Biology subjects

Padamsey, Z.

Publications and source records attributed to Padamsey, Z..

4 recordsLinked to original sources

bioRxiv2026

Neural mechanisms for resilient sensory computation under metabolic stress

Food-restricted mice can solve visual discrimination tasks despite reduced synaptic currents and increased noise resulting from cellular changes in the primary visual cortex. Combining neural recordings and modeling, we study the population structure of the noise and show it is mainly concentrated along task-irrelevant directions in high-dimensional population activity, hence preserving coding on the low-dimensional stimulus manifold. In addition, we predict that food restriction shortens decision times, conserving energy but limiting the evidence accumulation needed for fine discrimination.

neuroscience↗

bioRxiv2023

Sex-specific resilience of neocortex to food restriction

Mammals have evolved sex-specific adaptations to reduce energy usage in times of food scarcity. These adaptations are well described for peripheral tissue, though much less is known about how the energy-expensive brain adapts to food restriction, and how such adaptations differ across the sexes. Here, we examined how food restriction impacts energy usage and function in the primary visual cortex (V1) of adult male and female mice. Molecular analysis and RNA sequencing in V1 revealed that in males, but not in females, food restriction significantly modulated canonical, energy-regulating pathways, including pathways associated with AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor alpha (PPAR), mammalian target of rapamycin (mTOR), and oxidative phosphorylation. Moreover, we found that in contrast to males, food restriction in females did not significantly affect V1 ATP usage or visual coding precision (assessed by orientation selectivity). Decreased serum leptin is known to be necessary for triggering energy-saving changes in V1 during food restriction. Consistent with this, we found significantly decreased serum leptin in food-restricted males but no significant change in food-restricted females. Collectively, our findings demonstrate that cortical function and energy usage in female mice are more resilient to food restriction than in males. The neocortex, therefore, contributes to sex-specific, energy-saving adaptations in response to metabolic challenge.

neuroscience↗

bioRxiv2018

Minimally invasive deep-brain imaging through a 50 μm-core multimode fibre.

Achieving optical access to deep-brain structures represents an important step towards the goal of understanding the mammalian central nervous system. The complex refractive index distribution within brain tissue introduces severe aberrations to long-distance light propagation thereby prohibiting image reconstruction using currently available non-invasive techniques. In an attempt to overcome this challenge endoscopic approaches have been adopted, principally in the form of fibre bundles or GRIN-lens based endoscopes. Unfortunately, these approaches create substantial mechanical lesions of the tissue precipitating neuropathological responses that include inflammation and gliosis. Together, lesions and the associated neuropathology may compromise neural circuit performance. By replacing Fourier-based image relay with a holographic approach, we have been able to reduce the volume of tissue lesion by more than 100-fold, while preserving diffraction-limited imaging performance. Here we demonstrate high-resolution fluorescence imaging of neuronal structures, dendrites and synaptic specialisations, in deep-brain regions of living mice. These results represent a major breakthrough in the compromise between high-resolution imaging and tissue damage, heralding new possibilities for deep-brain imaging in vivo.

neuroscience↗

bioRxiv2017

Glutamate release is inhibitory and unnecessary for the long-term potentiation of presynaptic function

Long-term potentiation (LTP) and long-term depression (LTD) of transmitter release probability (Pr) are thought to be triggered by the activation of glutamate receptors. Here, we demonstrate that glutamate release at CA3-CA1 synapses is in fact inhibitory and unnecessary for increases in Pr. Instead, at active presynaptic terminals, postsynaptic depolarization alone can increase Pr by promoting the release of nitric oxide from neuronal dendrites in a manner dependent on L-type voltage-gated Ca2+ channels. The release of glutamate, in contrast, decreases Pr by activating presynaptic NMDA receptors (NMDAR). Thus, net changes in Pr are determined by the combined effect of both LTP-promoting and LTD-promoting processes, that is, by the amount of glutamate release and postsynaptic depolarization that accompany presynaptic activity, respectively. Neither of these processes directly depends on the activation of postsynaptic NMDARs. We further show that presynaptic changes can be captured by a simple learning rule, in which the role of presynaptic plasticity is to ensure that the ability for a presynaptic terminal to release glutamate is matched with its ability to predict postsynaptic spiking.

neuroscience↗