Evidence from animal experiments shows that the brain stem is involved in the pathophysiology of migraine. To investigate human migraine, we used positron emission tomography to examine the changes in regional cerebral blood flow as an index of neuronal activity in the human brain during spontaneous migraine attacks. During the attacks, increased blood flow was found in the cerebral hemispheres in cingulate, auditory and visual association cortices and in the brain stem. However, only the brain stem activation persisted after the injection of sumatriptan had induced complete relief from headache and phono- and photophobia. These findings support the idea that the pathogenesis of migraine is related to an imbalance in activity between brain stem nuclei regulating antinociception and vascular control.

Although beneficial effects were observed among caregivers in the PSI group, the lack of effects on problem-solving abilities implies other characteristics of the intervention might account for these benefits. The relative intensity and therapeutic contact during the first 3 months of the intervention may be particularly helpful to caregivers of stroke survivors.

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9. It is suggested that long-range inhibition is mediated by the recurrent pathway via perigeniculate neurones while the more specific types of inhibition (centre surround and binocular) might arise from intrageniculate interneurones. The cholinergic system seems to serve as a selective mechanism to modulate global inhibition and leave the specific types unaffected.

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