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J B Kelly

Publications and source records attributed to J B Kelly.

At least 73 records · Page 4Linked to original sources
PubMed1988

Organization of auditory cortex in the albino rat: sound frequency.

1. Responses of neurons in the auditory cortex of the albino rat were examined using microelectrode mapping techniques. Characteristic frequencies were determined for numerous electrode penetrations across the cortical surface in individual animals. A primary auditory area was identified in the posterolateral neocortex that was characterized by short latency responses to tone bursts and tonotopic organization with high frequencies represented rostrally and low frequencies, caudally. Within this area cells with similar characteristic frequencies were aligned in a dorsoventral orientation to form isofrequency contours. 2. Tuning curves obtained from primary auditory cortex were characteristically "V" shaped with Q10's ranging from 0.97 to 28.4. Maximum Q10 values increased monotonically with characteristic frequency (CF). The lowest thresholds at CF closely approximated the behavioral audiogram for the albino rat. Many neurons, however, had CF thresholds well above the behavioral limit. 3. Areas were found dorsal and ventral to the primary auditory cortex in which CF's were clearly discontinuous with the neighboring isofrequency contours. These data suggest the presence of other auditory fields, the detailed characteristics of which have yet to be examined.

Acoustic Stimulation↗
PubMed1988

Organization of auditory cortex in the albino rat: binaural response properties.

1. The binaural response properties of neurons in the auditory cortex of the albino rat were examined using microelectrode mapping techniques. Characteristic frequencies, binaural response classes, and interaural intensity differences for binaural interaction were determined for multiple electrode penetrations across the cortical surface. The location of electrode penetrations was determined by reference to the cortical vascular pattern in individual animals. 2. When examined over a wide range of interaural intensities binaural responses could be classified as one of the following types: summation, i.e., excited by stimulation of either ear alone and facilitated by stimulation of both ears together (35.3%); suppression, i.e., excited by contralateral stimulation, unaffected by ipsilateral stimulation alone, but inhibited under binaural stimulus conditions (42.2%); mixed, i.e., facilitated by binaural stimulation at near threshold levels, but strongly inhibited by increased sound pressure levels in the ipsilateral ear (18.5%); or other, i.e., responses that could not be classified as any other type (4%). 3. Neurons of the summation and suppression class often exhibited binaural interaction when the intensities at both ears were approximately equal. The modal interaural intensity difference for both response types was between 0 and +5 dB. Neurons of the mixed interaction class were facilitate at near equal dichotic intensity but suppressed when the intensity in the ipsilateral ear was increased. The modal value was between 0 and +5 dB for summation and +20 dB for suppression. 4. Summation, suppression, and mixed binaural response types were found over a wide range of sound frequencies from 1 to 40 kHz. There was some tendency for summation responses to prevail at lower frequencies and suppression responses to prevail at higher frequencies but the differences were not large. Generally, responses from each of the three binaural classes were well represented over the rat's hearing range. 5. Cells of the same binaural response type were grouped together to form aggregates of summation, suppression, or mixed interaction patterns. Cortical areas with similar binaural response properties appeared in some cases to extend across isofrequency contours.

Acoustic Stimulation↗
PubMed1988

Hearing in the ferret (Mustela putorius): effects of primary auditory cortical lesions on thresholds for pure tone detection.

1. Pure tone thresholds were determined for five adult male ferrets before and after bilateral ablation of primary auditory cortex. Complete audiograms ranging from 0.016 to 48 kHz were obtained for two animals. The remaining three animals were tested at five frequencies selected to assess hearing throughout the audible range (0.125, 0.5, 2.0, 8.0, and 32.0 kHz). 2. Shortly after surgery one animal had elevated thresholds across the entire frequency range with the most pronounced hearing loss above 12.0 kHz. Four other animals had no elevation of thresholds at low and midrange frequencies but suffered a hearing loss at very high frequencies (32 kHz). 3. Repeated testing over a period of several months revealed substantial recovery of sensitivity. There was complete recovery of sensitivity in the low- and middle-frequency range of the audiogram. Some hearing loss persisted at the extreme upper end of the audiogram (32 kHz), but in two cases there was evidence of recovery at this frequency as well. 4. Following determination of absolute thresholds all animals were assessed for their ability to localize sound in space. Minimum audible angles were obtained on midline as well as within both left and right hemifields, i.e., around 0, -60 and +60 degrees azimuth. All animals had severe and persistent deficits in their ability to localize brief sounds within the lateral fields, but were still capable of midline localization.

Animals↗
PubMed1987

The effect of cerebrovascular accident on the ability to localize sounds under conditions of the precedence effect.

