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Rickye S Heffner

Publications and source records attributed to Rickye S Heffner.

8 recordsLinked to original sources
PubMed2007

Hearing ranges of laboratory animals.

Any attempt to assess the effects of sounds on animals must consider species differences in hearing abilities. Although the hearing ranges of most species overlap to a large degree, considerable variation occurs in high- and low-frequency hearing as well as in absolute sensitivity. As a result, a sound that is easily audible to one species may be less audible, or even inaudible, to another. The purpose of this review is to describe the variation in the hearing ranges of common laboratory animals.

Amphibians↗
PubMed2004

Primate hearing from a mammalian perspective.

This review discusses hearing performance in primates and selective pressures that may influence it. The hearing sensitivity and sound-localization abilities of primates, as indicated by behavioral tests, are reviewed and compared to hearing and sound localization among mammals in general. Primates fit the mammalian pattern with small species hearing higher frequencies than larger species in order to use spectral/intensity cues for sound localization. In this broader comparative context, the restricted high-frequency hearing of humans is not unusual. All of the primates tested so far are able to hear frequencies below 125 Hz, placing them among the majority of mammals. Sound-localization acuity has been determined for only three primates, and here also they have relatively good localization acuity (with a minimum audible angle roughly similar to other mammals such as cats, pigs, and opossums). This is in keeping with the pattern among mammals in general, in which species with narrow fields of best vision, such as a fovea, are better localizers than those with broad fields of best vision. Multiple lines of evidence support the view that sound localization is the selective pressure on smaller primates and on other mammals with short interaural distances for hearing high frequencies.

Adaptation, Physiological↗
PubMed2003

Hearing in American leaf-nosed bats. II: Carollia perspicillata.

We determined the audiograms of two short-tailed fruit bats (Carollia perspicillata), 18-g phyllostomids from Central and South America. For testing, we used a conditioned suppression/avoidance procedure with a fruit juice reward. At an intensity of 60 dB SPL, the hearing of C. perspicillata extends from 5.2 to 150 kHz, showing a best sensitivity of 0 dB at 25 kHz and a secondary region of sensitivity at 71 kHz. Although C. perspicillata is frugivorous and therefore does not rely on sonar for detecting and pursuing insects, its audiogram is similar to that of insectivorous bats; similarly, there is no suggestion of unusual sensitivity associated with its low-intensity echolocation calls. The behavioral audiogram is compared to previously published physiological estimates of hearing.

Animals↗
PubMed2003

Hearing in American leaf-nosed bats. III: Artibeus jamaicensis.

We determined the audiogram of the Jamaican fruit-eating bat (Phyllostomidae: Artibeus jamaicensis), a relatively large (40-50 g) species that, like other phyllostomids, uses low-intensity echolocation calls. A conditioned suppression/avoidance procedure with a fruit juice reward was used for testing. At 60 dB SPL the hearing range of A. jamaicensis extends from 2.8 to 131 kHz, with an average best sensitivity of 8.5 dB SPL at 16 kHz. Although their echolocation calls are low-intensity, the absolute sensitivity of A. jamaicensis and other 'whispering' bats does not differ from that of other mammals, including other bats. The high-frequency hearing of A. jamaicensis and other Microchiroptera is slightly higher than expected on the basis of selective pressure for passive sound localization. Analysis suggests that the evolution of echolocation may have been accompanied by the extension of their high-frequency hearing by an average of one-half octave. With respect to low-frequency hearing, all bats tested so far belong to the group of mammals with poor low-frequency hearing, i.e., those unable to hear below 500 Hz.

Animals↗
PubMed2002

Hearing in American leaf-nosed bats. I: Phyllostomus hastatus.

We determined the audiogram of Phyllostomus hastatus (the greater spear-nosed bat), a large, omnivorous American leaf-nosed bat native to Central and South America. A conditioned suppression/avoidance procedure with a fruit juice reward was used for testing. At an intensity of 60 dB sound pressure level (SPL re 20 microN/m(2)), the hearing range of P. hastatus extends from 1.8 to 105 kHz, with a best sensitivity of 1 dB SPL at 20 kHz. Both its high-frequency and low-frequency hearing are not unusual for a small mammal. Despite its use of low-intensity echolocation calls there was no evidence for unusual sensitivity to either the frequencies used for echolocation or to the main frequencies of its communication calls, suggesting no selective "tuning" of the audiogram. Its behavioral pure-tone thresholds are lower than the multi-unit thresholds in the inferior colliculus.

Acoustic Stimulation↗
PubMed2002

Cross-modal neuroplasticity in neonatally enucleated hamsters: structure, electrophysiology and behaviour.

Potential auditory compensation in neonatally bilaterally enucleated Syrian hamsters was explored anatomically, electrophysiologically and behaviourally. Gross morphology of the visual cortex appeared normal and no obvious cytoarchitectural malformation was discerned. However, enucleation induced a significant increase in the spontaneous firing rate of visual cortex cells. Further, auditory stimuli elicited field potentials and single unit responses in the visual cortex of enucleated, but not normal, animals. About 63% of the cells isolated in the visual cortex of 16 enucleated hamsters responded to at least one type of auditory stimulus. Most of the responses were less vigorous and less time-locked than those of auditory cortex cells, and thresholds were typically higher. Projection tracing with WGA-HRP disclosed reciprocal connections between the visual cortex and the dorsal lateral geniculate nucleus in both intact and enucleated animals. However, in the enucleated animals retrogradely labelled cells were also found in the inferior colliculus, the major midbrain auditory nucleus. Behaviourally determined auditory sensitivity across the hearing range did not differ between enucleated and intact hamsters. Minimum audible angle, as determined by a conditioned suppression task, ranged from around 17 to 22 degrees, with no significant difference between normal and enucleated animals. The two groups also did not differ with regard to the direction of their unconditioned head orientating response to intermittent noise. However, the enucleated animals showed a more vigorous response and were slower to habituate to the noise. These results show that bilateral enucleation of newborn hamsters results in auditory activation of visual targets, in addition to the typical activation of the intact auditory pathway. Behaviourally it appears that enucleated hamsters, compared with their normal littermates, are slower to habituate in their response to an unexpected source of sound.

Action Potentials↗
PubMed1988

Sound localization in a predatory rodent, the northern grasshopper mouse (Onychomys leucogaster).

A comparison of the ability of mammals to localize sound revealed that among the animals examined to date, none of the rodents have been able to localize as accurately as the carnivores. Because all of these rodents are prey animals, the question arises as to whether their poor localization acuity is a phyletic trait of Rodentia or whether it is a trait common to prey species that may be under less selective pressure than predators to localize sound accurately. To answer this question, sound localization acuity was determined in a species that is both predatory and a rodent, the northern grasshopper mouse. Localization thresholds for a single 100-ms noise burst were determined for three grasshopper mice using a conditioned avoidance procedure. Their 50% discrimination threshold of 19 degrees is larger than that of any of the previously tested carnivores and well within the range of other rodents. However, calculations of the binaural sound localization cues available to rodents (based on their head size) suggest that the grasshopper mouse may make more efficient use of the available locus cues than other rodents. Thus, although the grasshopper mouse cannot localize as accurately as carnivores, it appears to be more accurate than predicted for a nonpredatory rodent of its size.

Animals↗