Striatum
links: Neuroanatomy reference:
(Corpus) Striatum #
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A nucleus (cluster of neurons) in the subcortical basal ganglia. (Indeed, it’s not a single anatomical… well, I was going to say body/‘corpus’ but clearly it is.)
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Dorsal: Caudate, Putamen; Ventral: Nucleus Accumbens, Olfactory Tubercle.
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95% of neurons in the striatum are Medium Spiny Neurons. Then, 1-2% cholinergic interneurons and 1-2% GABAergic interneurons.
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Critical part of motor and reward systems. Determines whether we will execute something we think about based on selections; without it, we think out loud and act impulsively.
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“Prepare and select” model: D1 provides a range of possible decisions (derived from cortical activity?), while D2 filters and selects.
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Dopaminergic neurons inhibit striatal output via non-canonical release of GABA (2012)
- *Activation of DA neurons (d1 or d2 or nonspecific????) in striatal slices rapidly inhibits action potential firing in both direct-and indirect-pathway striatal projection neurons (MSNs) through vesicular release of the inhibitory transmitter γ-aminobutyric acid (GABA).
- GABA is released directly from dopaminergic axons but in a manner that is independent of the vesicular GABA transporter VGAT. Instead GABA release requires activity of the vesicular monoamine transporter VMAT2, which is the vesicular transporter for DA. Furthermore, VMAT2 expression in GABAergic neurons lacking VGAT is sufficient to sustain GABA release*
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Striatal Dopamine Can Enhance Learning, Both Fast and Slow, and Also Make it Cheaper
- Promotes reinforcement learning plasticity, and WM, by facilitating updating and effort exertion.
- The D2 antagonist sulpiride reduces accuracy due to diminished WM involvement and faster WM decay
