Input
(Glutamate)
Most from cerebral cortex
Thalamic nuclei to striatum
Nearly all cerebral cortex
1. prefrontal cortex
Basal Ganglia circuitry
Output
Focused output (GABA)
Excitatory
Inhibitory
X





Thalamus: intralaminar & ventrolateral nuclei
(Glutamate)
Large aspiny neurons
(Cholinergic)
Adjacent medium spiny striated neurons (GABA,
Substance P, enkephalin)
 SN (DA neurons)
 Small interneurons (GABA)
Frontal cortex, primary motor cortex, premotor and
sup. motor cortex, frontal eye fields (Glutamate)
GPe (GABA)
Striatum (GABA, Subs P, dynorphin)
STN (Glutamate)
Faster than striatal
Striatum
1. Striosomes (Ach-esterase poor)
2. Extrastriosomal matrix (Ach-esterase
rich)
Midbrain spiny neurons
1. SN
X
X
Subthalamic nucleus
X
X
GPi
GABA
X
GPi: leg & arm
GP → Thalamus & BS→ motor & prefrontal cortex → Striatum
Indirect pathway: Cortex→ Striatum→ GPe→ STN (inhibitory)→GPi & SNpr (excitatory)
X
Direct Pathway: Cortex→ Striatum→ GPi & SNpr
Striatum (GABA, SP, dynorphin)
STN (glutamate)
X
SNpr
GABA
X
X
Striatum/STN → SNpr → GABA (inhibitory)→ thalamus→ premotor & prefrontal cortex
SNpr: eye movement
Striatum
STN
X
Striatum (Striosomes)
GPe
Majority to STN
SNpc
Caudate & putamen
X
Globus Pallidus (internal segment)
“Indirect pathway”




Input: STN axons
Excitatory
terminate on multiple GPi neurons
Faster, widespread, divergent
“Direct” striatopallidal pathway





Input: Striatum
Inhibitory
Slower, more focused, convergent
Contacts several GPi weakly
Terminates densely on single neuron
Large aspiny neurons:



NT: Ach
Interneurons
Terminate on Medium spiny neurons
Medium aspiny cells:


NT: somatostatin
Interneurons
Small aspiny cells:




NT: GABA
Inhibitory
interneurons
regulate medium spiny output neurons
Primary output: limbic movements
Large dendritic diameter
TAN: tonically active neurons


Striatum
Fire when ass w/ reward (learning + reinforcement)
Basal Ganglia neurons
Medium spiny neuron:




NT: GABA
Striatum output to GP and SN
large dendritic trees
2 populations:
1. GABA, dynorphin (opioids), Substance P/ D1 receptors/ send to
GP & SN
2. GABA & enkephalin (bind to opioid receptors -pain levels)/ D2
receptors/ to GPe
The hippocampus supports rapidly acquired memory that is experienced as
conscious recollection and that can be expressed flexibly.
The striatum supports gradual acquisition of habits.
The cerebellum supports learning related to timing and motor reflexes.
The amygdala supports acquisition of emotional dispositions toward
stimuli and also mediates the role of emotion arousal in modulating other
forms of memory.
The cerebral cortex participates in each of these types of memory, and
mediates perceptual learning and the phenomenon of priming.