Striatal glutamate antagonism induces contralateral neglect

To assess the role of striatal glutamatergic synapses in mediating sensorimotor orientation behavior, glutamate receptor antagonists were infused into the left striatum of awake rats and behavioral orientation to contralateral and ipsilateral stimuli were quantified. The AMPA-kainate antagonist, DNQX, and the NMDA antagonist, CPP, both induced a large asymmetry in responding, such that the rats oriented much less to stimuli presented contralateral to the antagonist infusions. Furthermore, intrastriatal glutamate antagonist infusions increased the occurrence of incorrect responses, or turning away from a contralaterally-presented stimulus. In a separate experiment, intrastriatal DNQX was shown to block kainic acid (KA)-induced Fos expression in the striatum, but not in adjacent cerebral cortex, suggesting that the diffusion of this drug is restricted to the striatum.