basal ganglia

Question 1

what is the main role of the basal ganglia

Answer 1

to provide feedback mechanism to the cerebral cortex for initiation control and cessation of motor response
motor control, motor learning, emotions and behaviours

Question 2

what are specific functions of the basal ganglia

Answer 2

excite or inhibit cortex to facilitate wanted or inhibit unwanted movements
unlike the cerebellum which modifies movement already initiated
perception, leanring, memory, abstract thought and emotion

Question 3

what are the three outcomes of neuronal input of the basal ganglia

Answer 3

enhanced activity ++
enhanced inhibition +-
disinhibition (actauvtion) –

Question 4

what structures make up the basal ganglia

Answer 4

corpus striatum and amygdala

corpus striatum is made up of neostriatum and globes pallidus

the neostritum is made up of the caudate nucleus and the putamen

Question 5

what subdivisions of the brain to these structures come from
corpus striatum
substantia nigra
sub thalamic nucleus

Answer 5

telen

mesen

dien

Question 6

what structures make up the functional basal ganglia

Answer 6

corpus striatum, substantia nigra and subthakamuc nucelus

Question 7

what strictures make up the substantial nigra

Answer 7

pars reticula and pars compacta

Question 8

what is the internal capsule in the brain

Answer 8

corticonucelar and corticospinal fibres communicating between corpus striatum and thalamus

Question 9

what neurotransmitter is found in the substantial nigra

Answer 9

dopamine

Question 10

how would you best describe the circuitry of the basal ganglia

Answer 10

multiple parallel looping circuits from cerebral cortex back to cerebral cortex through thalamus to modulate cortical output

Question 11

what are the general rules of basal ganglia circuitry

Answer 11

cerebral cortex is excitatory to the input nuclei (striatum = caudate and putamen)

GPi and Sor always inhibit the thalamus

the thalamus us excitatory to the cerebral cortex

Question 12

which fibre tracts excite the striatum

Answer 12

corticostriatal and nigrostriatal

Question 13

how does the putamen affect the GPi

Answer 13

excites or inhibits depending on neurotransmitter released

Question 14

what are the two pathways of the basal ganglia which are involved in influence of movement

Answer 14

direct - facilitate a specific movement programme
neurone from the striatum that project to the GPi directly
disinhibits the thalamus - excitation through the cortex

indirect pathway - inhibit a specific movement programme to allow direct pathway programmes
striatum to GPe to subthalamic nucelus and back to GPi - thalamus in inhibited with no excitation to the cortex

Question 15

what is the role of the substantial nigra pars compacta

Answer 15

releases dopamine
modulatory role in direct and indirect pathways
direct pathway acts on D1 receptors to further excite the neurones - enhanced moevemtn

indirect pathway - acts on D2 receptors to further inhibit neurones - enhanced inhibition of movement

Question 16

what in general would a lesion of the basal ganglia result in

Answer 16

disorder not paralysis on the contralateral side

slow movement and poor initiation, infrequent blinking or needing someone to help get you started in the movement

Question 17

what is the most common disease of the basal ganglia

Answer 17

disruption of nigrostriatal input which leads to Parkinsons

Question 18

hyperkinesia and unwanted movement is caused by diseases of the basal ganglia - which diseases are they and what causes them

Answer 18

chorea (Huntington’s) - degeneration of inhibitory fibres from striatum to globes pallidus

hemiballismus - degeneration of subthalamic nucleus (excitatory to globes pallidus)