John Fedota

Publications (2)8 Total impact

• Article: Early interaction between perceptual load and involuntary attention: An event-related potential study.

  Shimin Fu, John Fedota, Pamela M Greenwood, Raja Parasuraman
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  ABSTRACT: Whether selective attention affects C1, the first (earliest) visual cortical component of the event-related potential (ERP), remains controversial. We used a cued, involuntary attention task requiring discrimination of targets under low and high levels of perceptual load to examine early attentional modulation in visual cortex. Potential confounds due to physical stimulus differences between load conditions and cue-target sensory interaction were minimized. An interaction between perceptual load and involuntary attention was observed for the P1m component (peak latency between 100 and 140 ms). Furthermore, the parieto-central C1 component (peak latency 80 ms) was modulated by attention, but only under the high-load condition. Thus, whereas attention typically modulates the later P1 component, attentional modulation of C1 is possible under optimal conditions. Specifically, a high perceptual load is necessary for eliciting this earliest attentional effect on cortical processing.
  Neuroscience Letters 10/2009; 468(1):68-71. · 2.11 Impact Factor
• Article: Perceptual load interacts with involuntary attention at early processing stages: event-related potential studies.

  Shimin Fu, Yuxia Huang, Yuejia Luo, Yan Wang, John Fedota, Pamela M Greenwood, Raja Parasuraman
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  ABSTRACT: Perceptual load is known to influence the locus of attentional selection in the brain but through an unknown underlying mechanism. We used event-related potentials (ERPs) to investigate how perceptual load interacts with cue-driven involuntary attention. Perceptual load was manipulated in a line orientation discrimination task in which target location was cued involuntarily by means of peripheral cues. Attentional modulation was observed for P1m (the posterior midline P1 component with peak latency between 108 and 140 ms) with invalid trials eliciting larger P1m than valid trials. This attentional effect on P1m increased as a function of perceptual load, suggesting an early temporal locus for the interaction of perceptual load and involuntary attention. Attentional modulation for the C1 component (peak latency at approximately 80 ms) was also observed, but only for high-load stimuli that were presented intermixed with low-load stimuli. Results suggest that (a) perceptual load affects attentional selection at early processing stages; (b) perceptual load interacts with involuntary attention earlier and with different brain mechanisms relative to voluntary attention; and (c) attentional modulation in the C1 time range is possible under optimal experimental conditions.
  NeuroImage 07/2009; 48(1):191-9. · 5.89 Impact Factor