8 research outputs found
Estimation of linear and nonlinear spatial receptive fields from natural Images
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A new foreperiod effect on single-trial phase coherence. Part I: existence and relevance
Expecting events in time leads to more efficient behavior. A remarkable early
finding in the study of temporal expectancy is the foreperiod effect on
reaction times; i.e., the influence or reaction time of the time period between
a warning signal and an imperative stimulus to which subjects are instructed to
respond as quickly as possible. Recently it has been shown that the phase of
oscillatory activity preceding stimulus presentation is related to behavior.
Here we connect both of these findings by reporting a novel foreperiod effect
on the inter-trial phase coherence of the electroencephalogram (EEG) triggered
by stimuli to which subjects are instructed not to respond. Inter-trial phase
coherence has been used to describe regularities in phases of groups of trials
time locked to an event of interest. We propose a single-trial measure of
inter-trial phase coherence and prove its soundness. Equipped with this
measure, and using a multivariate decoding method, we demonstrate that the
foreperiod duration in and audiovisual attention-shifting task modulates
single-trial phase coherence. In principle, this modulation could be an
artifact of the decoding method used to detect it. We show that this is not the
case, since the modulation can also be observed using a simple averaging
method. We show that the strength of this modulation correlates with subject
behavior (both error rates and mean-reaction times). We anticipate that the new
foreperiod effect on inter-trial phase coherence, and the decoding method used
here to detect it, will be important tools to understand cognition at the
single-trial level. In Part II of this manuscript, we support this claim, by
showing that changes in attention modulate the strength of the new foreperiod
effect on a trial-by-trial basis
A new foreperiod effect on single-trial phase coherence. Part I: existence and relevance
Expecting events in time leads to more efficient behavior. A remarkable early
finding in the study of temporal expectancy is the foreperiod effect on
reaction times; i.e., the influence or reaction time of the time period between
a warning signal and an imperative stimulus to which subjects are instructed to
respond as quickly as possible. Recently it has been shown that the phase of
oscillatory activity preceding stimulus presentation is related to behavior.
Here we connect both of these findings by reporting a novel foreperiod effect
on the inter-trial phase coherence of the electroencephalogram (EEG) triggered
by stimuli to which subjects are instructed not to respond. Inter-trial phase
coherence has been used to describe regularities in phases of groups of trials
time locked to an event of interest. We propose a single-trial measure of
inter-trial phase coherence and prove its soundness. Equipped with this
measure, and using a multivariate decoding method, we demonstrate that the
foreperiod duration in and audiovisual attention-shifting task modulates
single-trial phase coherence. In principle, this modulation could be an
artifact of the decoding method used to detect it. We show that this is not the
case, since the modulation can also be observed using a simple averaging
method. We show that the strength of this modulation correlates with subject
behavior (both error rates and mean-reaction times). We anticipate that the new
foreperiod effect on inter-trial phase coherence, and the decoding method used
here to detect it, will be important tools to understand cognition at the
single-trial level. In Part II of this manuscript, we support this claim, by
showing that changes in attention modulate the strength of the new foreperiod
effect on a trial-by-trial basis