Neural responses during movement with auditory rhythms

Auditory-motor synchronization tasks (such as tapping to a beat) involve both auditory and sensorimotor neural networks. Electrophysiologically-recorded steady-state evoked potentials have shown enhanced amplitudes at specific stimulus frequencies during listening and tapping to external rhythms. We attempted to distinguish neural responses to percepts and actions during an auditory synchronization task, and to compare them with behavioral synchronization measures. Neural responses during Synchronization were compared with those during Listen-only (no movement, same stimulus) and Motor-only (no stimulus, same movement) tasks. Twenty-five right-handed musicians tapped to a rhythmically regular stimulus as their electroencephalogram (EEG) was recorded. The Synchronization stimuli varied in rhythmic complexity from low complexity (stimulus-to-tap ratio of 1:1) to moderate (1:2) and high complexity (3:2); thus, the tapping frequency was held constant while the stimulus rate varied. Participants synchronized with the stimulus (Synchronize), listened to the same stimulus rhythms (Listen-only) and detected occasional missing beats, or tapped at the same rate (Motor-only). As the rhythmic complexity increased across conditions, behavioral asynchrony (measured as tap onset minus stimulus onset times) increased, and peak amplitudes in the EEG power spectra at tap frequencies decreased. The Synchronize condition elicited greater ssEP peak amplitudes than Listen-only and Motor-only conditions at both stimulus and tap frequencies. Individuals’ entrainment strength in low complexity (1:1) was predictive of their entrainment in high complexity (1:2, 2:3) rhythms. An additional ssEP component emerged in the 3:2 condition at unique frequency where stimulus and taps aligned, suggesting neural interactions between auditory and sensorimotor networks during auditory-motor synchronizatio

Rhythm complexity modulates behavioral and neural dynamics during auditory–motor synchronization

We addressed how rhythm complexity influences auditory-motor synchronization in musically trained individuals who perceived and produced complex rhythms while EEG was recorded. Participants first listened to two-part auditory sequences (Listen condition). Each part featured a single pitch presented at a fixed rate; the integer ratio formed between the two rates varied in rhythmic complexity from low (1:1) to moderate (1:2) to high (3:2). One of the two parts occurred at a constant rate across conditions. Then, participants heard the same rhythms as they synchronized their tapping at a fixed rate (Synchronize condition). Finally, they tapped at the same fixed rate (Motor condition). Auditory feedback from their taps was present in all conditions. Behavioral effects of rhythmic complexity were evidenced in all tasks; detection of missing beats (Listen) worsened in the most complex (3:2) rhythm condition, and tap durations (Synchronize) were most variable and least synchronous with stimulus onsets in the 3:2 condition. EEG power spectral density was lowest at the fixed rate during the 3:2 rhythm and greatest during the 1:1 rhythm (Listen and Synchronize). ERP amplitudes corresponding to an N1 time window were smallest for the 3:2 rhythm and greatest for the 1:1 rhythm (Listen). Finally, synchronization accuracy (Synchronize) decreased as amplitudes in the N1 time window became more positive during the high rhythmic complexity condition (3:2). Thus, measures of neural entrainment corresponded to synchronization accuracy, and rhythmic complexity modulated the behavioral and neural measures similarly

Pituitary Abscess Manifesting as Meningitis and Photophobia Associated With Rathke's Cleft Cyst in a Child -Case Report-

A 12-year-old girl presented with complaints of headache, lethargy, photophobia, and fever. Cerebrospinal fluid examination revealed bacterial meningitis. Magnetic resonance (MR) imaging showed a cystic lesion with peripheral enhancement in the pituitary fossa. The patient underwent transnasal-transsphenoidal surgery (TSS). The diagnosis was pituitary abscess associated with Rathke's cleft cyst. Postoperatively, the patient recovered rapidly. However, recurrence of the pituitary abscess causing meningitis occurred four times and required repeated TSS. She had diabetes insipidus and received hormone replacement. This case requiring repeated emergency surgeries shows that follow-up examinations including MR imaging and pituitary endocrine evaluation are necessary because the rate of recurrence is high in patients with pituitary abscess associated with Rathke's cleft cyst.ArticleNEUROLOGIA MEDICO-CHIRURGICA. 51(6):455-459 (2011)journal articl