Lecture 13, Basal Ganglia

Question 1

Rigidity

Answer 1

increased resistance to passive movement of a limb

Question 2

Dystonia

Answer 2

co-contraction of agonist and antagonist muscles causing abnormal positions of limb, trunk, face

Question 3

Athetosis

Answer 3

writhing, twisting, movements of limbs, of face/trunk

Question 4

Chorea

Answer 4

dance–> continuous involuntary movements that have a fluid or jerky quality

Question 5

Myoclonus

Answer 5

sudden rapid muscular jerk

Question 6

Role of basal ganglia

Answer 6

motor center, participating in complex networks that influence motor systems & cognitive and affective functions

creates motor program, selects appropriate motor program and initiates them

lesions result in hyperkinesia or hypokinesia

Question 7

Components of Basal Ganglia

Answer 7

gray matter nuclei located deep within the white matter of the cerebral hemispheres

contains caudate nucleus, putamen, globus pallidus, subthalamic nucleus, substantia nigra, nucleus accumbnes, ventral pallidum

Question 8

Striatum

Answer 8

made of caudate and putamen
receives almost all imputs fro the BG

Question 9

Caudate Nucleus

Answer 9

C=shaped structure, follows structure of lateral ventricle

divided into 3 parts –> head, body, tail

Question 10

Putamen

Answer 10

forms lateral portion of basal ganglia

Question 11

Where do most inputs to the basal ganglia come from?

Answer 11

Arrive via the striatum

Question 12

Outputs leave the basal ganglia from _____

Answer 12

Gpi and SNpr

Question 13

Basal ganglia other functions besides motor

Answer 13

eye movements
cognitive functions
emotional functions

Question 14

Inputs to basal ganglia

Answer 14

comes form projects from entire cerebral cortex, intralaminar nuclei, putamen, substantia nigrao pars compacta

most are excitatory and use glutamate as a NT

Question 15

Outputs from basal ganglia

Answer 15

Main output is to the thalamus (VL and VA)
inhibitory, utilize GABA

outputs to intralaminar nuclei, will project back to striatum and MD nucleus

also projections to reticular formation and superior colliculus

Question 16

Direct Pathway

Answer 16

the GPi/SNpr wants to naturally inhibit the thalamus, inhibiting GPi allows the thalamus to stimulate the cortex

Travels directly from cortex to striatum (+)
Striatum to GPi (-)
GPi to Thalamus (-)
Back to motor areas of cortex (+)

Question 17

Indirect Pathway

Answer 17

Decreases motor output

Travels from cortex to striatum (+)
Striatum to GPe (-)
GPe to STN (-)
STN to GPi (+)
GPi to thalamus (-)
Back to motor areas of cortex (+)

Question 18

Dopamine

Answer 18

addition of dopamine strengthens the direct pathway and weakens the indirect pathway

adding dopamine still increases the motor output in both pathways

Question 19

Oculomotor Channel

Answer 19

basal ganglia regulation of eye movements
VA/MD
input is caudate, output is eye fields

Question 20

Prefrontal Channel

Answer 20

most important in cognitive processing
input comes from caudate, output to prefrontal cortex

Question 21

Limbic Channel

Answer 21

involved in limbic regulation of emotions and motivational drives, also neurobehavioral/psychiatric

Inputs are from limbic cortex, hippocampus, amygdala
Outputs are to ventral pallidum to thalamus