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Casana-Perez, Susana Maria (2004): Control of attention before reflexive and intentional saccades. Dissertation, LMU München: Medizinische Fakultät



The relation between covert and overt spatial attention and saccadic eye movements was investigated in control subjects, Parkinson’s Disease (PD) patients, and cerebellar patients in a dual-task paradigm. The main question was how different types of cues (reflexive/intentional) guide the spatial attention during fixation or during the preparation phase of a saccade. The subjects were asked to follow a reflexive or intentional cue, to discriminate a character that appeared either at the cued side (valid trials) or at the non-cued side (invalid trials), and to respond by pressing a joystick. The proportion of valid/invalid trials (cue relevance) was 75/25 and 50/50 for the control subjects, for the patients only the proportion 75/25 was used. All discrimination tasks were performed during the preparation of the saccade to the cued target and also during fixation. The results of the control subjects showed that discrimination of the character is always better at the cued side irrespective of the eye movement condition or the cue relevance, suggesting that spatial attention is engaged at the cued location even under fixation conditions and irrespective of the relevance of the cue. The results of the PD patients point to an intentional saccade impairment that does not correlate with the overall impairment in the attentional control. In the double task, also cerebellar patients showed an intentional saccade impairment that correlates with the deficit in the attentional control. After these experiments further research could investigate the impairment of the patients shown here is true for all cerebellar disorders.