DIFFERENT PROPERTIES OF FREQUENCY BAND ACTIVITIES UNDERLIE THE DIFFERENTIAL PROCESSING OF FIGURE-GROUND AND HOMOGENEOUS DISPLAYS

  • Alba Grieco
  • Armando Mónica Oliveira

Abstract

14 participants performed a perceptual learning task requiring the detection of a target defined by contrast-polarity. VEPs were recorded before and after the learning sessions, and learning-related changes on phase-locked frequency components analyzed. Increased amplitude in early-P3 was observed in the target-present condition, concurrent with increased amplitude of delta-activity. In the target-absent condition, decreased amplitude in late-P3 and reduced latency of N4 were found instead, concurrent with decreased latency of both delta and theta activities/Delta-activity has been related to the inhibition of non-relevant neural activity, and theta-activity associated with Hebbian learning (strengthening of synchronous synapses). Both mechanisms may play a role in the target-enhancement and distracters-exclusion effects documented along the learning process. Outcomes suggest that target-present and target-absent conditions are processed differently after the first 250-300 ms following stimulus onset, and that their differential processing relies on distinct aspects of the same phase-locked oscillatory activities.

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