Visual deprivation induces long-term memory consolidation of saccadic adaptation

Consolidation of motor learning is a complex process exceeding the duration of the practice. Saccadic adaptation as the response to a altering visual environment is a form of motor learning, wherein two temporal components seem to be involved in its consolidation: A long term learning process that leads to a slow but enduring effect, and a short term learning process that leads to a fast but less enduring effect¹. It has also been shown that an adapted amplitude can be maintained even days after one adaptation session². Up to now, extinction of saccadic adaptation was thought to be based on time and visual input.

In our study the effects of different visual conditions on long and short term learning effects were compared between two subsequent inward adaptation sessions (10 to 6°) in a cross-over design. We used the following sequence of stimulation periods: baseline, adaptation, extinction, adaptation, break (two hours), adaptation, extinction, adaptation. During the break subjects were either exposed to a normal visual environment without moving cues or blindfolded. Each subject (N=23) was tested in both visual conditions 4 weeks apart. We compared left amplitude gain after the break (short term) and after 4 weeks (long term).

Data revealed for the short term learning period that saccadic adaptation was better maintained in the viewing-group. The blindfolded group was not only less efficient in maintaining the adapted saccade amplitude but also showed less extinction after the visual deprivation period. After 4 weeks the previously blindfolded but not the viewing group showed partial maintenance of the previously adapted saccade gain.

Results imply that visual deprivation facilitates long term memory consolidation of an adapted saccade amplitude. Furthermore data disprove that the extinction of an adapted saccade is merely based on time and/or daily visual input.

Literatur: 1) Ethier, V. et al., 2008. Spontaneous Recovery of Motor Memory During Saccade Adaptation. J. Neurophysiol. 99, 2577–2583. 2) Alahyane, N. and Pélisson, D., 2005. Long-lasting modifications of saccadic eye movements following adaptation induced in the double-step target paradigm. LearnMem. 12, 433-443.