Auditory confounds can drive online effects of transcranial ultrasonic stimulation in humans.

Transcranial ultrasonic stimulation (TUS) is rapidly emerging as a promising non-invasive neuromodulation technique. TUS is already well-established in animal models, providing foundations to now optimize neuromodulatory efficacy for human applications. Across multiple studies, one promising protocol, pulsed at 1000 Hz, has consistently resulted in motor cortical inhibition in humans (Fomenko et al., 2020). At the same time, a parallel research line has highlighted the potentially confounding influence of peripheral auditory stimulation arising from TUS pulsing at audible frequencies. In this study, we disentangle direct neuromodulatory and indirect auditory contributions to motor inhibitory effects of TUS. To this end, we include tightly matched control conditions across four experiments, one preregistered, conducted independently at three institutions. We employed a combined transcranial ultrasonic and magnetic stimulation paradigm, where TMS-elicited motor-evoked potentials (MEPs) served as an index of corticospinal excitability. First, we replicated motor inhibitory effects of TUS but showed through both tight controls and manipulation of stimulation intensity, duration, and auditory masking conditions that this inhibition was driven by peripheral auditory stimulation, not direct neuromodulation. Furthermore, we consider neuromodulation beyond driving overall excitation/inhibition and show preliminary evidence of how TUS might interact with ongoing neural dynamics instead. Primarily, this study highlights the substantial shortcomings in accounting for the auditory confound in prior TUS-TMS work where only a flip-over sham and no active control was used. The field must critically reevaluate previous findings given the demonstrated impact of peripheral confounds. Furthermore, rigorous experimental design via (in)active control conditions is required to make substantiated claims in future TUS studies. Only when direct effects are disentangled from those driven by peripheral confounds can TUS fully realize its potential for research and clinical applications.

The relationship between parameters and effects in transcranial ultrasonic stimulation.

Transcranial ultrasonic stimulation (TUS) is rapidly gaining traction for non-invasive human neuromodulation, with a pressing need to establish protocols that maximise neuromodulatory efficacy. In this review, we aggregate and examine empirical evidence for the relationship between tunable TUS parameters and in vitro and in vivo outcomes. Based on this multiscale approach, TUS researchers can make better informed decisions about optimal parameter settings. Importantly, we also discuss the challenges involved in extrapolating results from prior empirical work to future interventions, including the translation of protocols between models and the complex interaction between TUS protocols and the brain. A synthesis of the empirical evidence suggests that larger effects will be observed at lower frequencies within the sub-MHz range, higher intensities and pressures than commonly administered thus far, and longer pulses and pulse train durations. Nevertheless, we emphasise the need for cautious interpretation of empirical data from different experimental paradigms when basing protocols on prior work as we advance towards refined TUS parameters for human neuromodulation.

Biophysical effects and neuromodulatory dose of transcranial ultrasonic stimulation.

Transcranial ultrasonic stimulation (TUS) has the potential to usher in a new era for human neuroscience by allowing spatially precise and high-resolution non-invasive targeting of both deep and superficial brain regions. Currently, fundamental research on the mechanisms of interaction between ultrasound and neural tissues is progressing in parallel with application-focused research. However, a major hurdle in the wider use of TUS is the selection of optimal parameters to enable safe and effective neuromodulation in humans. In this paper, we will discuss the major factors that determine both the safety and efficacy of TUS. We will discuss the thermal and mechanical biophysical effects of ultrasound, which underlie its biological effects, in the context of their relationships with tunable parameters. Based on this knowledge of biophysical effects, and drawing on concepts from radiotherapy, we propose a framework for conceptualising TUS dose.

Immunisation provider experiences with an automated short message service-based active surveillance system for monitoring adverse events following immunisation: A qualitative descriptive study.

