Startle reflex apparatus: a flexible system for assessing anxiety, hearing ability and sensory gating in mice

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Mice are widely-used model organisms and fascinating subjects in their own right. This team comprises three high impact neuroscientists who use mice as models, led by highly-regarded animal welfare researcher who studies effects of housing (e.g. cage enrichment) on laboratory mouse well-being. ******We need equipment to quantify startle reflexes in mice (rapid responses to sudden aversive stimuli like loud tones), in order to assess anxiety, hearing abilities and sensory gating as an integral part of our four research programmes. In rodent-based research, startle responses are standard assays for anxiety and fear. They are also widely-used for assessing prepulse inhibition (PPI): important because this captures ‘sensory gating', the brain's ability to filter out irrelevant information. We therefore need modern, mouse-dedicated startle apparatuses to assess anxiety (Mason & Choleris Labs), to investigate for example how mouse housing affects their welfare, and how early neuroendocrine events influences their affective states. We also need to assess PPI, as an important screen in cognitive tests for understanding whether any apparent effects (e.g. on social learning, cross-modal object recognition, or performance in prefrontal tasks) of the specific hormones, neurotransmitters and ‘DREADD'-manipulations to be studied, are actually acting instead via 'low-level' sensory processing effects (Choleris, Winters & Bailey Labs). In addition, PPI is being tested by the Mason Lab as a proxy for perseveration (inappropriate repetition): a likely correlate of stereotypic behaviour (a widely-used animal welfare indicator whose neurobiological bases are still little understood).******Crucially, since many strains of lab mice are prone to early-onset hearing loss -- a potential confound when using startle amplitudes to infer anxiety or PPI to assess sensory gating -- this apparatus also has 'tactile functions' (an air puff facility), meaning that its use does not rely on the usual acoustic-only factory default settings. This will allow us all to evaluate and parse out any confounding effects of hearing loss from the anxiety and sensory gating effects of interest (and even to use fully tactile functions for startle & PPI if any mice prove to be fully deaf). Finally, using acoustic startle as a convenient, non-invasive way to assess mouse hearing abilities will allow the Mason Lab to test novel hypotheses that standard-housed female mice are more aggressive than mice in enriched housing because they lose their hearing prematurely. ******In 5 years the equipment will train c. 89 HQP. But we estimate the equipment will last 10 years, so potentially training twice that number. We also estimate it will be used for 80 hours/month in total across our four labs.