Biomedical subjects

J L Cranford

Publications and source records attributed to J L Cranford.

At least 19 recordsLinked to original sources

PubMed2001

Relationships of sire predicted transmitting ability for somatic cell score with measures of daughter performance.

The relationship between sire predicted transmitting ability (PTA) for somatic cell score (SCS) and occurrence of mastitis in daughters was characterized with 304 Holsteins first freshening since 1991 in the Virginia Tech dairy herd. No direct sire selection for PTA SCS was practiced in the herd. Linear regressions of first lactation average SCS (1.3), number of cases of mastitis (0.80), days clinical (7.0), and number of treatments for mastitis (2.0) on PTA SCS were significant. Linear regression coefficients for second and third lactations were generally positive, but like quadratic and cubic coefficients in this study, were not significant. Relationship of sire PTA SCS and measures of lifetime (84 mo opportunity) performance were determined for 2,494,195 Holsteins born between 1979 and 1987. Linear coefficients from regression on PTA SCS for number of lactations (-0.31), days of productive life (-87.0), total days in milk (-72.2), lifetime milk (-1609.1), fat (-80.7), and protein (-48.2) production, relative net income adjusted for opportunity cost for fluid markets (+13.47), first lactation average SCS (+1.00), and first lactation mature equivalent milk (+429.9) were different from zero. Partial regressions holding PTA milk or PTA protein constant were substantially larger than linear coefficients. When PTA productive life was held constant, the relationship between PTA SCS and measures of herd life and lifetime yield became positive, and relative net income adjusted for opportunity cost variables became moderately positive. One of the major expenses associated with higher susceptibility (higher PTA SCS) may be shorter herd life.

Animals↗

PubMed2001

Effects of monaural versus binaural stimulation on P300 scalp topography in elderly listeners.

The P300 event-related potential was recorded from groups of young and elderly listeners in response to monaural and binaural stimulation. An oddball stimulus paradigm was used to record responses from 19 scalp locations. When listening to binaural stimuli, the young group showed midline and central P300 amplitude maxima, whereas the elderly group exhibited maximal responses in the midline and parietal regions. With monaural stimulation, the young group's responses were similar to those obtained with binaural stimulation. The elderly group, however, showed evidence of a greater contralateral hemisphere response to monaural stimulation during the early part of the P300 response. These findings support the possibility that the P300 neural generators may change with age with respect to temporal onset characteristics or their orientation and strength.

Adult↗

PubMed2001

Electrophysiologic correlates of attention versus stimulus competition in young male and female listeners.

The effects of attention and stimulus competition on the late auditory-evoked potential (LAEP) were compared in 10 young males and 10 young females. Listeners attended to discriminably different oddball tonal sequences presented binaurally or monaurally. Peak amplitudes in response to the frequent tones were measured for N1, P2, and early and late N2 (N2e and N21) components of the LAEP Whereas N1 amplitudes increased, the amplitudes of P2 decreased when listeners attended to, rather than ignored, the tones. Competition effects for both N1 and P2 resulted in reduced amplitudes in the presence of contralateral competition. Although findings with N2e and N21 suggested possible attention and competition effects, as well as gender differences, the data were inconsistent and will need further experimental verification. The present findings with the N1 and P2 components provide evidence that different neural processes underlie the attention and competition effects in the human brain.

Adolescent↗

PubMed2000

Electrophysiologic signs of auditory competition in the human brain.

The present project investigated the electrophysiologic effects of auditory competition on components of the late auditory evoked potential (LAEP). A group of 12 young female listeners attended to deviant tones interspersed among frequent tones in one ear while trains of deviant and frequent tones of a different frequency were either present or absent at the opposite ear. Comparison of event-related potential (ERP) waveforms with competition- and attention-related difference waves revealed evidence that the neural effects of competition were not simply a moderation of the effects of selective attention (i.e. the processing negativity). The two difference waves exhibited amplitude peaks that were not mirror-images with respect to polarity. This suggests the existence of a unique underlying neural process that is responsible for the effects of competition on the LAEP.

