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Dynamic representation of time in brain states

View Article: PubMed Central - PubMed

ABSTRACT

The ability to process time on the scale of milliseconds and seconds is essential for behaviour. A growing number of studies have started to focus on brain dynamics as a mechanism for temporal encoding. Although there is growing evidence in favour of this view from computational and in vitro studies, there is still a lack of results from experiments in humans. We show that high-dimensional brain states revealed by multivariate pattern analysis of human EEG are correlated to temporal judgements. First, we show that, as participants estimate temporal intervals, the spatiotemporal dynamics of their brain activity are consistent across trials. Second, we present evidence that these dynamics exhibit properties of temporal perception, such as scale invariance. Lastly, we show that it is possible to predict temporal judgements based on brain states. These results show how scalp recordings can reveal the spatiotemporal dynamics of human brain activity related to temporal processing.

No MeSH data available.


Correlation between position in state space and behaviour (a) Schematic representation of the methodology used to estimate position in state space for single trials. These analyses focused in intervals where participants had maximum uncertainty on whether the interval was shorter than or equal to 1.5 s (1.22 s) and equal to or longer than 1.5 s (1.85 s). For each of these trials, multivariate distances between activity in that trial and two other landmarks were estimated. The difference between these distances was used as an index of position in state space. (b) Proportion of equal responses as a function of position in state space. Each dot represents a quartile split of equal responses (mean ± s.e.m.) as a function of the position where participants are in state space. The continuous line represents the fitted function. For shorter intervals, proportion of equal responses increased as activity was more similar to the equal landmark (upper panel). For longer intervals, proportion of equal responses decreased when activity was more similar to the longer landmark (lower panel). (c) Position in state space as a function of the given response. Upper panel shows mean position in state space when participants responded shorter or equal for trials with a 1.22 s interval. Lighter circles and lines show data from individual participants and darker circles and lines show the mean across participants. Negative (positive) values indicate that activity is more similar to the shorter (equal) state. Lower panel shows mean position in state space when participants responded equal or longer for trials with a 1.85 s interval. Negative (positive) values indicate that activity is more similar to the equal (longer) state.
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f4: Correlation between position in state space and behaviour (a) Schematic representation of the methodology used to estimate position in state space for single trials. These analyses focused in intervals where participants had maximum uncertainty on whether the interval was shorter than or equal to 1.5 s (1.22 s) and equal to or longer than 1.5 s (1.85 s). For each of these trials, multivariate distances between activity in that trial and two other landmarks were estimated. The difference between these distances was used as an index of position in state space. (b) Proportion of equal responses as a function of position in state space. Each dot represents a quartile split of equal responses (mean ± s.e.m.) as a function of the position where participants are in state space. The continuous line represents the fitted function. For shorter intervals, proportion of equal responses increased as activity was more similar to the equal landmark (upper panel). For longer intervals, proportion of equal responses decreased when activity was more similar to the longer landmark (lower panel). (c) Position in state space as a function of the given response. Upper panel shows mean position in state space when participants responded shorter or equal for trials with a 1.22 s interval. Lighter circles and lines show data from individual participants and darker circles and lines show the mean across participants. Negative (positive) values indicate that activity is more similar to the shorter (equal) state. Lower panel shows mean position in state space when participants responded equal or longer for trials with a 1.85 s interval. Negative (positive) values indicate that activity is more similar to the equal (longer) state.

Mentions: When participants had a high uncertainty between shorter/equal responses, positions within the path of state space that were closer to the equal state increased the probability of equal responses (t-test on the estimated slopes, t12 = 2.28, p = 0.041, BF = 1.84 against the , Fig. 4b). In a related analysis, we compared the location in state space where participants were when they responded shorter or equal. We found that equal responses were associated with positions closer to the equal state (t12 = 2.20, p = 0.048, BF = 1.66 against the , Fig. 4c).


Dynamic representation of time in brain states
Correlation between position in state space and behaviour (a) Schematic representation of the methodology used to estimate position in state space for single trials. These analyses focused in intervals where participants had maximum uncertainty on whether the interval was shorter than or equal to 1.5 s (1.22 s) and equal to or longer than 1.5 s (1.85 s). For each of these trials, multivariate distances between activity in that trial and two other landmarks were estimated. The difference between these distances was used as an index of position in state space. (b) Proportion of equal responses as a function of position in state space. Each dot represents a quartile split of equal responses (mean ± s.e.m.) as a function of the position where participants are in state space. The continuous line represents the fitted function. For shorter intervals, proportion of equal responses increased as activity was more similar to the equal landmark (upper panel). For longer intervals, proportion of equal responses decreased when activity was more similar to the longer landmark (lower panel). (c) Position in state space as a function of the given response. Upper panel shows mean position in state space when participants responded shorter or equal for trials with a 1.22 s interval. Lighter circles and lines show data from individual participants and darker circles and lines show the mean across participants. Negative (positive) values indicate that activity is more similar to the shorter (equal) state. Lower panel shows mean position in state space when participants responded equal or longer for trials with a 1.85 s interval. Negative (positive) values indicate that activity is more similar to the equal (longer) state.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385543&req=5

f4: Correlation between position in state space and behaviour (a) Schematic representation of the methodology used to estimate position in state space for single trials. These analyses focused in intervals where participants had maximum uncertainty on whether the interval was shorter than or equal to 1.5 s (1.22 s) and equal to or longer than 1.5 s (1.85 s). For each of these trials, multivariate distances between activity in that trial and two other landmarks were estimated. The difference between these distances was used as an index of position in state space. (b) Proportion of equal responses as a function of position in state space. Each dot represents a quartile split of equal responses (mean ± s.e.m.) as a function of the position where participants are in state space. The continuous line represents the fitted function. For shorter intervals, proportion of equal responses increased as activity was more similar to the equal landmark (upper panel). For longer intervals, proportion of equal responses decreased when activity was more similar to the longer landmark (lower panel). (c) Position in state space as a function of the given response. Upper panel shows mean position in state space when participants responded shorter or equal for trials with a 1.22 s interval. Lighter circles and lines show data from individual participants and darker circles and lines show the mean across participants. Negative (positive) values indicate that activity is more similar to the shorter (equal) state. Lower panel shows mean position in state space when participants responded equal or longer for trials with a 1.85 s interval. Negative (positive) values indicate that activity is more similar to the equal (longer) state.
Mentions: When participants had a high uncertainty between shorter/equal responses, positions within the path of state space that were closer to the equal state increased the probability of equal responses (t-test on the estimated slopes, t12 = 2.28, p = 0.041, BF = 1.84 against the , Fig. 4b). In a related analysis, we compared the location in state space where participants were when they responded shorter or equal. We found that equal responses were associated with positions closer to the equal state (t12 = 2.20, p = 0.048, BF = 1.66 against the , Fig. 4c).

View Article: PubMed Central - PubMed

ABSTRACT

The ability to process time on the scale of milliseconds and seconds is essential for behaviour. A growing number of studies have started to focus on brain dynamics as a mechanism for temporal encoding. Although there is growing evidence in favour of this view from computational and in vitro studies, there is still a lack of results from experiments in humans. We show that high-dimensional brain states revealed by multivariate pattern analysis of human EEG are correlated to temporal judgements. First, we show that, as participants estimate temporal intervals, the spatiotemporal dynamics of their brain activity are consistent across trials. Second, we present evidence that these dynamics exhibit properties of temporal perception, such as scale invariance. Lastly, we show that it is possible to predict temporal judgements based on brain states. These results show how scalp recordings can reveal the spatiotemporal dynamics of human brain activity related to temporal processing.

No MeSH data available.