Transcranial magnetic stimulation as a complementary treatment for aphasia

Functional brain imaging with nonfluent aphasia patients has shown increased cortical activation (perhaps ‘‘overactivation’’) in right (R) hemisphere language homologues. These areas of overactivation may represent a maladaptive strategy that interferes with, rather than promotes, aphasia recovery. Repetitive transcranial magnetic stimulation (rTMS) is a painless, noninvasive procedure that utilizes magnetic fields to create electric currents in discrete brain areas affecting about a 1-cm square area of cortex. Slow frequency, 1 Hz rTMS reduces cortical excitability. When rTMS is applied to an appropriate cortical region, it may suppress the possible overactivation and thus modulate a distributed neural network for language. We provide information on rTMS and report preliminary results following rTMS application to R Broca’s area (posterior, R pars triangularis) in four stroke patients with nonfluent aphasia (5–11 years after left hemisphere stroke). Following 10 rTMS treatments, significant improvement in naming pictures was observed. This form of rTMS may provide a novel, complementary treatment for aphasia.This research was supported by NIH grant DC05672 from the National Institute on Deafness and Other Communication Disorders, Bethesda, MD; and in part by the Medical Research Service, Department of Veterans Affairs, Washington, DC; and NIH grant NCRR MO1 RR01032 to the Harvard-Thorndike General Clinical Research Center at the Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA; and NIH NIDCD grant P30 DC05207 to the Harold Goodglass Aphasia Research Center, Boston University School of Medicine, Boston, MAMedicin

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A prospective study of physician-observed concussion during a varsity university hockey season: metabolic changes in ice hockey players.

Object. Despite negative neuroimaging findings using traditional neuroimaging methods such as MRI and CT, sports-related concussions have been shown to cause neurometabolic changes in both the acute and subacute phases of head injury. However, no prospective clinical study has used an independent physician-observer design in the monitoring of these changes. The objective of this study was to evaluate the effects of repetitive concussive and subconcussive head impacts on neurometabolic concentrations in a prospective study of two Canadian Interuniversity Sports (CIS) ice hockey teams using MR spectroscopy (MRS). Methods. Forty-five ice hockey players (25 men and 20 women) participated in this study. All participants underwent pre- and postseason MRI, including spectroscopy imaging, using a 3-T MRI machine. The linear combination model was used to quantify the following ratios: glutamate/creatine-phosphocreatine (Cr), myoinositol/Cr, and N-acetylaspartate (NAA)/Cr. Individuals sustaining a medically diagnosed concussion were sent for MRI at 72 hours, 2 weeks, and 2 months after injury. Results. No statistically significant differences were observed between athletes who were diagnosed with a concussion and athletes who were not clinically diagnosed as sustaining a concussion. Although no statistically significant longitudinal metabolic changes were observed among athletes who were diagnosed with a concussion, the results demonstrated a predictable pattern of initial impairment, followed by a gradual return to ratios that were similar to, but lower than, baseline ratios. No significant pre- to postseason changes were demonstrated among men who were not observed to sustain a concussion. However, a substantively significant decrease in the NAA/Cr ratio was noted among the female hockey players (t(13) = 2.58, p = 0.02, h2 = 0.34). Conclusions. A key finding in this study, from the standpoint of future research design, is the demonstration of substantively significant metabolic changes among the players who were not diagnosed with a concussion. In addition, it may explain why there are few statistically significant differences demonstrated between players who were diagnosed with a concussion and players who were not diagnosed with a concussion (that is, the potency of the independent variable was diminished by the fact that the group of players not diagnosed with a concussion might be better described as a subgroup of the players who may have sustained a concussion but were not observed and diagnosed with a concussion). This result suggests that definitions of concussion may need to be revisited within sports with high levels of repetitive subconcussive head impacts. Future analysis of these data will examine the relationships between the modes of MRI (diffusion tensor imaging, MRS, and susceptibility-weighted MR imaging) used in this study, along with other more sensitive evaluative techniques. This type of intermodal comparison may improve the identification of concussions that were previously dependent on the unreliable self-reporting of recognized concussion symptomatology by the athlete or on poorly validated neuropsychological tests

Modulation of right motor cortex excitability without awareness following presentation of masked self-images

The neural substrates of self-awareness have been studied with a variety of neurophysiological and behavioral tools. In the present study, unconscious modulation of corticospinal excitability following presentation of self-images was probed with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEP) were collected from the contralateral first dorsal interosseus (FDI) muscle while subjects viewed masked pictures of their own face. MEP amplitudes were compared to those obtained when pictures of strangers were masked. Masked self-images induced a relative increase in corticospinal excitability when TMS was applied to the right primary motor cortex. These results demonstrate the utility of TMS to probe unconscious processing and support the notion of hemispheric asymmetry in the processing of self-images.Medicin

MEP-rc, SICI, and IHI measures.

<p>MEP-rc (A), SICI (B), and IHI (B) measures Pre- and Post- motor training are shown for the Val66Val Vs. the Vall6Met groups in the Experiment 1. The error bars represent standard errors of the mean. Dashed lines used for comparisons show simple effects. ** p < 0.01.</p

Experiment 2.

<p>The experimental design used in experiment 2 is displayed for the Control-Right (CR) group.</p

Correlation analyses between SICI modulation in the left M1 and GPB performance.

<p>Correlations between Post- to Pre- ratio of SICI in the left M1 (abscissa) and condition 2 to condition 1 ratio of GPB performance (ordinate) are displayed for the Val66Val participants’ left (A) and right (B) hands, and for the CR group’s performance with the right hand (C). Larger SICI ratios indicate a greater decrease in SICI following motor training, and smaller GPB ratios suggest greater improvement from condition 1 to condition 2 on the motor task.</p

Motor performances on the rapid tapping (RT), pinch grip strength (PGS), and the grooved pegboard (GPB).

<p>The mean scores on the RT, the PGS, and the GPB are presented for the Val66Val and the Val66Met participants in Experiment 1 on the R1 and R2 conditions with the right hand (A, B, and C, respectively), and the L1 and L2 conditions with the left hand (D, E, and F, respectively). The error bars represent standard errors of the mean. Full lines used for comparisons represent main effects. * p < 0.05; ** p < 0.01; *** p < 0.001.</p