Our brain needs to constantly fuse sensory information detected by our multiple senses in order to produce a seamless coherent representation of the world. Rather than being the exception, this binding process is ubiquitous to sensory-motor integration and is implicated in most cognitive functions. Its impairment is a cause of various pathologies, such as schizophrenia or autism. Multisensory processing operates on all brain levels from primary cortices over subcortical structures up to higher associative centers, while the smallest operational units are single multisensory neurons.
In an interdisciplinary effort, we combine optical developments, genetics and neuro-computation to obtain new insights into the activity of brain-wide neural circuits that process multisensory information. To reduce the complexity, we study the small transparent brain of zebrafish larvae as a model system. We focus on gaze stabilization as an inherently multisensory model task that is conserved among all vertebrates. This reflex uses both vestibular and visual information to drive eye movements in order to compensate forself-motion and maintain clear vision. We have developed a novel experimental platform in which a restrained larva can be submitted to vestibular and visual stimuli, as a pilot in a flight simulator. We can optically record the activity of all 100,000 neurons of the animal brain as it performs multisensory integration tasks. To extract basic principles of how behavior is coded in multisensory neuronal circuits we interpret the brain-wide activity and the observed behavior with methods from statistical physics. No other system can today provide a similar brain-scale, yet cell-resolved view on the neuronal network dynamics subserving such a complex integration process.
We use this system to address three fundamental and generic questions relevant to multi-sensory integration.
1 – Multi-sensory enhancement. How multi-modal congruent sensory cues are integrated at the circuit level to enhance the precision of the evoked motor response?
2 – Decision-making: Resolving conflicting sensory cues. When the brain is submitted to conflicting stimuli, which neuronal mechanism controls the prioritization of one sensory cue over the other?
3 – Cross-modal adaptation. How constantly out-of-register stimuli induces network plasticity in order to recover a coherent representation ?
Desired skills: Strong background in neuroscience or biophysics; matlab-based image and signal processing; labview programming; neuronal circuit modeling; electrophysiology; zebrafish genetics; motivation. Interested: Please, send a letter of motivation, your CV and the names of three references. Informal inquiries are welcome.