Existing motor state is favored at the expense of new movement during 13-35 Hz oscillatory synchrony in the human corticospinal system

Oscillations in local field potentials in the β-frequency band (13-35 Hz) are a pervasive feature of human and nonhuman primate motor cortical areas. However, the function of such synchronous activity across populations of neurons remains unknown. Here, we test the hypothesis that β activity may promote existing motor set and posture while compromising processing related to new movements. Three experiments were performed. First, healthy subjects were instructed to make reaction time movements of the outstretched index finger in response to imperative cues triggered by transient increases in corticospinal synchrony, as evidenced by phasic elevations of β-frequency band microtremor and intermuscular synchrony. Second, healthy subjects were instructed to resist a stretch to the index finger triggered in the same way. Finger acceleration in the reaction time task and transcortical components of the stretch reflex were measured and compared with those elicited by random cue or stretch presentation. Finally, we sought a correlation between finger acceleration in the reaction time task and cortical synchrony directly measured from the electrocorticogram in two patients undergoing functional neurosurgery. We demonstrate that movements are slowed and transcortical responses to stretch are potentiated during periods of elevated β-band cortical synchrony. The results suggest that physiological periods of β synchrony are associated with a cortical state in which postural set is reinforced, but the speed of new movements impaired. The findings are of relevance to Parkinson's disease, in which subcortical and cortical β-band synchronization is exaggerated in the setting of increased tone and slowed movements

Improvements to Existing Transit Detection Algorithms and Their Comparison

In Tingley (2003), all available transit detection algorithms were compared in a simple, rigorous test. However, the implementation of the Box-fitting Least Squares (BLS) approach of Kovacs et al. (2002) used in that paper was not ideal for those purposes. This letter revisits the comparison, using a version of the BLS better suited to the task at hand and made more efficient via the knowledge gained from the previous work. Multiple variations of the BLS and the matched filter are tested. Some of the modifications improve performance to such an extent that the conclusions of the original paper must be revised.Comment: 4 paper, 0 figures, accepted for publication in Astronomy & Astrophysics Letter

Vibrational quenching of the electronic ground state in ThO in cold collisions with 3^3He

We measure the ratio $\gamma$ of the momentum-transfer to the vibrational quenching cross section for the X ($^1\Sigma^+$), $\nu=1$, $\mathrm{J=0}$ state of molecular thorium monoxide (ThO) in collisions with atomic $^3$He between 800 mK and 2.4 K. We observe indirect evidence for ThO--He van der Waals' complex formation, which has been predicted by theory. We determine the 3-body recombination rate constant $\Gamma_3$ at 2.4 K, and establish that the binding energy E$_b >$ 4 K