RT Journal Article
SR Electronic
T1 Electrical Microstimulation of the Pulvinar Biases Saccade Choices and Reaction Times in a Time-Dependent Manner
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1984-16
DO 10.1523/JNEUROSCI.1984-16.2016
A1 Adan-Ulises Dominguez-Vargas
A1 Lukas Schneider
A1 Melanie Wilke
A1 Igor Kagan
YR 2017
UL http://www.jneurosci.org/content/early/2017/01/24/JNEUROSCI.1984-16.2016.abstract
AB The pulvinar complex is extensively interconnected with brain regions involved in spatial processing and eye movement control. Recent inactivation studies have shown that the dorsal pulvinar plays a role in saccade target selection. However, it remains unknown whether it exerts effects on visual processing or at planning/execution stages. We employed electrical microstimulation of the dorsal pulvinar while monkeys performed saccade tasks towards instructed and freely-chosen targets. Timing of stimulation was varied, starting before, at, or after onset of target(s). Stimulation affected saccade properties and target selection in a time-dependent manner. Stimulation starting before but overlapping with target onset shortened saccadic reaction times for ipsiversive (to the stimulation site) target locations; while stimulation starting at and after target onset caused systematic delays for both ipsiversive and contraversive locations. Similarly, stimulation starting before onset of bilateral targets increased ipsiversive target choices, while stimulation after target onset increased contraversive choices. Properties of dorsal pulvinar neurons and stimulation effects were consistent with an overall contraversive drive, with varying outcomes contingent upon behavioral demands. Reaction time and choice effects were largely congruent in the visually-guided task, but stimulation during memory-guided saccades, while influencing reaction times and errors, did not affect choice behavior. Taken together, these results show that the dorsal pulvinar plays a primary role in action planning as opposed to visual processing, that it exerts its strongest influence on spatial choices when decision and action are temporally close, and that this choice effect can be dissociated from motor effects on saccade initiation and execution.SIGNIFICANCE STATEMENTDespite a recent surge of interest, the core function of the pulvinar, the largest thalamic complex in primates, remains elusive. This understanding is crucial given the central role of the pulvinar in current theories of integrative brain functions supporting cognition and goal-directed behaviors, but electrophysiological and causal interference studies of dorsal pulvinar are rare. Building on our previous studies that pharmacologically suppressed dorsal pulvinar activity for several hours, here we used transient electrical microstimulation at different periods while monkeys performed instructed and choice eye movement tasks, to determine time-specific contributions of pulvinar to saccade generation and decision-making. We show that stimulation effects depend on timing and behavioral state, and that effects on choices can be dissociated from motor effects.