Topic: 2-photon calcium imaging

Natural visual environments are full of complex and diverse patterns. Recent neurophysiological experiments based on artificial patterns have suggested that macaque V1 neurons’ receptive fields are more complex and diverse in feature selectivity (Tang et al 2017) rather than just oriented Gabor filters. However, that finding was based on extensive parametric artificial stimuli used and might be biased. Hence, the nature of the neural codes of macaque V1 neurons remains controversial. To resolve this question, we performed 2-photon calcium imaging on three macaque monkeys to obtain 1689 V1 neur

Perception of vocalizations is critical for many species. In mammals, the central auditory pathway is highly interconnected, with corticofugal feedback projections from auditory cortex (AC) to the auditory midbrain that rival the density of feed-forward auditory input. These projections support sound localization, feature coding, and noise invariance. Because vocalizations are acoustically complex and carry social significance, we hypothesize that feedback projections from AC enable behavioral responses. Infant vocalizations that elicit parental care are highly conserved in mammals. In mice, e

To navigate, we must continuously estimate the direction we are headed in, and we must use this information to guide our path toward our goal (Schöne, 2014). Direction estimation is accomplished by ring attractor networks in the head direction system (Knierim et al., 2012, Hulse et al., 2020). However, we do not understand how the sense of direction is used to guide action. Drosophila connectome analyses (Rayshubskiy et al., 2020, Hulse et al., 2021) recently revealed two cell types (PFL2 and PFL3) that connect the head direction system to the locomotor system. These populations also receive a

Systems neuroscience experiments generate multimodal data streams, including neuronal activity, stimuli, movement, and behavior events. In analysis, it can be beneficial to avoid hypothesis-driven models and instead take a data-driven approach. For this, we need a general purpose framework to handle the diverse data, and identify relationships across space, time, and modalities in a computationally efficient manner. In this work, we introduce such a framework. Our model, called the Neuroformer, can simulate neuronal populations, and jointly process an arbitrary number of additional modalities

The hippocampus creates a cognitive map of the world to optimize predictions and guide behavior, with the dorsal and ventral hippocampus believed to play unique roles in this process. To understand how such representations evolve with learning and are updated with new experience, we used 2-photon calcium imaging to track the same dCA1 or vCA1 neurons across days as mice learned to associate odor stimuli with different outcomes. During reward (sucrose) associative learning, we find that, initially, odor cues elicited robust responses in dCA1, whereas in vCA1 encoding of odor identity was reduce

Along with other visual features, chromatic information is extracted by the retina. The excitatory, feedforward pathways of chromatic signals in the mouse retina have recently been investigated (Szatko et al., 2020), but it is unclear how inhibitory cell types contribute. In particular, a systematic characterization of chromatic responses in amacrine cells (ACs), the largest and most diverse retinal class of inhibitory neurons, is missing, and the ACs’ role in color processing remains unknown. One challenge in studying AC responses is the fact that most of them lack axons and signal primarily

Cortical activity changes dramatically upon changes in behavioral state, such as between sleep versus wake (McGinley et al 2015). Though the mechanisms enabling these distinct modes of cortical operation remain largely unknown, inhibitory neurons (INs) have been suggested repeatedly as a regulator of behavioral-state dependent neocortical activity (Batista-Brito et al 2018, Cardin et al 2019, Bugeon et al 2021). Here we investigate how a unique subpopulation of long-range INs impact cortical states. These cells are defined by the co-expression of somatostatin (SST) and neuronal nitric oxide sy

Recurrent neural networks (RNNs) have increasingly been employed to model cortical function, but conventional architectures lack biological realism. Notably, they often ignore two key biological principles: i) Dale’s Law, which constrains neurons to either be strictly excitatory or inhibitory, and ii) Sparse, structured connectivity motifs observed in the brain. Incorporating these constraints however poses challenges, as they often affect model performance negatively. Our work presents a novel approach that integrates Dale’s backpropagation, a sign-constrained training method, with topologica

Animals encode sensory stimuli with precisely timed activity across modalities. For example, mice can rapidly recognize odors, independent of their concentration, based on complex spatiotemporal patterns of mitral and tufted cell (MTC) activity in the olfactory bulb. Yet, it remains unknown how sequential MTC activity is organized, and what role sequential activity plays in guiding perception. Here, we performed fast 2-photon calcium imaging of hundreds of MTCs with sub-sniff temporal resolution to a battery of odors. We constructed a space of MTC tuning using the pairwise correlations between

The mammalian Prefrontal Cortex (PFC) has been suggested to modulate sensory information processing across multiple cortical regions via long-range axonal projections. These axonal projections arise from discrete PFC subregions with unique brain-wide connectivity and functional repertoires, which may provide the architecture for modular feedback intended to shape sensory processing. Here, we used axonal tracing, axonal and somatic 2-photon calcium imaging, and chemogenetic manipulations in mice to delineate how projections from the Anterior Cingulate Cortex (ACA) and ventrolateral Orbitofronta

