Voluntary control of semantic neural representations by imagery with conflicting visual stimulation.

Neural representations of visual perception are affected by mental imagery and attention. Although attention is known to modulate neural representations, it is unknown how imagery changes neural representations when imagined and perceived images semantically conflict. We hypothesized that imagining an image would activate a neural representation during its perception even while watching a conflicting image. To test this hypothesis, we developed a closed-loop system to show images inferred from electrocorticograms using a visual semantic space. The successful control of the feedback images demonstrated that the semantic vector inferred from electrocorticograms became closer to the vector of the imagined category, even while watching images from different categories. Moreover, modulation of the inferred vectors by mental imagery depended asymmetrically on the perceived and imagined categories. Shared neural representation between mental imagery and perception was still activated by the imagery under semantically conflicting perceptions depending on the semantic category.

Sturge-Weber syndrome with spontaneous intracerebral hemorrhage in childhood.

A girl aged 2 years 10 months suddenly went into a deep coma and demonstrated left hemiplegia. At birth, she had exhibited a left-sided facial port-wine stain typical of Sturge-Weber syndrome (SWS) and involving the V1 and V2 distributions of the trigeminal nerve. Computed tomography showed a right thalamic hemorrhage with acute hydrocephalus. Magnetic resonance imaging with Gd enhancement 8 months before the hemorrhage had shown a patent superior sagittal sinus (SSS) and deep venous system. Magnetic resonance imaging and MR angiography studies 2 months before the hemorrhage had revealed obstruction of the SSS and right internal cerebral vein (ICV). Given that a digital subtraction angiography study obtained after the hemorrhage did not show the SSS or right ICV, the authors assumed that impaired drainage was present in the deep venous system at that stage. The authors speculated that the patient's venous drainage pattern underwent compensatory changes because of the occluded SSS and deep venous collectors, shifting outflow through other cortical venous channels to nonoccluded dural sinuses. Sudden congestion (nearly total to total obstruction) of the ICV may have caused the thalamic hemorrhage in this case, which is the first reported instance of pediatric SWS with intracerebral hemorrhage and no other vascular lesion. Findings suggested that the appearance of major venous sinus occlusion in a child with SWS could be a warning sign of hemorrhage.