1.  neostriatum - caudate nucleus and putamen; major area for afferent projection to the basal ganglia
2. paleostraitum - globus pallidus; receives inputs from neostriatum and substantia nigra
3. subthalamic nuclei - receives inputs from the basal ganglia
4. sub nighra- pars compacta (DA) and pars reticularis (GABA)

1. cerebral cortex
2. centromedian nucleus (thalamus) - indirect source of cortical input to the neostriatum
3. substantia nigra pars compacta - DA to the neostriatum

patch configuration in the neostriatum

striosome - outer

matrix - inner

striosome - peptide rich

-  receive input from the limbic regions of the brain

-project to the substantia nigra; efferent GABAergic

matrix - receive inputs from sensory and motor cortex regions;

project to the globus pallidus via GABAergic projections

- ACh rich

1. primary motor cortex projects to the putamen

2. premotor cortex projects to putamen and caudate nucleus

3. prefrontal cortex projects to all parts of the caudate nucleus 

ansa lenticularis (around the internal capsule) and lenticular fasciculus (through the internal capsule)

both go to the thalamus

goal: disinhibit thalamic nuclei

neostriatum - active

GPi - inactive (normally tonically active)

thalamic nuclei - active

cerebral cortex - active, movement

goal: inhibit lateral GP and disinhibit subthalamic nuclei so it can further excite medial GP and cause further inhibition of thalamic nucleus

neostriatum: GABA

lateral GP : GABA

subthalamic nuclei: glutamate 

medial GP

• D1 receptors facilitate direct pathway by exiciting the neostriatal projections to the GPi and thus further facilitating disinhibition of thalamic nuclei
• D2 receptors inhibit the indirect pathway by inhibiting the neostriatal projections to the lateral GP and thus further inhibiting the subthalamic nuclei 

Hyperkinetic disorder

Basal ganglia disease, lesion at the Neostriatum

the GABAnergic neorons that project to the lateral globus pallidus segment are destroyed, so the lateral globus pallidus activity is higher than usual

genetic defect of C4p... normal 20 CAG repeats, in hunt's, you have 60

• Dosolateral prefrontal cortax
• dosolateral caudate
• medial GP
• medial dorsal and ventral anterior thalamic nuclei
• back to cerebral cortex

• Anterior cingulate cortex
• Ventral straitum
• ventral pallidum
• medial dorsal thalamic nucleus 
• back to cortex

• hypokinetic disorder
• lesion in the sub nigra pars compacta
• diminished stimulation of D1 and D2 receptors