Acoustic Stimulation↗

PubMed2000

Electrophysiologic signs of auditory distraction in elderly listeners.

Brain mapping was used to investigate the ability of young and elderly female listeners to attend to /ga/ syllabic events at one ear in the presence of speech babble competition at the opposite ear. An oddball stimulus presentation paradigm was used to record the N1 and P2 components of the late auditory evoked potential (LAEP) from 19 scalp locations. With speech competition, elderly listeners exhibited significantly larger reductions in P2 amplitude than did young listeners. The competition produced no changes in N1 amplitude in either group. These findings contrast with those of an earlier study in which age-related reductions in N1 but not P2 amplitude were found when listeners attended to tones rather than speech stimuli in the presence of speech competition. These studies suggest that amplitude reductions in different LAEP components may provide electrophysiologic indices of age-related breakdowns in processing sounds in the presence of competition. Which LAEP components are affected may depend on experimental variables such as task difficulty or the nature of the stimuli (e.g., speech vs nonspeech).

Adult↗

PubMed2000

Investigation of binaural interference in normal-hearing and hearing-impaired adults.

When speech recognition testing is performed under diotic conditions, some elderly persons with asymmetric hearing loss exhibit a phenomenon in which the performance of the poorer ear interferes with that of the better ear. This binaural interference phenomenon has been estimated to occur in 8 to 10 percent of elderly hearing aid users. The purpose of the present study was to investigate the prevalence of this phenomenon in groups (n = 12) of young and elderly listeners with normal hearing, plus groups of elderly listeners with hearing loss who were aided or unaided. Of 48 subjects tested, only 2 exhibited significant evidence of binaural interference, a result that is close to that expected by chance. Although both of these subjects were elderly, one had normal hearing and the other was aided binaurally. A third elderly unaided subject exhibited a significant binaural advantage. Further studies are needed to determine the prevalence of binaural interference in normal-hearing or hearing-impaired listeners in any decade of life.

Adult↗

PubMed1999

Brief-tone frequency discrimination by children.

This study investigated maturational changes in children's ability to discriminate the frequency of short-duration tone pulses. Frequency difference limens (DLs) were measured for digitally generated 1000-Hz tones with pulse durations of 200, 50, and 20 ms using a two-alternative, two-interval, forced-choice procedure. Participants were 16 5-year-old children; 10 children each in the age categories of 7, 9, and 11 years; and a control group of 10 young adults. Eleven of the 5-year-old children were unable to learn the experimental task. All children in the three older groups and the adults successfully completed the study. The five 5-year-old children who completed the task performed similarly to the 7-year-old children. All groups of participants showed an inverse relationship between duration of the signal and the size of the DL. The DLs at all three tone durations were significantly larger for the 7-year-old children than they were for the older children and adults. There were no significant differences in DL size among the 9-year-old, 11-year-old, and adult subjects at any tone duration. These findings suggest that the sensory and/or cognitive skills required to discriminate the frequency of brief-duration tones may not reach maturity until after age 7 years.

Age Factors↗

PubMed1998

Effects of contralateral speech competition on auditory event-related potentials recorded from elderly listeners: brain map study.

Topographic brain mapping was used to investigate the ability of young and elderly female listeners to attend to tones at one ear in the presence of speech competition at the opposite ear. An oddball stimulus presentation paradigm was used to record the N1, P2, and P300 components of the late auditory evoked potential from 19 scalp locations. With speech competition, elderly listeners exhibited significantly larger reductions in N1 amplitude than did young listeners. This suggests that N1 may provide an electrophysiologic index of age-related breakdowns in processing sounds in the presence of background competition. An unexpected difference was also found between young and elderly listeners in P300 scalp topography. While the young listeners' P300 response was centered at midline for both left and right ear stimulation, the elderly participants had P300 maxima centered in the parietal area of the hemisphere located contralateral to the test ear. This suggests that some of the functional properties (e.g., timing, strength, orientation) of the P300 neural generators may change with age or, alternatively, that different generators may be operative in elderly listeners.

Adult↗

PubMed1997

P300 event-related potentials in stutterers and nonstutterers.

