The posterior parietal cortex and the cerebellum are assumed to contribute to anticipatory motor control. Thus, it is reasonable that these areas act as a functional unit. To identify a neural signature of anticipatory motor control, 11 healthy volunteers performed a bimanual finger-tapping task with respect to isochronous (i.e., regular) and randomized (i.e., irregular) auditory pacing. Neuromagnetic activity was recorded using a 122-channel whole-head neuromagnetometer. Functional interaction between spatially distributed brain areas was determined by measures of tap-related phase synchronization. Assuming that (i) the cerebellum predicts sensory events by an internal model and (ii) the PPC maintains this prediction, we hypothesized that functional interaction between both structures varies depending on the predictability of the pacing signal. During isochronous pacing, functional connectivity within a cerebello-diencephalic-parietal network before tap onset was evident, suggesting anticipatory motor control. During randomized pacing, however, functional connectivity after tap onset was increased within a parietal-cerebellar loop, suggesting mismatch detection and update of the internal model. Data of the present study imply that anticipatory motor control is implemented in a network-like manner. Our data agree well with the hypothesis that functional connectivity in a cerebello-diencephalic-parietal loop might be crucial for anticipatory motor control, whereas parietal-cerebellar interaction might be critical for feedback processing.

Cortico-muscular coherence (CMC) at beta frequency (13-30 Hz) occurs particularly during weak to moderate isometric contraction. It is a well-established measure of communication between the primary motor cortex (M1) and corresponding muscles revealing information about the integrity of the pyramidal system. Although the slowing of brain and muscle dynamics during healthy aging has been evidenced, functional communication as determined by CMC has not been investigated so far. Since decline of motor functions at higher age is likely to be associated with CMC changes, the present study aims at shedding light on the functionality of the motor system from a functional interaction perspective. To this end, CMC was investigated in 27 healthy subjects aging between 22 and 77 years during isometric contraction of their right forearm. Neuromagnetic activity was measured using whole-head magnetoencephalography (MEG). Muscle activity was measured by means of surface electromyography (EMG) of the right extensor digitorum communis (EDC) muscle. Additionally, MEG-EMG phase lags were calculated in order to estimate conducting time. The analysis revealed CMC and M1 power amplitudes to be increased with age accompanied by slowing of M1, EMG, and CMC. Frequency changes were particularly found in subjects aged above 40 years suggesting that at this middle age, neurophysiological changes occur, possibly reflecting an early neurophysiological marker of seniority. Since MEG-EMG phase lags did not vary with age, changes cannot be explained by alterations of nerve conduction. We argue that the M1 power amplitude increase and the shift towards lower frequencies might represent a neurophysiological marker of healthy aging which is possibly compensated by increased CMC amplitude.

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Aggression in dementia is often reactive and seems to be more predictable than if occurring with other diagnoses. Prevention measures such as de-escalations techniques, warning notes in the patient's file with previous aggressive behavior and stepping up for evening shifts are of crucial importance. As nurses were primarily affected, employer support programs, and mental health interventions are proposed to avoid long-term consequences.