Abstract
Transcranial magnetic stimulation (TMS) impulses, (0.5 Hz, 3 impulses) were presented at threshold intensity to male WAG/Rij rats. One group received stimuli, which involved motor responses of hindlimbs, rats of the second group received sham stimulation. Electrocorticograms (ECoG) were recorded before and up to 2 hr from the moment of transcranial magnetic stimulation. It was established that such stimulation engendered a reduction of spike-wave discharge (SWD) bursts duration. This effect was most pronounced in 30 min from the moment of cessation of stimulation, when a decrease of 31.4% was noted in comparison with sham-stimulated control group. The number of bursts of spike-wave discharges was reduced, but did not reach significant difference when compared both with pre-stimulative base-line level and with sham-stimulated control rats. Bursts of spike-wave discharges restored up to pre-stimulative level in 90-150 minutes from the moment of cessation of transcranial stimulation. It can be concluded that transcranical magnetic stimulation possessed an ability to engender short- time suppression of bursts of spike-wave discharges in WAG/Rij rats. In this chapter I argue that the major symptoms of agrammatic aphasia reflect functional reorganization. The underlying deficit is characterized as a reduced possibility to keep sentence elements in computational simultaneity. Language adapts to this brain condition in two ways: by an increase in the frequency of ellipticali utterances and by an increase in the frequency of covert repair behaviors. From these adaptations the language output of these patients derives its telegraphic character and its slow rate. Linguistic, experimental, computational, and brain-imaging evidence for this theory is reviewed. Finally, I discuss functional reorganization in other disorders.