This study investigated possible differences between adult stutterers and nonstutterers in the P300 event-related potential. Responses to tonal stimuli were recorded from electrodes placed over the left (C3) and righ (C4) hemispheres. The two groups exhibited different patterns of interhemispheric activity. Although all 8 participants in the fluent group exhibited P300s that were higher in amplitude over the right hemisphere, 5 of the 8 disfluent participants had higher amplitude activity over the left hemisphere. These results provide evidence that stutterers and nonstutterers may exhibit differences between hemispheres in the processing of some types of nonlinguistic (tonal) stimuli.

Adolescent↗

PubMed1997

Brief tone discrimination by children with histories of early otitis media.

Twelve children, ranging in age from 8.9 to 12.4 years, with histories of severe otitis media with effusion (OME) before age 3, were compared to age-matched cohorts in their ability to discriminate the frequency of tone pulses of 20-, 50-, and 200-msec duration. An adaptive procedure was used in combination with a two-alternative forced-choice paradigm to measure difference limens (DLs) for digitally generated 1000-Hz tones. The OME group exhibited larger DLs than the non-OME group at all three stimulus durations. These results provide tentative evidence of possible long-term effects of early OME on brief tone frequency discrimination.

Auditory Perception↗

PubMed1996

Dynamic temporal processing of nonspeech acoustic information by children with specific language impairment.

The present study investigated whether children with specific language impairment (SLI) differed from children with normal language learning in their ability to process binaural temporal information. The SLI group was matched with peers of the same chronological age, as well as peers with similar language age. All three subject groups were tested with measures of complex sound localization involving the precedence effect phenomenon. Subjects were required to track the apparent motion of a "moving" fused auditory image (FAI). Movement of the FAI was simulated by varying the delay incrementally between pairs of clicks presented, one each, from two matched loudspeakers placed on opposite sides of the child's head. With this task, the SLI subjects' performances were found to be similar to their language age-matched but chronologically younger peers. Both groups exhibited tracking skills that were statistically poorer than that of the chronologically age-matched group. Additional tests indicated this effect was not due to differences in motoric tracking abilities nor to the SLI subjects' abilities to perceive small binaural time cues. Thus, children with SLI appear to be impaired in their ability to use binaural acoustic information in a dynamic ongoing fashion. The requirements for processing such nonlinguistic acoustic information in a "dynamic and ongoing" fashion may be similar to those involved in the ongoing processing of rapid changes in the temporal and spectral components of the speech chain.

Acoustics↗

PubMed1996

Auditory event-related potentials in multiple sclerosis.

The present study examined the effects of multiple sclerosis (MS) on the N1, P2, and P300 components of the late auditory evoked potential (LAEP). A group of 30 subjects with confirmed MS were compared with 30 control subjects who were pair-matched to the MS subjects with respect to age and gender. A standard stimulus oddball procedure was used to elicit the LAEP, in which subjects had to selectively attend to rare tones randomly interspersed among more frequently occurring tones of a different frequency. LAEPs were recorded with and without the presence of simultaneous speech competition in the nontest ear. Although the presence of speech competition produced significant latency and amplitude changes with the different components of the LAEP, the magnitude of the changes were similar for both subject groups. However, in comparison to the control group, a significantly higher proportion of MS subjects exhibited absent P300 responses on all test runs.

Adult↗

PubMed1996

Central auditory processing in an adult with congenital absence of left temporal lobe.

A young adult subject with congenital absence of the left temporal lobe received extensive behavioral and electrophysiologic tests to identify deficits in central auditory processing. Tests included the dichotic digits, staggered spondaic words (SSW), synthetic sentence identification with ipsilateral (SSI-ICM) and contralateral (SSI-CCM) competing messages, pitch pattern, and duration pattern measures. Additional special tests included the precedence effect in sound localization, measurement of frequency difference limens for short (5 msec) and long (200 msec) duration tones, and the P300 event-related potential. The subject's performance on all measures was well within normal limits. These findings provide important new evidence that reinforces the belief of neuroscientists that the developing nervous system exhibits a remarkable degree of functional plasticity.

