[TK2 mutations and late onset myopathy: first description in a Mexican patient]. / Mutacion del gen TK2 y miopatia de inicio tardio: descripcion del primer caso mexicano.

TITLE: Mutacion del gen TK2 y miopatia de inicio tardio: descripcion del primer caso mexicano.

Simultaneous TMS-fMRI of the Visual Cortex Reveals Functional Network, Even in Absence of Phosphene Sensation.

Phosphene sensation is commonly used to measure cortical excitability during transcranial magnetic stimulation (TMS) of the occipital cortex. However, some individuals lack this perception, and the reason for it is still unknown. In this work, we used functional magnetic resonance imaging (fMRI) to detect brain activation during local TMS of the occipital cortex in twelve healthy subjects. We found that TMS modulated brain activity in areas connected to the stimulation site, even in people unable to see phosphene. However, we observed a trend for a lower blood-oxygenation-level dependent (BOLD) signal, and smaller brain-activation clusters near the stimulated site than in the interconnected brain areas, suggesting that TMS pulse is more effective downstream than at its application site. Furthermore, we noted prominent differences in brain activation/deactivation patterns between subjects who perceived phosphene and those who did not, implying a functional distinction in their neuronal networks that might explain the origin of differences in phosphene generation.

Evolution of a focal brain lesion produced by interlaced microplanar X-rays.

Stereotactic radiosurgery has led to advances in the treatment of central nervous system disease. It relies upon the principle of delivering relatively high dose irradiation to a precise target, while exposing surrounding tissues to extremely low doses. We describe a novel radiosurgical approach using interlaced microplanar X-rays which we have termed "microradiosurgery." The use of microbeams allows for 1,000-times greater precision than current clinically employed techniques. As a demonstration of this new method, we produced a approximately 3.8 mm (3) lesion in the rat brain. The lesion was followed over a period of 216 days using 9.4 Tesla magnetic resonance imaging. Our results show a gradually developing lesion at the site of the interlaced beams. The lesion began as a high T2 signal only, but advanced to include a central area of low T1 and mixed T2 signal within 2 months. No lesion was observed in the other side of the brain which was exposed to non-interlaced microbeams only. Interlaced microbeams is an effective method to create focal brain microlesions. This technique may allow the future treatment of pathology not accessible by surgical or more traditional radiosurgical means.