Channelrhodopsin

…tagged c-fos activity combined with channelrhodopsin expression, we directly measured the synaptic strength between neurons in the Piriform cortex (PCx) following mice learning an odor discrimination task. Our results suggest that an assembly forms after learning, but

A fundamental property of neurons in the primary visual cortex is their preference for orientation of edges. It was shown that this orientation tuning is mostly invariant under contrast changes [1], a property that is not explained by a simple feed-forward scheme [2, 3]. We designed a synthetic hybrid neural circuit to study the emergence of orientation selectivity under different thalamo-cortical connections. To this end, a computational model of the retino-thalamic pathway was combined with an in-vitro model of cortical input layer 4. The latter was either a primary culture of cortical neur

In cases of profound cochlear dysfunction, electrical cochlear implants (eCIs) offer partial restoration of hearing. Nevertheless, the auditory experience with eCIs remains imperfect due to the broad excitation of auditory nerve neurons by electrical signals that limits the perceptual channels available to users. Optogenetics offers a breakthrough by enabling the stimulation of the auditory nerve by an optical cochlear implant (oCI). Light, unlike electrical signals, can be precisely confined in space, resulting in reduced spread of excitation and improved frequency selectivity. However, optog

Grid cells are believed to be key neurons in spatial navigation. Their mechanisms and operation have been described via the theoretical framework of continuous attractor networks (CANs). While increasing evidence points to a CAN mechanism for grid cells, one fundamental aspect of grid cell CAN models remains untested, namely the prediction that population activity is determined by specific patterns of recurrent connectivity. In particular, many CAN models require a Mexican hat connectivity profile with excitatory connections between functionally similar neurons and inhibition between more diss

Neuronal diversity in the cortex is the largest amongst GABAergic neurons. In the hippocampus, GABAergic cells have been sorted in several groups based on their morphology, firing patterns, connectivity, molecular profiling, and RNA content. Identification and manipulation of these neuron types is a prerequisite to deciphering their role in circuit dynamics, behavior, and the computational mechanisms of the cortical networks they are embedded in. We first grouped the virtual totality of GABAergic neurons into four major families. Parvalbumin-expressing neurons, Somatostatin-expressing neurons,

A fundamental property of neurons in the primary visual cortex is their preference for orientation of edges that is invariant under contrast changes. We designed a synthetic hybrid neural circuit to study the emergence of orientation selectivity under different thalamo-cortical connection schemes. To this end, a computational model of the retino-thalamic pathway was combined with an in-vitro model of cortical input layer 4. The latter was either a primary culture of cortical neurons or an acute horizontal brain slice of primary visual cortex. The two stages were interfaced optogenetically by e

…following a viral delivery of a Channelrhodopsin (ChR) transgene to the cochlea. Our group has provided in vivo evidence to support the clinical potential of the optical CI, but for clinical translation, it is critical to optimize individual components of the gene therapy. To this end, we have employed

When learning goal-directed behaviours, new associations are made to achieve the desired motor output. The secondary motor cortex (M2), a frontal area of the rodent cortex, is a key region for transforming sensory information into a motor output. M2 has also been linked anticipation, impulse control, and short-term memory. Yet, our understanding of how M2 is involved in goal-directed behaviours remains lacking. Here, we used widefield, calcium imaging to measure cortical activity as mice learnt to discriminate two tactile stimuli. During learning of this goal-directed sensory-discrimination ta

As part of the NeuChiP project aimed at developing Biological AI, we aimed to establish the plasticity properties of human-induced pluripotent stem cell (hiPSC) derived cortical networks. Objectives were to establish capacity and characteristics of human cultured networks.To achieve this, we engineered mouse cortical cultures and hiPSC-derived cortical neural networks into mature, specific configurations. Functional assessments were conducted with fluorescence calcium imaging and planar HD-MEA electrophysiological recording (3Brain - Duplex system).iPSC derived neural cultures were plated on c

…slices from mice expressing channelrhodopsin specifically i

We used dense (20 m site spacing) local field potential (LFP) and single unit recordings across all layers of the gRSC concurrent with CA1 LFP recordings in behaving mice to investigate circuit activity of high-frequency oscillations (HFOs) in theta and sharp wave-ripples (SWRs). By comparing HFOs occurring at times of SWRs (+/-50 ms) or during theta, we found using current-source density analysis that HFOs in different states are uniformly localized to layer 2/3 (L2/3) with current sources and sinks bridging the L1-L2/3 border. HFOs that occurred outside of SWR times where rhythmically locke