October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
Correlation between magnetoencephalogram (MEG) evoked by changes in motion velocity and reaction times or discrimination thresholds
Author Affiliations
  • Kaoru Amano
    Graduate School of Frontier Sciences, University of Tokyo, Japan
Journal of Vision October 2003, Vol.3, 402. doi:10.1167/3.9.402
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      Kaoru Amano, Tsunehiro Takeda; Correlation between magnetoencephalogram (MEG) evoked by changes in motion velocity and reaction times or discrimination thresholds. Journal of Vision 2003;3(9):402. doi: 10.1167/3.9.402.

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      © 2016 Association for Research in Vision and Ophthalmology.

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Abstract

Some studies have reported that reaction times (RTs) to the change in velocity of motion from V1 to V2 decreases with increasing |V2 − V1| almost independent of V1 (Mateeff et al., 1995). However, neural mechanisms to process the velocity changes have not been studied in detail. Besides, there were few studies measuring the effect of adaptation on RTs. Therefore the present study investigated the relationship between behavioral measurements like RTs or discrimination thresholds and the neural mechanisms under both the adapted and non-adapted conditions. Brain responses evoked by velocity increments from V1 to V2 were recorded by magnetoencephalogram (MEG), which has high temporal resolution. Contracting concentric half rings were used as visual stimuli, and the velocities increased after contractions for 2s preceded by expansions at the same velocity for 2s (non-adapted condition), or after contractions for 4s (adapted condition). V1 was 1.0, 2.0, 3.0, or 4.0 deg/s, and the increments of velocities (V2 – V1) were 40 or 80 % of V1 (e.g. from 1.0 deg/s to 1.4 or 1.8 deg/s). Velocity discrimination thresholds and RTs to the velocity changes were also measured for each V1 and were compared with the MEG amplitudes and latencies, respectively. Recorded MEG showed prominent peaks at between 200 and 280 ms (M1), whose latencies and amplitudes changed depending on the stimulus conditions. For both 40 and 80 % velocity increments under both the adapted and non-adapted conditions, the M1 latencies and RTs decreased with an increase of V1, which is also an increase of V2 – V1, while adaptation did not have significant effects on latencies and RTs. On the other hand, the M1 amplitudes increased and discrimination thresholds decreased with increasing V1. Adaptation increased the MEG amplitudes for 40% velocity increments, while it decreased the discrimination threshold. These results suggest that the M1 component is strongly related to the detection of velocity changes.

Amano, K., Takeda, T.(2003). Correlation between magnetoencephalogram (MEG) evoked by changes in motion velocity and reaction times or discrimination thresholds [Abstract]. Journal of Vision, 3( 9): 402, 402a, http://journalofvision.org/3/9/402/, doi:10.1167/3.9.402. [CrossRef]
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