Subthalamic deep brain stimulation for Parkinson's disease: Correlation between locations of oscillatory activity and optimal site of stimulation

Subthalamic nucleus deep brain stimulation (STN DBS) is an effective surgical treatment for Parkinson's disease (PD). Recent studies demonstrated that pathological oscillations are seen largely within the dorsolateral portion of the STN, which is the same location that predicts optimal therapeutic benefit with DBS; however, the precise nature of the relationship between these two phenomena remains unclear. The purpose of this study was to explore localization of oscillatory activity in relation to the optimal contacts of DBS which results in the best motor improvement. We studied 23 PD patients who underwent electrode implantation into the STN for motor symptoms.Microelectrode recordings were taken from the STN during surgery and neuronal activity was analyzed offline. Spectral characteristics were calculated. Clinical outcomes were evaluated pre- and post-STN DBS implantation using the Unified Parkinson's Disease Rating Scale (UPDRS III). The position of optimal electrode contacts was assessed by postoperative magnetic resonance imaging (MRI) and was compared to the location of oscillatory activity within the STN as well as its dorsal margin (where STN neuronal activity was first detected). Of the total 188 neurons obtained, 51 (27.1%) neurons showed significant oscillatory activity. Of those, 47 (92.2%) were localized in the dorsal portion of the STN. Furthermore, there was no significant difference between the averaged coordinates of the position of 40 optimal contacts and the coordinates of the dorsal margin of the STN. The data indicate that the positions of the best contacts correlate with the locations of the oscillatory neurons supporting the prediction that stimulation of the dorsolateral oscillatory region leads to an effective clinical outcome for STN DBS surgery.     

Hand preference for sending mobile-phone text messages: Associations with sex,writing hand,and throwing hand

Hand preference for sending mobile-phone text messages (“texting”) and its relationship with hand preference for other activities were investigated in a questionnaire study with 886 participants. Overall rates of both sinistrality and dextrality were reduced for texting, in comparison with other activities, due to the substantial number of individuals who use both hands simultaneously when performing this activity. Because they both involve verbal expression, it was hypothesised that the association between hand preferences for texting and writing might be stronger than the association between either of these tasks and more spatial activities, such as throwing. This prediction was not confirmed, either in the sample as a whole or in a sub-group of individuals who reported writing and throwing with opposite hands. Females were less likely than males to use their left hand when sending text messages. Implications of these findings are discussed, in relation to theoretical views of handedness and in relation to practical aspects of mobile-phone design.     

Mapping Different Intra-Hemispheric Parietal-Motor Networks Using Twin Coil TMS

BackgroundAccumulating evidence suggests anatomical and functional differences in connectivity between the anterior and posterior parts of the inferior-parietal lobule (IPL) and the frontal motor areas.Objective/HypothesisThis study investigates whether different intra-hemispheric parietal-motor interactions can be observed along the anterior–posterior axis of the IPL in the resting human brain.MethodsWe use a twin coil transcranial magnetic stimulation technique to test intra-hemispheric interactions between three points adjacent to the intra-parietal sulcus (anterior, central, posterior) and the ipsilateral primary motor cortex (M1) at rest in both hemispheres.ResultsWe found that stimulation of the anterior IPL resulted in an inhibition of the ipsilateral M1 in both hemispheres. Stimulation of the central and posterior IPL resulted in a facilitatory effect on ipsilateral M1 in the left but not for the right hemisphere. Additionally we show that there is considerable inter-subject variability concerning the optimal parietal facilitatory and inhibitory position.ConclusionsThe IPL has distinct inhibitory and facilitatory connections to the ipsilateral M1. Whereas inhibitory connections are observed in both hemispheres, facilitatory connections are asymmetric. These parietal-motor networks may represent the basis for the functional differences between these regions in reaching and grasping tasks and mirror the functional asymmetry observed in the motor system. From a practical point of view, we note that the inter-subject variability means that future TMS studies of the parietal area might consider a hot-spot localization similar to the procedures commonly used for M1.     

Exploring the Manifestations of Anxiety in Children with Autism Spectrum Disorders

This study explores the manifestation and measurement of anxiety symptoms in 415 children with ASDs on a 20-item, parent-rated, DSM-IV referenced anxiety scale. In both high and low-functioning children (IQ above vs. below 70), commonly endorsed items assessed restlessness, tension and sleep difficulties. Items requiring verbal expression of worry by the child were rarely endorsed. Higher anxiety was associated with functional language, IQ above 70 and higher scores on several other behavioral measures. Four underlying factors emerged: Generalized Anxiety, Separation Anxiety, Social Anxiety and Over-arousal. Our findings extend our understanding of anxiety across IQ in ASD and provide guidance for improving anxiety outcome measurement.     

Changes in spinal excitability after PAS

Repetitive pairing of a peripheral stimulation with a magnetic transcortical stimulation (PAS) is widely used to induce plastic changes in the human motor cortex noninvasively. Based on the contrast between PAS-induced increase of corticospinal excitability and absence of PAS-induced increase of the spinal F wave size, it has been generally accepted that PAS-induced plasticity is cortical in origin. Here, instead of F waves, we used H reflex recruitment curves to assess spinal excitability, and we demonstrate that PAS induces parallel changes in cortical and spinal excitability.