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Systems and Behavioural Neuroscience Laboratory

 

General Description

 

We are continually in motion. This self-motion is sensed by the vestibular system, which contributes to an impressive range of brain functions, from the most automatic reflexes to spatial perception and motor coordination. The objective of Dr. Cullen’s labs research program is to understand the mechanisms by which self motion (vestibular) information is encoded and then integrated with signals from other modalities to ensure accurate perception and control of gaze and posture. Our studies investigate the sensorimotor transformations required for the control of movement, by tracing the coding of vestibular stimuli from peripheral afferents, to behaviorally-contingent responses in central pathways, to the readout of accurate perception and behavior. Our experimental approach is multidisciplinary and includes a combination of behavioral, neurophysiological and computational approaches in alert behaving non-human primates and mice. Funding for the laboratory is provided by the Canadian Institutes for Health Research (CIHR), The National Institutes of Health (NIH), the National Sciences and Engineering Research Council of Canada (NSERC), FQRNT / FQRSC (Quebec), and McGill University.

Current Research Projects

The Neuronal Encoding of Active Self-Motion

How we generate our perception of the outside world is an important question that is relevant to sensory, behavioral, and cognitive neurosciences. It is well known that the ability to distinguish sensory inputs that signal unexpected events from those resulting from voluntary actions is vital for this perception as well as accurate behavior. What is not known is the nature of the neural mechanisms by which this is achieved during self-motion. Thus, one central emphasis of our research program is to understand how sensory inputs are processed during active motion. The findings of our current studies continue to provide new insight into how our brain determines whether it is we or the world that is moving.

This work is funded by the CIHR and NIH.

The Physiology underlying Vestibular Compensation in Health and Disease

The loss of vestibular function cause disequilibrium, dizziness, and visual blurring, and thus has enormous implications for the quality of life of hundreds of thousands affected North Americans alone. Thus another major goal of our group’s research program is to understand the neural mechanisms by which the brain recovers after loss of vestibular sensation to advance the development new prosthetic-based approaches to maximize quality of life for disabled individuals. The findings of our recent experiments provide new insights into the origin of vestibular disorders, enhancing our understanding of how the central nervous system adapts after initially disabling injuries. In addition, our current work is advancing the development of a novel neural prosthetic-based approach for the replacement of labyrinthine sensation.

This work is funded by the NIH.

Information Coding in the Vestibular System

Understanding how sensory information is processed remains an important goal in modern neuroscience. However, this understanding is complicated by the fact that most neurons display strongly nonlinear behaviour in response to sensory input including oscillations and synchronization; and further because neurons display variability in their responses to repeated presentations of a given stimulus (i.e., sensory noise). Our laboratory is currently using a combination of mathematical modeling, in vivo electrophysiological recordings from peripheral and central vestibular neurons, as well as the parallel characterization of animal behaviour to explore how neural variability and system nonlinearities transmit information about specific features of vestibular sensory stimuli. Further, our recent findings provide insight into how this information is actually used by the organism for perception and behavior.

This work is funded by the CIHR and FQRNT.

The Neural Control of Eye Movements in Health and Disease

When looking between targets located in our visual world, information about relative depth is sent from the visual cortex to the motor control centers in the brainstem, which are responsible for generating appropriate motor commands to precisely move the eyes. Notably, eye movements of different angles are required whenever we voluntarily shifts our point of visual attention from a near to a far target (and vice versa). Surprisingly, however, how the brain precisely aims each eye on a visual target has remained a mystery. The results of our recent experiments are now providing new insight into how the brain controls eye movements made to shift gaze in three-dimensional space. Our results have important implications for understanding normal vision as well as for understanding the neural circuits involved in binocular disorders such as strabismus and amblyopia.

 

This work is funded by the NSERC.