Term
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Definition
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Caudate Nucleus
Putamen
Accumbens
(Olfactory Tubercle)
External Segment
Internal Segment (Endopeduncular Nu in Rodents)
Reticular part of Substantia Nigra
Ventral Pallidum
[image]
[image]
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Term
| Development of Cortex and Basal Ganglion |
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Definition
Cells from ventricular zone migrate out along radial glia. Other cells - most of the GABAergicinterneurons - come from ganglionic eminence. The ganglionic eminence also gives rise to the basal ganglion.
[image]
Coronal section in the forebrain of an embryonic mouse at 12.5 days of gestation (preplate stage), showing the lateral and medial ganglionic eminences (LGE, MGE) from which GABAergic interneurons migrate to the cortical anlage (left, yellow). Glutamatergic neurons destined for the cortex are generated locally in the cortical ventricular zone and migrate radially (right, red). |
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Term
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Definition
[image]
Image of the internal capsule as fiber bundle growing down to pons, brainstem, & spinal cord. But also fibers to and from thalamus, and to striatum.
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Term
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Definition
1. Not Divided into Caudate & Putame by clear internal capsule.
2.the equivalent of GPi is within the internal capsule or cerebral peduncle = endopeduncular nucleus.
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Term
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Definition
the fiber output is mostly from the internal segment of GP, and there are complex fiber pathways around and through the internal capsule. Also note connections with subthalamic nucleus
[image]
Cortex to striatum, striatum to GP, GP to thalamus, thalamus to cortex. Plus interactions with subthalamic nucleus, substantianigra, etc.
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Term
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Definition
Medium Spiny Projection Neurons (GABA) ~98%
The co-localize with either substance p or enkephalin.
[image]
Fast Spiking Interneuron (GABA + PV) <1%
Magnocellular Interneuron (ACh) <1% |
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Term
| Striatum Cellular Circuit |
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Definition
[image]
Cortex goes onto MSN and FS cells. FS cells go onto MSN and ACh cells, which in turn synapse on MSN. Dopamine cells act on all types. The MSN provide the output. |
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Term
| Function of Basal Ganglia |
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Definition
That is: Function of Cortico-Striatal-Pallidal-Thalamic Loops.
Degeneration (Huntington’s disease) gives “unconstrained movement”.
Parkinson’s disease gives complex disorder.
Blockage of Globus Pallidus does not alter latency or accuracy of movements.
Blockage of Globus Pallidus results in co-contraction of agonists & antagonist muscles.
? Is Role to Facilitate Desired Movement, etc, and Suppress Non-Desired Movement, etc ? |
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Term
| Larger Striatal Circuitry |
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Definition
Direct and Indirect pathways.
Direct: Ctx-striatum (sub P)-GPi-thalamus.
Indirect: Ctx-striatum (enk)-GPe-GPi-thalalmus.
Note that all the striatal projection onto GP is GABAergic.
Excitatory drive comes from subthalamic nucleus.
[image] |
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Term
| Functional Zones in the Striatum |
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Definition
[image]
Different parts of cortex project to different zones of striatum.
DL: Motor
Central: Association
VM: Limbic |
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Term
| Is Basal Ganglia only concerned with Motor Function? |
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Definition
Non-motor (Limbic, Sensory, Sensory Association) Cortex has Connections to Striatum.
Parkinson’s disease often associated with emotional disturbance.
Basal Ganglia implicated in Addiction, Tourettes disease, Obsessive-Compulsive Disorder, Mood Disorders.
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Term
| Frontal-striatal connection |
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Definition
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Term
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Definition
Reward signals in ventromedial striatum.
Dopamine response to reward seems to signal a movement or behavior that has been rewarded and should be repeated.
Habenular nuclei inhibit Dopamine response in absence of reward, and disinhibit Dopamine cells in presence of reward. |
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Term
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Definition
An abnormal focus in striatum may result in ability to suppress some movement or other behavior.
[image] |
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