ABSTRACT
The striatum is a large subcortical nucleus involved in motor coordination, cognition, as well as disorders such as Parkinson’s disease, Tourette’s syndrome, Huntington’s disease, schizophrenia, and drug addiction (Wilson 2004). The principal neurons of the striatum are the medium spiny neurons (MSNs) which constitute ∼90% of the striatal neuron population and form the striatal output
6.1 Introduction .................................................................................................. 119 6.2 Dopamine and Acetylcholine Systems in the Striatum ................................ 121
6.2.1 Striatal Subterritories ........................................................................ 121 6.2.2 Dopaminergic and Cholinergic Innervations in Striatum ................ 121
6.3 Activity-Dependent Regulation of Dopamine Release Probability by Presynaptic Nicotinic Receptors (nAChRs) ............................................. 123 6.3.1 nAChR Subunits on Striatal Dopamine Axons ................................ 125 6.3.2 nAChR Subunits Responsible for Regulation of Striatal
Dopamine Transmission in Dorsal versus Ventral Striatum ............ 126 6.4 Activity-Dependent Regulation of Dopamine Release Probability
by mAChRs on Cholinergic Interneurons .................................................... 126 6.4.1 mAChR Subtypes and Locations within Striatum ........................... 128 6.4.2 mAChR Subtypes Responsible for Regulation of Striatal
Dopamine in Dorsal versus Ventral Striatum .................................. 128 6.5 Summary and Perspective ............................................................................ 129 Acknowledgments .................................................................................................. 131 References .............................................................................................................. 131
(Bolam et al. 2000). The remaining striatal neurons comprise at least three types of interneuron, including the large, aspiny, tonically active cholinergic interneuron (Kawaguchi 1993). As the input nucleus of the basal ganglia, the striatum receives and gates massive convergent innervation via the MSNs to generate appropriate behaviors. Among this convergent innervation, striatal projection neurons receive excitatory inputs from both cortex and thalamus and dopaminergic inputs from the midbrain. Nigrostriatal dopaminergic afferents and corticostriatal/thalamostriatal glutamatergic afferents commonly synapse onto the same MSN dendritic spine (Moss and Bolam 2008), and this synaptic triad is likely to be of great importance within the striatum helping to powerfully shape basal ganglia network activity. At the level of this synaptic triad, dopamine is able to modulate corticostriatal transmission via presynaptic D2 receptors (Bamford et al. 2004) and is also able to regulate corticostriatal plasticity (Calabresi et al. 2007; Surmeier et al. 2007) as well as directly regulating the excitability of MSNs (Albin et al. 1995; Day et al. 2008; Nicola et al. 2000). The intimacy of the dopamine-glutamate striatal interaction has recently been highlighted further with the discovery that dopamine and glutamate may be co-released within ventral but not dorsal striatum (Stuber et al. 2010; Tecuapetla et al. 2010).
