bioRxiv Science⌕ Search

Biology subjects

Gauthier, E. A.

Publications and source records attributed to Gauthier, E. A..

3 recordsLinked to original sources

A toolbox for navigating and analyzing the spatiotemporal properties of retinal waves

The precise development of the visual system is driven by retinal waves, which are bursts of spontaneous activity that propagate across retinal neurons in a wave-like fashion. In mice, retinal waves begin embryonically and continue until eye opening at the end of the second postnatal week. During this time, the mechanisms for generating and propagating retinal waves are changing, thus causing retinal waves to exhibit highly dynamic spatiotemporal properties from one day to the next. Critically, the spatiotemporal properties of retinal waves have been shown to instruct the development of the visual system, including eye-specific segregation, retinotopic mapping, direction selectivity, and potentially retinal vascularization. Currently, there is no method for the automatic detection and high-throughput quantitative analysis of the spatiotemporal properties of retinal waves. To overcome this barrier, we developed WaveMiner, an automated, high-throughput toolbox for detecting, segregating, and quantifying retinal waves from microelectrode-array (MEA) and calcium-imaging recordings. After first validating our toolbox, we use it to uncover novel dynamic spatiotemporal properties of retinal waves in the first two postnatal weeks. We also use this toolbox to analyze ultra long physiological recordings, revealing that waves exhibit both stable and dynamic spatiotemporal properties on an hourly basis. Finally, we demonstrate that this toolbox can detect waves in the presence of pharmacological agents that increase the baseline firing of neurons, enabling the discovery of novel factors that perturb the spatiotemporal properties of retinal waves and visual development. In summary, WaveMiner is a platform to standardize the detection and quantification of retinal waves across recording modalities and experimental conditions, enabling novel discoveries about their dynamic spatiotemporal properties and the factors that govern them.

neuroscience↗

Mu opioid receptor expression by nucleus accumbens inhibitory interneurons promotes affiliative social behavior

Mu opioid receptors in the nucleus accumbens regulate motivated behavior, including pursuit of natural rewards like social interaction as well as exogenous opioids. We used a suite of genetic and viral strategies to conditionally delete mu opioid receptor expression from all major neuron types in the nucleus accumbens. We pinpoint inhibitory interneurons as an essential site of mu opioid receptor expression for typical social behavior, independent from exogenous opioid sensitivity.

neuroscience↗

Differential Patterns of Synaptic Plasticity in the Nucleus Accumbens Caused by Continuous and Interrupted Morphine Exposure

Opioid exposure and withdrawal both cause adaptations in brain circuits that may contribute to abuse liability. These adaptations vary in magnitude and direction following different patterns of opioid exposure, but few studies have systematically manipulated the pattern of opioid administration while measuring neurobiological impact. In this study, we compared cellular and synaptic adaptations in the nucleus accumbens shell caused by morphine exposure that was either continuous, or interrupted by daily bouts of naloxone-precipitated withdrawal. At the behavioral level, continuous morphine administration caused psychomotor tolerance, which was reversed when the continuity of morphine action was interrupted by naloxone-precipitated withdrawal. Using ex vivo slice electrophysiology in female and male mice, we investigated how these patterns of morphine administration altered intrinsic excitability and synaptic plasticity of medium spiny neurons (MSNs) expressing the D1 or D2 dopamine receptor. We found that morphine-evoked adaptations at excitatory synapses were predominately conserved between patterns of administration, but there were divergent effects on inhibitory synapses and the subsequent balance between excitatory and inhibitory synaptic input. Overall, our data suggest that continuous morphine administration produces adaptations that dampen the output of D1-MSNs, which are canonically thought to promote reward-related behaviors. Interruption of otherwise continuous morphine exposure does not dampen D1-MSN functional output to the same extent, which may enhance behavioral responses to subsequent opioid exposure. Our findings support the hypothesis that maintaining continuity of opioid administration could be an effective therapeutic strategy to minimize the vulnerability to opioid use disorders.

neuroscience↗