Sleep and circadian rhythms monitoring systems for mice

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Sleep is essential to life in higher organisms. According to current models, sleep is orchestrated by two mechanisms: circadian and homeostatic processes. In mammals, the circadian process originates from the main biological clock in the brain and generates an about 24-h rhythm in physiological functions (body temperature, alertness). The homeostatic process is an hourglass mechanism that regulates sleep intensity according to the duration and quality of prior wakefulness. Its nature has not been clearly defined and the way the processes interact is also unknown. However, recent work supports the involvement of synapses, the functional unit of communication between neuronal cells, in sleep regulation. Synaptic adhesion molecules hold the two sides of the synapse together but, more importantly, these proteins control the strength of the communication between neurons. In this project, the contribution of adhesion systems to sleep regulation will be investigated. First, the markers of the homeostatic process (i.e. brain electrical activity and gene expression) will be evaluated using sleep deprivation in mice where specific synaptic molecules are downregulated using RNA interference. To do so, the acquisition of a sleep monitoring system for simultaneous recording of 8 mice is required. Second, the properties of the circadian timing system (e.g. the length of the endogenous period and the phase-shift response to light stimulus) will be evaluated using temperature and activity recording in mice in which synaptic molecules are downregulated using RNA interference as well. This aim will be accomplish via the acquisition of a telemetry system for continuous recording of temperature and activity in mice. The results of the project will advance our understanding of sleep physiology and neuronal functions, and assist in the development of treatments and interventions for patients suffering from disorders involving disturbance in sleep regulatory processes, including age-related changes and insomnia. Accordingly, funds are requested for the purchase of the required sleep and telemetry monitoring systems to perform the research.