Biology subjects

Hunter, S. C.

Publications and source records attributed to Hunter, S. C..

3 recordsLinked to original sources

bioRxiv2024

Monosynaptic ventral tegmental area glutamate projections to the locus coeruleus enhance aversive processing

Distinct excitatory synaptic inputs to the locus coeruleus (LC) modulate behavioral flexibility. Here we identify a novel monosynaptic glutamatergic input to the LC from the ventral tegmental area (VTA). We show robust VTA axonal projections provide direct glutamatergic transmission to LC. Despite weak synaptic summation, optogenetic activation of these axons enhances LC tonic firing and facilitates real-time and conditioned aversive behaviors. We hypothesized this projection may modulate synaptic integration with other excitatory inputs. We then used coincident VTA-LC photostimulation with local electrical stimulation and observed enhanced LC burst induction. To determine whether this integration also occurs in vivo, we took an analogous approach measuring reward-seeking behavior during unpredictable probabilistic punishment. Here, glutamatergic VTA-LC photostimulation during a concurrent noxious stimulus did not delay reward-seeking behavior, but increased probability of task failure. Together, we identified a novel VTA-LC glutamatergic projection that drives concurrent synaptic summation during salient stimuli to promote behavioral avoidance.

neuroscience↗

bioRxiv2022

Punishment Risk Task: Monitoring anxiogenic states during goal directed actions in mice

Summary/AbstractCanonical preclinical studies of anxiety-related behavioral states use exploration of novel spaces to test approach-avoidance conflicts such as the open field test, elevated plus maze, and light-dark box. However, these assays cannot evaluate complicated behaviors in which competing states of motivation result in anxiogenic behaviors. Furthermore, these assays can only test the approach-avoidance conflict once due to a reliance on spatial novelty. Here we demonstrate the punishment risk task (PRT) in male and female, group- and singly-housed mice, a model initially described in singly-housed male rats by Park and Moghaddam (2017). The task tests how probabilistic punishment affects reward-seeking behavior. In particular, it measures the delay to pursue a reward (sweetened food pellet) while the likelihood of punishment (foot shock) actively impinges reward-associated actions. Here, we found that mice show increased latency to respond to food reward cues in trials in which the probability of punishment is highest. Further, anxiolytic treatment with diazepam or propranolol block any increase in response latency, indicating the models potential to for study of anxiogenesis in mice. Elucidating how these competitive behavioral states are integral to adaptive behavior and change over time and experience to coordinate anxiogenesis should greatly benefit anxiety disorder research. Specifically, implementing this assay in mice will enable cell-type selective interrogation of these processes and further our understanding of the neural basis of anxiogenesis.

neuroscience↗

bioRxiv2019

Proximate causes and consequences of intergenerational influences of salient sensory experience.

Salient sensory environments experienced by a parental generation can exert intergenerational influences on offspring, including offspring not conceived at the time of the parental experience. While these data provide an exciting new perspective on biological inheritance, questions remain about causes and consequences of intergenerational influences of salient sensory experience. We have previously shown that exposing male mice to a salient olfactory experience like olfactory fear conditioning results in offspring demonstrating a sensitivity to the odor used to condition the paternal generation and possessing an enhanced neuroanatomical representation for that odor. In this study, we first injected RNA extracted from sperm of male mice that underwent olfactory fear conditioning into naive single cell zygotes and found that both male and female adults that develop from these embryos have increased sensitivity and enhanced neuroanatomical representation for the odor (Odor A) with which the paternal male had been conditioned. Next, we found that female, but not male offspring sired by males conditioned with Odor A show enhanced freezing when presented with Odor A after being exposed to a sub-threshold olfactory fear conditioning protocol that consisted of only a single Odor A + shock pairing. Our data provide evidence that RNA found in the paternal germline after exposure to salient sensory experiences can contribute to intergenerational influences of such experiences, and that such intergenerational influences confer an element of adaptation to the filial generation. In so doing, our work suggests that some causes (sperm RNA) and consequences (behavioral flexibility) of intergenerational influences of parental experiences are conserved across experiences as diverse as stressors, dietary manipulations, and sensory experiences.

zoology↗