糖心TV

How does the brain perceive the world around us? There is a long history of behavioural work, using psychophysics, to measure sensitivity to auditory and visual stimuli, but modern neuroscience offers the chance to directly observe links between these sensory stimuli and underlying brain activity, using neurophysiological recordings from advanced imaging techniques such as magnetoencephalography (MEG).

One view of brain function considers it to be a complex, nonlinear dynamical system which operates in a state of near-criticality. In this view, inputs to the system (e.g. our senses) are thought to result in finely tuned, scale-free 鈥渘eural avalanches鈥� through which stimulus processing occurs. So, we can make predictions about the patterns of brain activity that we expect to see; for example, as a system exhibiting critical dynamics, brain data should exhibit power-law relations between stimulus strength and neural activity, not the logarithmic function that is typically accepted for behavioural data.

Perception depends on a combination of processes. For example, ongoing brain activity biases perception by changing the underlying excitability of cortex, which leads to changes in how likely participants are to report the sensation of a stimulus. MEG-based source analysis provides an ideal way to separate the sensory and cognitive components of perception, by resolving their distinct spatiotemporal patterns.

This project will therefore use brain recordings using novel helium-OPM-MEG, and mathematical methods, to interrogate the role of sensory and other processes in determining behavioural psychophysical threshold, trial-by-trial by using techniques for sub-noise MEG signal detection; and to reconcile the differing statistical predictions of psychophysics and brain dynamics. The results of the project will lead to a new understanding of this important aspect of brain function, and to new objective measures that can be used for further study.