A systematic review and meta-analysis of the efficacy of intermittent theta burst stimulation (iTBS) on cognitive enhancement.

Intermittent theta-burst stimulation (iTBS) has been used to focally regulate excitability of neural cortex over the past decade - however there is little consensus on the generalizability of effects reported in individual studies. Many studies use small sample sizes (N < 30), and there is a considerable amount of methodological heterogeneity in application of the stimulation itself. This systematic meta-analysis aims to consolidate the extant literature and determine if up-regulatory theta-burst stimulation reliably enhances cognition through measurable behavior. Results show that iTBS - when compared to suitable control conditions - may enhance cognition when outlier studies are removed, but also that there is a significant amount of heterogeneity across studies. Significant contributors to between-study heterogeneity include location of stimulation and method of navigation to the stimulation site. Surprisingly, the type of cognitive domain investigated was not a significant contributor of heterogeneity. The findings of this meta-analysis demonstrate that standardization of iTBS is urgent and necessary to determine if neuroenhancement of particular cognitive faculties are reliable and robust, and measurable through observable behavior.

Motor and Predictive Processes in Auditory Beat and Rhythm Perception.

In this article, we review recent advances in research on rhythm and musical beat perception, focusing on the role of predictive processes in auditory motor interactions. We suggest that experimental evidence of the motor system's role in beat perception, including in passive listening, may be explained by the generation and maintenance of internal predictive models, concordant with the Active Inference framework of sensory processing. We highlight two complementary hypotheses for the neural underpinnings of rhythm perception: The Action Simulation for Auditory Prediction hypothesis (Patel and Iversen, 2014) and the Gradual Audiomotor Evolution hypothesis (Merchant and Honing, 2014) and review recent experimental progress supporting each of these hypotheses. While initial formulations of ASAP and GAE explain different aspects of beat-based timing-the involvement of motor structures in the absence of movement, and physical entrainment to an auditory beat respectively-we suggest that work under both hypotheses provide converging evidence toward understanding the predictive role of the motor system in the perception of rhythm, and the specific neural mechanisms involved. We discuss future experimental work necessary to further evaluate the causal neural mechanisms underlying beat and rhythm perception.

Trajectory formation during sensorimotor synchronization and syncopation to auditory and visual metronomes.

Previous work on sensorimotor synchronization has investigated the dynamics of finger tapping and how individual movement trajectories contribute to timing accuracy via asymmetry in movement velocities. The present study investigated sensorimotor synchronization (in-phase) and syncopation (anti-phase) to both an auditory metronome and a visual flashing light at multiple frequencies to understand how individual movement phases contribute to the variability of timekeeping and error correction in different sensory modalities and with different task constraints. Results demonstrate that the proportional time spent in both the upward phase of movement and the holding phase of movement (time spent on the surface of the table) remain relatively invariant across both stimulus modalities and across tapping styles (syncopation and synchronization), but changes with interval duration, increasing as interval duration increases. The time spent in the downward phase of movement did significantly differ across stimulus modality and tapping style, increasing during both visuomotor timing and syncopation, accompanied by a significant decrease in flexion velocity during syncopation. Extension velocity and flexion time were found to be the main contributors to differences between visual and auditory timing, while flexion velocity and flexion time were found to be the main contributors to differences between synchronization and syncopation. No correlations were found between asynchrony and the upward, downward, or holding phases of movement, suggesting the existence of multiple error correction strategies.

Recruitment and baseline characteristics of the Community of Voices choir study to promote the health and well-being of diverse older adults.

OBJECTIVE: To describe the recruitment and baseline results of the Community of Voices study that aims to examine the effect of a community choir intervention on the health and well-being of older adults from diverse racial/ethnic and socioeconomic backgrounds. METHOD: Using community-based participatory research methods, we recruited adults age 60 and over from 12 Administration on Aging-supported senior centers in San Francisco into a 2-arm cluster-randomized controlled trial of the community choir intervention. Multiple outreach methods were used. We tracked outreach, screening, and recruitment metrics and collected demographics and baseline outcomes via community-based, interviewer-administered surveys and performance measures of cognition, physical function, and psychosocial variables. RESULTS: The study contacted 819 individuals, screened 636, and enrolled 390 diverse older adults over a 42-month, phased recruitment period. The mean age was 71.2 (SD = 7.3), and the majority were women. Two-thirds of the sample are non-white, and 20% of participants reported having financial hardship. DISCUSSION: Outreach and recruitment methods used in the Community of Voices trial facilitated enrollment of a large proportion of minority and lower-SES older adults in the final sample. Similar recruitment approaches could serve as a model for recruiting diverse racial/ethnic and socioeconomic older adults into research.