Publications by authors named "Brett D Mensh"

All cells in an animal collectively ensure, moment-to-moment, the survival of the whole organism in the face of environmental stressors. Physiology seeks to elucidate the intricate network of interactions that sustain life, which often span multiple organs, cell types, and timescales, but a major challenge lies in the inability to simultaneously record time-varying cellular activity throughout the entire body. We developed WHOLISTIC, a method to image second-timescale, time-varying intracellular dynamics across cell-types of the vertebrate body.

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From an eagle spotting a fish in shimmering water to a scientist extracting patterns from noisy data, many cognitive tasks require untangling overlapping signals. Neural circuits achieve this by transforming complex sensory inputs into distinct, separable representations that guide behavior. Data-visualization techniques convey the geometry of these transformations, and decoding approaches quantify performance efficiency.

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Objective: Spinal cord injury (SCI) damages synaptic connections between corticospinal axons and motoneurons of many muscles, resulting in devastating paralysis. We hypothesized that strengthening corticospinal-motoneuronal synapses at multiple spinal cord levels through Hebbian plasticity (i.e.

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Article Synopsis
  • - Animals use their movements to track where they are in space, but it’s unclear how this works in older brain structures compared to the mammalian brain.
  • - In a study with larval zebrafish in a virtual swimming environment, researchers found that the fish could remember their previous locations and swim back to them after being moved involuntarily.
  • - The study identified a network in the brain that helps remember these locations and influences movement, showing that even ancient brain regions in vertebrates play a crucial role in integrating motion and controlling behavior.
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Brain function is mediated by the physiological coordination of a vast, intricately connected network of molecular and cellular components. The physiological properties of neural network components can be quantified with high throughput. The ability to assess many animals per study has been critical in relating physiological properties to behavior.

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  • Folded proteins typically have a stable structure made of α-helices and β-sheets, but recent evidence from about 100 proteins suggests some can switch between these folds.
  • A study predicts that 24% of sequences in the NusG transcription factor family may exhibit this fold-switching behavior, despite other methods not confirming this.
  • Experimental validation through techniques like circular dichroism and NMR confirms the predictions for all tested variants, indicating that fold switching could be an important way of regulating gene expression across different life forms.
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In severe viral pneumonia, including Coronavirus disease 2019 (COVID-19), the viral replication phase is often followed by hyperinflammation, which can lead to acute respiratory distress syndrome, multi-organ failure, and death. We previously demonstrated that alpha-1 adrenergic receptor (⍺-AR) antagonists can prevent hyperinflammation and death in mice. Here, we conducted retrospective analyses in two cohorts of patients with acute respiratory distress (ARD, n = 18,547) and three cohorts with pneumonia (n = 400,907).

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Article Synopsis
  • - The brain's primary role is to select actions that enhance an animal's survival and reproduction, adapting based on environmental conditions, bodily needs, and past experiences.
  • - Understanding the neural interactions that drive behavior requires examining processes at various spatial levels, from individual synapses to whole brain networks.
  • - Larval zebrafish serve as an effective research model due to their size and transparency, facilitating advanced techniques that reveal the mechanisms behind behavioral states, with findings being compared to similar research in mammals.
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Adaptive movements are critical for animal survival. To guide future actions, the brain monitors various outcomes, including achievement of movement and appetitive goals. The nature of these outcome signals and their neuronal and network realization in the motor cortex (M1), which directs skilled movements, is largely unknown.

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Genetically encoded voltage indicators (GEVIs) enable monitoring of neuronal activity at high spatial and temporal resolution. However, the utility of existing GEVIs has been limited by the brightness and photostability of fluorescent proteins and rhodopsins. We engineered a GEVI, called Voltron, that uses bright and photostable synthetic dyes instead of protein-based fluorophores, thereby extending the number of neurons imaged simultaneously in vivo by a factor of 10 and enabling imaging for significantly longer durations relative to existing GEVIs.

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  • Animals often give up and become passive after repeated behavioral failures, which can help them conserve energy or regroup.
  • In a study with larval zebrafish in virtual reality, visual feedback was controlled to induce swim failures, leading to periods of passivity after several unsuccessful attempts.
  • Research showed that noradrenergic neurons and radial astrocytes in the brain respond to these failures; specifically, astrocytes accumulate evidence of failed attempts and influence the decision to stop swimming.
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To effortlessly complete an intentional movement, the brain needs feedback from the body regarding the movement's progress. This largely nonconscious kinesthetic sense helps the brain to learn relationships between motor commands and outcomes to correct movement errors. Prosthetic systems for restoring function have predominantly focused on controlling motorized joint movement.

