Neuro 33: Basal Ganglia

Front 1

Describe the blood supply to the basal ganglia

Back 1

medial striate from anterior cerebral artery, lateral striate and anterior choridal from middle cerebral, branches of PCA

Front 2

What is the net result of signaling through the direct pathway

Back 2

the thalamus is disinhibited, movement is facilitaed

Front 3

What is the net result of signaling through the indirect pathway

Back 3

The thalamus inhibited and movement is inhibited

Front 4

Describe the role of the nigrostriatal pathway in basal ganglia function

Back 4

Dopaminergic synapses to the stratum acting on both the direct and indirect pathways. The D1 receptors of the direct pathway for an excitatory synapse that ultimately facilitates movement. The D2 receptors of the indirect pathway form an inhibitory synapse that also leads to movement (inhibit the inhibitory pathway)

Front 5

Extrinsic inputs to the basal ganglia terminate mainly in the striatum. Where do thse inputs come from?

Back 5

1. cerebral cortex (corticostriatal pathway) 2. Intralaminar nuclei of the thalamus (thalamostriate pathway)

Front 6

Describe the output from the basal ganglia

Back 6

Output arises from inhibitory (GABA) synapses from the GPi and SNr to the thalamus motor nuclei (VA/VL) and the superior colliculus of the midbrain (SNr)

Front 7

What is the function of the subthalamic nucleus

Back 7

Recieves input from the motor and premotor cortices, relay in the indirect pathway. It receivs an inhibitory synapse from the GPe and then provides a excitatory stimulus to the GPi/SNr.

Front 8

What is the usual cause of basal ganglia disorder? Sxs?

Back 8

Usually a disruption of transmitter metabolism. Sxs include involuntary movements, akinesia and bradykinesia, changes in posture, muslce tone, and muscular rigidity.

Front 9

What is the cause or Parkinson's disease? How does this affect basal ganglia function? What sxs woudl be expected

Back 9

Degeneartion of dopaminergic cells in the SNC leads to a decrease in the ability to facilitate movement. The result is a hypokinetic movement disroder with tremor at rest, rigidty, and bradykinesia

Front 10

What is the cause of hemiballismus? How does this affect the basal ganglia? What sxs would you expect?

Back 10

Caused by a lesion of the contralateral subthalamic nucleus. This lesion disrupts the STN's excitatory synapse onto the GPi/SNr so the inhibition that the GPi/SNr provides to the thalamus is decreased.

Front 11

How do the basal ganglia and cerebellum differ in terms of: input from the spinal cord

Back 11

cerebellum= direct input via spinocerebellar tracts; basal ganglia=none

Front 12

How do the basal ganglia and cerebellum differ in terms of: output to the spinal cord

Back 12

Neither system has direct output to the spinal cord, they relay through DCN or teh thalamus

Front 13

How do the basal ganglia and cerebellum differ in terms of: input from the cortex

Back 13

Cerebellum=indirect input form cortex via the pons (corticopontine tract); basal ganglia=direct input from cortex

Front 14

How do the basal ganglia and cerebellum differ in terms of: projects to the cortex

Back 14

both systems project to the cortex via the thalamus

Front 15

How do the basal ganglia and cerebellum differ in terms of: output inhibitory vs. exhibitory

Back 15

The output from the by the DCN is excitatory (note purkinje to DCN is inhibitory), the output from the basal ganglia to the thalamus is inhibitory

Front 16

How do the basal ganglia and cerebellum differ in terms of: their effect on movement

Back 16

Cerebellum-coordinates the execution of movements, compares intended with executed; Basal ganglia-planning and execution of complex motor strategies, amplitude and velocity of movements

Front 17

How do the basal ganglia and cerebellum differ in terms of: the localization of lesions

Back 17

Cerebellum=ipsilateral symptions; Basal ganglia=often contralateral symptoms but an be bilateral

Front 18

How do the basal ganglia and cerebellum differ in terms of: the sxs of lesions

Back 18

cerebellum-ataxia, impaired balance, intentional tremor; basal ganglia-hyper/hypo kinesia, resting tremor