Monkeys Share the Human Ability to Internally Maintain a Temporal Rhythm.

Otto García-Garibay,Victor De Lafuente,Hugo Merchant,Jaime Cadena-Valencia

doi:10.3389/fpsyg.2016.01971

Otto García-Garibay, Victor De Lafuente + Show 2 more

Open Access

https://doi.org/10.3389/fpsyg.2016.01971

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Abstract

Timing is a fundamental variable for behavior. However, the mechanisms allowing human and non-human primates to synchronize their actions with periodic events are not yet completely understood. Here we characterize the ability of rhesus monkeys and humans to perceive and maintain rhythms of different paces in the absence of sensory cues or motor actions. In our rhythm task subjects had to observe and then internally follow a visual stimulus that periodically changed its location along a circular perimeter. Crucially, they had to maintain this visuospatial tempo in the absence of movements. Our results show that the probability of remaining in synchrony with the rhythm decreased, and the variability in the timing estimates increased, as a function of elapsed time, and these trends were well described by the generalized law of Weber. Additionally, the pattern of errors shows that human subjects tended to lag behind fast rhythms and to get ahead of slow ones, suggesting that a mean tempo might be incorporated as prior information. Overall, our results demonstrate that rhythm perception and maintenance are cognitive abilities that we share with rhesus monkeys, and these abilities do not depend on overt motor commands.

Highlights

The ability to estimate time intervals is fundamental to behavior
The increase in variability of the tapping responses that define time intervals is well described by the generalized Weber’s law: σ 2 = k · T2 + σi2ndep in which T is elapsed time, k approaches the square root of the Weber fraction at long elapsed times, and the term σi2ndep represents a basal variance that does not increase with time (Getty, 1975; Killeen and Weiss, 1987; Gibbon et al, 1997; Bizo et al, 2006; Merchant et al, 2008; Zarco et al, 2009; Laje et al, 2011)
This will support the notion that rhythmic interval timing is a higher cognitive function not tied to particular motor actions, which is shared among primates

Summary

INTRODUCTION

The ability to estimate time intervals is fundamental to behavior. Motor actions performed outside their intended temporal window often have reduced effectiveness or a complete loss of purpose. We hypothesize that human and monkey subjects share the ability to maintain a temporal rhythm in working memory, and that this is not dependent on overt motor actions. This will support the notion that rhythmic interval timing is a higher cognitive function not tied to particular motor actions, which is shared among primates. At a random time during this continuation phase, subjects were asked to indicate the estimated position of the stimulus (Gotime) This task generated a visuospatial rhythm defined by the time interval between location changes (Doherty et al, 2005), much like the rhythm defined by the motion of a discretely moving second hand in a clock. The evidence suggests that short (0.5 s), medium (0.75 s), and long intervals (1.0 s) seem to be timed by mechanisms with increasingly large time-independent variance

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