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Article Synopsis
  • Behavior is influenced by molecular, cellular, and circuit factors, making it challenging to manipulate proteins in specific cell types due to their widespread expression.
  • The DART technique uses targeted pharmacology to deliver drugs specifically to defined cells while preserving the native targets, enabling faster and more precise studies.
  • In experiments with parkinsonian mice, the DART AMPAR antagonist revealed that motor deficits are linked to specific neuronal activity, demonstrating the effectiveness of DART for studying different cellular targets.
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To execute accurate movements, animals must continuously adapt their behavior to changes in their bodies and environments. Animals can learn changes in the relationship between their locomotor commands and the resulting distance moved, then adjust command strength to achieve a desired travel distance. It is largely unknown which circuits implement this form of motor learning, or how.

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Even a simple sensory stimulus can elicit distinct innate behaviors and sequences. During sensorimotor decisions, competitive interactions among neurons that promote distinct behaviors must ensure the selection and maintenance of one behavior, while suppressing others. The circuit implementation of these competitive interactions is still an open question.

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Myelin is best known for its role in increasing the conduction velocity and metabolic efficiency of long-range excitatory axons. Accordingly, the myelin observed in neocortical gray matter is thought to mostly ensheath excitatory axons connecting to subcortical regions and distant cortical areas. Using independent analyses of light and electron microscopy data from mouse neocortex, we show that a surprisingly large fraction of cortical myelin (half the myelin in layer 2/3 and a quarter in layer 4) ensheathes axons of inhibitory neurons, specifically of parvalbumin-positive basket cells.

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Emotional processes are central to behavior, yet their deeply subjective nature has been a challenge for neuroscientific study as well as for psychiatric diagnosis. Here we explore the relationships between subjective feelings and their underlying brain circuits from a computational perspective. We apply recent insights from systems neuroscience-approaching subjective behavior as the result of mental computations instantiated in the brain-to the study of emotions.

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Understanding the functions of a brain region requires knowing the neural representations of its myriad inputs, local neurons and outputs. Primary visual cortex (V1) has long been thought to compute visual orientation from untuned thalamic inputs, but very few thalamic inputs have been measured in any mammal. We determined the response properties of ∼ 28,000 thalamic boutons and ∼ 4,000 cortical neurons in layers 1-5 of awake mouse V1.

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Mammalian cerebral cortex is accepted as being critical for voluntary motor control, but what functions depend on cortex is still unclear. Here we used rapid, reversible optogenetic inhibition to test the role of cortex during a head-fixed task in which mice reach, grab, and eat a food pellet. Sudden cortical inhibition blocked initiation or froze execution of this skilled prehension behavior, but left untrained forelimb movements unaffected.

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Progressive depletion of midbrain dopamine neurons (PDD) is associated with deficits in the initiation, speed, and fluidity of voluntary movement. Models of basal ganglia function focus on initiation deficits; however, it is unclear how they account for deficits in the speed or amplitude of movement (vigor). Using an effort-based operant conditioning task for head-fixed mice, we discovered distinct functional classes of neurons in the dorsal striatum that represent movement vigor.

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Dendritic integration of synaptic inputs mediates rapid neural computation as well as longer-lasting plasticity. Several channel types can mediate dendritically initiated spikes (dSpikes), which may impact information processing and storage across multiple timescales; however, the roles of different channels in the rapid vs long-term effects of dSpikes are unknown. We show here that dSpikes mediated by Nav channels (blocked by a low concentration of TTX) are required for long-term potentiation (LTP) in the distal apical dendrites of hippocampal pyramidal neurons.

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To adapt to an ever-changing environment, animals consolidate some, but not all, learning experiences to long-term memory. In mammals, long-term memory consolidation often involves neural pathway reactivation hours after memory acquisition. It is not known whether this delayed-reactivation schema is common across the animal kingdom or how information is stored during the delay period.

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Natural events present multiple types of sensory cues, each detected by a specialized sensory modality. Combining information from several modalities is essential for the selection of appropriate actions. Key to understanding multimodal computations is determining the structural patterns of multimodal convergence and how these patterns contribute to behaviour.

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Motor sequences are formed through the serial execution of different movements, but how nervous systems implement this process remains largely unknown. We determined the organizational principles governing how dirty fruit flies groom their bodies with sequential movements. Using genetically targeted activation of neural subsets, we drove distinct motor programs that clean individual body parts.

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