Publications by authors named "Antonin Blot"

7 Publications

  • Page 1 of 1

A database and deep learning toolbox for noise-optimized, generalized spike inference from calcium imaging.

Nat Neurosci 2021 09 2;24(9):1324-1337. Epub 2021 Aug 2.

Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.

Inference of action potentials ('spikes') from neuronal calcium signals is complicated by the scarcity of simultaneous measurements of action potentials and calcium signals ('ground truth'). In this study, we compiled a large, diverse ground truth database from publicly available and newly performed recordings in zebrafish and mice covering a broad range of calcium indicators, cell types and signal-to-noise ratios, comprising a total of more than 35 recording hours from 298 neurons. We developed an algorithm for spike inference (termed CASCADE) that is based on supervised deep networks, takes advantage of the ground truth database, infers absolute spike rates and outperforms existing model-based algorithms. To optimize performance for unseen imaging data, CASCADE retrains itself by resampling ground truth data to match the respective sampling rate and noise level; therefore, no parameters need to be adjusted by the user. In addition, we developed systematic performance assessments for unseen data, openly released a resource toolbox and provide a user-friendly cloud-based implementation.
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http://dx.doi.org/10.1038/s41593-021-00895-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611618PMC
September 2021

Visual intracortical and transthalamic pathways carry distinct information to cortical areas.

Neuron 2021 06 11;109(12):1996-2008.e6. Epub 2021 May 11.

Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, London, UK; Biozentrum, University of Basel, Basel, Switzerland. Electronic address:

Sensory processing involves information flow between neocortical areas, assumed to rely on direct intracortical projections. However, cortical areas may also communicate indirectly via higher-order nuclei in the thalamus, such as the pulvinar or lateral posterior nucleus (LP) in the visual system of rodents. The fine-scale organization and function of these cortico-thalamo-cortical pathways remains unclear. We find that responses of mouse LP neurons projecting to higher visual areas likely derive from feedforward input from primary visual cortex (V1) combined with information from many cortical and subcortical areas, including superior colliculus. Signals from LP projections to different higher visual areas are tuned to specific features of visual stimuli and their locomotor context, distinct from the signals carried by direct intracortical projections from V1. Thus, visual transthalamic pathways are functionally specific to their cortical target, different from feedforward cortical pathways, and combine information from multiple brain regions, linking sensory signals with behavioral context.
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http://dx.doi.org/10.1016/j.neuron.2021.04.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8221812PMC
June 2021

Cerebellar Contribution to Preparatory Activity in Motor Neocortex.

Neuron 2019 08 11;103(3):506-519.e4. Epub 2019 Jun 11.

Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland; Sainsbury Wellcome Center, University College London, 25 Howland Street, London W1T 4JG, UK. Electronic address:

In motor neocortex, preparatory activity predictive of specific movements is maintained by a positive feedback loop with the thalamus. Motor thalamus receives excitatory input from the cerebellum, which learns to generate predictive signals for motor control. The contribution of this pathway to neocortical preparatory signals remains poorly understood. Here, we show that, in a virtual reality conditioning task, cerebellar output neurons in the dentate nucleus exhibit preparatory activity similar to that in anterolateral motor cortex prior to reward acquisition. Silencing activity in dentate nucleus by photoactivating inhibitory Purkinje cells in the cerebellar cortex caused robust, short-latency suppression of preparatory activity in anterolateral motor cortex. Our results suggest that preparatory activity is controlled by a learned decrease of Purkinje cell firing in advance of reward under supervision of climbing fiber inputs signaling reward delivery. Thus, cerebellar computations exert a powerful influence on preparatory activity in motor neocortex.
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http://dx.doi.org/10.1016/j.neuron.2019.05.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6693889PMC
August 2019

Cerebellar learning using perturbations.

Elife 2018 11 12;7. Epub 2018 Nov 12.

Institut de biologie de l'École normale supérieure (IBENS), École normale supérieure, CNRS, INSERM, PSL University, Paris, France.

The cerebellum aids the learning of fast, coordinated movements. According to current consensus, erroneously active parallel fibre synapses are depressed by complex spikes signalling movement errors. However, this theory cannot solve the of processing a global movement evaluation into multiple cell-specific error signals. We identify a possible implementation of an algorithm solving this problem, whereby spontaneous complex spikes perturb ongoing movements, create eligibility traces and signal error changes guiding plasticity. Error changes are extracted by adaptively cancelling the average error. This framework, (SGDEGE), predicts synaptic plasticity rules that apparently contradict the current consensus but were supported by plasticity experiments in slices from mice under conditions designed to be physiological, highlighting the sensitivity of plasticity studies to experimental conditions. We analyse the algorithm's convergence and capacity. Finally, we suggest SGDEGE may also operate in the basal ganglia.
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http://dx.doi.org/10.7554/eLife.31599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231762PMC
November 2018

Distinct learning-induced changes in stimulus selectivity and interactions of GABAergic interneuron classes in visual cortex.

