Research Highlight : Temporal asymmetries in auditory coding and perception reflect multi-layered nonlinearities

The physiological bases of the perceptual asymmetry to sounds up- or down-ramping in intensity are still unknown. To understand the neural mechanisms underlying this asymmetrical perception, ENP group leader Brice Bathellier and colleagues recorded a large number of auditory cortical neurons using 2-photon calcium imaging in awake mice and behavioural assays. Authors found that the positive bias to up-ramping sounds is present in mice both at cortical and perceptual level. Authors also found that functional cell types correspond to cellular assemblies clustered in space that detect specific combinations of time-intensity modulation features. Rather than the usual linear-nonlinear model (LN model) that does not reflect the computations underlying the observed cortical responses, the authors proposed a multilayer model encoding non-linear combinations of linear features. 

Check out the article:

Temporal asymmetries in auditory coding and perception reflect multi-layered nonlinearities. Deneux T, Kempf A, Daret A, Ponsot E, Bathellier B. Nat Commun. 2016 Sep 1;7:12682.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025791/pdf/ncomms12682.pdf

Doi: 10.1038/ncomms12682 (open access)

Figure: Two-photon calcium imaging of the mouse auditory cortex (top) shows a surprising asymmetry between the neuronal population responses to up- versus down-ramping sounds.