Biology subjects

Connor, C. W.

Publications and source records attributed to Connor, C. W..

4 recordsLinked to original sources

bioRxiv2026

Early Amyloid-β Toxicity Disrupts Nervous System Connectivity During Aging in Caenorhabditis elegans

Alzheimers disease (AD) is characterized by progressive functional neuronal decline ultimately resulting in severe cognitive impairment. However, how neuron function is altered at the cellular level during the critical early stages of the disease and how disease progression relates to the process of normal neuronal aging are poorly understood. To address these fundamental questions, we performed comprehensive multi-neuron imaging in Caenorhabditis elegans (C. elegans) with pan-neuronal expression of human amyloid {beta}1-42 peptide (nA{beta}), the major plaque forming peptide in early AD progression. Measuring neuron activity, connectivity and system wide dynamics with single cell resolution across the C. elegans lifespan, we compare A{beta}-associated neuronal dysfunction with that of normal aging. Our experiments revealed that nA{beta} expressing animals exhibit a unique loss of positively correlated neuron connectivity, premature disruption of system wide dynamics, and reduced overall neuronal activity. These neuronal effects correspond to premature impairments in behavior including mechanosensory response as well as the animals ability to navigate its environment (i.e., chemotaxis and thermotaxis). The effects of nA{beta} expression are distinct from, and in addition to, the process of normal aging that is characterized by a progressive loss of anti-correlated (i.e. inhibitory) neuronal signaling and slower behavioral decline. An increase in resistance to aldicarb, an acetylcholinesterase inhibitor, as well as downregulation of key one-carbon metabolism (OCM) genes (metr-1, sams-1, involved in choline metabolism, the precursor of acetylcholine synthesis) implicate compromised acetylcholine-mediated excitatory transmission in nA{beta} expressing worms. Supplementation with OCM metabolites (choline, methionine, cysteine) in nA{beta} expressing worms improved behavior and helped restore OCM gene expression as well as levels of Ach signaling. Likewise, perturbation of the serine synthesis pathway (SSP) that links glycolysis to OCM, altered Ach signaling and OCM gene expression in nA{beta} animals. Genetic mutations that directly regulate excitatory/inhibitory balance neuronal signaling (unc-2/CaV2) also help to reduce nA{beta}-associated behavioral deficits, while NMDA receptor (nmr-1) mutants showed neither protective effect nor it directly rescue the loss of positive neuron correlativity unique to nA{beta} animals. Our results demonstrate the unique effects of nA{beta} toxicity on neuronal dynamics and connectivity as well as the role of key metabolic pathways within the context of a complete, intact, aging nervous system.

neuroscience↗

bioRxiv2025

Global excitatory synchrony: Ketamine induces global common-mode excitatory network oscillation by decoupling key interneurons

Ketamine is a dissociative anesthetic used in subanesthetic doses with analgesic and anti-depressive properties. However, its mechanistic effects on neuronal signaling and circuit function remain underexplored. We address this shortcoming by employing multi-neuronal imaging in the simple nematode C. elegans that allows measurement of neuron activity across the animals entire head with single-cell resolution. Neuronal imaging during low dose ketamine induction reveals two distinct phases: an early/low dose state of hyperactive synchronized dynamics and late/higher dose state of system disorganization and spastic microscale motion. Specifically examining the activity of the NMDA-receptive interneuron AVA, we find it decouples from the system under low dose ketamine. These results are consistent with the clinical hypothesis that ketamine causes neuronal disinhibition through suppression of key inhibitory interneurons. We identify functional differences between low and high dose activity dynamics and elucidate a mechanism of action of ketamine in a complete, intact nervous system.

biophysics↗

bioRxiv2025

Comprehensive profiling of anaesthetised brain dynamics across phylogeny

Intrinsic dynamics of neuronal circuits shape information processing. Combining neuroimaging with causal perturbation offers the opportunity to understand how local dynamics mediate the link between neurobiology and functional repertoire. We compile a unique dataset of multi-scale neural activity during wakefulness and anaesthetic-induced suppression of information processing encompassing human, macaque, marmoset, mouse, zebrafish and nematode. Applying massive feature extraction, we comprehensively characterise local neural dynamics across >6,000 time-series features. Using dynamics as a common space for cross-species comparison reveals a conserved dynamical profile of anaesthesia across species, characterised by shorter intrinsic timescales of neural activity and dampened interregional synchrony. This dynamical regime is experimentally reversed in vivo by deep-brain stimulation of the macaque centromedian thalamus, restoring behavioural responsiveness. Spatially, this conserved dynamical phenotype covaries with conserved transcriptional profiles of excitatory and inhibitory neurotransmission across human, macaque, marmoset and mouse cortex. Biophysical modelling provides a mechanistic link between the macroscale dynamical phenotype of anaesthesia, and microscale effects of key molecular targets on the timescales of synaptic excitation and inhibition. Altogether, comprehensive dynamical phenotyping reveals a shared neural endpoint of anaesthesia: across species and scales, anaesthetics induce spatio-temporal isolation of local neural activity.

neuroscience↗

bioRxiv2021

Age-associated changes to neuronal dynamics involve a loss of inhibitory signaling in C. elegans

In the aging brain, many of the alterations underlying cognitive and behavioral decline remain opaque. C. elegans offers a powerful model for aging research, with a simple, well-studied nervous system to further our understanding of the cellular modifications and functional alterations accompanying senescence. We perform multi-neuronal functional imaging across the aged C. elegans nervous system, measuring an age-associated breakdown in system-wide functional organization. At single-cell resolution, we detect shifts in activity dynamics toward higher frequencies. In addition, we measure a specific loss of inhibitory signaling that occurs early in the aging process and alters the systems critical excitatory/inhibitory balance. These effects are recapitulated with mutation of the calcium channel subunit UNC-2/CaV2. We find that manipulation of inhibitory GABA signaling can partially ameliorate or accelerate the effects of aging. The effects of aging are also partially mitigated by disruption of the insulin signaling pathway, known to increase longevity, or by a reduction of caspase activation. Data from mammals are consistent with our findings, suggesting a conserved shift in the balance of excitatory/inhibitory signaling with age that leads to breakdown in global neuronal dynamics and functional decline.

neuroscience↗