Steve Lomber

A remarkable property of the brain is its capacity to respond to change. Among other functions, this neuroplastic process endows a complex nervous system with the ability to adapt itself to its environment, while at the same time making it vulnerable to impoverished sensory or developmental experiences. In all sensory modalities, the processes underlying normal cortical development depend upon external stimuli. During development, sensitive periods exist during which external stimuli are required in order to trigger the subsequent steps in normal development. Unfortunately, in cases of sensory deprivation, such as congenital deafness, this process is arrested. Fortunately, it appears that this situation can be reversed in individuals that receive cochlear prosthetic devices.

Hearing impairment is the most common sensory disability in adults and one of the most common birth defects in the developed world. It is therefore critical to understand how the absence of auditory input affects the brain. The cerebral cortex is a complex, yet efficient, sensory processing structure. External inputs received through the sensory organs early in development help to establish sensory maps in cortex. When the brain is deprived of this early experience, the remaining sensory systems adapt and exploit the additional cortical circuitry available to them. Although our current research is expanding understanding of cerebral processing and organization in the deaf, the cortical consequences of restoring acoustic input to a deprived auditory system remain relatively unknown.

The central objective of our research program is to understand how the brain responds to changes in sensory input. Specifically, we study these processes using an integrative approach of combining intervention methods (congenital deafness, induced hearing loss, and reversible cooling deactivation) with electrophysiological recording, psychophysical testing, and functional imaging.

The goal of our research program is to advance our understanding of how the auditory cortex responds to hearing loss and to the initiation of hearing with cochlear prosthetics. We will use a synergistic combination of functional magnetic resonance imaging (fMRI), single-unit electrophysiological recording, connectional anatomy, and behavioural/psychophysical techniques. We examine auditory, visual, and somatosensory function in auditory and visual cortex.