DUGi

Auditory Target and Novelty Processing in Patients with Unilateral Hippocampal Sclerosis: A Current-Source Density Study

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@289383

The capacity to respond to novel events is crucial for adapting to the constantly changing environment.Here, we recorded 29-channel Event Related Brain Potentials (ERPs) during an active auditory noveltyoddball paradigm and used for the first time Current Source Density-transformed Event Related BrainPotentials and associated time-frequency spectra to study target and novelty processing in a group ofepileptic patients with unilateral damage of the hippocampus (N = 18) and in healthy matched controlparticipants (N = 18). Importantly, we used Voxel-Based Morphometry to ensure that our group ofpatients had a focal unilateral damage restricted to the hippocampus and especially its medial part.We found a clear deficit for target processing at the behavioral level. In addition, compared to controls,our group of patients presented (i) a reduction of theta event-related synchronization (ERS) for targetsand (ii) a reduction and delayed P3a source accompanied by reduced theta and low-beta ERS and alphaevent-related synchronization (ERD) for novel stimuli. These results suggest that the integrity of thehippocampus might be crucial for the functioning of the complex cortico-subcortical network involvedin the detection of novel and target stimuli

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