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.