Basal Ganglia Flashcards
What are the three subdivisions of the corpus striatum
- me-striatum or striatum
- Globus Pallidus or Pallidum
- Amygdaloid nuclear complex
The striatum is one nucleus that is divided into 2 by the anterior limb of the internal capsule. What are the 2 subdivisions?
Caudate and Putamen
What are the other structures that are functionally related to the basal ganglia?
- Subthalamic nuclues
- Substantia Nigra
- Thalamic nuclei
- pedunculopontine nucleus- sets up a rhythmic cholinergic input to the striatum (Plays a role in the coordination of synergistic movements)
What are the 2 parts of the substantial nigra?
- pars compacta- dopamine neurons (with black pigment)
2. pars reticulata- GABA neurons
Why does the basal ganglia exist?
motor function, cognition, motivation
involved with cortical loops (motor cortex, limbic cortex, frontal lobe association cortex)
Dorsal striatum
consists of the pathways involving the caudate and putamen (caudate- cognitive processing, putamen- sensorimotor processing)
ventral striatum
more preferential involvement with the limbic system and emotion
What does the direct circuit of the dorsal striatum function in?
increases motor activity by disinhibiting thalamic activity
what does the indirect circuit of the dorsal striatum function in?
decreases cortical activity
what does the nigrostriatal pathway of the dorsal striatum function in?
dopamine releases depolarizing neurons on D1 receptors in the putamen (associated with direct loop). This reduced the amount of inhibition coming from GPi, allowing for movement to occur.
Hyperpolarizes D2 receptors associated with the indirect loop.
What is the efferent output of the basal ganglia?
There is no direct output of basal ganglia to the brainstem or spinal cord LMNs
What are the major efferents of the BG?
GPi and SNr
Basal Ganglia functions through disinhibition
inhibition of a tonically active inhibitory pathway or an inhibitory neuron inhabiting a tonically active inhibitory neuron
How is disinhibition accomplished
balance of signals from the direct and indirect loops covering on the output nuclei (GPi and SNr)
This part of the Basal Ganglia is linked to internally generated initiation of movement (initiation is not from sensory cued stimuli such as vision or proprioception)
cells of GPi
what is the secondary function of the basal ganglia?
procedural of motor activity
Are Alzheimers or PD patients better at procedural memory?
Alzheimers can learn new motor tasks but not new facts
PD have trouble with procedural memory
Which part of the striatum is primary a motor function nucleus and functions in more habit formation and procedural or implicit memory
Putamen
What is the 3rd function of the basal ganglia?
cognitive function (head of caudate nucleus receives projections from the frontal lobe of the association cortex)
What is the blood supply to the Basal Ganglia?
Striatal or Ganlgionic Arteries (deeply penetrating branches of the Circle of Willis) - supply caudate, anterior GP, putamen, internal capsule
The Thalamo-geniculate branch of the PCA supplies what?
subthalamic nucleus, thalamus, posterior limb of the internal capsule
What is a result of Basal Ganglia dysfunction
Dyskinesia (movement disorders)
Hyperkinetic and Hypokinetic
This is a hyperkinetic disorder that involves slow and writhing movement such as with CP. Probably involves striatum
Athetoses
This is a hyperkinetic disorder that involves involuntary jerking, dancing, grimacing movements. Involves stratum or VL of the thalamus
Choreas
