Dopamine influences attentional rate modulation in Macaque posterior parietal cortex

Selective attention facilitates the prioritization of task-relevant sensory inputs over those which are irrelevant. Although cognitive neuroscience has made great strides in understanding the neural substrates of attention, our understanding of its neuropharmacology is incomplete. Cholinergic and glutamatergic contributions have been demonstrated, but emerging evidence also suggests an important influence of dopamine (DA). DA has historically been investigated in the context of frontal/prefrontal function arguing that dopaminergic receptor density in the posterior/parietal cortex is sparse. However, this notion was derived from rodent data, whereas in primates DA innervation in parietal cortex matches that of many prefrontal areas. We recorded single- and multi-unit activity whilst iontophoretically administering dopaminergic agonists and antagonists to posterior parietal cortex of rhesus macaques engaged in a spatial attention task. Out of 88 neurons, 50 showed modulation of activity induced by drug administration. Dopamine inhibited firing rates across the population according to an inverted-U shaped dose-response curve. D1 receptor antagonists diminished firing rates in broad-spiking units according to a monotonically increasing function. Additionally, dopamine modulated attentional signals in broad, but not narrow-spiking cells. Finally, both drugs modulated the pupil light reflex. These data show that dopamine plays an important role in shaping neuronal responses and modulates attentional processing in macaque parietal cortex.Significance statementDopamine is critically involved in high-level cognitive functions, and dopaminergic dysfunctions pertain to ageing and neurological and psychiatric disorders. Most previous studies focused on dopaminergic effects on prefrontal activity or its role in basal ganglia circuitry. The effects of dopamine in other brain areas such as parietal cortex, despite its well-established role in cognition and cognitive dysfunction, have largely been overlooked. This study is the first to show dopaminergic modulation of parietal activity in general, and specific to spatial attention in the non-human primate, revealing cell-type specific effects of dopamine on attentional modulation.