Walking the talk--speech activates the leg motor cortex.

Speech may have evolved from earlier modes of communication based on gestures. Consistent with such a motor theory of speech, cortical orofacial and hand motor areas are activated by both speech production and speech perception. However, the extent of speech-related activation of the motor cortex remains unclear. Therefore, we examined if reading and listening to continuous prose also activates non-brachiofacial motor representations like the leg motor cortex. We found corticospinal excitability of bilateral leg muscle representations to be enhanced by speech production and silent reading. Control experiments showed that speech production yielded stronger facilitation of the leg motor system than non-verbal tongue-mouth mobilization and silent reading more than a visuo-attentional task thus indicating speech-specificity of the effect. In the frame of the motor theory of speech this finding suggests that the system of gestural communication, from which speech may have evolved, is not confined to the hand but includes gestural movements of other body parts as well.

Obesity in neurobiology.

Obesity reflects an imbalance between energy uptake and expenditure that is mediated by behavior. Obesity is a growing epidemic and a major risk factor for neurobiological diseases like stroke, dementia, intracranial hypertension and sleep disorders. Conversely, obesity can also be induced by neurobiological disorders and drugs. The etiology of obesity is complex and includes biology, behavior and environment. Physicians are faced with the need to manage obesity while strategies for prevention and sustained weight reduction are limited. Present treatment options comprise lifestyle modification, diet, pharmacotherapy and bariatric surgery. Considerable headway has been made into elucidating the neurobiological underpinnings of obesogenic behavior. There is now a growing understanding of the metabolic, hormonal and behavioral circuitries that contribute to the complex and redundant system for energy balance. Changing the net balance of this system to prevent or reduce obesity requires multimodal and long-term interventions.

Pregabalin-associated acute psychosis and epileptiform EEG-changes.

Pregabalin is a novel anticonvulsive and analgesic drug that has been marketed in Europe for more than a year. The typical side effects are dizziness, somnolence and weight gain. We present a patient who, after unintended rapid up-titration of pregabalin, experienced psychotic symptoms associated with rhythmic EEG-changes resolving completely after discontinuation of pregabalin and benzodiazepine administration.

Idiopathic spinal cord herniation causing progressive Brown-Séquard syndrome.

We report a 59-year-old woman with a 2.5 year history of progressive loss of temperature sensation and dysesthesia in the right and weakness in the contralateral lower limb. Magnetic resonance imaging (MRI) and computed tomography myelography of the spinal cord demonstrated transdural herniation and deformation of the spinal cord in the upper thoracic spine. The herniated part of the spinal cord was untethered and replaced, and the anterior dural defect was closed. At a clinical follow-up 3 months later, the motor and sensory functions were almost restored. MRI at this time showed disentanglement of spinal cord adherence.

The clinical spectrum of musical hallucinations.

Musical hallucinations are a well known although rare phenomenon in neurological and psychiatric patients. Many case reports have been published to date. However, an accepted common theory on the classification and on the pathophysiology of musical hallucinations is still missing. We analysed all cases published to date, including two own cases, with respect to their demographic and clinical features and to the possible pathomechanisms underlying the hallucinations. In total, 132 cases could be analysed statistically and separated into five groups according to their aetiology (hypacusis; psychiatric disorder; focal brain lesion; epilepsy; intoxication). There was a female preponderance of 70% and a mean age of 61.5 years. Patients with focal brain lesions were significantly younger than the other groups, the hemisphere of the lesion did not play a major role. No systematic studies on treatment are available. However, anticonvulsant and antidepressive substances were reported to be effective most consistently. The pathophysiology of musical hallucinations is discussed considering the theories of deafferentiation including the concept of auditory Charles-Bonnet syndrome, of sensory auditory deprivation, of parasitic memory, and of spontaneous activity in a cognitive network module. In conclusion, musical hallucinations are a phenomenon with heterogeneous clinical and pathophysiological backgrounds.

Language perception activates the hand motor cortex: implications for motor theories of speech perception.

The precise mechanisms of how speech may have developed are still unknown to a large extent. Gestures have proven a powerful concept for explaining how planning and analysing of motor acts could have evolved into verbal communication. According to this concept, development of an action-perception network allowed for coding and decoding of communicative gestures. These were manual or manual/articulatory in the beginning and then became increasingly elaborate in the articulatory mode. The theory predicts that listening to the 'gestures' that compose spoken language should activate an extended articulatory and manual action-perception network. To examine this hypothesis, we assessed the effects of language on cortical excitability of the hand muscle representation by transcranial magnetic stimulation. We found the hand motor system to be activated by linguistic tasks, most notably pure linguistic perception, but not by auditory or visuospatial processing. The amount of motor system activation was comparable in both hemispheres. Our data support the theory that language may have evolved within a general and bilateral action-perception network.

Changing cortical excitability with low-frequency transcranial magnetic stimulation can induce sustained disruption of tactile perception.

Transcranial magnetic stimulation (TMS) is promising as a therapeutic tool, and TMS of the motor system has served as a model for regionally specific modulations of cortical excitability. It is unclear, however, to what extent response characteristics of the motor cortex are representative of other brain systems. We wanted to determine whether TMS could induce a sustained disruption of somatosensory processing beyond the stimulation duration, similar to observations in the motor system. We applied 1-Hz TMS at 110% of subjects' motor thresholds for a variable duration over the right and left somatosensory cortex before subjects performed a tactile frequency discrimination task with the left hand. Tactile discrimination was impaired only after TMS over the right somatosensory cortex (analysis of variance: p <.01). The duration of this impairment correlated with the duration of the preceding TMS; the effect lasted approximately 2 min after 5 min of TMS, 4 min after 10 min of TMS, and 8 min after 20 min of TMS. Two conclusions arise: 1) low-frequency TMS can interfere with tactile perception in a robust and sustained way, and 2) TMS dosing parameters effective in the motor system are also effective in the somatosensory system and may reflect a modality-independent response characteristic of the cerebral cortex.

Event-related potentials in different subtypes of multiple sclerosis--a cross-sectional study.

Impairment of cognitive skills is found in up to 65% of patients suffering from multiple sclerosis (MS). Little is known concerning the natural history or characteristics of progression of these cognitive dysfunctions. Furthermore, it has not been investigated to date whether there are differences in the course of cognitive impairment with respect to different diagnostic subgroups of MS. Event-related potentials (ERP) are an objective tool to evaluate cognitive processing. We performed a cross-sectional study on 179 consecutive patients suffering from MS (107 relapsing-remitting MS; 17 primary progressive MS; 50 secondary progressive MS; 5 undetermined). ERP were measured by a visual oddball paradigm, latencies of P3 components were correlated with demographic and clinical data. We found pathologically increased P3 latencies in 56% of all patients. Patients with secondary progressive MS showed significantly increased P3 latencies as compared to the other subgroups. There was a significant correlation between expanded disability status scale (EDSS) score and P3 latency (r=0.48; p<0.001). We conclude that ERP are an appropriate method to follow up cognitive dysfunction in MS and that cognitive dysfunction as measured by ERP is progressively impaired in the course of MS, in particular in the secondary progressive subtype.

Is hemispheric language dominance relevant in musical hallucinations? Two case reports.

It has been suggested that musical hallucinations are often due to a focal brain lesion predominantly of right hemispheric pathologies. We report about two patients with musical hallucinations associated with a brain tumor of the right hemisphere. Although both patients were right-handed, one of them had a right hemispheric dominance for language as proven by the Wada test. The musical ability as measured by the Seashore test was not impaired. We conclude that the language dominance of the hemisphere is not primarily relevant for the development of musical hallucinations.