Topic: GCaMP6s

Recent population imaging studies in mouse primary visual cortex (V1) have revisited and questioned the traditional view of 'salt-and-pepper' organization of orientation tuning preference. A controversy has emerged on whether the organization is truly spatially disorganized, or if there is long-range (~100 μm) or short range (~10 μm) spatial clustering of orientation tuning. We imaged and analyzed the response profile (to orientated gratings) of in vivo populations of layer 2/3 (L2/3) and layer 4 (L4) neurons with a neuropil-free nuclear-targeted GCaMP6s indicator. These datasets provide an un

In ferret visual cortex, spontaneous activity prior to eye-opening is organized into large-scale, modular patterns in the absence of long-range horizontal projections. This correlated activity reveals endogenous networks that predict aspects of future orientation selectivity [1]. Previous modelling works have shown that the long-range correlations observed in these networks can arise from purely locally connected neurons through multi-synaptic interactions [1][2]. Here we seek to explicitly map the structure of cortical lateral interactions through localized perturbations in vivo. We first con

Understanding how cortical circuits generate complex behavior requires investigating the cell types that comprise them. Here, much effort has been focused on inhibitory neuron types but the functional roles of distinct classes of excitatory pyramidal neurons (PyNs) are less well un-derstood. We, therefore, used widefield imaging to measure the cortex-wide activity of distinct PyN types and investigated their functional role in mice that performed an auditory decision-making task. We used two mouse lines, expressing the calcium indicator GCaMP6s in two major PyN types: FezF2 for pyramidal-tract

Sensory experience and perceptual learning changes receptive field properties of cortical pyramidal neurons possibly mediated by long-term potentiation (LTP) of synapses. We have previously shown in the mouse somatosensory cortex (S1) that sensory-driven LTP in layer (L) 2/3 pyramidal neurons is dependent on higher order thalamic feedback from the posteromedial nucleus (POm), which is thought to convey contextual information from various cortical regions integrated with sensory input. We have followed up on this work by dissecting the cortical microcircuitry that underlies this form of LTP

Global excitatory activity patterns across the dorsal cortex are reorganized when mice perform perceptual decision-making tasks that involve different underlying computations and vary in complexity. However, the circuit mechanisms enabling such large-scale activity reorganization remain unknown. An interesting possibility is that they depend on neuromodulatory input to the cortex. In particular, cholinergic neurons in the basal forebrain project widely across cortical areas while exhibiting topographical and functional heterogeneity. They are therefore well equipped to serve as an orchestrator

Hippocampal dentate gyrus (DG) is essential for encoding highly similar inputs into distinct neural representations. This function is mainly attributed to the sparsely firing excitatory granule cells. It is not known how excitatory DG neurons modify their firing patterns in response to different conditions, to facilitate learning. We studied the activity of excitatory DG neurons during discrimination fear conditioning task (FC) using in vivo one-photon calcium imaging in adult, healthy C57/black mice. We compared learning in males (n = 6) and females (n = 6) and further, in voluntarily running

Auditory processing is widely understood to occur differently in autism, though the exact brain activity underlying these differences is not well understood. The diversity of autism also means there may be multiple ways the network can change to produce a similar behavioural output. We used larval zebrafish to investigate auditory habituation in four genetic models of autism: fmr1, mecp2, scn1lab and cntnap2. Larval zebrafish are optically transparent, enabling whole-brain imaging of neural activity at single-cell resolution using genetically encoded calcium indicator GCaMP6s. In free-swimming

The interplay between spontaneous and sensory-driven activity plays a critical role in regulating neuronal structure and function of neuronal circuits during development. Here, we investigated how deprivation of visual inputs (dark rearing) during the early stage of development affects sensori-motor integration at the behavior and neuronal circuit level. Due to the intrinsic characteristic of the mammalian brain, it has not been possible to analyze simultaneously the impact of neuronal activity in shaping circuits across neuronal populations in distinct brain areas. To overcome this limitation

Standard models of episodic memory emphasise that parallel streams of spatial information, arriving from medial entorhinal cortex (MEC), and object information, arriving from lateral entorhinal cortex (LEC), are integrated within the hippocampus. However, we recently discovered that fan cells in the LEC send direct projections to MEC, suggesting that spatial and object information could be integrated within MEC (Vandrey et al. 2022, doi:10.7554/eLife.83008). Evidence for object-related firing in the MEC is consistent with this possibility, but whether LEC projections influence spatial and obje

