We investigated whether damage to the right posterior parietal cortex (PPC) affects direction specific trans-saccadic memory. It has been hypothesized that damage to the right PPC impairs trans-saccadic memory specifically after a rightward eye movement compared to a leftward eye movement. This has, however, never been tested directly. We compared location memory performance for central items that had to be remembered while making a left- versus rightward eye movement, or for items that were remapped within the left versus right visual field. We included stroke patients with damage in the right PPC and healthy control subjects. Participants memorized the location of a briefly presented item, had to make one saccade (either towards the left, right, upward or downward), and subsequently had to decide in what direction the probe had shifted. We used a staircase algorithm to enhance task sensitivity. In general, patients showed worse location memory performance compared to healthy subjects. However, we found no difference in location memory performance after leftward versus rightward saccades. Two patients showed worse performance for items that were presented in the left versus right visual field, which can be explained by reduced attention for the contralesional, left side, due to the lesion in the right hemisphere (as seen in hemispatial neglect). To conclude, we found that damage in the right PPC did not lead to gaze direction specific impairments in trans-saccadic memory, but instead caused more general spatial memory impairments.
Ten Brink, A.F., Fabius, J.H., Weaver, N.A., Nijboer, T.C.W., Van der Stigchel, S. (In Press). Trans-saccadic memory after right parietal brain damage. Cortex