In an attempt

to uncover the nature of the underlying def

In an attempt

to uncover the nature of the underlying deficit, some studies have manipulated the temporal characteristics of stimulus presentation. Contra- and ipsilesional stimuli with different stimulus onset asynchronies are typically used. In the present study, visual extinction was investigated in a group of left neglect patients (N=10) using a psychophysical selleck compound paradigm with different stimulus onset asynchronies of target and distractor stimuli presented in different hemifields. Contrast thresholds for a target grating were determined with the target either in isolation or in the presence of an irrelevant distractor grating. When target and distractor gratings were presented simultaneously, neglect patients showed a significant extinction effect, i.e., a significant interference from the right hemifield distractor with left hemifield selleck chemical contrast sensitivity. When the right hemifield distractor preceded the left hemifield target stimulus by 250 ms, two different patterns of results were observed in the neglect patients. Five patients showed a significant improvement compared to the simultaneous presentation condition, five other patients showed a significant increase of the extinction effect. The results suggest that different underlying mechanisms, maybe due to different lesion locations,

can cause extinction in neglect patients. “
“Earlier research has found cross-sectional attentional control deficits in manifest Huntington’s disease (HD) using neuropsychological testing combined with simultaneous P300 registration. In the current pilot-study, we investigate attentional control in pre-manifest and manifest HD over a 3-year follow-up period. Five manifest HD (MHD), 9 pre-manifest HD (PMHD), and 12 control subjects were included. Sustained attention to response task (SART) and P300 registration resulted in number of errors, reaction time (RT), and P300 amplitude and latency. Morin Hydrate RT change patterns surrounding No-go trials were

also investigated. Within-subject differences were tested using paired-samples t-tests and between-group results with ANCOVA on delta scores (follow-up – baseline scores). Manifest HD made more errors and were slower than controls and PMHD. Longitudinally, MHD showed an overall RT increase and a specific slowing on trials preceding a correct No-go trial (within-group effects). The latter was also seen in PMHD. P300 latency prolongation was found for controls on No-go and for MHD on Go trials. On specific trials surrounding both correct and incorrect No-go trials, MHD became significantly slower over time than controls and PMHD (between-group effects). Over 3-years, MHD subjects became slower on the SART and showed a prolongation of P300 latency on specific SART trials.

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