basal ganglia part 2 Flashcards Preview

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Flashcards in basal ganglia part 2 Deck (45):
1

2

general loop structure

Cortex 2 BG 2 Thalamus 2 Cortex

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Motor Loop

putamen of BG(step 2)

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ventral caudate (C) and n. accumbens(step 2)

Orbitofrontal loop

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nucleus accumbens (A) [and other BG nuclei](step 2)

Limbic loop: 

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caudate (C) [and other BG](step 2)

Oculomotor loop and Dorsolateral prefrontal Loop:

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cortical neurons project to the ----- where glutamate is released.

cortical neurons project to the striatum where glutamate is released.

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------ neurons in the substantia nigra, ------- project to the striatum

Dopaminergic neurons in the substantia nigra, pars compacta (SNc) project to the striatum

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----- projections provide an important pathway for the modulation of the ----- and ------ pathways

nigrostriatal projections provide an important pathway for the modulation of the direct and indirect pathways

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Di +

Direct pathway: facilitates motor (or cognitive) programs

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D2, –

Indirect pathway: inhibits the execution of competing motor programs

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Direct pathway by D1 +

GPi/ SNr

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Indirect pathway

D2-

-->GPe

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excited by dopamine and project to Gpi

(direct pathway)

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Striatal neurons with D1 receptors are excited by 

Striatal neurons with D1 receptors are excited by dopamine

 

(direct pathway)

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Striatal neurons with D2 receptors are inhibited

Striatal neurons with D2 receptors are inhibited by dopamine

(indirect pathway)

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project to Gpe

Striatal neurons with D2 receptors

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dopaminergic projections

 lost in Parkinson’s disease.

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Increased Activity of the Direct Pathway Occurs in the Presence of

Direct Pathway

Glutamate and Dopamine

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inc GABA in GPi/ SNr from striatum

decreased GABA release in the thalamus

Direct path

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low GABA put in from (GPi/SNr) ; more Glu excreted from

thalamus

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more glu neurons from thalamus

more glu neurons from motor cortex(CC)

Direct pathway

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1.Dopamine released from SN leads to ----- of GABAergic neurons projecting from striatum to GPe.

Direct path

1.Dopamine released from SN leads to inhibition of GABAergic neurons projecting from striatum to GPe.

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STN in direct pathwya

inc GABA

 

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decrease firing of glutamatergic neurons projecting from STN to Gpi/ SNr

caused from 3. Increased GABA levels in STN

(Direct pathway)

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decreased GABA release into thalamus

b/c of Reduced excitation of GPi /SNr-GABAergic neurons

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tf in the direct path

STN has inc firing of glutamatergic neurons projecting from STN to Gpi/ SNr

STN has  decrease firing of glutamatergic neurons projecting from STN to Gpi/ SNr

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tf dopaminergic neurons only relased from

Snc

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leff; more ;less

direct path

GABAergic neurons projecting from striatum to GPe.;

GPe neurons are disinhibited, leading to increased GABA levels in STN

Increased GABA levels in STN causes decrease firing of glutamatergic neurons projecting from STN to Gpi/ SNr

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Glutamate released from corticostriatal fibers leads to --------activity of----- neurons projecting from striatum to GPe

indirect path

Glutamate released from corticostriatal fibers leads to increased activity of GABAergic neurons projecting from striatum to GPe

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inhibition of GPe neurons

indirect path

occurs from Activation of GABAergic projections from striatum to GPe

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disinhibition of glutamatergic neurons projecting from STN to Gpi/ SNr

indirect pathway

from Inhibition of GPe neurons

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Gpi/SNr - GABAergic neurons excited

in indirect pathway3

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inc GABA release in indirect pathway from

Striatum

and (GPi/SNr)

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inhibited glutamatergic projections  in indirect path

Thalamus (VA,VL)

and motor cortex

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Increased Activity of the Indirect Pathway

presense Glutamate (absence of dopamine)

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degeneration of dopaminergic neurons in SNc

Parkinson’s Disease

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Dopamine inhibits

GABAergic neurons projecting from striatum to GPe

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Dopamine excites

GABAergic neurons projecting from striatum to GPi

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lesion of the subthalamic nucleus

resulting hyperkinesia

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less Glu from STN and less GABA from GBI

hyperkinesia

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more GABA from striatum and GPI/SNR

indirect pathway and hyperkinesia

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Degeneration of neurons in caudate and putamen

(indirect pathway)

Huntington’s Disease/ Huntington’s Chorea

excess movement

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GABA D2 not stimulated much

Huntington’s Chorea

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