Sensory surprise signals in the visual cortex of the anesthetized mouse

The primary visual cortex is thought to encode low-level features (orientation/direction, contrast, brightness, etc.), while also enabling adaptation and gain control. However, the kinds of computations it is capable of performing, as an isolated circuit, are not clear.Here, we describe a sensory surprise signal in the local field potential (LFP) in the primary visual cortex (V1) of the anesthetized mouse in response to contrast rate change – a complex, time dependent stimulus parameter. We investigate the population activity responsible for this surprise signal and identify neuronal subgroups that react to contrast rate change based on their pattern of activation.We have found putative inhibitory neurons changing their activation pattern nonlinearly at the point of contrast rate change, potentially involved in implementing processes that are more complex than what has been previously thought possible in primary visual cortex. Since they occur under anesthesia, these processes may imply that local cortical circuits in V1 could be capable of computing complex predictions about sensory trajectories.In our study, we show that complex stimulus features can be integrated locally in the primary visual areas and their perturbation can give rise to surprise signals, mediated by the firing of sparse subpopulations of neurons. Further research should elucidate if V1 can construct internal models of dynamical inputs, leveraging prediction-like mechanisms already at this level.Funding: NO (Norway) Grants 2014-2021, Project contract number 20/2020 (RO-NO-2019-0504), three Romanian National Authority for Scientific Research and Innovation, CNCS-UEFISCDI grants (PN-III-P3-3.6-H2020-2020-0109, ERA-NET-FLAG-ERA-ModelDXConsciousness, and ERANET-NEURON-Unscrambly), and a H2020 (grant 952096, NEUROTWIN).