Continuous theta burst stimulation (cTBS) on left cerebellar hemisphere affects mental rotation tasks during music listening.

Converging evidence suggests an association between spatial and music domains. A cerebellar role in music-related information processing as well as in spatial-temporal tasks has been documented. Here, we investigated the cerebellar role in the association between spatial and musical domains, by testing performances in embodied (EMR) or abstract (AMR) mental rotation tasks of subjects listening Mozart Sonata K.448, which is reported to improve spatial-temporal reasoning, in the presence or in the absence of continuous theta burst stimulation (cTBS) of the left cerebellar hemisphere. In the absence of cerebellar cTBS, music listening did not influence either MR task, thus not revealing a "Mozart Effect". Cerebellar cTBS applied before musical listening made subjects faster (P = 0.005) and less accurate (P = 0.005) in performing the EMR but not the AMR task. Thus, cerebellar inhibition by TBS unmasked the effect of musical listening on motor imagery. These data support a coupling between music listening and sensory-motor integration in cerebellar networks for embodied representations.

Differential involvement of the left frontal and temporal regions in verb naming: a tDCS treatment study.

PURPOSE: In aphasic patients, some studies have already emphasized the efficacy of transcranial direct current stimulation (tDCS) during the treatment of noun retrieval deficits. To date, in the same population, there are have been no studies addressing tDCS effects in the recovery of verb retrieval deficits. In this study, we wanted to test the potential of tDCS to improve verb production in a group of aphasic patients. METHODS: Seven chronic subjects participated in an intensive language training for their difficulties in action naming. Each subject was treated with tDCS (20 min., 1 mA) over the left hemisphere in three different conditions: anodic tDCS over Wernicke's area, anodic tDCS and sham stimulation over Broca's area. Each experimental condition was performed in five consecutive daily sessions over three weeks with 6 days of intersession interval. RESULTS: In all patients, results showed a significantly better response accuracy during the anodic tDCS over Broca's area with respect to the other two conditions which still persisted at one month after the end of the treatment suggesting a long-term effect on the recovery of their verb retrieval deficits. CONCLUSION: These findings further confirm that tDCS represents a useful new therapeutic interventions for the rehabilitation of lexical deficits in aphasic patients.

Timing flickers across sensory modalities.

In tasks requiring a comparison of the duration of a reference and a test visual cue, the spatial position of test cue is likely to be implicitly coded, providing a form of a congruency effect or introducing a response bias according to the environmental scale or its vectorial reference. The precise mechanism generating these perceptual shifts in subjective duration is not understood, although several studies suggest that spatial attentional factors may play a critical role. Here we use a duration comparison task within and across sensory modalities to examine if temporal performance is also modulated when people are exposed to spatial distractors involving different sensory modalities. Different groups of healthy participants performed duration comparison tasks in separate sessions: a time comparison task of visual stimuli during exposure to spatially presented auditory distractors; and a time comparison task of auditory stimuli during exposure to spatially presented visual distractors. We found the duration of visual stimuli biased depending on the spatial position of auditory distractors. Observers underestimated the duration of stimuli presented in the left spatial field, while there was an overestimation trend in estimating the duration of stimuli presented in the right spatial field. In contrast, timing of auditory stimuli was unaffected by exposure to visual distractors. These results support the existence of multisensory interactions between space and time showing that, in cross-modal paradigms, the presence of auditory distractors can modify visuo-temporal perception but not vice versa. This asymmetry is discussed in terms of sensory perceptual differences between the two systems.

Efficacy of repetitive transcranial magnetic stimulation/transcranial direct current stimulation in cognitive neurorehabilitation.

Cognitive deficits are a common consequence of neurologic disease, in particular, of traumatic brain injury, stroke, and neurodegenerative disorders, and there is evidence that specific cognitive training may be effective in cognitive rehabilitation. Several investigations emphasize the fact that interacting with cortical activity, by means of cortical stimulation, can positively affect the short-term cognitive performance and improve the rehabilitation potential of neurologic patients. In this respect, preliminary evidence suggests that cortical stimulation may play a role in treating aphasia, unilateral neglect, and other cognitive disorders. Several possible mechanisms can account for the effects of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) on cognitive performance. They all reflect the potential of these methods to improve the subject's ability to relearn or to acquire new strategies for carrying out behavioral tasks. The responsible mechanisms remain unclear but they are most likely related to the activation of impeded pathways or inhibition of maladaptive responses. Modifications of the brain activity may assist relearning by facilitating local activity or by suppressing interfering activity from other brain areas. Notwithstanding the promise of these preliminary findings, to date no systematic application of these methods to neurorehabilitation research has been reported. Considering the potential benefit of these interventions, further studies taking into consideration large patient populations, long treatment periods, or the combination of different rehabilitation strategies are needed. Brain stimulation is indeed an exciting opportunity in the field of cognitive neurorehabilitation, which is clearly in need of further research.

All talk and no action: a transcranial magnetic stimulation study of motor cortex activation during action word production.

A number of researchers have proposed that the premotor and motor areas are critical for the representation of words that refer to actions, but not objects. Recent evidence against this hypothesis indicates that the left premotor cortex is more sensitive to grammatical differences than to conceptual differences between words. However, it may still be the case that other anterior motor regions are engaged in processing a word's sensorimotor features. In the present study, we used single- and paired-pulse transcranial magnetic stimulation to test the hypothesis that left primary motor cortex is activated during the retrieval of words (nouns and verbs) associated with specific actions. We found that activation in the motor cortex increased for action words compared with non-action words, but was not sensitive to the grammatical category of the word being produced. These results complement previous findings and support the notion that producing a word activates some brain regions relevant to the sensorimotor properties associated with that word regardless of its grammatical category.

Subthalamic deep brain stimulation improves time perception in Parkinson's disease.

Alterations in temporal estimation have been observed in Parkinson's disease (PD) and have been associated with dopaminergic dysfunction. To investigate whether deep brain stimulation might reverse these abnormalities in PD, patients treated with electrode implantation for subthalamic deep brain stimulation were required to reproduce time intervals in different experimental conditions (off deep brain stimulation/off therapy, on deep brain stimulation/off therapy, on therapy/off deep brain stimulation). Patients treated with deep brain stimulation in off deep brain stimulation/off therapy displayed the anomalous pattern of responses typically observed in PD. When subthalamic deep brain stimulation was turned on these abnormalities were significantly attenuated. Our findings reveal that subthalamic deep brain stimulation improves time perception in PD patients, supporting the critical role of basal ganglia in this cognitive function, probably mediated by facilitated thalamo-cortical projections to the prefrontal cortex.