scholarly journals Dichotic sound localization properties of duration-tuned neurons in the inferior colliculus of the big brown bat

2014 ◽  
Vol 5 ◽  
Author(s):  
Riziq Sayegh ◽  
Brandon Aubie ◽  
Paul A. Faure
Keyword(s):  
Inferior Colliculus ◽  
Sound Localization ◽  
Big Brown Bat

Local field potentials in the big brown bat inferior colliculus track the flow of objects moving past the bat

2013 ◽  
Vol 134 (5) ◽  
pp. 4087-4087
Author(s):  
James A. Simmons ◽  
Andrea M. Simmons ◽  
Michaela Warnecke ◽  
Jonathan R. Barchi
Keyword(s):  
Inferior Colliculus ◽  
Local Field ◽  
Local Field Potentials ◽  
Field Potentials ◽  
Big Brown Bat

Neural Selectivity and Tuning for Sinusoidal Frequency Modulations in the Inferior Colliculus of the Big Brown Bat, Eptesicus fuscus

1997 ◽  
Vol 77 (3) ◽  
pp. 1595-1605 ◽  
Author(s):  
John H. Casseday ◽  
Ellen Covey ◽  
Benedikt Grothe
Keyword(s):  
Inferior Colliculus ◽  
High Frequency ◽  
Limited Range ◽  
Eptesicus Fuscus ◽  
Fm Signals ◽  
Big Brown Bat ◽  
Pure Tones ◽  
Sinusoidal Frequency Modulations ◽  
Frequency Modulations ◽  
Neural Selectivity

Casseday, John H., Ellen Covey, and Benedikt Grothe. Neural selectivity and tuning for sinusoidal frequency modulations in the inferior colliculus of the big brown bat, Eptesicus fuscus. J. Neurophysiol. 77: 1595–1605, 1997. Most communication sounds and most echolocation sounds, including those used by the big brown bat ( Eptesicus fuscus), contain frequency-modulated (FM) components, including cyclical FM. Because previous studies have shown that some neurons in the inferior colliculus (IC) of this bat respond to linear FM sweeps but not to pure tones or noise, we asked whether these or other neurons are specialized for conveying information about cyclical FM signals. In unanesthetized bats, we tested the response of 116 neurons in the IC to pure tones, noise with various bandwidths, single linear FM sweeps, sinusoidally amplitude-modulated signals, and sinusoidally frequency-modulated (SFM) signals. With the use of these stimuli, 20 neurons (17%) responded only to SFM, and 10 (9%) responded best to SFM but also responded to one other test stimulus. We refer to the total 26% of neurons that responded best to SFM as SFM-selective neurons. Fifty-nine neurons (51%) responded about equally well to SFM and other stimuli, and 27 (23%) did not respond to SFM but did respond to other stimuli. Most SFM-selective neurons responded to a limited range of modulation rates and a limited range of modulation depths. The range of modulationrates over which individual neurons responded was 5–170 Hz( n = 20). Thus SFM-selective neurons respond to low modulation rates. The depths of modulations to which the neurons responded ranged from ±0.4 to ±19 kHz ( n = 15). Half of the SFM-selective neurons did not respond to the first cycle of SFM. This finding suggests that the mechanism for selective response to SFM involves neural delays and coincidence detectors in which the response to one part of the SFM cycle coincides in time either with the response to a later part of the SFM cycle or with the response to the first part of the next cycle. The SFM-selective neurons in the IC responded to a lower and more limited range of SFM rates than do neurons in the nuclei of the lateral lemniscus of this bat. Because the FM components of biological sounds usually have low rates of modulation, we suggest that the tuning of these neurons is related to biologically important sound parameters. The tuning could be used to detect FM in echolocation signals, modulations in high-frequency sounds that are generated by wing beats of some beetles, or social communication sounds of Eptesicus.

scholarly journals Tuning for rate and duration of frequency-modulated sweeps in the mammalian inferior colliculus

