MetaTOC stay on top of your field, easily

Laminar‐specific encoding of texture elements in rat barrel cortex

, ,

The Journal of Physiology

Published online on

Abstract

Key points For rats texture discrimination is signalled by the large face whiskers by stick‐slip events. Neural encoding of repetitive stick‐slip events will be influenced by intrinsic properties of adaptation. We show that texture coding in the barrel cortex is laminar specific and follows a power function. Our results also show layer 2 codes for novel feature elements via robust firing rates and temporal fidelity. We conclude that texture coding relies on a subtle neural ensemble to provide important object information. Abstract Texture discrimination by rats is exquisitely guided by fine‐grain mechanical stick‐slip motions of the face whiskers as they encounter, stick to and slip past successive texture‐defining surface features such as bumps and grooves. Neural encoding of successive stick‐slip texture events will be shaped by adaptation, common to all sensory systems, whereby receptor and neural responses to a stimulus are affected by responses to preceding stimuli, allowing resetting to signal novel information. Additionally, when a whisker is actively moved to contact and brush over surfaces, that motion itself generates neural responses that could cause adaptation of responses to subsequent stick‐slip events. Nothing is known about encoding in the rat whisker system of stick‐slip events defining textures of different grain or the influence of adaptation from whisker protraction or successive texture‐defining stick‐slip events. Here we recorded responses from halothane‐anaesthetized rats in response to texture‐defining stimuli applied to passive whiskers. We demonstrate that: across the columnar network of the whisker‐recipient barrel cortex, adaptation in response to repetitive stick‐slip events is strongest in uppermost layers and equally lower thereafter; neither whisker protraction speed nor stick‐slip frequency impede encoding of stick‐slip events at rates up to 34.08 Hz; and layer 2 normalizes responses to whisker protraction to resist effects on texture signalling. Thus, within laminar‐specific response patterns, barrel cortex reliably encodes texture‐defining elements even to high frequencies.