Objective. The goal of this study was to investigate whetherP. acnes infection of the intervertebral disc can be detected noninvasivelyby NMR spectroscopy.Summary of Background Data. Microbiological studies of surgical samples suggest that a significant subpopulation of back pain patients may have occult disc infection with P.acnes bacteria. This hypothesis is further supported by a double-blind clinical trial showing that back pain patients with Modic type 1 changes may respond to antibiotic treatment. Because significant side effects are associated with antibiotic treatment, there is a need for a noninvasive method to detect whether specific discs in back pain patients are infected with P. acnesbacteria.Methods. P.acnes bacteria were obtained from human patients. NMR detection of a propionic acid in the bacteria extracts was conducted on 500MHz high-resolution spectrometer while in vivo NMR spectroscopy of an isolated bovine disk tissue infected with P.acnes was conducted on 7T MRI scanner.Results. NMR spectra of P. acnes metabolites revealed a distinct NMR signal with identical chemical shits (1.05 and 2.18 ppm) as propionic acid (a primary P.acne metabolite). The 1.05 ppm signal does not overlap with other bacteria metabolites, and its intensity increases linearly with P. acnes concentration. Bovine disks injected with P. acnes bacteria revealed a very distinct NMR signal at 1.05 ppm, which linearly increased with P. acnes concentration.Conclusions. The 1.05 ppm NMR signal from propionic acid can be used as a marker of P. acnes infection of discs. This signal does not overlap with other disc metabolites and linearly depends on P.acnes concentration. Consequently, NMR spectroscopy may provide a non-invasively method to detect disc infection in the clinical setting.

Bimanual in-phase and anti-phase coordination modes represent two basic movement patterns with distinct characteristics—homologous muscle contraction and non-homologous muscle contraction, respectively. A method to understand the contribution of each limb to the overall coordination pattern involves detuning (Δω) the natural eigenfrequency of each limb. In the present experiment, we experimentally broke the symmetry between the two upper limbs by adding elastic and viscous force fields using a Kinarm robot exoskeleton. We measured the effect of this symmetry breaking on coordination stability as participants performed bimanual in-phase and anti-phase movements using their left and right hand in 1:1 frequency locking mode. Differences between uncoupled frequencies were manipulated via the application of viscous & elastic force fields and using fast and slow oscillation frequencies with a custom task developed using the Kinarm robotic exoskeleton. The effects of manipulating the asymmetry between the limbs were measured through the mean and variability of relative phase (ϕ) from the intended modes of 0 ° or 180 °. In general, participants deviated less from intended phase irrespective of coordination mode in all matched conditions, except for when elastic loads are applied to both arms in the anti-phase coordination. Second, we found that when force fields were mismatched participants exhibited a larger deviation from the intended phase. Overall, there was increased phase deviation during anti-phase coordination. Finally, participants exhibited higher variability in relative phase in mismatched force conditions compared to matched force conditions, with overall higher variability during anti-phase coordination mode. We extend previous research by demonstrating that symmetry breaking caused by force differences between the limbs disrupts stability in each coordination mode.

The serial reaction time task (SRTT) is commonly used to study motor learning and memory. The task is traditionally administered in a lab setting with participants responding via button box or keyboard to targets on a screen. By comparing response times of sequential versus random trials and accuracy across sequential trials, different forms of learning can be studied. The present study utilized an online version of the SRTT to study the effects of instructions on learning. Participants were randomly assigned to an explicit learning condition (with instructions to learn the visual sequence and associated tone) or an implicit learning condition (without instructions). Stimuli in both learning conditions were presented in two phases: auditory and visual (training phase), followed by auditory only (testing phase). Results indicated that learning occurred in both training and testing phases, as shown by a significant decrease in response times. There was no significant main effect of learning condition (explicit or implicit) on sequence learning. This suggests that providing explicit instructions does not seem to influence sequence learning in the SRTT learning paradigm. Future online studies utilizing the SRTT should explore varying task instructions in a parametric manner to better understand cognitive processes that underlie sequence learning.

Bimanual coordination modes, namely in-phase and anti-phase, represent two distinct movement patterns characterized by simultaneous & symmetrical movements of both hands and alternating complementary actions, respectively. These coordination modes are integral in various activities, such as playing musical instruments, typing, and participating in sports that demand precise hand-eye coordination. The objective of the present experiment was to investigate the impact of continuous theta burst stimulation (cTBS) targeting the left supplementary motor area (lSMA) on bimanual coordination during in/anti-phase coordination modes. To explore this, we utilized a steady-state system of coordination dynamics and evaluated the continuous relative phase (ϕ) and variability of relative phase (SDϕ) during cued and non-cued trials in both pre- and post-transcranial magnetic stimulation (TMS) conditions. The results revealed that visual cues (cued trials) significantly enhanced bimanual coordination performance in both in/anti-phase coordination modes. However, contrary to expectations, the downregulation of lSMA through cTBS did not lead to significant disruptions in movement during in/anti-phase bimanual coordination in pre- and post-TMS stimulation. Potential factors for the lack of observed effects include methodological limitations, individual differences, and functional redundancy within the motor system. Further research is needed to optimize stimulation parameters, increase sample sizes, and explore the interactions between the lSMA, and other brain regions involved in motor control to gain a comprehensive understanding of the contributions of the lSMA in bimanual coordination.