Corticocollicular (CC) projections arise in deep layers of the auditory cortex and modulate upstream auditory information in the inferior colliculus (IC), forming feedback loops. They are crucially involved in auditory-related learning and frequency response modulations in auditory brainstem. Through widefield and 2-photon calcium imaging in awake mice we prior were able to show that layer 5 CC neurons display only a subtle topographic organization when compared to other layer 5 neuron types (Schmitt et al., 2023, Front Neural Circuit). However, these data were acquired under passive listening

Retinal ganglion cells (RGCs) transmit visual information from the retina to the brain and are conserved among vertebrates. In zebrafish, RGCs project their axons to downstream brain areas known as arborization fields (AFs). Previous anatomical studies have demonstrated that each RGC axon targets one or a few of AF1-9 and 10 distinct layers of AF10 (optic tectum). Although it was proposed that each projection type represents one functional type, the correspondence between morphology and function of genetically defined RGC subtypes is still unclear. To address this question, we focused on RGC s

Brains of different individuals perform common essential functions despite differences in character, skills, perception or learning abilities. These fundamental observations suggest that neuronal computations exhibit different degrees of invariance to natural variability in the structure and dynamics of neuronal circuits. To understand the relation between structural and functional variability in a complex sensory network we focus on the olfactory bulb (OB) of larval zebrafish. The OB is optically accessible and sufficiently small to enable dense ultrastructural reconstructions of neuronal cir

In adult mouse visual cortex, neuronal responses to visual stimuli undergo gradual and continuous changes over time. This phenomenon called “representational drift” has also been observed in other sensory and higher cortical areas and has profound implications for coding strategies in the brain.It is unknown which tuning feature changes of individual neurons underlie representational drift in the primary visual cortex (V1), and what regulates their drift. Using repeated 2-photon calcium imaging in awake mice, we show a slow, time-dependent drift of the preferred orientation of V1 neurons over

In all metazoans, neural circuit function is subject to regulation by state-specific neuromodulation. Here, we mapped the expression of neuromodulatory systems in the zebrafish telencephalon to ultimately understand their contributions to memory formation. We first generated a comprehensive single-cell RNA sequencing dataset of the telencephalon of adult zebrafish and mapped the diversity of neuronal cell types to anatomical brain areas. Gene expression data of G-protein coupled receptors were mined to embed individual cell types in neuromodulatory networks, allowing inference about which modu

The Dentate Gyrus (DG) receives rich multimodal inputs from the entorhinal cortex through the perforant path, and it translates them into a sparse code for the CA3. During the exploration of new environments, groups of DG granule cells (GCs) become active and form new memories. The activity of GCs is strongly modulated by a large network of inhibitory interneurons (INs) that allow the sparsification and orthogonalization of cortical inputs. Recently, a novel population of GABAergic INs expressing the Neuron-Derived Neutrophic Factor (NDNFIs) has been identified as a key component in the modula

Behavioural responses to identical stimuli differ depending on the context, history and goals of the individual. One way to dynamically modulate sensorimotor transformations is to emphasise or de-emphasise particular spatial locations, a process called selective spatial attention. Spatial processing and goal-directed behaviour are thought to be critically dependent on the superior colliculus (SC). Evidence for this comes from local single-unit recordings that reveal a spatial organisation of visual and behavioural representations. However, the broader population dynamics and mechanisms orchest

For many animals color vision is critical to make sense of their environment. Whether it's choosing the ripest fruit or identifying a potential mate, the perception of color is vital for the execution of these complex behaviors. How colors are processed in the central nervous system of di- and trichromatic vertebrate species has been topic of considerable research over the last decades. In contrast, the neuronal circuits supporting color vision in tetrachromatic vertebrates, such as birds, remain less well understood. Using newly developed in vivo 2-photon calcium imaging methodology and high-

Exaggerated responses to sensory stimuli is a hallmark of Fragile X syndrome (FXS), contributes to, inattention, anxiety, and learning challenges. Such sensory hypersensitivity are recapitulated in the Fmr1 knockout (KO). Recent studies in Fmr1 KO mice have demonstrated differences in GABAergic inhibition, including activity of cortical interneurons as well as a delayed switch in the polarity of GABA signaling during development. Previously, we found that administration of bumetanide to block the chloride (Cl-) transporter NKCC1, could rescue synaptic circuit phenotypes in primary somatosensor

Binocular viewing improves several aspects of visual detection compared to viewing with one eye alone, in a process known as binocular summation. A striking example of this perceptual binocular enhancement is how binocular viewing enables the detection of lower contrasts compared to monocular viewing. However, the neuronal substrate of such improved binocular contrast detection in the visual system has so far been poorly understood. The majority of binocular interactions are thought to occur in binocular neurons of the visual cortex. Earlier parts of the image-forming visual pathway have been

Rapid eye movement (REM, also called paradoxical) sleep correlates with enhanced cellular activity in region-specific thalamo-cortical circuits and subcortical structures including the hippocampus, midbrain or hypothalamus. This REM sleep specific neuronal activity is hypothesized to promote structural plasticity and provide a window for the consolidation of contextual and emotional memories previously acquired during wakefulness, yet the underlying mechanism remains unclear.Amongst the cortical structures, the activity of neurons located in the retrosplenial cortex (RSC) is increased during R