This study examines the ability of patients with cerebrovascular accident to localize single clicks and assign spatial locations to paired clicks presented from loudspeakers on the left and right of midline. The clicks within each pair were separated by intervals of either 2, 4, 8, or 16 msec. Normal subjects and brain-damaged patients without evidence of discrete lesions in their CT scans were able to localize both single and paired clicks. Patients with discrete right temporo-parietal lobe lesions were able to localize single clicks, but frequently reversed the apparent perceptual locus of paired clicks in the hemifield contralateral to the side of lesion. Patients with lesions in the left hemisphere, in areas outside the temporo-parietal region, did not display deficits under any condition.

Acoustic Stimulation↗
PubMed1987

Contribution of auditory cortex to sound localization by the ferret (Mustela putorius).

Ferrets were tested in a semicircular apparatus to determine the effects of auditory cortical lesions on their ability to localize sounds in space. They were trained to initiate trials while facing forward in the apparatus, and sounds were presented from one of two loudspeakers located in the horizontal plane. Minimum audible angles were obtained for three different positions, viz., the left hemifield, with loudspeakers centered around -60 degrees azimuth; the right hemifield, with loudspeakers centered around +60 degrees azimuth; and the midline with loudspeakers centered around 0 degrees azimuth. Animals with large bilateral lesions had severe impairments in localizing a single click in the midline test. Following complete destruction of the auditory cortex performance was only marginally above the level expected by chance even at large angles of speaker separation. Severe impairments were also found in localization of single clicks in both left and right lateral fields. In contrast, bilateral lesions restricted to the primary auditory cortex resulted in minimal impairments in midline localization. The same lesions, however, produced severe impairments in localization of single clicks in both left and right lateral fields. Large unilateral lesions that destroyed auditory cortex in one hemisphere resulted in an inability to localize single clicks in the contralateral hemifield. In contrast, no impairments were found in the midline test or in the ipsilateral hemifield. Unilateral lesions of the primary auditory cortex resulted in severe contralateral field deficits equivalent to those seen following complete unilateral destruction of auditory cortex. No deficits were seen in either the midline or the ipsilateral tests.

Animals↗
PubMed1987

Development of the auditory orientation response in the albino rat (Rattus norvegicus).

The development of head orientation to auditory stimulation was examined in rat pups at Postnatal Days 8, 11, 14, 17, and 20. The animals were tested in a quiet environment with single bursts of 65 dB (SPL) broad-band noise. A reflexive head turn toward the sound was first seen on Postnatal Day 14 and subsequently on Days 17 and 20. This result demonstrates that the onset of directional auditory responses occurred between Day 11 and Day 14. The role of binaural cues in early sound orientation was examined in 17-day-old pups with monaural ligation of the external meatus. These animals were unable to localize a sound source and consistently turned toward the side of the unligated ear regardless of the position of the stimulus. Thus binaural cues were shown to be important for head orientation to sound in early development. In a separate study, head orientation to high and low frequency tone pips was examined. Directional responses were first seen on Day 12 for a 16-kHz tone and Day 14 for a 2-kHz tone. These results indicate an earlier onset for orientation to high frequency sounds in the rat.

Aging↗
PubMed1986

Hearing in the ferret (Mustela putorius): thresholds for pure tone detection.

Thresholds for pure tone detection were determined for two male ferrets (Mustela putorius) using standard behavioral testing procedures. Both animals had a broad range of hearing comparable to that seen in other Carnivores. The lower limit of hearing at 60 dB SPL was estimated from the average audiogram to be 36 Hz, and the upper limit of hearing was 44 kHz. The lowest thresholds were found in the region of 8-12 kHz with both animals exhibiting sharp tuning at best frequency.

Acoustic Stimulation↗
PubMed1986

Representation of the cochlea in primary auditory cortex of the ferret (Mustela putorius).

In seven barbiturate-anesthetized ferrets, we explored the acoustically sensitive cortex with conventional microelectrode mapping techniques. A tonotopically organized field was found whose orientation was such that high tonal frequencies were represented dorsally, and low frequencies ventrally. Within this field, neurons typically had short (12-20 ms) latent periods to first spikes. In conjunction with extant anatomical evidence on the connectivity of this region, these data suggest that this field represents the ferret's primary auditory cortex.

Animals↗
PubMed1986

Midline and lateral field sound localization in the albino rat (Rattus norvegicus).

Six albino rats were used in tests of sound localization around midline and in left and right lateral field positions (i.e., 0 degree, -60 degrees, and +60 degrees azimuth). Each of the animals performed at high levels on the midline task but had great difficulty with tests in the left and right fields. Minimum audible angles for midline localization were obtained for 2 subjects and were estimated as 11.5 degrees and 13.5 degrees. Performance levels on the hemifield tests for each of the 6 animals, however, were too low to permit estimates of threshold even with speakers separated by 60 degrees. The differences between midline and lateral field sound localization are discussed.