Nat Neurosci 2018 06 21;21(6):851-859. Epub 2018 May 21.

Biozentrum, University of Basel, Basel, Switzerland.

How learning enhances neural representations for behaviorally relevant stimuli via activity changes of cortical cell types remains unclear. We simultaneously imaged responses of pyramidal cells (PYR) along with parvalbumin (PV), somatostatin (SOM), and vasoactive intestinal peptide (VIP) inhibitory interneurons in primary visual cortex while mice learned to discriminate visual patterns. Learning increased selectivity for task-relevant stimuli of PYR, PV and SOM subsets but not VIP cells. Strikingly, PV neurons became as selective as PYR cells, and their functional interactions reorganized, leading to the emergence of stimulus-selective PYR-PV ensembles. Conversely, SOM activity became strongly decorrelated from the network, and PYR-SOM coupling before learning predicted selectivity increases in individual PYR cells. Thus, learning differentially shapes the activity and interactions of multiple cell classes: while SOM inhibition may gate selectivity changes, PV interneurons become recruited into stimulus-specific ensembles and provide more selective inhibition as the network becomes better at discriminating behaviorally relevant stimuli.
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http://dx.doi.org/10.1038/s41593-018-0143-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390950PMC
June 2018

Time-invariant feed-forward inhibition of Purkinje cells in the cerebellar cortex in vivo.

J Physiol 2016 05 10;594(10):2729-49. Epub 2016 Apr 10.

IBENS, École Normale Supérieure, PSL Research University, CNRS, INSERM, Paris, France.

Key Points: We performed extracellular recording of pairs of interneuron-Purkinje cells in vivo. A single interneuron produces a substantial, short-lasting, inhibition of Purkinje cells. Feed-forward inhibition is associated with characteristic asymmetric cross-correlograms. In vivo, Purkinje cell spikes only depend on the most recent synaptic activity.

Abstract: Cerebellar molecular layer interneurons are considered to control the firing rate and spike timing of Purkinje cells. However, interactions between these cell types are largely unexplored in vivo. Using tetrodes, we performed simultaneous extracellular recordings of neighbouring Purkinje cells and molecular layer interneurons, presumably basket cells, in adult rats in vivo. The high levels of afferent synaptic activity encountered in vivo yield irregular spiking and reveal discharge patterns characteristic of feed-forward inhibition, thus suggesting an overlap of the afferent excitatory inputs between Purkinje cells and basket cells. Under conditions of intense background synaptic inputs, interneuron spikes exert a short-lasting inhibitory effect, delaying the following Purkinje cell spike by an amount remarkably independent of the Purkinje cell firing cycle. This effect can be explained by the short memory time of the Purkinje cell potential as a result of the intense incoming synaptic activity. Finally, we found little evidence for any involvement of the interneurons that we recorded with the cerebellar high-frequency oscillations promoting Purkinje cell synchrony. The rapid interactions between interneurons and Purkinje cells might be of particular importance in fine motor control because the inhibitory action of interneurons on Purkinje cells leads to deep cerebellar nuclear disinhibition and hence increased cerebellar output.
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http://dx.doi.org/10.1113/JP271518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865585PMC
May 2016

Ultra-rapid axon-axon ephaptic inhibition of cerebellar Purkinje cells by the pinceau.

Nat Neurosci 2014 Feb 12;17(2):289-95. Epub 2014 Jan 12.

1] Ecole Normale Supérieure, IBENS, Paris, France. [2] CNRS, UMR 8197, Paris, France. [3] INSERM, U1024, Paris, France.

Excitatory synaptic activity in the brain is shaped and balanced by inhibition. Because inhibition cannot propagate, it is often recruited with a synaptic delay by incoming excitation. Cerebellar Purkinje cells are driven by long-range excitatory parallel fiber inputs, which also recruit local inhibitory basket cells. The axon initial segment of each Purkinje cell is ensheathed by basket cell axons in a structure called the pinceau, which is largely devoid of chemical synapses. In mice, we found at the single-cell level that the pinceau mediates ephaptic inhibition of Purkinje cell firing at the site of spike initiation. The reduction of firing rate was synchronous with the presynaptic action potential, eliminating a synaptic delay and allowing granule cells to inhibit Purkinje cells without a preceding phase of excitation. Axon-axon ephaptic intercellular signaling can therefore mediate near-instantaneous feedforward and lateral inhibition.
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http://dx.doi.org/10.1038/nn.3624DOI Listing
February 2014
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