A sensory integration account for time perception.

Alessandro Toso,Luciano Paz,Arash Fassihi,Francesca Pulecchi,Mathew E Diamond,Samuel J Gershman

doi:10.1371/journal.pcbi.1008668

Abstract

The connection between stimulus perception and time perception remains unknown. The present study combines human and rat psychophysics with sensory cortical neuronal firing to construct a computational model for the percept of elapsed time embedded within sense of touch. When subjects judged the duration of a vibration applied to the fingertip (human) or whiskers (rat), increasing stimulus intensity led to increasing perceived duration. Symmetrically, increasing vibration duration led to increasing perceived intensity. We modeled real spike trains recorded from vibrissal somatosensory cortex as input to dual leaky integrators-an intensity integrator with short time constant and a duration integrator with long time constant-generating neurometric functions that replicated the actual psychophysical functions of rats. Returning to human psychophysics, we then confirmed specific predictions of the dual leaky integrator model. This study offers a framework, based on sensory coding and subsequent accumulation of sensory drive, to account for how a feeling of the passage of time accompanies the tactile sensory experience.

Highlights

Every sensory experience is embedded in time, and is accompanied by the perception of the passage of time
The challenge to neuroscience posed by the sense of time lies, first and foremost, in the fact there do not exist dedicated receptors–the passage of time is a sensory experience constructed without sensors
Our data uncover this robust relationship–“stronger is judged as longer”–in the psychophysical results both of human subjects and rats, indicating a general mechanism linking stimulus features to perceived time

Summary

Introduction

Every sensory experience is embedded in time, and is accompanied by the perception of the passage of time. The psychophysical experiments reveal a systematic interaction between perceived intensity and perceived duration, both in humans and in rats, leading us to propose that an early-stage sensory representation provides common sensory input to two downstream integrators that generate two corresponding percepts. To test this model, we use neuronal activity recorded from somatosensory cortex of behaving rats to generate neurometric curves for perceived intensity and perceived duration, and derive a close match to observed psychophysical curves. We propose a framework, general to humans and to rats, for the construction of the feeling of the intensity of a stimulus and the time occupied by that same stimulus

Methods

Results

Discussion

Conclusion