This study investigated the fine-grained development of the EEG power spectra in early adolescence, and the extent to which it is reflected in changes in peak frequency. It also sought to determine whether sex differences in the EEG power spectra reflect differential patterns of maturation. A group of 56 adolescents were tested at age 10 years and then at two further time-points approximately 18 months apart. The EEG was recorded during both eyes-closed and eyes-open conditions and Fourier transformed to provide estimates of absolute and relative spectral power at 0.5 Hz intervals from 0.5 to 40 Hz. The peak alpha frequency for each individual at each time-point was also determined for relative spectral power. Partial Least Squares (PLS) analysis was used to determine the combination of electrodes and frequencies that showed developmental change, or differed between the sexes. As a function of age, absolute delta and theta frequencies power decreased, and relative alpha2 and beta frequencies increased, replicating the standard findings of a decrease in lower, and increase in higher, frequencies with age. A small but significant increase in peak alpha frequency with age was detected. Moreover PLS analysis performed with individual alpha frequencies aligned to 10 Hz suggested that the age-related increase seen in alpha2 relative power was driven by changes in the peak frequency. Although males demonstrated higher alpha power than females, there were no sex differences in peak frequency, suggesting that there may be more to sex differences in EEG power than simply different rates of maturation between the two sexes.

The basal ganglia and the cerebellum are anatomically and functionally linked to the cerebral cortex through a series of well-established circuits. The disruption of dopaminergic projections in Parkinson's disease (PD) leads to an imbalance within these circuits, leading to motor and cognitive symptoms. The cortico-cerebellar (CC) network has often been viewed as a compensatory network, helping the dysfunction of the cortico-basal ganglia (CBG) circuits in PD. However, evidence for this compensatory role is scarce; most changes in cerebellar activity could equally be attributed to pathophysiological changes underlying PD. This paper will review the anatomy, interaction and function of the CBG and CC circuits, the pathophysiological, metabolic, and functional changes observed in PD, as well as the effect of levodopa and deep brain stimulation on these changes. We will use this framework to discuss the pathophysiological and compensatory mechanisms behind CBG and CC circuit activity in PD.

Although there are a number of functional neuroimaging studies that have investigated self-initiated and externally-triggered movements, data directly comparing right and left hands in this context are very scarce. The goal of this study was to further understand the role of the basal ganglia and prefrontal cortex in the realm of self-initiated and externally-triggered right and left hand movements. Young healthy right-handed adults performed random, follow and repeat conditions of a finger moving task with their right and left hands, while being scanned with functional magnetic resonance imaging. Significant activation of the dorsolateral prefrontal cortex was observed when comparing the self-initiated movements with the repeated control and externally-triggered movements when using either hand in agreement with its role in monitoring. The caudate nucleus activation was found during self-initiated conditions compared with the control condition when either hand was used, showing that it is particularly involved when a new movement needs to be planned. Significant putamen activation was observed in all within-hand contrasts except for the externally-triggered vs. control condition when using the left hand. Furthermore, greater putaminal activation was found for the left vs. the right hand during the control condition, but for the right vs. the left hand subtraction for the self-initiated condition. Our results show that the putamen is particularly involved in the execution of non-routine movements, especially if those are self-initiated. Furthermore, we propose that, for right-handed people performing fine movements, as far as putamen involvement is concerned, the lack of proficiency of the non-dominant hand may prevail over other task demands.