The study the book refers to seems to be DaSilva et al. (2007).
Thickening in the SSC is in line with diffusional abnormalities observed in the subcortical trigeminal somatosensory pathway of the same migraine cohort in a previous study. Repetitive migraine attacks may lead to, or be the result of, neuroplastic changes in cortical and subcortical structures of the trigeminal somatosensory system.
Kim et al. (2014) studied this.
Fifty-six female migraine patients without aura and T2-visible white matter hyperintensities and 34 female controls were scanned on a 3T magnetic resonance imager. Cortical thickness was estimated and compared between patients and controls using a whole-brain vertex-by-vertex analysis. Correlation analysis was conducted between cortical thickness of significant clusters and clinical variables.
We have provided evidence for interictal cortical abnormalities of thickened prefrontal cortex and somatosensory cortex in female migraine patients without aura. Our findings of greater thickening of the somatosensory cortex in relation to increasing disease duration and increasing headache frequency suggest that repeated migraine attacks over time may lead to structural changes of the somatosensory cortex through increased noxious afferent input within the trigemino-thalamo-cortical pathway in migraine.
A longitudinal study over 4 years was conducted by Messina et al. (2018)
To explore cross-sectional and longitudinal gray matter (GM) volume changes in patients with migraine and their association with patients' clinical characteristics and disease activity.
Over the follow-up, migraineurs developed an increased volume of frontotemporoparietal regions, which was more prominent in patients with a higher baseline disease activity: long disease duration and high attack frequency. Migraineurs also developed decreased GM volume of visual areas, which was related to higher pain severity. Patients with an increased attack frequency at follow-up experienced both increased and decreased volume of nociceptive regions. In migraineurs, reduced GM volume of extrastriate visual areas during the follow-up was significantly correlated to baseline disease activity: shorter disease duration and lower attack frequency.
In this cohort, the migraine brain changes dynamically over time, and different pathophysiologic mechanisms can occur in response to patients' disease severity. The interaction between predisposing brain traits and experience-dependent responses might vary across different nociceptive and visual areas, thus leading to distinct patterns of longitudinal GM volume changes.
DaSilva, A. F., Granziera, C., Snyder, J., & Hadjikhani, N. (2007). Thickening in the somatosensory cortex of patients with migraine. Neurology, 69(21), 1990-1995. https://doi.org/10.1212/01.wnl.0000291618.32247.2d
Kim, J. H., Kim, J. B., Suh, S. I., Seo, W. K., Oh, K., & Koh, S. B. (2014). Thickening of the somatosensory cortex in migraine without aura. Cephalalgia : an international journal of headache, 34(14), 1125–1133. https://doi.org/10.1177/0333102414531155
Messina, R., Rocca, M. A., Colombo, B., Pagani, E., Falini, A., Goadsby, P. J., & Filippi, M. (2018). Gray matter volume modifications in migraine: a cross-sectional and longitudinal study. Neurology, 91(3), e280-e292. https://doi.org/10.1212/wnl.0000000000005819