Biomedical subjects

V Kazmerski

Publications and source records attributed to V Kazmerski.

4 recordsLinked to original sources

PubMed1997

An overview of age-related changes in the scalp distribution of P3b.

In this overview of 7 studies, the scalp distribution of the P3b component (i.e. the P3 or P300) of the event-related potential elicited by target events in young and older adults was assessed. The target P3b data were recorded in either auditory oddball paradigms or in visual study tasks in which orienting activity was manipulated (as a within-subjects variable) in investigations of indirect memory. Some of the studies required choice reaction time responses, whereas others required responses only to the target stimuli. Motor response requirements had a profound effect on the P3b scalp distribution of older but not of younger subjects. The presence of a frontally oriented scalp focus in the topographies of the older adults in most of the tasks described here is consistent with older adults continuing to use prefrontal processes for stimuli that should have already been well encoded and/or categorized. However, although older subjects generally had different P3b scalp distributions than younger subjects, their scalp distributions were modulated similarly by task requirements. These data suggest that similar mechanisms modulate the scalp distribution of P3b in older compared to younger adults. However, in the older adult, these scalp distribution changes in response to task demands are superimposed on a frontally oriented scalp focus due to a putative frontal lobe contribution to target P3b topography.

Adult↗

PubMed1997

Auditory ERPs during rhyme and semantic processing: effects of reading ability in college students.

Event-related potential (ERP), reaction time (RT), and response accuracy measures were obtained during the phonological and semantic categorization of spoken words in 14 undergraduates: 7 were average readers and 7 were reading-impaired. For the impaired readers, motor responses were significantly slower and less accurate than were those of the average readers in both classification tasks. ERPs obtained during rhyme processing displayed a relatively larger amplitude negativity at about 480 ms for the impaired readers as compared to the average readers, whereas semantic processing resulted in no major group differences in the ERPs at this latency. Also, N480 amplitude was larger during semantic relative to phonological classification for the average readers but not for the impaired readers. Results are compared to a previous study of reading-impaired children on the same tasks.

Adolescent↗

PubMed1994

A developmental study of visual ERP distributions during spatial and phonetic processing.

Ten adults (mean age 19.5 years; S.D. = 1.65) and 10 children (12.2 years; S.D. = 1.28) participated in a choice reaction time study of event-related potential (ERP) correlates of pattern and phonological discriminations of letters. In the form condition, the subjects responded discriminately to letters that did (e.g., b, p) and did not (e.g., f, h) have an enclosed area. Likewise, the subjects responded to letters that did and did not rhyme with "e" in the rhyme task. For both groups, the two late positivities (P600 and P3) were significantly later in the rhyme ERPs than the form as were the RTs associated with the tasks. Distribution and group differences were most notable for the positivity at 380 msec. The P380 distribution did not vary between the conditions for the adults, but there was a more negative distribution in the rhyme condition compared to the form at fronto-central sites for the children. The topographic differences between the form and rhyme tasks at 380 msec were consistent with the involvement of auditory areas in the rhyme task. Generally, however, the children's and adults' wave forms were similar in terms of morphology, peak latency and distribution.

Adolescent↗

PubMed1993

Event-related potential asymmetries in children during pattern and phonemic processing of letters.

Event-related potentials (ERPs) were recorded at left and right anterior temporal, temporal, and parietal sites from ten children (mean age 10.45 years) during three tasks. In the detection task every letter required a response; in the form and rhyme discrimination tasks, a response was required to letters without an enclosed area or to those that did not rhyme with 'e', respectively. For all tasks, N170 peak latency was later at right temporal sites and was more negative in amplitude at right anterior temporal locations than homologous left locations. Also, left-right difference waveforms indicated that right hemisphere ERPs were more negative than the left at 200, 300 and 470 ms for most sites. These lateral differences may reflect a differential activation of the hemispheres during letter processing. Differences among the conditions were most evident for the latest positive peak at 475 ms in which detection resulted in shorter latencies and smaller amplitudes than the discrimination tasks.

Age Factors↗