Research Fellows Directory
Martha Nari Havenith
Dr Martha Nari Havenith
University College London
Does time determine what we see? In music, we know that two songs with exactly the same notes can sound very different depending on the timing of the notes – time changes the ‘message’ of the song. Does the brain transmit information about the visual world by similar principles? In other words, if the same amount of neuronal activity is distributed either evenly in time, or in waves of different rhythms, does this affect the message that is conveyed?
Although studies have shown that rhythmic waves of activity (oscillations) appear during crucial moments of visual processing, e.g. when we direct attention to a visual stimulus, the causal link between oscillations and visual processing has been missing - oscillations may just be a by-product of neuronal activity. To tackle this question experimentally, we utilize a recently developed technique by which specific groups of neurons are genetically modified to respond to blue light. By shining light onto the cortex of genetically modified mice, we activate the modified neurons and use them to impose temporal patterns onto the neuronal activity. This allows us to selectively alter the timing of neuronal activity, leaving the overall intensity unchanged. We then study how this affects the activity in other neurons, other brain areas, and most importantly, the animal’s visual perception. To this end, we train mice to respond to visual cues by running in different directions on a treadmill. We then test if and how introducing oscillations into the visual system changes the mice’ success in the visual task.
Understanding the ‘code’ by which neurons convey information has been one of the great riddles of neuroscience. It not only affects us in philosophical terms, telling us about the building blocks and limits of our perception. It also impacts the way we treat illnesses based on neuronal miscommunication. In the future, pacemakers may be available to treatnot only arrhythmic hearts but also arrhythmic brains.
Interests and expertise (Subject groups)