Basal Ganglia

Question 1

List the structures that are generally included as part of the basal ganglia and describe their anatomical features/locations

Answer 1

caudate nucleus and putamen form the striatum

MPS and LPS

subthalamic nucleus

substantia nigra

Question 2

Describe the functions of the basal ganglia with particular emphasis on their role in controlling somatic motor activity.

Answer 2

it controls how much intensity in generated in a motor movement, kinetic activity

Question 3

Describe the cytology of the striatum and list the sources of its input, including the neurotransmitters involved.

Answer 3

glutamate, excitatory, from cerebral cortex all lobes

has spiny neurons which is the output source and consists of the two types (sub p and enkephalin)

also has aspiny neurons which are interneurons and modulate spiny neuron activity, these epsp on D2 spiny neurons and are inactivated by dopamine

Question 4

Draw a diagram of the direct and indirect pathways through the basal ganglia, and the subsequent connections to the thalamus and cerebral cortex. Specify the neurotransmitter involved in each projection

Answer 4

cerebral cortex epsp glutamate to striatum

direct: striatum ipsp gaba/sub p to MPS and SNr

gaba ipsp to thalamus

thalamus glutamate epsp to cortex

indirect: striatum gaba/enkephalin ipsp to LPS

gaba ipsp to STN

STN glutamate epsp to MPS and SNr, then gaba to thalamus

Question 5

Explain how the direct pathway facilitates movement and the indirect pathway suppresses movement.

Answer 5

direct is a double negative on supplemental motor area, whereas indirect pway is a triple negative

Question 6

Describe how dopaminergic neurons in the substantia nigra, pars compact affect the activity of the direct and indirect basal ganglia pathways

Answer 6

dopamine causes epsp on D1 dopamine receptors to cause direct pway firing while inhibiting D2 receptors to inhibit indirect pway firing

Question 7

Explain the mechanistic basis for hypokinetic and hyperkinetic movement disorders.

Answer 7

hypokinetic is caused by low dopamine (parkinson’s) and causes little muscle movement

hyperkinetic is caused by damage to caudate nucleus, huntington’s diseas, too much movement

Question 8

Describe and recognize the specific types of movement abnormalities associated with hypokinetic and hyperkinetic movement disorders

Answer 8

hypokinetic are bradykinesia (slow movement), hypokinesia (little movement) or akinesia (no movement)

hyper are resting tremors, tics, dystonia, athetosis (slow, twisting, writhing movements of trunk), chorea, ballismus

Question 9

Describe the causes and clinical signs associated with Parkinson’s disease, Huntington’s disease and hemiballism, and explain how these conditions are related to dysfunction of the direct or indirect basal ganglia pathways.

Answer 9

hypokinetic is parkinson’s

hyperkinetic is huntington’s, autosomal dominant and damage to D2 spiny neurons of striatum

hyper is also hemiballism, damage to subthalamic nucleus, usually due to vascular lesion