How and Why do we sleep?
Sleep is a primary and essential biological need for higher and lower vertebrates since subtle sleep perturbations dramatically impair brain and body functions including development, cognition or metabolism. Although we and others have dissected important subcortical and cortical sleep-wake circuits, the precise mechanism orchestrating sleep in space and time in the mammalian brain remains unclear.
Our experimental goal aims at understanding the wiring diagram, dynamics and plasticity of sleep circuits and their implication in the structure and sleep functions by combining molecular, cellular, circuit-based, and behavioural techniques. Ultimately, our research will improve our understanding and treatment of disorders of sleep and consciousness, but also major neurological and neuropsychiatric disorders associated with sleep curtailments.
The multi-tasking lateral hypothalamus
The lateral hypothalamus (LH) is a phylogenetically conserved region in the vertebrate brain that is critical for maintaining physiological and behavioural homeostasis, including energy homeostasis, stress response, and goal-oriented behaviours to natural (food, sex) and artificial (drug) rewards. Anatomical and functional evidence indicates that the LH contains a large diversity of cell populations with complex neurochemical profiles. These neuronal populations form an intricate local and extensive network of excitatory and inhibitory cells, each of which has a specific role in hypothalamic physiological functions. The LH is likely to play a role in the ‘Sleep-Metabolism’ association because it contains neuronal circuits implicated in sleep-wake states and goal-oriented behaviours. In this context, our goal is to better understand how sleep-wake circuits share other hypothalamic functions including metabolism and goal-directed behaviours.
REM-Sleep - from circuits to functions
REM sleep is a unique sleep state that features brain activity distinct from NREM sleep or wakefulness. Although recent evidence indicates that non-rapid-eye movement sleep (NREMs) is directly involved in memory consolidation, the role of rapid-eye movement sleep (REMs) in this process has remained controversial. In this context we investigate the brain circuiteries the onset, maintenance and termination of REM sleep and the brain-wide mechanisms supporting REM sleep functions including memory modulation.
NREM sleep - convergence to thalamic neurons
The thalamus is a symmetrical collection of nuclei in the diencephalon, with functions including sensory relaying to neocortex, alertness, consciousness, and motoric output; which is heavily implicated in the genesis of sleep oscillations, and cortical activity during sleep. Following our identification of direct pathways between the LH and the reticular nuclei of the thalamus, we are investigating the thalamic orchestration of brain activity during sleep through distinct neural circuits. We aim at understanding the role of inhibitory input to thalamic nuclei and their relevance to modulation of sleep oscillations including slow wave, delta and spindles oscillations, sleep homeostasis, cognition and sensory processing.
Our research projects are further nourish by exciting interaction with our collborators from the Brown Lab, Celio Lab, Grewe technological development, clinical aspects from the Bassetti Lab and support form our institutions and funding agencies.