Animals↗
PubMed1986

Effects of auditory cortical lesions on pure-tone sound localization by the albino rat.

Two-choice and three-choice tests were used to evaluate the effects of bilateral auditory cortical lesions on pure-tone sound localization by the albino rat. Both tests required that animals approach a distant sound source to obtain water reinforcement. Stimuli were single noise and tone bursts, 65 ms in duration including 20-ms rise and fall times. Tone frequencies were 2, 4, 8, 16, and 32 kHz adjusted to 40 dB (SPL) above the rat's absolute threshold. Five animals were tested in the two-choice situation following bilateral ablation of auditory cortex. Some reduction in performance was observed relative to normals, but impairments were not severe. Similar results were obtained for 2 brain-damaged animals tested in the three-choice situation. Thus, the ability to localize sounds in space remained intact after complete destruction of auditory cortex, and there was no indication of a frequency-dependent deficit.

Animals↗
PubMed1986

Directional responses to sounds in young gerbils (Meriones unguiculatus).

Three experiments were conducted to determine the ability of infant gerbils to approach an auditory stimulus. In the first experiment, gerbil pups, 16-23 days of age, were tested in a circular apparatus with a central start area and a movable sound source located at one of eight positions around the perimeter. Stimuli included high- and low-intensity presentations of a tape-recorded gerbil social call, a broad-band white noise stimulus, and a no-stimulus control condition. The subjects showed a strong tendency to approach the low-intensity social call and a less pronounced tendency to approach the white noise. In the second experiment, gerbil pups were tested in the same apparatus with or without ear blocks to determine the role of binaural cues in directional approach responding. The tendency to approach a low-intensity vocalization was disrupted by obstruction of one ear but not by blocking both ears. Thus, binaural balance was shown to be important for early sound localization. In the third experiment, the tendency to approach a social call was compared at different ages, 12-15, 16-19, 20-23, and 24-27 days after birth. Approach responses were first seen at 16-19 days. The responses continued during the 20-23-day period but began to wane at 24-27 days of age.

Animals↗
PubMed1985

Effects of medial geniculate lesions on sound localization by the rat.

Rats with bilateral lesions of the medial geniculate body were tested on a two-choice sound-localization task that required a directional response to a distant sound source. Stimuli included both broadband and filtered noise bursts presented singly or in repetitive trains. Separate tests were conducted with loudspeakers 180 and 60 degrees apart, centered around 0 degree azimuth. With complete bilateral destruction of the medial geniculate, rats could localize both trains and single bursts of noise and were capable of high levels of performance even at small angles of speaker separation. Some evidence of impaired performance was noted with high-frequency noise bursts, but generally the deficits were not severe. Animals with lesions that extended caudally into the brachium of the inferior colliculus and lateral tegmentum were severely impaired in their ability to localize sounds even at large angles of speaker separation. Three of the four animals in this group were incapable of localizing single bursts even with loudspeakers separated by 180 degrees, and the fourth was unable to perform above chance at 60 degrees. The effects of medial geniculate lesions were very similar to those reported previously for rats with lesions of the auditory cortex, but contrasted with reports of severe impairments in sound localization following damage to the auditory cortex in other mammalian species.

Animals↗
PubMed1980

Effects of auditory cortical lesions on sound localization by the rat.

1. Studies with cats, dogs, and monkeys have shown that bilateral ablation of auditory cortex can result in severe deficits in the ability to localize sounds in space. In the present series of studies we sought to extend this observation to include the laboratory rat. 2. Rats were tested in a two-choice sound-localization task, which required a spatial response to a distant goal box. Although the test conditions were very similar to those employed with cat, dog, and monkey, deficits following cortical ablation were minimal. Indeed, following bilateral ablation of both primary and secondary auditory projection areas, rats were still capable of localization at small angles. 3. Several possibilities were considered to explain the apparent species difference in the effect of cortical ablations. It seemed unlikely that the difference was due simply to testing procedures or details of stimulus presentation. Central nervous system factors were discussed, including the possibility that the degree of impairment was related to the extent of cortical development in different species. It was concluded that the effects of auditory cortical ablation are not the same for all mammals and that for some species auditory cortex is not essential for sound localization.

Animals↗
PubMed1980

Effects of divorce on the visiting father-child relationship.

Findings from a 5-year longitudinal study of 131 children from 60 divorcing families, drawn from a predominantly white, middle-class California population, revealed unexpected changes in the relationship between the visiting parent and the child after the marital separation. The changes that showed improvement and that showed deterioration in 50% of the father-child relationships were substantially related to the difficulties and psychological conflicts engendered by visitation and divorce, the father's capacity to accommodate to the constraints of the visiting relationship, and the age and sex of the child.

Adaptation, Psychological↗