Biomedical subjects

D J Wegesin

Publications and source records attributed to D J Wegesin.

4 recordsLinked to original sources

PubMed2000

Effects of inter-item lag on recognition memory in seizure patients preceding temporal lobe resection: evidence from event-related potentials.

The electrophysiological correlates of word recognition are well characterized. Repeated 'old' words evoke a more positive-going waveform starting at approximately 300 ms compared with first-presented, 'new' words. The old/new effect is thought to be generated, in part, by structures within the medial temporal lobe. In the present study, event-related potentials were recorded during a continuous verbal recognition memory task in unoperated patients with either left (L) or right (R) unilateral temporal lobe epilepsy (Epil) and neurologically intact controls. To manipulate the difficulty of the memory task, the lag between the initial and subsequent presentation of the repeated words was varied from one, four to 16 items. In the controls, ERPs to old words were more positive going than new words from approximately 350-650 ms. The old/new effect diminished as the inter-item lag increased. Patient old/new effects showed a later onset (450 ms) and resolution (750 ms) compared with the controls. Furthermore, the late component of the old/new effect was significantly reduced in the L Epil. Although patient behavioral performance did not differ significantly from that of the controls, neuropsychological testing revealed impaired verbal memory function in the L Epil patients. It is concluded that the reduced old/new effect in the L Epil patients provides evidence that medial temporal lobe structures contribute to the scalp-recorded old/new effect.

Adolescent↗

PubMed2000

Source memory and encoding strategy in normal aging.

Of the memory deficits associated with aging, elders are most impaired at attributing the source to remembered information. Additionally, aging is marked by a decrease in the use of encoding strategies that are thought to enhance the acquisition and retention of information. We examined how manipulating the encoding strategy during acquisition affected item and source memory in 32 young and 68 elderly participants. Elderly participants were dichotomized into young-old and old-old based upon the median age (74 years). Memory was assessed using Word List A from the California Verbal Learning Test (CVLT) and its alternate form. Encoding strategy was manipulated by semantic clustering. For the Blocked List, words were presented grouped into their semantic categories, whereas for the Unblocked List categories were intermixed within the list. Item and source memory judgments were made 20 minutes after the final CVLT recall trial and again one week later. Results revealed a disproportionate decline in source, compared to item memory in the two older groups. Semantic blocking enhanced item memory for the elders, but not for the young. The amount of semantic clustering performed by the elders showed a decline with age and was positively related to source performance. Results also suggest that subtle age-related changes in semantic knowledge may be related to declines in semantic clustering and memory performance.

Adult↗

PubMed1998

Event-related potentials in homosexual and heterosexual men and women: sex-dimorphic patterns in verbal asymmetries and mental rotation.

To elucidate neurobiological factors related to gender and sexual orientation, event-related brain potentials of 20 heterosexual (HT) men, 20 HT women, 20 homosexual (HM) men, and 20 HM women were examined for neurophysiological differences. Cognitive tasks which typically elicit sex differences were administered. A mental rotation (MR) task assessed spatial ability, and a divided-visual-field lexical-decision/semantic monitoring task (LD/SM) assessed verbal ability and relative degrees of language lateralization. Slow wave activity recorded during MR was greater for HT men than for HT women and gay men. N400 asymmetries recorded during the LD/SM task revealed differences between men and women, but no intrasex differences.

Evoked Potentials↗

PubMed1998

A neuropsychologic profile of homosexual and heterosexual men and women.

To examine the applicability of psychosexual differentiation theory to the development of sexual orientation, heterosexual (HT) women, HT men, lesbians, and gay men (20 per group) completed a lexical-decision/semantic monitoring task (LD/SM) to assess verbal ability, as well as a Water Level Task (WLT) and two Mental Rotation (MR) Tasks designed to assess spatial ability. All tests have been shown to differentiate HT men and women. Results replicated previously reported sex differences between the HT men and women. Further, gay men performed akin to HT women on the verbal task and the MR tasks, but not in the WLT. Lesbians, however, primarily performed in a sex-typical manner. The dissociation in sex-atypicality between lesbians and gay men is discussed in relation to neurobiological factors related to the development of both sex-dimorphic cognitive ability and sexual orientation.

Adult↗