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Biomedical subjects

James Jerger

Publications and source records attributed to James Jerger.

At least 19 recordsLinked to original sources
PubMed2004

Hemispheric asymmetry of the right ear advantage in dichotic listening.

ERP waveforms evoked by target-right and target-left stimuli in a directed-attention, dichotic-listening paradigm were examined using cross-correlation analysis. We analyzed data from two experiments involving linguistic processing. They involved listening for (1) a phonemic feature, and (2) a series of morpho-syntactic anomalies. The maximum correlation between target-right and target-left waveforms was achieved when the target-right waveform was delayed relative to the target-left waveform (the tau shift), reflecting the shorter latency of the target-right waveform. We interpret the direction of displacement as equivalent to a "right-ear advantage" in the dichotic listening paradigm. In both tasks, tau shifts were not uniformly distributed across the parietal electrode array. They were greatest on the extreme left side of the head and systematically declined as the electrode site moved rightward, indicating a temporal gradient in the relative latencies of the two waveforms. Results are interpreted in relation to both structural and attentional aspects of dichotic listening.

Adolescent↗
PubMed2004

Principles and clinical applications of auditory evoked potentials in the geriatric population.

Age-related changes in auditory evoked potentials are complex and complicated by the confounding effects of gender; concomitant high-frequency hearing sensitivity loss; and, in the case of event-related responses, the nature of the task used to elicit the response. There is a tendency for amplitude to decline and latency to increase, but these trends are not always clear-cut. There is also a tendency for activation patterns to move forward from parietal to frontal areas as age increases. The dichotic listening tool has revealed age-related changes in interaural and interhemispheric asymmetries. These asymmetries seem to be related to loss in the efficiency of interhemispheric transfer via the corpus callosum.

Aged↗
PubMed2004

Interaural cross correlation of event-related potentials and diffusion tensor imaging in the evaluation of auditory processing disorder: a case study.

In a previous publication (Jerger et al, 2002), we presented event-related potential (ERP) data on a pair of 10-year-old twin girls (Twins C and E), one of whom (Twin E) showed strong evidence of auditory processing disorder. For the present paper, we analyzed cross-correlation functions of ERP waveforms generated in response to the presentation of target stimuli to either the right or left ears in a dichotic paradigm. There were four conditions; three involved the processing of real words for either phonemic, semantic, or spectral targets; one involved the processing of a nonword acoustic signal. Marked differences in the cross-correlation functions were observed. In the case of Twin C, cross-correlation functions were uniformly normal across both hemispheres. The functions for Twin E, however, suggest poorly correlated neural activity over the left parietal region during the three word processing conditions, and over the right parietal area in the nonword acoustic condition. Differences between the twins' brains were evaluated using diffusion tensor magnetic resonance imaging (DTI). For Twin E, results showed reduced anisotropy over the length of the midline corpus callosum and adjacent lateral structures, implying reduced myelin integrity. Taken together, these findings suggest that failure to achieve appropriate temporally correlated bihemispheric brain activity in response to auditory stimulation, perhaps as a result of faulty interhemispheric communication via corpus callosum, may be a factor in at least some children with auditory processing disorder.

Acoustic Stimulation↗
PubMed2003

Neuroelectric correlates of hemispheric asymmetry: spectral discrimination and stimulus competition.

In an effort to explore further the role of the right hemisphere in auditory processing, this study utilized brain event-related potentials (ERPs) to investigate hemispheric asymmetry for the processing of complex spectral tones. Subjects participated in two pitch discrimination tasks, one diotic, the other dichotic. ERP components were recorded from 28 electrodes on the scalp and analyzed via individual/group average area measurements. Results showed that ERPs recorded in response to the dichotic target pairs exhibited a larger P3 area when the target tone was presented to the left ear, while the N1 area showed no significant difference. ERPs recorded in the diotic condition showed a larger P3 area and smaller N1 area compared to the dichotic conditions. Finally, all experimental tasks showed that topographic hemispheric activation patterns were asymmetric to the right hemisphere. Findings support the notion that ERP topographic asymmetries may be dependent on specific cognitive task demands (e.g., diotic vs. dichotic modes of presentation). In addition, the data suggest that the P3 component may better reflect interaural advantages for complex tones than the N1 component and may, therefore, be a more sensitive indicator of hemispheric specialization.

Adult↗
PubMed2003

Decisions! Decisions!

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False Negative Reactions↗
PubMed2002

Asymmetry in event-related potentials to simulated auditory motion in children, young adults, and seniors.

We studied auditory evoked responses to the apparent movement of a burst of noise in the horizontal plane. Event-related potentials (ERPs) were measured in three groups of participants: children in the age range from 9 to 12 years, young adults in the age range from 18 to 34 years, and seniors in the age range from 65 to 80 years. The topographic distribution of grand-averaged ERP activity was substantially greater over the right hemisphere in children and seniors but slightly greater over the left hemisphere in young adults. This finding may be related to age-related differences in the extent to which judgments of sound movement are based on displacement versus velocity information.

Adolescent↗
PubMed2002

Quo vadis?

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Audiology↗
PubMed2002

Reversal of hemispheric asymmetry on auditory tasks in children who are poor listeners.

We examined hemispheric activation patterns during auditory and visual processing in two groups of children: 13 boys in the age range from 9 to 12 years rated by their parents and teachers as poor listeners and 11 boys in the same age range rated as normal listeners. Three tasks were employed: auditory gap detection, detection of auditory movement, and a control task involving visuospatial discrimination. Electrical activity was recorded from 30 scalp electrodes as participants responded to target stimuli in an event-related potential paradigm. In the visual task, hemispheric activation was relatively symmetric around the midsagittal plane in both groups. In the two auditory tasks, however, hemispheric activation patterns differed significantly between groups. In the normal-listener group, activation was asymmetric to the right hemisphere. In the poor-listener group, however, activation tended toward asymmetry, favoring the left hemisphere. These results suggest that abnormalities in hemispheric lateralization of function may underlie the auditory processing problems of at least some children described as poor listeners.

Attention↗