Solving the mystery of migraines and hallucinations

Lancaster scientists are pioneering new approaches to understanding and influencing the brain networks behind the unusual visual hallucinations and distortions experienced in migraine with aura - and even by people without the condition.

As part of a £600,000 neuroscience project, they will investigate why the brain sometimes becomes overloaded by visual information, producing unusual perceptions, visual distortions and hallucination-like experiences.

The four-year research programme, funded by the Biotechnology and Biological Sciences Research Council, is entitled “Navigating Neural Overload: Decoding Cortical Hyperexcitability and Aberrant Visual Perceptions” and involves world-leading, computationally optimised non-invasive brain-stimulation technology to investigate the neural mechanisms responsible.

The lead researcher is neuroscientist Dr Jason Braithwaite who said: “Our research will address one of the fundamental questions in neuroscience: How does the brain normally maintain stable, reliable perception, and what happens when the neural mechanisms responsible for this stability become disrupted?”

“An important objective is to understand why individual brains respond differently to identical sensory stimulation or brain-stimulation procedures, potentially providing a foundation for more effective and personalised approaches.”

The research employs a phenomenon known as “pattern glare”, in which particular visual patterns can trigger striking perceptual disturbances, including illusory movement, shimmering, flickering, phantoms and strange colours. Pattern-glare phenomena and atypical visual sensitivity have been investigated in patients, particularly people with migraine with aura. Researchers can now use realistic anatomical computer models to calculate and optimise where the applied electrical fields are expected to travel in the brain.

The programme involves an international collaboration with the company Neuroelectrics, based in Barcelona, whose expertise in sophisticated multi-channel brain-stimulation technology and computational modelling is central to the research.

Sophisticated computer modelling takes account of how electrical current travels through the scalp, skull, cerebrospinal fluid and brain tissue, allowing researchers to predict how stimulation will be targeted and distributed within specific brain networks.

Instead of relying on relatively simple arrangements of electrodes placed on the scalp, the research uses advanced multi-channel transcranial direct current stimulation (MtDCS), enabling much greater targeting, focality, and control over how electrical fields are directed towards particular regions of the brain.

For the first time, the programme will investigate the effects of targeting early and later visual processing regions separately, before using innovative stimulation protocols designed to increase excitability in one brain region while simultaneously decreasing it in another.

Rather than simply recording whether somebody experiences visual distortions, the programme uses newly developed experimental methods to examine how different kinds of perceptual disturbances emerge and change as visual stimulation becomes more demanding.

By carefully manipulating visual aspects of experimental stimuli and distinguishing between different forms and intensities of visual disturbance, researchers aim to develop a more detailed understanding of cortical responsiveness than has been possible using more conventional approaches.

These discoveries could advance the fundamental understanding of why some people experience unusual visual disturbances, including the striking aura symptoms associated with migraine, while others do not.

Dr Braithwaite said: “Understanding the underlying neural mechanisms could provide new insights into why some individuals experience abnormal sensory processing and visual disturbances, thus advancing our knowledge of the underlying neural mechanisms.”

By exploring these processes in both people with migraine and those without neurological conditions, the research could also ultimately help inform more personalised, individualised and ‘tailor-made’ approaches to understanding and treating atypical sensory experiences across several disorders and conditions.