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ABSTRACT Lateralization of neuronal functions plays a critical role in regulating behavioral flexibility, but the underlying molecular mechanisms are challenging to establish at a single-neuron level. We previously showed that attraction ofC. elegansto a medium-chain alcohol switches to avoidance in a uniform background of a second attractive odorant. This context-dependent behavioral plasticity is mediated by symmetric inversion of the odor-evoked response sign in the bilateral AWC olfactory neurons. Here we show that this symmetric response plasticity is driven by asymmetric molecular mechanisms in the AWC neuron pair. Mutations in thegcy-12receptor guanylyl cyclase abolish odor response plasticity only in AWCOFF; the opposing odor-evoked response signs in AWCOFFand AWCONingcy-12mutants results in these animals being behaviorally indifferent to this chemical. We find thatgcy-12is expressed, and required, in both AWC neurons to regulate odor response plasticity only in AWCOFF. We further show that disruption of AWC fate lateralization results in loss of asymmetry in the response plasticity ingcy-12mutants. Our results indicate that symmetric neuronal response plasticity can arise from asymmetry in underlying molecular mechanisms, and suggest that lateralization of signaling pathways in defined conditions may enhance neuronal and behavioral flexibility.
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Immediate‐early gene Homer1a intranuclear transcription focus intensity as a measure of relative neural activation
Abstract Immediate‐early genes (IEGs) exhibit a rapid, transient transcription response to neuronal activation. Fluorescently labeled mRNA transcripts appear as bright intranuclear transcription foci (INF), which have been used as an all‐or‐nothing indicator of recent neuronal activity; however, it would be useful to know whether INF fluorescence can be used effectively to assess relative activations within a neural population. We quantified theHomer1a(H1a) response of hippocampal neurons to systematically varied numbers of exposures to the same places by inducing male Long‐Evans rats to run laps around a track. Previous studies reveal relatively stable firing rates across laps on a familiar track. A strong linear trend (r2 > 0.9) in INF intensity was observed between 1 and 25 laps, after which INF intensity declined as a consequence of dispersion related to the greater elapsed time. When the integrated fluorescence of the entire nucleus was considered instead, the linear relationship extended to 50 laps. However, there was only an approximate doubling ofH1adetected for this 50‐fold variation in total spiking. Thus, the intranuclearH1aRNA fluorescent signal does provide a relative measure of how many times a set of neurons was activated over a ~10 min period, but the dynamic range and hence signal‐to‐noise ratios are poor. This low dynamic range may reflect previously reported reductions in the IEG response during repeated episodes of behavior over longer time scales. It remains to be determined how well theH1asignal reflects relative firing rates within a population of neurons in response to a single, discrete behavioral event.
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- Award ID(s):
- 1631465
- PAR ID:
- 10460860
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Hippocampus
- Volume:
- 29
- Issue:
- 6
- ISSN:
- 1050-9631
- Page Range / eLocation ID:
- p. 481-490
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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