Topic: GCaMP

A fundamental goal in neuroscience is to connect an animal's behavior to its neural activity. However, imaging neural activity in a behaving animal presents unique challenges because the animal's movements create motion artifacts that, in the worst cases, cannot be distinguished from neural signals of interest. One approach to mitigating motion artifacts is to image two channels simultaneously: one that captures a calcium sensitive fluorophore, such as GCaMP, and another that captures a calcium insensitive fluorophore such as RFP. In principle, because the calcium insensitive channel contains

Efficient spatial navigation in complex environments relies on the construction of an egocentric cognitive map. Recent studies have reported that subpopulations of excitatory neurons in the granular retrosplenial cortex (RSC) are selectively activated at specific distances and orientations relative to environmental boundaries and vertices, tuned by the heading directions of the animal, to perform egocentric vector coding of the environmental geometry. However, the neural circuit mechanisms explaining how egocentric representation of vertices and boundaries emerges are yet unknown. One possible

Neural circuits are reconfigured to tune behaviour to the prevailing conditions. For instance, resting Xenopus laevis tadpoles start swimming when appropriately stimulated, but halt if the same stimulation is applied during ongoing locomotion. These opposite responses can be explained by a reconfiguration of the sensorimotor circuit, so that the same sensory pathway can exert either an excitatory or inhibitory effect on locomotion, depending on the current motor state. This form of neuronal network reconfiguration could be shared by different neuronal networks and across different species.Prev

Perception is inherently variable; the same external stimulus might be detected or missed in different instances. Neuronal signals governing this variability remain elusive. Past studies have shown that mice can be trained to report optogenetic stimulation of primary somatosensory cortex (S1), bypassing the trial-by-trial perceptual variability associated with external stimuli. These studies, however, stimulated different populations of S1 neurons on different trials which may also contribute to perceptual variability. Our aim is to use spatial light modulation (SLM) to stimulate the same S1 n

Episodic memories are crucial elements that determine our sense of identity. Episodic memory formation is mostly dependent on the proper function of the hippocampus. However, mechanisms of episodic memory formation, maintenance and retrieval are only beginning to be elucidated. One of the leading scientific theories about the hippocampal role in memory is indexing theory. This concept builds on the premise that hippocampal neurons are multi-synaptically bi-directionally linked with sensory and associative cortical regions. Nevertheless, it is not clear if cortical reinstating occurs on a neuro

Astrocytes are crucial mediators of brain function on a multimodal level such as energy metabolism or synapse formation and maturation. They form a vast network in the brain and signal both with each other and with neurons. Calcium is the primary information carrier in astrocytes and can be measured using fluorescent indicators. Therapeutic approaches for cognitive diseases are commonly designed to influence neurons, but neglect astrocytes, despite them accounting for half the mass of the brain.Here we use astrocytic calcium signals and recent advances in analysis to develop an astrocytic comp

Deficits in sensory perception characterize Huntington disease (HD), alongside motor and cognitive impairments. This study investigates altered cortical network connectivity in HD, focusing on sensory spread, where sensory stimulation provokes more extensive cortical activity in HD model mice compared to wild-type (WT) controls.In vivo, we utilized widefield, mesoscale calcium imaging in the awake, head-fixed zQ175 mouse model of HD, crossed with Thy1-GCaMP mice, expressing GCaMP in cortical pyramidal neurons. In vivo, LED flashes induced visual responses imaged through an intact-skull cranial

Fluorescent calcium imaging is an essential tool for measuring cellular activity, particularly as it applies to neurons and reporting action potentials. Genetically encoded calcium indicators are incredibly versatile and particularly useful for both in vivo and in vitro research. Depending on the application and use of indicators, the desired properties can drastically change from being very bright, to a very strong signal, to having fast dynamics, or any combination of the three. However, there are several disadvantages to using existing red shifted calcium indicators, those limitations being

As the field of neuroscience has undergone significant advancements in understanding individual brain regions, research aimed at elucidating neural networks within multiple brain areas is increased. Techniques like fluorescence imaging, including GCaMP, stand out as formidable methodologies within brain function research. However, conventional imaging applications face challenges in simultaneously capturing data from multiple regions, particularly including deep brain area. Therefore, we have developed a system for multiple measurements based on a CMOS imaging device that can be directly impla

Head-mounted miniscopes offer an interesting tradeoff: at the expense of image quality and versatility, they enable the correlation of animal behavior with neuronal activity without limiting free movement. Combining this with the ability to use additional fluorescent markers in-vivo, would allow us to gather further information on the observed neurons, such as genetic traits, specific cell-types, or connections to other brain regions. Unfortunately, current miniscopes cannot discriminate more than one additional fluorophore, and sacrificing the animals for post-experiment brain fixation and ex

Synapse loss is an early phenomenon in several neurodegenerative disorders such as Alzheimer’s disease (AD) and strongly correlates with cognitive decline. It can occur via neuron-autonomous responses, or via active removal by microglia and astrocytes.We recently showed that astrocytes contain ingested synapses around plaques in human post-mortem AD brains, and cultured astrocytes show increased ingestion of synapses isolated from AD tissue (Tzioras, Cell.Rep.Medicine2023). It is unclear however if synapse engulfment is a protective event removing dysfunctional synapses or a detrimental phenom

Olfaction is a crucial sense for many species, influencing behavioral responses like mating and reproduction. A significant dopaminergic (DA) population is found in the mouse main olfactory bulb (OB), with inhibitory interneurons identified by tyrosine hydroxylase (TH) expression and divided into two major groups (i.e., small and large cells) according to their shape, generation time, and biophysical characteristics. Although it is known that salient stimuli activate midbrain DA neurons, it is unclear if OB DA cells are involved in processing ethologically relevant odorants, especially those a

The brain allows animals to make dynamic behavioral changes in response to changing internal or external demands. Determining precisely how this happens is challenging because existing methods for recording neural activity perturb natural behavior. With the recent advent of tracking microscopy, the larval zebrafish is an ideal vertebrate model for recording brain-wide cellular-resolution neural activity in freely behaving animals during natural behavior. However, current imaging methods such as structured illumination or light field microscopy, compatible with tracking microscopy, rely on high

The posterior medial nucleus (POm) of the thalamus represents a higher-order thalamic nucleus characterized by its reciprocal connections with the primary somatosensory cortex (S1). It exhibits intricate projections to and from motor, premotor, association cortices, and the brainstem. Owing to its distinct firing characteristics and multifaced connectivity profiles, various functions ranging from maintaining arousal to higher somatosensory processing have been attributed to it. To address functional features of the mouse POm, we image relay neuron activity in freely moving mice while they perf