Basal Ganglia Flashcards
Basal ganglia functions
Regulate movement
Process info related to emotion, motivation, cognition
How does the basal ganglia regulate movement
Role in initiation
Switching motor programmes
Inhibit antagonistic and unnecessary movements
Regulate force
What makes up the dorsal striatum
Caudate nucleus + putamen
What makes up the lentiform nucleus
Putamen + globus pallidus
What separates the putamen and thalamus
Internal capsule
Are the basal ganglia grey matter or white matter
Grey
What shape is the caudate nucleus and what lobes if it in
C shape
Head in frontal, tail in temporal
What shape are the putamen nuclei
Round
2 parts of the globus pallidus and their functions
External - relay information between other basal ganglia nuclei and internal globus pallidus
Internal - sends output to thalamus
Internal capsule
White matter structure separating lentiform nucleus and mandate nucleus from thalamus
Internal capsule function
Carries info past basal ganglia
What basal ganglia function involves the subthalamic nucleus and substantia nigra
Motor function
Main blood supply of basal ganglia
Lenticulostriate arteries - body of caudate + putamen
Anterior cerebral artery - head of caudate + putamen + globus pallidus
Anterior choroidal artery - int globus pallidus
Posterior cerebral artery - substantia nigra, subthalamic nucleus
Where do the lenticulostriate arteries branch from
Middle cerebral artery
What structure receives all inputs to the basal ganglia
Dorsal striatum
What brain structures send inputs to the basal ganglia
Cerebral cortex
Substantia nigra pars compacta
What pathway brings inputs from the cerebral cortex to the basal ganglia
Corticostriatal pathway
What pathway brings dopaminergic inputs
Nigrostriatal pathway
What are the most abundant type of neurones in the dorsal striatum
Medium spiny neurones
Why do medium spiny neurons have large dendritic trees
Receive a lot of info from different brain regions
What types of convergent inputs go to the medium spiny neurons
Glutamergic
Dopaminergic
GABAergic
Where are the medium spiny neurones
Striatum
Output zone of basal ganglia
Globus pallidus ext and int
Substantia nigra pars reticula
Where do the basal ganglia output zones project to
GPe -> subthalamic nucleus
GPi -> ventral anterior/ ventrolateral thalamic nuclear complex
SNr -> superior colliculus
Are inputs to the basal ganglia convergent or divergent
Convergent
3 loops between the cortex, basal ganglia, and thalamus
Motor loop
Associative loop
Limbic loop
Where are the upper motor neurones influenced by the GPi and SNr
GPi - frontal cortex (via thalamus)
SNr - superior colliculus
Disinhibition
Excitation by double inhibition
Are glutamate and GABA excitatory or inhibitory
Glutamate excitatory
GABA inhibitory
Are inputs and outputs of the striatum excitatory or inhibitory
Inputs excitatory
Outputs inhibitory -> disinhibition of thalamus
When the striatum is excited, are the GP, VA/VL complex of the thalamus, and UMNs in the cortex excited or inhibited in the direct pathway
GP inhibited
VA/VL of thalamus disinhibited (excited)
UMNs excited
Direct pathway effect on thalamus
Excites motor thalamus by removing tonic inhibition from GPi
Direct pathway
Sensory+assoc cornices -> dorsal striatum -> GPi -> motor thalamus -> supplementary motor cortex
