New

Projects we are actively working on at the moment.

Dissociating attentional allocation from evidence accumulation 

The lateral intraparietal area (LIP) contains spatially selective neurons that help guide attention and eye movements.  In addition, numerous studies have suggested that the same neurons accumulate sensory evidence in favor of one choice (e.g., look left) or another (look right).  These two functions, however, are not identical.  In order to dissociate them, and better understand the role of LIP, we designed a task that puts them in conflict, and trained two monkeys to perform it.  Using such task (an urgent version of the random-dot motion discrimination task), we found that while choice accuracy increased steeply with time, and thus with increasing sensory evidence, at the same time, the LIP selection signal became progressively weaker, as if it hindered performance.  The results were consistent with LIP activity regulating the spatial allocation of attention, and suggest that the ramping activity traditionally interpreted as evidence accumulation may correspond, instead, to a slow, post-decision shift of spatial attention from a central location (where the relevant stimulus is) to a peripheral one (where the saccade target is).  

We are currently extending this research to another prominent oculomotor area, the frontal eye field (FEF). We are also exploring the consequences of these findings to visuomotor behavior using human psychophysics.