cortex via the internal capsule
The lentiform nucleus is divided by vertical sheet of white matter into a
the putamen (dark large lateral portion ) and the
globus pallidus (an inner paler portion)
where do thalamocortical fibres travel
thalamus to frontal lobe
what is the function of the pars reticulata
plays a part in controlling eye movements
what are the basal ganglia
the corpus striatum, amygdaloid nucleus and claustru
what fibres travel through the posterior limb of the internal capsule
corticospinal fibres (cortex to spinal cord)
ascending sensory fibres
describe the indirect pathway of movemnet modulation through inhibition in the basal ganglia
Efferents from the striatum terminate in the external pallidal segment and their activation induces inhibition of external pallidal neurons.
The principal efferent projection of the external pallidum is to the subthalamic nucleus which therefore becomes disinhibited.
The resultant increase in discharge of subthalamic neurons causes activation of internal pallidal and nigral neurons and in turn inhibition of thalamic and cortical cells.
This has the effect of inhibiting unwanted movement.
what is the function of the caudate nucleus
sends information to the thalamus concerning body and limb posture
what do axons of the globus pallidus synapse with
thalamus
