, 2011), and computational studies in the machine learning field (Dayan and Daw, 2008; Dayan et al., 2000; Oudeyer et al., AZD2281 chemical structure 2007). Because of the complexity and vastness of the topic, my discussion will be necessarily incomplete. I will eschew circuit-level mechanisms (most of which are currently unknown), and detailed mathematical considerations (for which excellent descriptions can be found elsewhere [Dayan and Daw, 2008;

Dayan et al., 2000; Oudeyer et al., 2007]). Despite these limitations however, I hope that it will become clear in the forthcoming discussion that appreciating the cognitive dimensions of eye movement control is both a necessity and a source of strength. Gaining this appreciation is necessary for explaining a range of observations regarding the neural responses to target selection, which have no good explanation in sensory or motor terms. More importantly perhaps, broadening our perspective will strengthen the field of oculomotor research and allow us to use the full power of this system as a window into high-level but poorly understood cognitive functions. Research on selective attention in humans and nonhuman primates spans numerous studies, using a vast array of psychophysical

and neurophysiological techniques. While these studies differ widely in their specific details, many share the common feature that they direct subjects to attend to a specific item—be it an object, feature, or location—and

buy GDC-0973 measure the effects of attentional selection on perception Bay 11-7085 or action. These studies have shown that attention produces widespread effects throughout early and late visual areas, which collectively increase the signal from the attended item and suppress noise from unattended distractors (Reynolds and Heeger, 2009). A shift of attention can remain covert—generating only an improvement in perceptual discrimination—or can be accompanied by saccades—rapid eye movements that place the fovea on the attended item. The oculomotor component of an attentional response is generated by a network of cortical and subcortical structures that includes portions of the basal ganglia, the superior colliculus, and the frontal eye field (Schall et al., 2011; Stanford et al., 2010). Neurophysiological studies have also shown that, interposed between visual processing and saccade production is an intermediate layer of target selection, which has been most intensively investigated in the frontal eye field and the lateral intraparietal area (Figure 1A). A large fraction of neurons in these areas have spatial receptive fields and respond both to visual stimuli and/or to a planned saccade. Rather than being selective for a visual features, these cells encode a more abstract quantity of target selection—i.e., discriminate between targets and distractors in a variety of tasks (Gottlieb and Balan, 2010; Thompson and Bichot, 2005).