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Biomedical subjects

M Hamberger

Publications and source records attributed to M Hamberger.

6 recordsLinked to original sources
PubMed1993

Event-related potentials as indicators of repetition priming in young and older adults: amplitude, duration, and scalp distribution.

Event-related brain potentials (ERPs) were recorded in young and older adults in an indirect repetition priming paradigm. Compared with the young adults, the older adults' ERP repetition effect was larger and of longer duration, due entirely to greater amplitude elicited by the repeated item. These data suggest that, although indirect memory (as indexed by a robust ERP repetition effect) appeared to be intact in the older adult, the possibility exists for qualitative age-related differences consistent with inefficient and/or additional processing of the repeated item.

Adult↗
PubMed1993

Age-related changes in scalp topography to novel and target stimuli.

Event-related brain potentials (ERPs) were recorded from young, middle-aged, and older adults to infrequent target and novel stimuli during a version of the oddball paradigm. Analyses of scalp distribution suggested that the shift to a more frontally oriented topography with increasing age was confined to the P3 component (as compared to N1 and P2) elicited by both target and novel stimuli. This first demonstration of an age-related shift in the scalp distribution of the novelty P3 elicited by auditory stimuli was associated with an age-related increase in the false-alarm rate to novel stimuli. These age-associated differences in scalp distribution and false-alarm rate are consistent with a change in frontal lobe activity with increasing age.

Acoustic Stimulation↗
PubMed1992

Event-related potentials (ERPs) during repetition priming in Alzheimer's patients and young and older controls.

Although memory tested explicitly (e.g., recognition) is clearly deficient in the early stages of Alzheimer's disease, it is less clear if memory tested implicitly is similarly affected. To assess this, event-related potentials (ERPs) were recorded during a word-repetition priming paradigm, with semantic and orthographic orienting tasks, from 10 patients with mild probable Alzheimer's disease (PAD; mean age of 70.6), 10 young (24.1) and 10 older (69.8) controls. The extent of priming by word repetition was assessed using the new minus old ERP repetition effect. The young and older control groups showed clear ERP repetition effects that were larger during semantic than orthographic blocks. Although the PAD patients displayed the same general trends, their ERP repetition effects were not nearly as marked when compared to controls. To the extent that the ERP repetition effect recorded during this repetition priming paradigm is a measure of implicit performance, the data suggest that memory assessed in this fashion is spared in at least some Alzheimer's patients in the early stages of the disease.

Adult↗
PubMed1992

Event-related potential correlates of repetition priming and stimulus classification in young, middle-aged, and older adults.

Electrophysiological and behavioral measures were concurrently recorded from young, middle-aged, and elderly subjects during two classification tasks that required different levels of processing. In both tasks, a portion of stimuli repeated after lags of 2, 8, and 32 intervening items following their first presentation, although these repetitions were incidental to the primary task. All three age groups showed similar patterns of behavioral and event-related potential (ERP) responses associated with stimulus classification and item repetition. ERPs to repeated words were characterized by greater positive amplitude relative to words at first presentation. Similarly, ERPs elicited by items in a primed category were more positive compared with unprimed items. Reaction times were faster to both repeated and primed items. Behavioral and ERP effects were more marked when subjects were required to discriminate items based on meaning rather than on orthography. This study supports previous behavioral evidence suggesting that processes associated with repetition priming and stimulus classification are preserved with age, and demonstrates that ERPs are responsive to repetition throughout the life cycle. Implications for the cognitive processes underlying repetition effects are also discussed.

Adult↗
PubMed1992

A developmental event-related potential study of picture matching in children, adolescents, and young adults: a replication and extension.

Event-related potentials were recorded in a developmental study of picture matching using an adaptation of Posner's (1978) letter-matching tasks. Subjects ranging in age from 6-39 were asked to decide whether two line drawings, presented sequentially, were the same or different on the basis of physical (physical identity), nominal (name identity), or categorical (category identity) criteria. The amplitude of a negativity at 400 ms (Neg400) increased as the number of dimensions on which the two line drawings differed increased. This effect held for all age groups, and was interpreted as reflecting the degree of semantic and/or physical relationship between the two pictures. However, one finding for Neg400 did suggest a qualitative difference in processing mode between the younger and older subjects. Both Neg400 and P3b latencies showed highly significant linear age trends, decreasing with increasing age. These age-related changes were interpreted as demonstrating quantitative speed of processing differences among age groups. The latencies of both Neg400 and P3b increased as the matching criteria became more complex. Moreover, P3b latency increased as the number of dimensions on which the two pictures differed increased, and this did not interact with age. Although both Neg400 and P3b showed age-related changes in scalp distribution, the fact that each was related to the experimental variables in similar fashion in all age groups suggested that they were homologous components across the age range studied. Taken as a whole, the data support continuity of information processing during these tasks across a wide age range.

Adolescent↗