Reversible Block of Nerve Conduction by Ultrasound
ROBERT R. YOUNG
Archives of Neurology 1961 · 10.1001/archneur.1961.00450070085009
ex vivo tissuehealthyinvasive electrophysiology
Speciesfrog
Subjects15 preparations
Sessions per subjectnot applicable
Randomisednot applicable
Blindingnot applicable
Sham / controlnone
Auditory controlnot reported
Readout timingboth
Anaesthesianot applicable
Readoutsinvasive electrophysiology — Compound action potentials of alpha, beta and gamma fibre groups recorded from the sciatic nerve
Direction of effectinhibitoryFocused ultrasound reversibly or irreversibly blocked conduction in the sciatic nerve; smaller myelinated fibres (gamma, then beta) were blocked before larger alpha fibres, and repeated ultrasound produced cumulative, increasing depression of conduction.
Adverse eventsnot applicable
Exposures
Exposure 1: Focused ultrasound irradiation of frog sciatic nerve
Target: sciatic nerve — “sciatic nerve”
Device: custom-built
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 2,700 | ✓✓✓ |
| Pulse duration (ms) | 140, 1,200swept | ✓✓✓ |
| Pulse repetition frequency (Hz) | not reported | ⚑ |
| Duty cycle (%) | not reported | |
| Sonication duration (s) | not reported |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | ⚑ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not applicable | |
| In-situ pressure (kPa) | not applicable | |
| In-situ Isppa (W/cm²) | not applicable | |
| In-situ Ispta (W/cm²) | not applicable | |
| Isppa, domain unspecified (W/cm²) | 1,150 | ✓✓✓ |
Protocol, in the paper’s words
The ultrasound (2.7 megacycles per sec.) was administered in pulses of 0.14-1.2 sec. duration, with a 2-3 sec. interval between pulses. In each experiment the flux of ultrasound (pulse width and train length) was increased gradually until a level was reached which would affect conduction of impulses; depending on the effect desired, a pulse width of 0.5-0.8 sec. and a train length of 1-20 pulses were usually employed.
Flags from extraction
exposures[0].free_field.isppa_w_cm2— Paper states only an undifferentiated 'intensity' (1,150 W/cm^2) calibrated at the focal region in saline; it does not specify spatial-peak pulse-average vs. temporal-average, and the nerve itself was covered in liquid petrolatum rather than saline during exposure, so the domain of this calibration value is uncertain.exposures[0].timing.pulse_repetition_frequency_hz— Only an inter-pulse interval (2-3 s) and train lengths (1-20 pulses) are given; no explicit repetition rate or duty cycle is stated.