Cortical Hyperexcitability Underlies Aberrant Auditory Perception

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Aberrant perceptual experiences are associated with underlying excitation of neural activity known as cortical hyperexcitability (CH; Wilkins, 1995). Resulting percepts are cytoarchitecturally specific, that is the perceptual domain is dependent on the cortical region of hyperexcitability (Burke, 2002). These aberrations and underlying CH are characteristic of several disorders and psychopathologies such as Migraine with Aura (MwA) and Schizophrenia (Palmer et al., 2000; Spencer et al., 2009). MwA patients are known to have a hyperexcitable visual cortex (Mulleners et al., 2001). Using TMS we know phosphene thresholds, the intensity of magnetic stimulation required to induce illusory phosphenes, is lower in MwA patients than controls (Aurora et al., 2003). BOLD response data suggests MwA patients experience significantly elevated V1 activity time-locked to aberrant visual migraine symptoms (Hadjikhani et al., 2001). This suggests visual symptoms of migraine are intrinsically linked to underlying CH.As such, Wilkins (1995) presented a series of grating patterns of high, medium, and low frequency to MwA patients and collected data on the visual distortions (pattern glare) elicited, thus creating the pattern glare test. MwA patients consistently show greater susceptibility to pattern glare than control participants (Evans & Stevenson, 2008). Neuroimaging studies suggest the most distressing patterns produce short, high amplitude Bloody Oxygen Level Dependent (BOLD) responses in the visual cortex (Haigh, Cooper & Wilkins, 2015). Such responses are associated with lower GABA concentrations, a proposed modulator for localised CH (Muthukurmaraswamy et al., 2012).