Effect of Reversible Inactivation of Macaque Lateral Intraparietal Area on Saccades and Search

Yuqing Liu & Lawrence H. Snyder

Washington University School of Medicine

St. Louis, MO

Area LIP, in the posterior parietal cortex, is involved in the sensorimotor transformation for eye movements. LIP has been hypothesized to either play a specific role in specifying targets for possible eye movements, or as playing a more general role in registering salient spatial locations. An oculomotor role was supported by the study of Li & Andersen (1999), who found that reversible inactivation of LIP with muscimol led to delayed reaction times for visually- and memory-guided saccades. A non-specific role was supported by studies of Wardak and colleagues (2002, 2004), who found normal saccadic reaction times to single targets, but prolonged search times. We repeated these experiments, coinjecting manganese with muscimol so that injection sites could be directly visualized using anatomical magnetic resonance imaging. Data from one animal show deficits in both memory-guided saccade reaction times and in search times, and no effects in memory-guided reach reaction time. We are currently testing the hypothesis that injection sites underlying saccadic and search effects may be dissociable.

Gordon Research Conference 2007

Bates College in Lewiston, ME