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Investigating Visual Perception with Neurofeedback

Final Report Summary - NEUROFEEDBACK (Investigating Visual Perception with Neurofeedback)

A major unresolved challenge for neuroscience is to understand how any physical process, such as neural activity, can give rise to a subjective phenomenon, such as a conscious experience. This question has been empirically addressed by seeking to characterize patterns of neural activity that specifically correlate with conscious experience using neuroimaging. Such conventional imaging experiments are purely observational and cannot establish a causal role for any brain areas whose activity correlates with consciousness. Approaches that disrupt brain activity either temporarily (e.g. transcranial magnetic stimulation) or permanently (e.g. brain lesions) have been used to address causality. We proposed using a new approach to investigate causal links between brain activity and perception. We used real-time fMRI with neurofeedback to teach participants to voluntarily regulate the level of brain activity in early visual cortex. We then tested how self-regulating activity to different pre-specified levels influenced subsequent processing of a visual stimulus. We hypothesised that when the level of ongoing activity in early visual cortex is increased, participants will become better at detecting visual stimuli.

To achieve these objectives, we have implemented a real-time fMRI setup at the Wellcome Trust Centre for Neuroimaging at UCL. We used this setup to teach 11 participants voluntary control over their visual cortex activity. After 6-10 training sessions 7 out of the 11 participants learned to control early visual cortex activity. They showed significant improvements in visual sensitivity when they up-regulated activity. This improvement is specific to stimuli that are presented at a location overlapping with the self-regulated visual region, i.e. no improvements were found for other visual field positions. The 4 participants who did not learn to regulate visual cortex activity did not show any significant changes in visual sensitivity. A control group (5 participants) who received feedback from a non-visual region did not learn to control visual cortex activity. They also did not show any significant changes in visual sensitivity. Hence, we showed that the level of ongoing activity in retinotopically specific areas of human visual cortex caused by effective self-regulation has a causal effect on the detectability of visual stimuli.

The neurofeedback approach, which we applied here for the first time to the visual system, allowed participants to learn to voluntarily control visual cortex activity in a self-organized, endogenous way. Increasing visual cortex activity caused improved visual sensitivity. This approach goes beyond conventional functional imaging studies, which are purely correlational. Similar to approaches that disrupt brain activity either temporarily (e.g. transcranial magnetic stimulation) or permanently (e.g. brain lesions), the neurofeedback approach allows us to regard perception or behaviour as the variable which is dependent on the manipulation of brain activity; it therefore allows to establish a causal link between brain activity and perception. These results show that the non-invasive and non-pharmacological neurofeedback method is a promising tool for improving normal brain function. Further, it might also lead to important clinical applications. In principle, any psychological or psychiatric disorder which is associated with abnormal levels of activity in specific brain regions can be challenged with neurofeedback.