Primates base perceptual judgments on some sensory inputs while ignoring others. The covert selection of sensory information for perception is often thought to be accomplished mostly by the cerebral cortex, whereas the overt orienting toward relevant stimuli involves various additional structures such as the superior colliculus, a subcortical region… (More)
We used a dual-task paradigm to investigate the spatial allocation of attention during smooth pursuit. Subjects tracked one character in a translating string of characters (block letter 8's), and during maintained pursuit, one of the characters briefly changed to an E or 3. Based on the ability of subjects to correctly discriminate the probed character, we… (More)
The use of awake, fixating monkeys in neuroscience has allowed significant advances in understanding numerous brain functions. However, fixation is an active process, with the occurrence of incessant eye movements, including rapid ones called microsaccades. Even though microsaccades have been shown to be modulated by stimulus and cognitive processes in… (More)
Microsaccades are tiny saccades that occur during gaze fixation. Whereas these movements have traditionally been viewed as random, it was recently discovered that microsaccade directions can be significantly biased by covertly attended visual stimuli. The detailed mechanisms mediating such a bias are neither known nor immediately obvious, especially because… (More)
The superior colliculus (SC) has long been known to be part of the network of brain areas involved in spatial attention, but recent findings have dramatically refined our understanding of its functional role. The SC both implements the motor consequences of attention and plays a crucial role in the process of target selection that precedes movement.… (More)
Markov chains (stochastic processes where probabilities are assigned based on the previous outcome) are commonly used to examine the transitions between behavioral states, such as those that occur during foraging or social interactions. However, relatively little is known about how well primates can incorporate knowledge about Markov chains into their… (More)
The neural mechanisms that decide when and where to walk are not well understood. In this issue of Neuron, Felsen and Mainen use an olfactory-guided orienting task to show that the superior colliculus is necessary in rodents for the normal execution of spatial locomotor choices.