Basal Ganglia Flashcards
What are the four nuclear masses associated with the basal ganglia?
Corpus striatum, globus pallidus, substantia nigra, and subthalamic nuclei
Describe how information is relayed to and from the basal ganglia.
Basal ganglia receives information from the cerebral cortex and sends information to the thalamus and the brainstem
What are the two structures associated with the corpus striatum?
Caudate and putamen
What is the function of the basal ganglia?
Modulate the output of descending motor systems and govern the initiation and cessation of movement
What is the function of the caudate nucleus?
Important in learning and memory functions and feedback processing
What is the caudate nucleus innervated by?
Dopamine neurons
What is the cofunction of the caudate and putamen?
Receive information from the descending pathways (specifically the lateral corticospinal tract) and innervate ipsilateral globus pallidus via GABA (Gamma aminobutyric acid) fibers
What are the two types of caudate and putamen neurons?
Principal neurons and local circuit neurons
What are the three types of hyperkinetic states that are caused by lesions from the caudate and putamen neurons?
- Chorea - rapid, jerky movements
- Athetosis - slow, sinus movements
- Dystonia - slow, sustained movements
Restricted to just the putamen, what do the lesions result in?
Motor dysfunction in contralateral limbs
Restricted to just the caudate, what do the lesions result in?
Behavioral defects
What type of impairment results from lesions to the globus pallidus?
Hypokinesia - similar to Parkinsonian rigidity
What type of impairment results from lesions to the substantia nigra?
Parkinsonian signs and symptoms in the contralateral side of the body
What part of the basal ganglia is associated with the production of dopamine?
Substantia nigra
What is the input connection to the basal ganglia?
All regions of the cerebral cortex project to the basal ganglia
What is the output connections from the basal ganglia?
Basal ganglia is directed towards the frontal lobe, particularly the pre-motor and supplementary motor cortex
What part of the basal ganglia is the main recipient of input to the basal ganglia?
Striatum (caudate and putamen)
What are the two parts of the basal ganglia that deal with output?
Globus pallidus interna and substantia nigra pars reticulata
Are output pathways regarding the basal ganglia inhibitory or excitatory?
Inhibitory
What are the three neurotransmitters involved in the basal ganglia circuit and what type are they?
- Glutamate - excitatory
- GABA - inhibitory
- Dopamine - excitatory in direct pathway and inhibitory in indirect pathway
What are the two types of pathways and what type are they?
- Direct - excitatory
2. Indirect - inhibitory
What are the four parallel channels through the basal ganglia?
Motor channel, oculomotor channel, prefrontal channel, and the limbic channel
What are two types of disorders caused by basal ganglia impairments?
- Hypokinetic disorders - Parkinson’s (excessive inhibition from the BG)
- Hyperkinetic disorders - Huntington’s (inadequate inhibition from the BG)
What is a common characteristic of Parkinson’s and what is it caused by?
Muscular rigidity - caused by degeneration of dopamine neurons in the substantia nigra
