Role of the superior colliculus in balancing cognitive versus reflexive actions.

• Applicant: Jeremie Sibille, Ph.D.
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559449034

Mammalian behavior transforms perception into action in many diverse ways. This diversity is in part inherited from cognitive processes that modulate actions in response to past or even anticipated events. Strikingly, most physical actions produced by the muscles of all mammals are stemming from lower autonomous neuronal circuits which are barely related to higher cognitive processes. For example, while walking we are not conscious of which muscles in our own body activate which leg and when. The main aim of this project is to characterize the diversity of perception-action circuits produced in lower reflexive brain regions. Such an understanding would permit us to describe how higher cognitive processes modulate these lower autonomous circuits. To do so we propose to examine one of the lower reflex brain areas - the superior colliculus - to unravel how different overlapping threatening multisensory inputs may produce reflexive (re)actions within local circuits. Our recent technological breakthrough using high-density silicone probes will provide an unprecedented resolution in the measurement of the moment-to-moment dynamics within the superior colliculus as it can measure functional connectivity. These connectivity measures, capturing the underlying buildup of reflexive perception-action circuits, will be complemented with different optogenetic tools to specifically modulate two pathways from higher brain areas. Consequently, this combination will help to unravel how higher cognitive processes dynamically influence threatening perception-action circuits in the superior colliculus. The specific aims of this project are: 1) to study the functional connectivity within the superior colliculus during different overlapping sensory modalities in order to understand the relationship between overlapping threatening sensory representations and premotor neurons. 2) to characterize the influence of two different corticotectal pathways on the physiology of the superior colliculus, in order to reveal possible changes of functional connectivity in these perception-action circuits. We aim to answer whether corticotectal projections functionally target multisensory representations directly or rather gate multisensory connections toward premotor neurons. Overall, this project will shed a new light on the function(s) of the superior colliculus, with possible medical relevance in autism as transgenic mice mimicking autistic symptoms exhibit a near absence of habituation to threatening stimuli. This lack of habituation may either come from overactivated sensory representation(s) or a lack of proper cognitive modulation(s) in the superior colliculus.

• DFG Programme: Research Grants