Microsecond sensitivity to envelope interaural time differences in rats

Abstract

Currently, there is controversy around whether rats can use interaural time differences (ITDs) to localize sound. Here, naturalistic pulse train stimuli were used to evaluate the rat's sensitivity to onset and ongoing ITDs using a two-alternative forced choice sound lateralization task. Pulse rates between 50 Hz and 4.8 kHz with rectangular or Hanning windows were delivered with ITDs between ±175 μs over a near-field acoustic setup. Similar to other mammals, rats performed with 75% accuracy at ∼50 μs ITD, demonstrating that rats are highly sensitive to envelope ITDs.

Microsecond interaural time difference discrimination restored by cochlear implants after neonatal deafness

“…This study is the first demonstration that, at least in rats, severely degraded auditory experience in early development does not inevitably lead to impaired binaural time processing in adulthood. In fact, the ITD thresholds of our NDCI-B rats (≈ 50 µs) were as good as the ITD thresholds of NH-B rats Li et al (2019), and many times better than those typically reported for early deaf human CI patients with thresholds often too large to measure (Litovsky et al 2010;Gordon et al 2014;Ehlers et al 2017). The good performance exhibited by our NDCI-B animals raises the important question of whether early deaf human CI patients might perhaps also be able to achieve near normal ITD sensitivity if supplied with optimal bilateral CI stimulation capable of delivering adequate ITDs from the first electric stimulation even in the absence of hearing experience during a period what has been thought to be critical for the development of ITD sensitivity.…”

“…High frequency "envelope" ITD sensitivity is also bound to be of great importance in prosthetic hearing given that CIs rarely reach the apex of the cochlea. In Li et al (2019) we recently demonstrate that NH rats can use ITD cues for 2AFC sound lateralization tasks and thus conclude that, at least to broadband clicks, rats show ITD sensitivity. Here, we focused on broad-band acoustic or electrical pulse stimuli which provide plenty of "onset" and "envelope"…”

“…1), and we compared their performance against behavioral data from five age-matched NH rats trained to discriminate the ITDs of acoustic pulse trains (NH-B; see Fig. 1; Li et al (2019)). Animals initiated trials by licking a center "start spout", and responded to 200 ms long 50 Hz binaural pulse trains by licking either a left or a right "response spout" to receive drinking water as positive reinforcement (Figs.…”

“…Stimuli were delivered at sound intensities of ≈ 80 dB SPL. A 3D printed "rat acoustical manikin" with miniature microphones in each ear canal was used for validating that the acoustic setup delivered the desired ITDs and no usable intensity cues (see supplementary Figure S2 and Li et al (2019). Note that the residual ILDs are much smaller than the reported behavioral thresholds for ferrets (~ 1.3 dB (Keating et al 2014)) or rats (~3 dB (Wesolek et al 2010)).…”

Optimal Multichannel Artifact Prediction and Removal for Neural Stimulation and Brain Machine Interfaces

“…Advances in neural implant and electrical stimulation technologies, such as cochlear implants (CIs) and vagal nerve stimulators, increasingly rely on concurrent neural stimulation and recordings to either assess functional transformations between connected brain regions ( Lim and Anderson, 2007 ; Kral et al, 2009 ; Atencio et al, 2014 ; Hancock et al, 2017 ; Vollmer, 2018 ; Li et al, 2019 ) or to optimize electrical stimulation via closed-loop feedback control ( Wilson et al, 1991 ; Schachter and Saper, 1998 ; Dhillon and Horch, 2005 ; Lebedev and Nicolelis, 2006 ; O’Doherty et al, 2011 ; Mc Laughlin et al, 2012 ; Hartmann et al, 2014 ). In such applications, capacitive and inductive coupling between the stimulating and recording electrodes leads to stimulus-evoked artifacts in the extracellular recordings that are often several orders of magnitude larger (i.e., milli-volts) than the extracellular neural signals (typically micro-volts).…”