# Neuronal populations across the cortex underlie discrete, categorical, and subjective representations of visual durations

## TL;DR

The study reveals how different brain regions process time perception during visual tasks, showing distinct and hierarchical neural representations.

## Contribution

The study identifies specialized roles of cortical regions in encoding discrete and categorical representations of visual durations.

## Key findings

- Parietal and premotor cortices, along with caudal SMA, contain neurons tuned to specific durations.
- Frontal regions encode categorical durations centered around mean values used in behavior.
- Neuronal preferences across areas suggest a hierarchical organization of duration tuning.

## Abstract

The neural processing of subsecond durations recruits a wide network of areas. Although unimodal tuning has been shown in many of these regions, its role and link to perception remain unclear. Here, we used 7T functional MRI while participants performed a visual duration categorization task to characterize unimodal responses along the cortical hierarchy. We found topographically organized neuronal populations tuned to all presented durations in parietal and premotor cortices, and in the caudal supplementary motor area (SMA). In contrast, rostral SMA, inferior frontal cortex, and anterior insula showed neuronal preferences centered around the mean duration, which correlated with the boundary duration participants employed in the task. These differences suggest specialized roles of duration tuning across cortical regions —from discrete to categorical and subjective duration representations. Finally, correlations of neuronal preferences across areas highlighted a hierarchical organization of duration tuning. Together, our findings provide a mechanistic framework for duration perception in vision.

Duration perception involves multiple brain regions, but how unimodal tuning across this network supports subjective timing remains unclear. This study shows that parietal, premotor, and caudal SMA encode distinct durations, whereas frontal regions encode categorical, mean‑centered durations aligned with behavioral boundaries, revealing a hierarchical cortical organization for visual time perception.