PhD defence of Sharbatanu Chatterjee (Sharbat)
13
DEC 2024
DEC 2024
I have the pleasure of inviting you to save the date for my thesis defence, under the supervision of Dr. Volker Bormuth, in the Fish Team of our wonderful LJP!
Title : Behavioural strategies & neuronal circuits for postural control
Date : 13 December 2024 (Friday)
Time : 10h00 (CET)
Place : Durand Amphitheatre, Esclangon Building, 4 Place Jussieu, 75005 Paris
The defence will be in English. Details about the defence and a form to organise the subsequent pot de thèse (RSVP!) are available on the following webpage : http://sharbat.ch/phddefence
Summary :
Postural control, essential for balance and spatial orientation, involves maintaining a stable position relative to gravity, largely through the vestibular system. This system and related postural behaviors are highly conserved across vertebrates, and impairments in postural control are key symptoms in several motor-related neurological disorders, underscoring the importance of investigating these mechanisms. The larval zebrafish, with its simple structure, small size, and transparency, is an ideal model to study vertebrate postural control as it allows for whole-brain neural recordings. In this thesis, we demonstrate that vestibular stimulation in larval zebrafish — through tilts along the roll axis — consistently elicits two main behavioral strategies on different timescales: a continuous bending reflex and a discrete swimming response. The bending reflex has phasic and tonic components, both reaching limits at high tilt angles, which then trigger discrete tail movements. Neural recordings identified specific brain circuits and distinct neuron types that project into the spinal cord, guiding these behaviors and controlling swim direction. In particular, certain reticulospinal neurons showed high responsiveness to roll-axis stimulation. Additionally, we compared brain circuit activity in response to tilting along the roll versus pitch axes in a genetic line that marks neurons especially responsive to roll stimulation. This research provides insights into how vertebrates employ varied strategies and neural pathways to maintain posture, advancing our understanding of neural control over fine kinematic movements and laying groundwork for further studies in this area.
