Sound localization behavior in ferrets: Comparison of acoustic orientation and approach-to-target responses

Abstract

Auditory localization experiments typically either require subjects to judge the location of a sound source from a discrete set of response alternatives or involve measurements of the accuracy of orienting responses made toward the source location. To compare the results obtained by both methods, we trained ferrets by positive conditioning to stand on a platform at the center of a circular arena prior to stimulus presentation and then approach the source of a broadband noise burst delivered from 1 of 12 loudspeakers arranged at 30 degrees intervals in the horizontal plane. Animals were rewarded for making a correct choice. We also obtained a non-categorized measure of localization accuracy by recording head-orienting movements made during the first second following stimulus onset. The accuracy of the approach-to-target responses declined as the stimulus duration was reduced, particularly for lateral and posterior locations, although responses to sounds presented in the frontal region of space and directly behind the animal remained quite accurate. Head movements had a latency of approximately 200 ms and varied systematically in amplitude with stimulus direction. However, the final head bearing progressively undershot the target with increasing eccentricity and rarely exceeded 60 degrees to each side of the midline. In contrast to the approach-to-target responses, the accuracy of the head orienting responses did not change much with stimulus duration, suggesting that the improvement in percent correct scores with longer stimuli was due, at least in part, to re-sampling of the acoustical stimulus after the initial head turn had been made. Nevertheless, for incorrect trials, head orienting responses were more closely correlated with the direction approached by the animals than with the actual target direction, implying that at least part of the neural circuitry for translating sensory spatial signals into motor commands is shared by these two behaviors.

The precedence effect and its buildup and breakdown in ferrets and humans

“…In keeping with this, we found that the ferrets’ reaction times on single source trials were significantly longer when they approached the incorrect speaker than when they made a correct choice. Similar results have previously been reported when ferrets are engaged in a multiple speaker localization task ( Nodal et al, 2008 ).…”

Adaptations for Substrate Gleaning in Bats: The Pallid Bat as a Case Study

“…This predicts that the pallid bat should show high acuity sound localization near the midline. Similar midline preferring neurons are also seen in other mammals [Stecker et al, 2005;Higgins et al, 2010] and may explain the generally better localization accuracy near midline compared to more eccentric locations [Nodal et al, 2008]. In EI neurons, response is strong for CL locations and weakens as the sound moves to more IL locations.…”

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“…These circuits allow the brain to suppress competing or non-synergistic motor programs that would otherwise interfere with sensory and goal-directed behaviors (Purves et al, 2008). In the case of C. elegans , as its pharynx cannot efficiently take up surrounding bacteria (i.e.…”