2018 ◽  
Vol 120 (3) ◽  
pp. 985-997 ◽  
Author(s):  
James A. Morrison ◽  
Roberto Valdizón-Rodríguez ◽  
Daniel Goldreich ◽  
Paul A. Faure
Keyword(s):  
Inferior Colliculus ◽  
Bayesian Model ◽  
Model Comparison ◽  
Tuning Curve ◽  
Extracellular Recording ◽  
Sweep Rate ◽  
Center Frequency ◽  
Bayesian Model Comparison ◽  
Fm Signals ◽  
Big Brown Bat

Responses of auditory duration-tuned neurons (DTNs) are selective for stimulus duration. We used single-unit extracellular recording to investigate how the inferior colliculus (IC) encodes frequency-modulated (FM) sweeps in the big brown bat. It was unclear whether the responses of so-called “FM DTNs” encode signal duration, like classic pure-tone DTNs, or the FM sweep rate. Most FM cells had spiking responses selective for downward FM sweeps. We presented cells with linear FM sweeps whose center frequency (CEF) was set to the best excitatory frequency and whose bandwidth (BW) maximized the spike count. With these baseline parameters, we stimulated cells with linear FM sweeps randomly varied in duration to measure the range of excitatory FM durations and/or sweep rates. To separate FM rate and FM duration tuning, we doubled (and halved) the BW of the baseline FM stimulus while keeping the CEF constant and then recollected each cell’s FM duration tuning curve. If the cell was tuned to FM duration, then the best duration (or range of excitatory durations) should remain constant despite changes in signal BW; however, if the cell was tuned to the FM rate, then the best duration should covary with the same FM rate at each BW. A Bayesian model comparison revealed that the majority of neurons were tuned to the FM sweep rate, although a few cells showed tuning for FM duration. We conclude that the dominant parameter for temporal tuning of FM neurons in the IC is FM sweep rate and not FM duration. NEW & NOTEWORTHY Reports of inferior colliculus neurons with response selectivity to the duration of frequency-modulated (FM) stimuli exist, yet it remains unclear whether such cells are tuned to the FM duration or the FM sweep rate. To disambiguate these hypotheses, we presented neurons with variable-duration FM signals that were systematically manipulated in bandwidth. A Bayesian model comparison revealed that most temporally selective midbrain cells were tuned to the FM sweep rate and not the FM duration.

Neural Correlates of the Precedence Effect in the Inferior Colliculus of Behaving Cats

2004 ◽  
Vol 92 (6) ◽  
pp. 3286-3297 ◽  
Author(s):  
Daniel J. Tollin ◽  
Luis C. Populin ◽  
Tom C. T. Yin
Keyword(s):  
Inferior Colliculus ◽  
Sound Localization ◽  
Species Differences ◽  
Behavioral Responses ◽  
Neural Correlates ◽  
Precedence Effect ◽  
Single Neurons ◽  
Localization Dominance ◽  
Echo Threshold ◽  
Spatial Locations

Several auditory spatial illusions, collectively called the precedence effect (PE), occur when transient sounds are presented from two different spatial locations but separated in time by an interstimulus delay (ISD). For ISDs in the range of localization dominance (<10 ms), a single fused sound is typically located near the leading source location only, as if the location of the lagging source were suppressed. For longer ISDs, both the leading and lagging sources can be heard and localized, and the shortest ISD where this occurs is called the echo threshold. Previous physiological studies of the extracellular responses of single neurons in the inferior colliculus (IC) of anesthetized cats and unanesthetized rabbits with sounds known to elicit the PE have shown correlates of these phenomena though there were differences in the physiologically measured echo thresholds. Here we recorded in the IC of awake, behaving cats using stimuli that we have shown to evoke behavioral responses that are consistent with the precedence effect. For small ISDs, responses to the lag were reduced or eliminated consistent with psychophysical data showing that sound localization is based on the leading source. At longer ISDs, the responses to the lagging source recovered at ISDs comparable to psychophysically measured echo thresholds. Thus it appears that anesthesia, and not species differences, accounts for the discrepancies in the earlier studies.

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