Following a hemispheric stroke, various degrees of neuronal reorganization around the lesion occur immediately after disease onset and thereafter up to several months. These include transcallosal excitability, changes of the intact motor cortex and ipsilateral motor responses after transcranial magnetic stimulation (TMS) on the intact hemisphere. To elucidate the relationship between lesion localization and motor cortex excitability (intracortical inhibition; ICI) in the intact hemisphere, we applied a paired conditioning-test TMS paradigm in 12 patients with unilateral cortical stroke (cortical group) and nine patients with subcortical stroke caudal to the corpus callosum (subcortical group), with interstimulus intervals varying from 1 to 10 ms. All patients exhibited unilateral complete hand palsy. ICI was significantly less in the cortical group than in age-matched healthy control subjects. It was especially more marked in the cortical group patients with a disease duration of less than 4 months after onset. Patients in the cortical group with a duration longer than 4 months showed a tendency for ICI to be normalized, and there was a significant correlation between ICI and disease duration. Patients in the subcortical group showed normal excitability curves. All patients in the cortical group showed no transcallosal inhibition (TCI) in the active unaffected hand muscle after TMS of the affected motor cortex, whereas all the subcortical patients showed some TCI. No ipsilateral motor responses were elicited in the paretic hand in any of the patients. The reduced ICI in the cortical group might have been a result of disruption of TCI. The normalization of ICI in the patients with longer disease duration and the normal ICI in the subcortical group patients do not support the functional significance of motor cortex hyperexcitability in the unaffected hemisphere, at least in a patient population with poor motor recovery.

Background and Purpose-Despite the findings that motor imagery and execution are supposed to share common neural networks, previous studies using imagery-based rehabilitation have revealed inconsistent results. In the present study, we investigated whether feedback of cortical activities (neurofeedback) using near-infrared spectroscopy could enhance the efficacy of imagery-based rehabilitation in stroke patients. Methods-Twenty hemiplegic patients with subcortical stroke received 6 sessions of mental practice with motor imagery of the distal upper limb in addition to standard rehabilitation. Subjects were randomly allocated to REAL and SHAM groups. In the REAL group, cortical hemoglobin signals detected by near-infrared spectroscopy were fed back during imagery. In the SHAM group, irrelevant randomized signals were fed back. Upper limb function was assessed using the finger and arm subscales of the

In mammalian cells, siRNAs have been used to induce RNA interference (RNAi) in an attempt to prevent nonspecific effects (including the interferon (IFN) response) which are caused by long double-stranded RNAs (dsRNAs) of more than 30 bp. In this report, we describe a novel and simple strategy for avoiding activation of the IFN response by dsRNA. We show that modified hairpin-RNAs (mhRNAs) of more than 100 bp, with multiple specific point-mutations within the sense strand and transcribed from the U6 or tRNA(Val) promoters, can cause RNAi without inducing the IFN pathway genes. Moreover, we demonstrate that the 50-bp mhRNA vector could effectively suppress the replication of multiple hepatitis C viruses (the genomes of which differ slightly, thus the 21-bp siRNA vector failed to suppress one of them). Our findings should enhance the exploitation of RNAi in mammalian cells, especially in the field of RNAi therapy against pathogenic viruses.

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