The European journal of neuroscience
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When viewing the needle of a syringe approaching your skin, anticipation of a painful prick may lead to increased arousal. How this anticipation is reflected in neural oscillatory activity and how it relates to activity within the autonomic nervous system is thus far unknown. Recently, we found that viewing needle pricks compared with Q-tip touches increases the pupil dilation response (PDR) and perceived unpleasantness of electrical stimuli. ⋯ Source reconstruction using linear beamforming revealed reduced alpha-band activity in the posterior cingulate cortex (PCC) and fusiform gyrus before the onset of electrical stimuli when participants viewed needle pricks compared with Q-tip touches. Moreover, alpha-band activity in the PCC predicted PDR on a single trial level. The anticipatory reduction of alpha-band activity in the PCC may reflect a neural mechanism that serves to protect the body from forthcoming harm by facilitating the preparation of adequate defense responses.
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A range of techniques are now available for modulating the activity of the brain in healthy people and people with neurological conditions. These techniques, including transcranial magnetic stimulation (TMS) and transcranial current stimulation (tCS, which includes direct and alternating current), create magnetic or electrical fields that cross the intact skull and affect neural processing in brain areas near to the scalp location where the stimulation is delivered. ⋯ In clinical neuroscience, the techniques offer the promise of correcting abnormal activity, such as when a stroke leaves a brain area underactive. As the use of brain stimulation becomes more commonplace in laboratories and clinics, we discuss the safety and ethical issues inherent in using the techniques with human participants, and we suggest how to balance scientific integrity with the safety of the participant.
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Randomized Controlled Trial
One hertz repetitive transcranial magnetic stimulation over dorsal premotor cortex enhances offline motor memory consolidation for sequence-specific implicit learning.
Consolidation of motor memories associated with skilled practice can occur both online, concurrent with practice, and offline, after practice has ended. The current study investigated the role of dorsal premotor cortex (PMd) in early offline motor memory consolidation of implicit sequence-specific learning. Thirty-three participants were assigned to one of three groups of repetitive transcranial magnetic stimulation (rTMS) over left PMd (5 Hz, 1 Hz or control) immediately following practice of a novel continuous tracking task. ⋯ Enhanced sequence-specific learning with 1 Hz rTMS following practice was due to greater offline consolidation, not differences in online learning between the groups within practice days. A follow-up experiment revealed that stimulation of PMd following practice did not differentially change motor cortical excitability, suggesting that changes in offline consolidation can be largely attributed to stimulation-induced changes in PMd. These findings support a differential role for the PMd in support of online and offline sequence-specific learning of a visuomotor task and offer converging evidence for competing memory systems.
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Speech motor control develops gradually as the acoustics of speech are mapped onto the positions and movements of the articulators. In this event-related potential (ERP) study, children and adults aged 4-30 years produced vocalizations while exposed to frequency-altered feedback. Vocal pitch variability and the latency of vocal responses were found to differ as a function of age. ⋯ P1 amplitudes decreased with age, whereas N1 and P2 amplitudes increased with age. In addition, a correlation between vocal variability and N1 amplitudes was found, suggesting a complex interaction between behavioural and neurological responses to frequency-altered feedback. These results suggest that the neural systems that integrate auditory feedback during vocal motor control undergo robust changes with age and physiological development.
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The insular cortex (IC) is known to play important roles in higher brain functions such as memory and pain. Activity-dependent long-term depression (LTD) is a major form of synaptic plasticity related to memory and chronic pain. Previous studies of LTD have mainly focused on the hippocampus, and no study in the IC has been reported. ⋯ In contrast, inhibiting protein kinase C, protein kinase A, protein kinase Mζ or calcium/calmodulin-dependent protein kinase II did not affect LFS-evoked LTD in the IC. Bath application of the group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine produced another form of LTD in the IC, which was NMDA receptor-independent and could not be occluded by LFS-induced LTD. Our studies have characterised the basic mechanisms of LTD in the IC at the network level, and suggest that two different forms of LTD may co-exist in the same population of IC synapses.