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Flashcards in Hirsch - Basal Ganglia Deck (29):
1


Gross Anatomy of the Basal Ganglia

(draw and label)


striatum: caudate and putamen

Globus pallidus (palladium): pars externa and pars interna

substania nigra: pars compacta and pars reticulata

VA/VL complex of thalamus

Subthalamic nuclei

2


striatum

- know location


caudate and putamen

3


globus pallidus (palladium)

- know location


pars externa and pars interna

4


substania nigra

- know location


pars compacta and pars reticulata

5


structure of caudate, putamen, and pallidum


caudate is a round/circle outside

larger portion right inside is putamen

inner core there is a pallidum

6


medium spiny neurons have ----- targets


medium spiny neurons have 3 targets

7


medium spiny neuron body locates in --(2)-- and targets ---(3)---

caudate - > internal globus pallidus

caudate -> substantia nigra pars retinulata

putamen -> internal globus pallidus

putamen -> external globus pallidus

 

8


dopaminergic neurons excite ---- inhibit-----


dopaminergic neurons excite medium spiny cells and inhibit others

9


medium spiny neurons receive ----


medium spiny neurons receive many excitatory cortical inputs

each input contribute little

 

10


medium spiny neurons are silent unless...


medium spiny neurons are silent unless excited

= gabergic

11


globus pallidus or substantia nigra pars retinulata


targets for medium spiny neurons

active unless inhibited

gabergic

medium spiny neurons wrap it aroundth

12


there is topographic representation of the body in the putamen


mapped with respect to the body and function

receive info from multimodal association cortices & frontal eye fields

receive info from somatosensory, visual, premotor, and motor cortices

discharge in anticipation of body movements

13


diverse function of basal ganglia


non motor loop: 1. executive/prefrontal loop 2. limbic loop (OCD related) 3. oculomotor loop

motor loop: upper motor neurons initiate and help coordinate voluntary movement 1. direct pathway (accelerate movement, huntingtons) 2. indirect pathway (brakes movement, parkinsons)

14


direct pathway


accelerate movement

dis-inhibit thalamus (upper motor neurons)

know what happens when switched on

link:

1. cortex (glutamate excites)

2. putamen (gaba inhibits)

3. globus pallidus internal (gaba inhibits)

4. VA/VL thalamus (glutamate excites)

15


direct pathway switch on

postive feedback

1. cortex (glutamate excites)

2. putamen (gaba inhibits)

3. globus pallidus internal (gaba inhibits)

4. VA/VL thalamus (glutamate excites)

* Know the diagram

16


indirect pathway


brakes movement

link:

1. cortex (glutamate, excite)

2. putamen (gaba, inhibit)

3. globus pallidus external (gaba, inhibit)

4. sub thalamus nucleous (glutamate, excite)

5. globus pallidus internal (gaba inhibit)

6. VA/VL thalamus (glutamate excite)

know the diagram when it is on

17


direct and indirect pathways are regulated by...


dopamine

excites direct pathway (D1 receptor) ==> ultimately excites movement

inhibits the indirect pathway (D2 receptor) ==> ultimately excites movement

** Net excitatory effect

18

dopamine synthesized in ...

substantia nigra pars compacta

* medium spiny cells project to

1. globus pallidus internal excited by dopamine via D1 receptor

2. globus pallidus external inhibited by D2 receptor

19


Basal Ganglia


caudate

putamen

globus pallidus

20


Basal Ganglia (caudate, putamen, globus pallidus) : projection neurons are ...


 GABAergic (inhibitory)

cells in striatum (caudate, putamen) are usually silent

cells in globus pallidus are usually active

21


cortex, thalamus, subthalamic nucleus: projection neurons are ...


glutamatergic (excitatory)

22


substantia nigra, pars compacta: projection neurons are...


dopaminergic

can excite (D1 direct pathway) or inhibit (D2 indirect pathway) the medium spiny neurons

23


Hyperkinesia - increased movements

- loss of subthalamic nucleus


hemiballismus

huntington's disease

24


hypokinesia - loss of substantia nigra pars compacta


parkinson's disease

drug induced (neuroleptics, MPTP)

25


Parkinson's disease


brady kinesia (hypokinesia)

rigidity

pill rolling tremor

* remove dopamine that excites direct pathway and inhibits indirect pathway

direct pathway will decrease

indirect pathway will increase

26


Hemiballimus; lesion in indirect pathway (subthalamic nucleus)


activity in globus pallidus internal is reduced ---> ultimately excites cortex

27


Huntington's disease


loss of striatal neurons

chromosome 4 mutation (huntingtin)

involuntary movement (chorea) difficulty

think through problems

depressed irritable mood

severe movement disorder

akinesia (can hear and understand but not speak)

28


huntington's disease is loss of


 loss of putamen

which decrease inhibitation of globus pallidus external

ultimately increase in cortex activity

29


therapies for parkinson's


L-Dopa

Thalamotomy and Pallidotomy

Deep brain stimulation of subthalamic nucleus

Implantation of fetal dopaminergic neurons

optically gated ion channels in damaged regions

 

* no cure; surgical procedure sometimes works