Basal ganglia focused Flashcards
Inhibitory neurotransmitter
GABA
Excitatory neurotrnasmitter
Glutamate
What inhibits the thalamus?
Globus pallidus internal
What is the direct pathway?
Motor cortex sends excitatory neuron glutamate to striata. Striata sends inhibtiory GABA to the globus pallidus internal segment which reduces thalamic inhibiton. Substantia nigra sends dopamine via D1 receptors to striata and inhibitory GABA to globus pallidus internal segment. Subthalamic nucleus sends excitatory glutamate to further stimulate sbustantia nigra but this is inhibied by substantia nigra via GABA. Thalamus sends signals to cortex to move muscles.
What is the indirect loop indirect pathway?
Cortex releases glutamate to stria. Striata releases GABA to inhibt the external segment of the globus pallidus. The globus pallidus internal segment and the subthalamic nucleus act to increase the thalamic inhibition. Substantia nigra compacta releases dopamine which acts on D2 receptors to increase thalamic inhibiton
What are the input neurons to the basal ganglia?
Medium spiny neurons which are inhibitory and use GABA
Input zone of basal ganglia?
Striata- receives input via Glutamate to the medium spiny neurons
Output zone of basal ganglia
Globus pallidus, substantia nigra pars reticulata
Clonus
Involuntary rhythmic muscular contractions
What is Huntington’s disease?
Mutation on chromosome 4. Death of the medium spiny neurons which release GABA which leads to reduced inhibition of the internal globus pallidus. This leads to chorea (overexcessive movements). To treat this, deplete dopamine levels using tetrabenazide.
What is hemiballismus disease?
Caused by a lesion in the subthalamic nucleus which causes reduced inhibition leading to jerky movements on one side of the body/.
What begins the direct/indirect pathway?
Cortex acting on striata via glutamate
