Topic: sensory cortex

The sensory cortex is widely considered to be specialized for perception by interpreting complex sensory patterns while also exhibiting structured forms of representational plasticity of behaviorally-relevant stimuli. Recent evidence, however, suggests that sensory cortical neurons directly encode non-sensory variables such as movement and valence. Conjoint representations of sensory and non-sensory variables in the same network could further hone perception or, alternatively, subserve more integrative cognitive processes. Here, we ask the extent to which the sensory cortex is an associative e

Exploring novel approaches to auditory rehabilitation, we aim to demonstrate, in mice, the efficiency of an optogenetic cortical implant. Several studies have shown that mice can use patterned optogenetic stimulations of the sensory cortex to drive their behaviour. It was however never tested if it is possible to provide a detailed representation of sensory inputs through such stimulation patterns. To explore this key question for cortical implant devices, we developed a novel sensory encoding model based on a convolutional autoencoder, which is able to temporally compress and denoise 500ms so

Pyramidal neurons have apical dendrites that are both physically and electrically segregated from their cell bodies. In sensory cortex, these apical dendrites receive primarily top-down signals from associative and motor regions, while the cell bodies and nearby dendrites of these same pyramidal neurons are mostly targeted by bottom-up or locally recurrent inputs from the sensory periphery. Due to these differences, a number of theories in computational neuroscience postulate a unique role for apical dendrites in shaping sensory processing and plasticity in the face of new or surprising stimul

Neurons are typically sensitive to a small fraction of possible stimuli in sensory space. If the environment changes, making certain stimuli more prevalent, neurons sensitive to those stimuli respond more often and therefore have a higher average firing rate. Prolonged exposure to such an environment often causes such neurons to adapt by responding less vigorously. If adaptation consistently returns the average firing rate to its value prior to environmental shift, it is termed firing-rate homeostasis. We present a normative explanation of firing-rate homeostasis grounded in the Infomax princi

To generate brain circuits that are both flexible and stable requires the coordination of powerful developmental mechanisms acting at different scales, including activity-dependent synaptic plasticity and changes in single neuron properties. The brain prepares to efficiently compute information and reliably generate behavior during early development without any prior sensory experience but through patterned spontaneous activity. After the onset of sensory experience, ongoing activity continues to modify sensory circuits, and plays an important functional role in the mature brain. Using quantit

The response of sensory neurons to different stimuli are largely characterized by tuning curves, with a peak of activity at a preferred stimulus. Tuning curves are thought to be shaped by Hebbian plasticity during development through the strengthening of synapses between neurons with similar functional preferences. This raises the hypothesis that the strength of synapses should correlate with the difference in functional preference between pre- and postsynaptic activity. A recent study, however, found that the functional preference of cortical neurons was correlated with the number of spines a

Sensory cortex exhibits highly variable responses to the same stimulus across trials. This variability is correlated across neurons. The pattern of correlated variability is important because it informs us about stimulus encoding and the underlying structural connectivity. In visual areas, it has been shown that correlated variability depends on orientation tuning. However, it is challenging to interpret this tuning dependence when the spikes are generated from a doubly stochastic Poisson process, which is commonly assumed. In this case, spikes can exhibit tuning-dependent noise correlation, e

Neural activity in sensory cortex combines stimulus responses and ongoing activity, but it remains unclear whether they reflect the same underlying dynamics or separate processes. Here we show that during wakefulness, the neuronal assemblies evoked by sounds in the auditory cortex and thalamus are specific to the stimulus and distinct from the assemblies observed in ongoing activity. In contrast, during anesthesia, evoked assemblies are indistinguishable from ongoing assemblies in the cortex, while they remain distinct in the thalamus. A strong remapping of sensory responses accompanies this d

Animals naturally display a wide range of behaviours in varying contexts. Not only do their actions depend on their internal states, but also how their early sensory cortex processes information. Here, we propose that contextual top-down afferents adapt the receptive fields of sensory neurons to accommodate varying task demands. Although this view is widely supported by connectomic and electrophysiological evidence, a mechanistic and, in particular, a normative understanding is still lacking. We investigate how task-dependent top-down signals can reshape the functional mapping of sensory proce

Neuronal sensitivity and selectivity to our environment arise from the transformation of external inputs by the cortical circuitry. We dissect the circuitry for this emergence using a combination of large-scale simultaneous measurements from single cells in awake animals and computational models. In area MT, an area of the neocortex that processes visual motion, even weak motion signals evoke selective responses in the presence of noise. We also observe tuned patterns of activity in the absence of visual motion that suggest feature-selective amplification within the circuit. In addition, respo

Regulation of information flow in the brain is critical for many forms of behavior. In the process of sensory based decision-making, decisions about future actions are held in memory until enacted, making them potentially vulnerable to distracting sensory input. Therefore, gating of information flow from sensory to motor areas could protect memory from interference during decision-making, but the underlying network mechanisms are not understood. I will present our recent experimental and modeling work describing how information flow from the sensory cortex can be gated by state-dependent front

Flexible decision making is an indispensable ability for humans. Although neurons in decision-related cortex accumulate relevant information preferentially depending on context, how sensory information represented in sensory cortex is conveyed to decision-related cortex remains unclear. To elucidate this question, we investigated the functional connectivity between sensory cortex (area MT) and decision-related cortex (area LIP) by recording simultaneously from both areas using two electrodes while monkeys performed a switching task.Two Japanese macaques were trained to flexibly switch between