Leor N Katz¹, Ricahrd J Krauzlis¹; ¹NIH

The primate superior colliculus (SC) plays a crucial role in visual selective attention, and how it interacts with cortical attention mechanisms remains a controversial area of research. Here we investigated the effects of inactivating primate SC on neurons in the frontal eye fields (FEF), a prefrontal cortical region also important for the control of attention and eye movements. We used multichannel probes to record electrophysiological signals in FEF of two macaque monkeys as they performed a selective attention task, before and during reversible inactivation of SC using muscimol. In the attention task, patches of visual motion were presented on either side of a central fixation point, one of which was positioned within the response fields of the recorded FEF neurons. In “Attend” blocks, monkeys were rewarded for attending to the motion patches and releasing a joystick in response to a change in motion direction. In “Ignore” blocks, reward was delivered for ignoring the change in motion direction and instead, for responding to a change in fixation point luminance. FEF neurons were strongly modulated by the attentional manipulation, exhibiting significantly stronger responses during trials of the Attend blocks versus Ignore (i.e., attention-related modulation). They also exhibited a strong phasic increase in activity in response to the motion stimulus change, and this response was stronger for “hits” versus “misses” (i.e., ‘detect-probability’). Inactivation of SC caused reductions in hit rates during the attention task, as well as reductions in the attention-related modulations of FEF neurons, both during stimulus presentation and during the change in motion direction. The causal effect of SC on FEF neurons implicates the FEF in a network of cortical areas that interact with the SC during attention tasks and suggests that ascending pathways from SC to the prefrontal cortex are important for enabling the FEF contributions to visual selective attention.