To investigate the modulatory effect of a subthreshold low frequency repetitive transcranial magn... more To investigate the modulatory effect of a subthreshold low frequency repetitive transcranial magnetic stimulation (rTMS) train on motor cortex excitability. The study consisted of two separate experiments. Subjects received a 10 min long subthreshold 1 Hz rTMS train. In the first experiment, (single pulse paradigm), cortical excitability was assessed by measuring the amplitude of motor evoked potentials (MEPs) before and after the rTMS train. In the second experiment, a paired pulse paradigm was employed. Corticospinal excitability, as measured by the MEP amplitude, was reduced by the rTMS train (experiment 1), with a significant effect lasting for about 10 min after the train completion. There was notable inter-individual as well as intra-individual variability in the effect. rTMS produced a significant decrease in intra-cortical facilitation as measured by the paired pulse paradigm (experiment 2). This effect lasted for up to 15 min following the train. Intra-cortical inhibition was not significantly affected. Subthreshold low frequency rTMS depresses cortical excitability beyond the duration of the train. This effect seems primarily due to cortical dysfacilitation. These results have implications on the therapeutic use of rTMS.
Page 421. LABORATORY DIAGNOSIS OF ENTEROVIRAL INFECTIONS Harley A. Rotbart and Jose R. Romero 17 ... more Page 421. LABORATORY DIAGNOSIS OF ENTEROVIRAL INFECTIONS Harley A. Rotbart and Jose R. Romero 17 In the United States alone, the enteroviruses (EVs) are estimated to cause 5 to 10 million symptomatic infections annually (78). ...
Electroencephalography and Clinical Neurophysiology/electromyography and Motor Control, 2002
Objectives: Exploring the modulatory effects of different frequencies of repetitive transcranial ... more Objectives: Exploring the modulatory effects of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on the excitability of the motor cortex as measured by the input–output curve technique (I–O curve).Methods: Sixteen healthy subjects participated in this experiment. On two different sessions, conducted 1 week apart, rTMS was applied either at a frequency of 20 or 1 Hz at 90% of individual motor threshold (MT) for a total of 1600 pulses each. Before and after rTMS, the cortical excitability was assessed by measuring MT and the size of motor evoked potentials (MEPs) collected at different intensities of stimulation.Results: The analysis on the whole population showed a significant decrease of cortical excitability after 1 Hz rTMS and an increase after 20 Hz rTMS. A subsequent cluster analysis pointed out the presence of two distinct groups of subjects with opposite responses at the same frequency of stimulation. Significant variations on MT were found for both groups only for the facilitatory effect irrespective of the frequency of stimulation.Conclusions: The results provide further insight into interindividual differences in the effects of rTMS and suggest the existence of subpopulations with specific patterns of response to rTMS.
To investigate the modulatory effect of a subthreshold low frequency repetitive transcranial magn... more To investigate the modulatory effect of a subthreshold low frequency repetitive transcranial magnetic stimulation (rTMS) train on motor cortex excitability. The study consisted of two separate experiments. Subjects received a 10 min long subthreshold 1 Hz rTMS train. In the first experiment, (single pulse paradigm), cortical excitability was assessed by measuring the amplitude of motor evoked potentials (MEPs) before and after the rTMS train. In the second experiment, a paired pulse paradigm was employed. Corticospinal excitability, as measured by the MEP amplitude, was reduced by the rTMS train (experiment 1), with a significant effect lasting for about 10 min after the train completion. There was notable inter-individual as well as intra-individual variability in the effect. rTMS produced a significant decrease in intra-cortical facilitation as measured by the paired pulse paradigm (experiment 2). This effect lasted for up to 15 min following the train. Intra-cortical inhibition was not significantly affected. Subthreshold low frequency rTMS depresses cortical excitability beyond the duration of the train. This effect seems primarily due to cortical dysfacilitation. These results have implications on the therapeutic use of rTMS.
Page 421. LABORATORY DIAGNOSIS OF ENTEROVIRAL INFECTIONS Harley A. Rotbart and Jose R. Romero 17 ... more Page 421. LABORATORY DIAGNOSIS OF ENTEROVIRAL INFECTIONS Harley A. Rotbart and Jose R. Romero 17 In the United States alone, the enteroviruses (EVs) are estimated to cause 5 to 10 million symptomatic infections annually (78). ...
Electroencephalography and Clinical Neurophysiology/electromyography and Motor Control, 2002
Objectives: Exploring the modulatory effects of different frequencies of repetitive transcranial ... more Objectives: Exploring the modulatory effects of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on the excitability of the motor cortex as measured by the input–output curve technique (I–O curve).Methods: Sixteen healthy subjects participated in this experiment. On two different sessions, conducted 1 week apart, rTMS was applied either at a frequency of 20 or 1 Hz at 90% of individual motor threshold (MT) for a total of 1600 pulses each. Before and after rTMS, the cortical excitability was assessed by measuring MT and the size of motor evoked potentials (MEPs) collected at different intensities of stimulation.Results: The analysis on the whole population showed a significant decrease of cortical excitability after 1 Hz rTMS and an increase after 20 Hz rTMS. A subsequent cluster analysis pointed out the presence of two distinct groups of subjects with opposite responses at the same frequency of stimulation. Significant variations on MT were found for both groups only for the facilitatory effect irrespective of the frequency of stimulation.Conclusions: The results provide further insight into interindividual differences in the effects of rTMS and suggest the existence of subpopulations with specific patterns of response to rTMS.
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