Adult↗

PubMed1996

Changes in central auditory processing following temporal lobectomies in children.

Unilateral temporal lobe ablations have become a common treatment procedure for intractable epilepsy. Five children, ranging in age from 11 to 16 years, received a battery of tests to evaluate possible postoperative changes in central auditory processing functions. Children were tested before surgery and at 1 year following surgery. Tests included the SCAN test for central auditory processing, the duration pattern and dichotic digits tests, and the P300 event-related potential. With each test, some children exhibited postoperative improvement, while others exhibited either no changes or poorer postoperative performances. These results indicate that temporal lobectomies, while controlling seizures, may not always result in improved central auditory processing.

Adolescent↗

PubMed1994

Effects of contralateral speech competition on the late auditory evoked potential in children.

Researchers recently reported evidence of a possible electrophysiologic correlate of impaired binaural processing or attention in elderly subjects. This experiment found that the presence of speech competition in the contralateral nontest ear produced significantly greater decreases in the peak-to-peak amplitude of the N1-P2 component of the late auditory evoked potential (LAEP) in an older group of subjects (50 to 80 years of age) than in a younger group (20 to 49 years). The present study used this same test paradigm with groups of children ranging in age from 7.5 to 14.9 years of age to investigate whether a comparable age-related effect might be found at the other end of the normal age spectrum in younger children. While the present children did exhibit statistically significant reductions in LAEP amplitude in the presence of speech competition, the magnitude of this effect did not differ among the different age groups.

Adult↗

PubMed1993

Tracking of "moving" fused auditory images by children.

Recent investigations (Cranford, Boose, & Moore, 1990a,b; Moore, Cranford, & Rahn, 1990) studied the ability of normal adult subjects to localize sounds under conditions that elicit the Precedence Effect. In different tests, subjects were required either to report the perceived location of a stationary fused auditory image (FAI) or track the apparent motion of a "moving" FAI. Movement of the FAI was simulated by incrementally varying the delay between pairs of clicks presented, one each, from two matched loudspeakers placed on opposite sides of the listener. In the present study, groups of normally developing children, ranging in age from 6 to 12 years of age, were tested with these two procedures. Although subjects performed at normal adult levels with the stationary FAI test, a significant age-related trend was observed with the moving FAI test. The younger children exhibited poorer tracking performances than did the older children. These results provide evidence that significant changes in binaural temporal processing abilities may occur in the early childhood years.

Acoustic Stimulation↗

PubMed1993

Influences of age and hearing loss on the precedence effect in sound localization.

Cranford, Boose, & Moore (1990a) reported that many elderly persons exhibit problems in perceiving the apparent location of fused auditory images in a sound localization task involving the Precedence Effect (PE). In the earlier study, differences in peripheral hearing sensitivity between young and elderly subjects were not controlled. In the present study, four groups of young and elderly subjects, matched with respect to age and the presence or absence of sensorineural hearing loss, were examined to determine the effects of these two factors on performance with the PE task. Although significantly poorer performances on the PE task were found to be associated with both increased age and hearing loss, additional tentative evidence was obtained that the presence of hearing loss may have a relatively greater detrimental effect on the performance of at least some elderly subjects than it does on younger persons.

Adult↗

PubMed1992

Precedence effect and speech understanding in elderly listeners.

It has been reported that many elderly persons exhibit problems in identifying the location of fused auditory images in a test of the precedence effect in sound localization. The precedence effect involves the neural integration of multiple competing binaural temporal cues, and may reflect subtle age-related neural timing or integration problems. This study investigated whether elderly persons who have difficulty with this test also exhibit problems with speech understanding. The speech measures involved a comparison of performance-intensity functions for phonetically balanced (PB) words and for synthetic sentences presented with ipsilateral speech competition (SSI-ICM). The performance of the elderly subjects on the precedence effect test was significantly correlated with the SSI-max scores but not with PB-max. These findings suggest that age-related difficulties in speech understanding may reflect, at least in part, breakdowns in auditory temporal acuity or resolution.

Acoustic Stimulation↗