Biology subjects

Robbe, D.

Publications and source records attributed to Robbe, D..

3 recordsLinked to original sources

bioRxiv2018

Response outcomes gate the impact of expectations on perceptual decisions

Perceptual decisions are not only determined by current sensory information but are also influenced by recent experience. Can the magnitude of expectation-based decision biases be flexibly modulated based on the outcome of previous decisions? We trained rats in several two-alternative forced choice auditory tasks, where the probability to repeat the previous stimulus category was varied in blocks of trials. All rats capitalized on the serial correlations of the stimulus sequence by consistently exploiting a transition bias: a tendency to repeat or alternate their previous response using an internal trial-by-trial estimate of the sequence repeating probability. Surprisingly, this expectation bias was null in trials immediately following an error. The internal estimate however was not reset and it became effective again causing a bias after the next correct response. This ability to rapidly activate and inactivate the bias was captured by a non-linear generative model of rat behavior, whereby a reward-driven modulatory signal gated the use of the latent estimate of the environment statistics on the current decision. These results demonstrate that rats use behavioral outcomes to flexibly modulate how expectations derived from the recent history influence their decisions.

neuroscience↗

bioRxiv2018

Dynamic Control of Hippocampal Spatial Coding Resolution by Local Visual Cues

The ability to flexibly navigate an environment relies on a hippocampal-dependent internal cognitive map. Explored space can be internally mapped at different spatial resolutions. However, whether hippocampal spatial coding resolution can be dynamically controlled within and between environments is unknown. In this work we recorded the firing of hippocampal principal cells in mice navigating virtual reality environments, which differed by the presence of local visual cues (virtual 3D objects). Objects improved spatial coding resolution globally with a higher proportion of place cells, smaller place fields, increased spatial selectivity and stability. Spatial coding resolution was notably enhanced locally near objects and could be rapidly tuned by their manipulations. In the presence of objects, place cells also displayed improved theta phase precession and theta timescale spike coordination. These results suggest that local visual cues can rapidly tune the resolution of the hippocampal mapping system within and between environments.

neuroscience↗

bioRxiv2017

A minority-ruled population coding of kinematics in the striatum

The structure of population activity in the dorsolateral striatum during the performance of motor sequences has not been characterized and it is unclear if striatal ensembles encode (predict) kinematic parameters defining how sequences are executed. Here we analyzed hundreds of striatal spike trains from naive and trained rats performing a running sequence. We found that the population response was composed of a diversity of phasic modulations covering the entire sequence. The accuracy of kinematics encoding by single neurons was around chance level but improved when neuronal ensembles were considered. The distribution of single-neuron contributions to ensemble encoding was highly skewed with a minority of neurons responsible for most of the encoding accuracy. Importantly, running speed ensemble encoding improved after learning. We propose that during motor learning, striatal ensembles adjust their task representation by tuning the activity of a minority of neurons to the kinematic parameters most relevant to motor performance.

neuroscience↗