Abstract
Some studies with extracellular recordings from the brain of awake and unrestrained rats show that psychomotor stimulants such as amphetamine activate most of motor-related striatal neurons at low doses that elicit nonfocused motor activation, while at high doses that induce focused stereotyped behaviour individual motor-related units are further activated or suppressed depending on their behavioural response characteristics. We studied the modulation by methamphetamine on synaptic inputs derived from the pyramidal tract by intracellular recordings, and morphological features of their receptive neurons with intracellular staining in the rat striatum. The excitatory synaptic potentials on the medium spiny neurons evoked by electrical stimulation of the pyramid were enhanced by the administration of methamphetamine, and the neurons projected to the both of the globus pallidus and entopeduncular nucleus. These findings suggest the convergence of glutamatergic excitatory inputs from the pyramidal tract, the final output of motor commands, and dopaminergic excitatory inputs from the substantia nigra pars compact on the medium spiny projection neurons that are involved in the both of the direct and indirect pathways in the rat striatum. [Jpn J Physiol 54 Suppl:S183 (2004)]