OBJECTIVE: Currently, active surveillance systems to monitor adverse events following immunisation are limited to hospitals, and medical and immunisation clinics. Globally, community pharmacies represent a significant destination for immunisation services. However, until recently, pharmacies lacked active surveillance systems. We therefore wished to explore pharmacists' experiences with SmartVax: an active surveillance system that has recently been integrated for use in Australian community pharmacies. Specifically, we wished to explore pharmacists' perceived (1) benefits of using SmartVax, (2) areas for improvement in the system, and (3) issues with future/ongoing access to the system. METHODS: The present study forms the qualitative arm of a convergent mixed-methods pilot study. In the present study, we performed semi-structured interviews with pharmacist immunisers after a 21- to 22-week trial period with SmartVax. Thematic analysis of interview transcripts was performed independently by two researchers in QSR NVivo 12, using the framework method. RESULTS: Fifteen participants completed the semi-structured interviews. A broad range of perceived benefits were cited by participants, including the usability of SmartVax, the ease of patient follow-up facilitated by the system, and enhancement to the patient-pharmacist relationship. Participants voiced a desire for the system to have more granularity and a faster response time in the report generated for pharmacies. When asked about issues with future/ongoing access to SmartVax, cost concerns of the system were the prevailing theme. CONCLUSIONS: The present study suggests that, among pharmacist immuniser end-users of SmartVax, the system is perceived to be easy-to-use, facilitates patient follow-up, and enhances the patient-pharmacist relationship.

Active vaccine safety surveillance of seasonal influenza vaccination via a scalable, integrated system in Western Australian pharmacies: a prospective cohort study.

OBJECTIVES: We integrated an established participant-centred active vaccine safety surveillance system with a cloud-based pharmacy immunisation-recording program in order to measure adverse events following immunisation (AEFI) reported via the new surveillance system in pharmacies, compared with AEFI reported via an existing surveillance system in non-pharmacy sites (general practice and other clinics). DESIGN: A prospective cohort study. PARTICIPANTS AND SETTING: Individuals >10 years receiving influenza immunisations from 22 pharmacies and 90 non-pharmacy (general practice and other clinic) sites between March and October 2020 in Western Australia. Active vaccine safety surveillance was conducted using short message service and smartphone technology, via an opt-out system. OUTCOME MEASURES: Multivariable logistic regression was used to assess the primary outcome: differences in proportions of AEFI between participants immunised in pharmacies compared with non-pharmacy sites, adjusting for confounders of age, sex and influenza vaccine brand. A subgroup analysis of participants over 65 years was also performed. RESULTS: Of 101 440 participants (6992 from pharmacies; 94 448 from non-pharmacy sites), 77 498 (76.4%) responded; 96.1% (n=74 448) within 24 hours. Overall, 4.8% (n=247) pharmacy participants reported any AEFI, compared with 6% (n=4356) non-pharmacy participants (adjusted OR: 0.87; 95% CI: 0.76 to 0.99; p=0.039). Similar proportions of AEFIs were reported in pharmacy (5.8%; n=31) and non-pharmacy participants (6; n=1617) aged over 65 years (adjusted OR: 0.94; 95% CI: 0.65 to 1.35; p=0.725). The most common AEFIs in pharmacy were: pain (2%; n=104), tiredness (1.9%; n=95) and headache (1.7%; n=88); and in non-pharmacy sites: pain (2.3%; n=1660), tiredness (1.9%; n=1362) and swelling (1.5%; n=1121). CONCLUSIONS: High and rapid response rates demonstrate good participant engagement with active surveillance in both pharmacy and non-pharmacy participants. Significantly fewer AEFIs reported after pharmacist immunisations compared with non-pharmacy immunisations, with no difference in older adults, may suggest different cohorts attend pharmacy versus non-pharmacy immunisers. The integrated pharmacy system is rapidly scalable across Australia with global potential.

Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration.

Brain connectivity plays a major role in the encoding, transfer, and integration of sensory information. Interregional synchronization of neural oscillations in the γ-frequency band has been suggested as a key mechanism underlying perceptual integration. In a recent study, we found evidence for this hypothesis showing that the modulation of interhemispheric oscillatory synchrony by means of bihemispheric high-density transcranial alternating current stimulation (HD-TACS) affects binaural integration of dichotic acoustic features. Here, we aimed to establish a direct link between oscillatory synchrony, effective brain connectivity, and binaural integration. We experimentally manipulated oscillatory synchrony (using bihemispheric γ-TACS with different interhemispheric phase lags) and assessed the effect on effective brain connectivity and binaural integration (as measured with functional MRI and a dichotic listening task, respectively). We found that TACS reduced intrahemispheric connectivity within the auditory cortices and antiphase (interhemispheric phase lag 180°) TACS modulated connectivity between the two auditory cortices. Importantly, the changes in intra- and interhemispheric connectivity induced by TACS were correlated with changes in perceptual integration. Our results indicate that γ-band synchronization between the two auditory cortices plays a functional role in binaural integration, supporting the proposed role of interregional oscillatory synchrony in perceptual integration.