Retention of oculomotor changes after adaptive lengthening of voluntary saccades

Adaptation of saccadic eye movements is one of the most studied model of sensori-motor adaptation. Several studies have investigated saccadic adaptation over the short-term, but the retention of adaptive oculomotor changes over days or weeks remains debated. Here, we tested whether the amplitude lengthening adaptation of voluntary saccades (VS) can be retained over several days. We induced adaptation in seven human subjects, using a modified version (Panouillères et al. JEMR. 2012) of the target double-step paradigm (Mc Laughlin. Percept & Psychophys. 1967). Adaptation was induced progressively by displacing the target during horizontal VS and in the same direction (forward step of 30% in the first three blocks of trials and of 45% in the last three blocks); both leftward and rightward saccades were simultaneously adapted. Saccadic gain changes relative to the pre-adaptation baseline were calculated immediately after and at five different time points after adaptation: 5 min (day 0) and 1, 5, 11, and 19 days. Results revealed significant increases of saccadic gain relative to baseline, reaching 15% and 16% immediately after adaptation of leftward and rightward VS, respectively. Further, the gain of leftward VS remained significantly elevated on days 0, 1, 5 and 11 (average saccadic gain change: 13%, 6.8%, 3.3% and 3.7%, respectively). In contrast, for rightward VS, the average change of gain remained significant on day 0 only (13 %) and decreased to a non significant 1.3% value on day 1. These data reveal that adaptation after-effects persisted up to 11 days for leftward VS but had already disappeared after 1 day for rightward VS. In agreement with a similar study of amplitude shortening adaptation of reactive saccades (RS) (Alahyane et al. Learn & Mem. 2005), these results suggest that saccade direction (leftward or rightward) interacts with the long term retention of adaptive oculomotor changes. Meeting abstract presented at VSS 2013