Basal Ganglia Flashcards
What is the function of the Basal Ganglia?
regulate the scale (size) of movements, aiding in both the inhibition and facilitation of skeletal muscle groups to ensure smooth coordination of movements
What structures compose the Striatum of the Basal Ganglia?
- Caudate nucleus
- Putamen
- Nucleus accumbens
What structures compose the Lenticular/ Lentiform Nucleus of the Basal Ganglia?
- Putamen
- Globus Pallidus
What structures compose the Ventral Striatum of the Basal Ganglia?
- Nucleus Accumbens
- Surrounding structures that receive limbic information
What are the 2 parts of the Substantia Nigra?
- Reticular Part - basal ganglia output
- Compact Part - Provides widespread, modulatory, dopaminergic projections to other parts of basal ganglia
Principle circuit of Basal Ganglia is a ______ _______ _______.
- Cortical Feedback Loop
Describe the pathway and function of the Basal Ganglia Circuit
- Projection area of cerebral cortex –> basal ganglia –> returns by way of thalamus back to cerebral cortex
- involved in most cortical function and movement, cognition, emotion, motivation
What do Basal Ganglia circuits NOT do?
It does NOT directly affect lower motor neurons, only interneurons which in turn change the motor activity
Describe the function of the Putamen; input and output
- Heavily involved with movement
- Input: somatosensory cortex and motor cortex
- Output: globus pallidus and thalamus (VL/VA) to motor, premotor, and supplementary motor areas
Describe the function of the Caudate Nucleus; input and output
- Cognitive functions (planning and movement)
- Input: Association Cortex (especially prefrontal)
- Output: Projects via globus pallidus, substantia nigra, and thalamus to prefrontal areas
Describe the function of the Ventral Striatum: input and output
- initiation of drive-related behaviors
- Input: limbic areas (hippocampus and amygdala)
- output: globus pallidus and thalamus to limbic areas
Know the Direct and Indirect pathways of the Basal Ganglia
Refer to charts
What are some characteristics of Parkinson’s Diseases?
What is the treatment?
- Hypokinetic/ bradykinetic Disorder
- Rigidity and difficulty with movement (tremor)
- Results in loss of excitatory effect on direct pathway and increased inhibitory effect on indirect pathway
- Resting tremor due to increased oscillatory discharge in basal ganglia nuclei (thalamic feedback)
- Treatment: administer the depleted levels of neurotransmitters (L-Dopa)
What is the blood supply to: Striatum, Globus Pallidus and Substantia Nigra
- Striatum: anterior and middle ceberal artery (speciffically lenticulostriate or medial and lateral straite)
- Globus Pallidus: anterior choroidal artery
- Subthalamic nuclei and Substantia Nigra: penetrating braches of Posterior Cerebral Artery
What are some hyperkinetic disorders?
- Tremors - rhythmic, oscillatory, involuntary movements
- Ballismus - uncoordinated swinging of the limbs and jerky movements
- Chorea - a series of nearly continuous, rapid movements of the face, tongue, or limbs
- Athetosis - slow, writhing movements
What are some characteristics of Huntington’s Disease?
- continuous rapid movements of face and limbs
- Degeneration of caudate nucleus resulting in involuntary movements (genetic disease)
What are some characteristics of Hemiballismus?
- wild flailing movement of the arm and leg of one side
- Lesion in contralateral subthalamic nucleus (stroke of posterior perforating arteries)
- Causes decreased output from subthalamic nucleus
Treatments for disorders of the Basal Ganglia
- Perform lesion of the globus pallidus (pallidotomy) or VL/VA thalamic (thalamotomy) nuclei; In effect, disconnecting the troublesome feedback loops
- Deep brain stimulation – high frequency stimulation of globus pallidus or subthalamic nuclei; Has effect of replacing abnormal activity in nuclei with regular trains of action potentials
