The Matrix: A new tool for probing the whisker-to-barrel system with natural stimuli

CNRS, Unité de Neurosciences, Information et Complexité (UNIC), 1 avenue de la Terrasse, 91190 Gif sur Yvette, France.
Journal of Neuroscience Methods (Impact Factor: 2.05). 03/2010; 189(1):65-74. DOI: 10.1016/j.jneumeth.2010.03.020
Source: PubMed


The whisker to barrel system in rodents has become one of the major models for the study of sensory processing. Several tens of whiskers (or vibrissae) are distributed in a regular manner on both sides of the snout. Many tactile discrimination tasks using this system need multiple contacts with more than one whisker to be solved. With the aim of mimicking those multi-whisker stimuli during electrophysiological recordings, we developed a novel mechanical stimulator composed of 24 independent multi-directional piezoelectric benders adapted to the five rows and the five caudal arcs of the rat whisker pad. The most widely used technology for producing mechanical deflections of the whiskers is based on piezoelectric benders that display a non-linear behavior when driven with high frequency input commands and, if not compensated, show high unwanted ringing at particular resonance frequencies. If not corrected, this non-linear behavior precludes the application of high frequency deflections and the study of cortical responses to behaviorally relevant stimuli. To cope with the ringing problem, a mechanical and a software based solutions have been developed. With these corrections, the upper bound of the linear range of the bender is increased to 1 kHz. This new device allows the controlled delivery of large scale natural patterns of whisker deflections characterized by rapid high frequency vibrations of multiple whiskers.

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Available from: Luc Estebanez
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    • "To finally validate our 2-D barrel map reconstruction method, we confronted its resulting map with the functional organization of the barrel cortex established in vivo by real time imaging of cortical responses to individual whisker deflections under urethane anesthesia (n = 4 experiments). Using a mechanical multi-whisker stimulator (Jacob et al., 2010), we deflected independently the 24 principal whiskers in a pseudo random order, and imaged the evoked cortical responses in the contralateral barrel cortex using the VSD RH1691. Fig. 5 illustrates the results obtained from one experiment. "
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    ABSTRACT: Background: The rodent barrel cortex is a widely used model to study the cortical processing of tactile sensory information. It is notable by the cytoarchitecture of its layer IV, which contains distinguishable structural units called barrels that can be considered as anatomical landmarks of the functional columnar organization of the cerebral cortex. To study sensory integration in the barrel cortex it is therefore essential to map recorded functional data onto the underlying barrel topography, which can be reconstructed from the post hoc alignment of tangential brain slices stained for cytochrome oxidase. New method: This article presents an automated workflow to perform the registration of histological slices of the barrel cortex followed by the 2-D reconstruction of the barrel map from the registered slices. The registration of two successive slices is obtained by computing a rigid transformation to align sets of detected blood vessel cross-sections. This is achieved by using a robust variant of the classical iterative closest point method. A single fused image of the barrel field is then generated by computing a nonlinear merging of the gradients from the registered images. Comparison with existing methods: This novel anatomo-functional mapping tool leads to a substantial gain in time and precision compared to conventional manual methods. It provides a flexible interface for the user with only a few parameters to tune. Conclusions: We demonstrate here the usefulness of the method for voltage sensitive dye imaging of the mouse barrel cortex. The method could also benefit other experimental approaches and model species.
    Full-text · Article · Sep 2015 · Journal of Neuroscience Methods
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    • "We used sparse noise stimuli applied via a nine-whisker stimulator (Jacob et al., 2010) to map receptive fields (Figures 3A and 3B). Examples of LV receptive fields evaluated using peristimulus time histograms (PSTH) and whisker-evoked postsynaptic potentials (wPSP) are shown in Figure 3C (neurons 2 and 4 are D-row deprived). "
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    ABSTRACT: Most functional plasticity studies in the cortex have focused on layers (L) II/III and IV, whereas relatively little is known of LV. Structural measurements of dendritic spines in vivo suggest some specialization among LV cell subtypes. We therefore studied experience-dependent plasticity in the barrel cortex using intracellular recordings to distinguish regular spiking (RS) and intrinsic bursting (IB) subtypes. Postsynaptic potentials and suprathreshold responses in vivo revealed a remarkable dichotomy in RS and IB cell plasticity; spared whisker potentiation occurred in IB but not RS cells while deprived whisker depression occurred in RS but not IB cells. Similar RS/IB differences were found in the LII/III to V connections in brain slices. Modeling studies showed that subthreshold changes predicted the suprathreshold changes. These studies demonstrate the major functional partition of plasticity within a single cortical layer and reveal the LII/III to LV connection as a major excitatory locus of cortical plasticity.
    Full-text · Article · Jan 2012 · Neuron
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    • "A recently developed whisker stimulation matrix based on piezoelectric benders (Jacob et al. 2010) was used to deflect independently the 24 most caudal whiskers of the right whisker pad (Fig. 1A). Whiskers were trimmed to 10-mm length and were inserted 3 mm into small plastic tubes of calibrated diameter glued on each bender. "
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    ABSTRACT: The tactile sensations mediated by the whisker-trigeminal system allow rodents to efficiently detect and discriminate objects. These capabilities rely strongly on the temporal and spatial structure of whisker deflections. Subthreshold but also spiking receptive fields in the barrel cortex encompass a large number of vibrissae, and it seems likely that the functional properties of these multiwhisker receptive fields reflect the multiple-whisker interactions encountered by the animal during exploration of its environment. The aim of this study was to examine the dependence of the spatial structure of cortical receptive fields on stimulus parameters. Using a newly developed 24-whisker stimulation matrix, we applied a forward correlation analysis of spiking activity to randomized whisker deflections (sparse noise) to characterize the receptive fields that result from caudal and rostral directions of whisker deflection. We observed that the functionally determined principal whisker, the whisker eliciting the strongest response with the shortest latency, differed according to the direction of whisker deflection. Thus, for a given neuron, maximal responses to opposite directions of whisker deflections could be spatially separated. This spatial separation resulted in a displacement of the center of mass between the rostral and caudal subfields and was accompanied by differences between response latencies in rostral and caudal directions of whisker deflection. Such direction-dependent receptive field organization was observed in every cortical layer. We conclude that the spatial structure of receptive fields in the barrel cortex is not an intrinsic property of the neuron but depends on the properties of sensory input.
    Full-text · Article · Jun 2011 · Journal of Neurophysiology
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