Properties of echo delay-tuning receptive fields in the inferior colliculus of the mustached bat

• Published in: Hearing research Vol. 286; no. 1-2; pp. 1 - 8
• Main Authors: Macías, Silvio, Mora, Emanuel C., Hechavarría, Julio C., Kössl, Manfred
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2012
• Subjects: Acoustic Stimulation; Acoustics; Animals; Auditory Cortex - physiology; Auditory pathways; Auditory Pathways - physiology; Auditory system; Behavior, Animal; Chiroptera; Cortex (auditory); Depth perception; Echolocation; Echolocation - physiology; Electrodes; Electrophysiology - methods; Female; Frequency dependence; Hearing; Inferior Colliculi - anatomy & histology; Inferior Colliculi - physiology; Inferior colliculus; Male; Neurons; Neurons - metabolism; Neurons - physiology; Pteronotus parnellii; Receptive field; Time Factors; ChF; CD; AC; CF; PT; FM; MT; PSTH; DTC; DRA; FTC; FRA; IC
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2012.02.013

One role of the inferior colliculus (IC) in bats is to create neuronal delay-tuning, which is used for the estimation of target distance in the echolocating bat’s auditory system. In this study, we describe response properties of IC delay-tuned neurons of the mustached bat (Pteronotus parnellii) and compare it with those of delay-tuned neurons of the auditory cortex (AC). We also address the question if frequency content of the stimulus (pure-tone (PT) or frequency-modulated (FM) pairs stimulation) affects combination-sensitive interaction in the same neuron. Sharpness and sensitivity of delay-tuned neurons in the IC are similar to those described in the AC. However, in contrast to cortical responses, in collicular neurons the delay at which the neurons show the maximum response does not change with changes in echo level. This tolerance to changes in the echo level seems to be a property of collicular delay-tuned neurons, which is modified along the ascending auditory pathway. In the IC we found neurons that showed a facilitated delay-tuned response when stimulated with FM components and did not show any delay-tuning with PT stimulation. This result suggests that not only is echo delay-tuning generated in the IC but also its FM-specificity observed in the cortex could be created to some extent in the IC and then topographically organized at higher levels. ► Delay-tuning was studied in neurons of the inferior colliculus of the mustached bat. ► Delay-tuned neurons (DTNs) in the IC of the mustached bat respond only with FM pulses. ► DTN curves in the IC of the mustached bat are not tilted unlike that of the AC.