Effective Temporal Envelopes for Transcranial Ultrasound Stimulation in the Absence of Auditory Peripheral Responses

Area of Science:

• Neuroscience
• Biomedical Engineering
• Acoustics

Background:

• Transcranial ultrasound stimulation (TUS) offers minimally invasive deep brain stimulation.
• Auditory side effects are a concern in rodent TUS experiments.
• Tapered envelopes can mitigate auditory responses, but their precise impact is unclear.

Purpose of the Study:

• To investigate the relationship between TUS temporal parameters and auditory responses.
• To determine how stimulus duration and tapering affect auditory and non-auditory neural activity.
• To optimize TUS protocols for reduced auditory interference.

Main Methods:

• Manipulated TUS stimulus duration and tapering slope rates (0-45%).
• Used computational simulations to analyze acoustic pressure energy spectra.
• Recorded acoustic emissions (AE) in vivo and auditory brainstem responses (ABRs) and local field potentials (LFPs) in anesthetized mice.

Main Results:

• Increased tapering rates monotonically reduced audible frequency energy at the skull.
• Specific tapering and duration ranges minimized peripheral auditory activity (ABRs).
• Cortical activity (LFPs) was evoked with minimal peripheral auditory response using <15% tapering.

Conclusions:

• TUS temporal parameter optimization, particularly tapering, effectively reduces audible acoustic components.
• Cortical activation via TUS is achievable with significantly reduced peripheral auditory activation.
• Findings provide a framework for minimizing auditory confounds in rodent TUS studies.