Movement disorders Basal Ganglia Flashcards
basal ganglia reflect the embryologically determined migaration of
neurons away from the cerebral parventrictular zone which embeds an island of gray matter in the white matter
putamen and caudate are collectively called
the striatum
putamen and globus pallidus collectively from
the lentiform nucleus
basal gangliar output inhibits
the thalamus suppressing an excitatory thalamo-cortical projections.
the degree of thalamic inhibitions dictates
modulation of the cortex dependent motor activity
lesions affecting the basal ganglia commonly disturb
basal ganliar output.
corticostriatal fibers release
glutamate to excite striatal neurons(cells forming caudate and putamen
striatal cells are either
excited or inhibited by dopamine arising from the substantia nigra pars compacta (SNc)
the substantia nigra receives
inhbitory GABAergic signals from the striatum
GABAergic output from the internal(medial)Globus inhibits
cells of the ventral anterior and ventral lateral thalamic nuclei.
Thalamic cells excite
he motor cortex via the release of glutamate.
Direct basal gangliar motor loop
SNc via D1 receptors sends input to neostriatusm which sends inhibitory GABA to globus pallidus(internal) -decerased output form GPi increaseses thalamic activity which increases cortical acitivty to facilitate movement
Indirect basal gangliar motor loop
Striatal output suppreses GPe, decreases output from GPe increases output from Sth. increased output form Sth increases activity within GPi. increased activity of GPi inhibits thalamic acitivty which will decrease thalamic output and diminish movement.
dopamine from substantia nigra
optimizes output of the two basal ganliar circuits to normalize movement.
normal basal gangliar activity regulates
motor cortices to optimize communication between upper and lower motor neurons
optimization of communication depends on
activities of direct and indirect basal gangliar components.
unbalanced direct and indirect pathways can cause
hypo or hyper kinesis
hypokinesis in parkinsons reflects
diminished release of striatal dopamine secondary to degeneration of nigrostriatal tract
diminished dopamine in direct pathway.
diminished D1 reduces striatal putput, which diminishes the inhibition of GPi, this suppreses the thalamus and the thalamus activity decreases coritcal output suppressing movement.