In this study, we investigate how contextual memory is shaped by observational fear learning during encoding and recall. We are imaging neurons in layer 2/3 of the retrosplenial cortex in GCaMP6s mice with two-photon Ca2+ imaging using a head-fixed observational fear learning paradigm in virtual reality. The animals are surrounded by three screens and run on a running wheel as they travel through 3 different VR environments. In two of the environments, we play recordings of mouse vocalisations emitted while they were receiving foot shocks, and a neutral sound in the third environment. A single

In ferret visual cortex, spontaneous activity before eye-opening is organised into large-scale, modular patterns in the absence of long-range projections. This correlated activity reveals endogenous networks that predict aspects of future orientation selectivity. Previous modelling works have shown that the long-range correlations observed in these networks can arise from locally connected neurons through multi-synaptic interactions. Here we seek to map the structure of cortical lateral interactions through localised perturbations in vivo.We first constructed a rectified recurrent neural netwo

Spontaneous activity in peripheral sensory neurons has been associated with pain in people with chronic neuropathic and musculoskeletal conditions. It can also be observed in rodent models of chronic pain, where it has traditionally been studied by making electrophysiology recordings from nerve fibres emerging from the dorsal root ganglion. However, these experiments are technically challenging, low-throughput, and prone to bias, with small diameter fibres being most at risk of being under sampled. More recently, in vivo calcium imaging has been adopted to study sensory neuron activity in rode

The basal ganglia (BG) is a group of sub-cortical nuclei involved in motor control, learning and attention. The primary input nucleus of the BG is the striatum which receives cortical, thalamic and midbrain afferences on its two striatal projecting neurons’ (SPN) populations (the direct (d) and indirect (i) pathways) in a manner that remains elusive. Research on SPNs has mainly focused on characterizing its involvement in motor control rather than single neuron activity evolution during the process of action learning. This project aimed to dissect the relative contributions of both d- and i-SP

[Aims] Neurons in mouse visual cortex encode high-dimensional sensory information and lower-dimensional behavioral variables. Here we asked how behavioral signals are organized across the cortical volume, and whether they follow the organization of visual activity.[Methods] We used Light Beads Microscopy (Demas et al, 2021) to functionally image Ca2+ transients at cellular resolution from large volumes of cortex (3 x 3 x 0.5 mm^3) in awake, headfixed transgenic mice expressing GCaMP6s. To segment individual cells, we developed a novel volumetric cell extraction pipeline by accelerating and ext

The mammalian cerebral cortex presents a modular organization, enabling the segregation of specialized functions and the generation of complex cognitive states. In the mouse, the anatomical and functional correlates of this network topology arise during the perinatal period. Especially after birth, spontaneous neural activity and sensory inputs trigger complex spatio-temporal firing patterns, which affect the cytoarchitecture and connectivity of cortical regions. Thus, understanding how local activity patterns emerge, interact and impinge on cortex-wide dynamics is essential to elucidate the p

This study is aimed to understand sensory nerve endings’ functional organization and morphology in the adult mouse cornea. Free nerve endings are essential for the sensory transduction of noxious and innocuous stimuli. However, their functional organization still needs to be fully understood. To investigate this, we used GCaMP6s-based in vivo imaging of calcium signals evoked by menthol and capsaicin in corneal nerve endings of 5-6 week-old C57 mice (Fig. 1A). We then acquired 3D confocal images of their morphological structure and examined the contribution of voltage-gated calcium channels (V

The inferior olive (IO) is an evolutionary conserved brain region important for motor learning. As part of the olivo-cerebellar system (OCS), the IO sends climbing fiber projections to the Purkinje neurons (PN) and generates complex spikes. Despite its significance, the mechanisms guiding IO responses to sensory inputs for complex spike generation are unclear. This project aims to uncover how IO neurons integrate sensory input, impacting cerebellar control of movement.Focusing on IO afferents from the superior colliculus (SC), crucial for orienting behavior, we identified a novel target area f

Living functions depend on temperature: an optimal one may increase the rate of development and reproduction, while extreme ones may stop basic biochemical reactions affecting an organism irreversibly. Therefore, sensing temperature and thermoregulatory behaviours may have been core functions of the nervous system since its origin in multicellular animals. It is possible to shed light on this hypothesis by studying cnidarians. Cnidarians (e.g., jellyfish) and bilaterians split from a common ancestor, the first carrier of neurons, about 750 million years ago. Neural thermal responses and thermo