Assessment of amnesia in Dissociative Identity Disorder (DID) typically relies on self-report, the veracity of which cannot often be independently verified. Memory in DID was therefore assessed using an objective method that involved event-related potentials (ERPs) as well as indirect behavioral measures of memory, and that provided statistically supported assessments for each participant. Four participants who met DSM-IV criteria for DID participated in an ERP memory assessment task, in which words learned by one identity (identity A) were then presented to a second identity (identity B). All four participants - tested as identity B - produced ERP and behavioral evidence consistent with recognition of the material learned by identity A. While it would be premature to generalize all cases of DID, the results suggest that there may be reasons to question the veracity of reports by individuals who meet diagnostic criteria for DID on the basis of a structured clinical interview. (C) 2000 Elsevier Science B.V.
PMID: 20677839;PMCID: PMC2916182;Abstract:
Resting frontal electroencephalographic (EEG) asymmetry has been hypothesized as a marker of risk for major depressive disorder (MDD), but the extant literature is based predominately on female samples. Resting frontal asymmetry was assessed on 4 occasions within a 2-week period in 306 individuals aged 18-34 (31% male) with (n = 143) and without (n = 163) lifetime MDD as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (American Psychiatric Association, 1994). Lifetime MDD was linked to relatively less left frontal activity for both sexes using a current source density (CSD) reference, findings that were not accounted for solely by current MDD status or current depression severity, suggesting that CSD-referenced EEG asymmetry is a possible endophenotype for depression. In contrast, results for average and linked mastoid references were less consistent but demonstrated a link between less left frontal activity and current depression severity in women. © 2010 American Psychological Association.
Event-related potentials (ERPs) were recorded during an auditory word-recognition task to determine whether they can be used as indirect measures of recognition memory, defined as the ability to differentiate learned from unlearned material when no overt recognition response from the subject is required. A modified version of the two-choice reaction time task developed by Allen, Iacono and Danielson was used. In three recognition tasks, administered on two consecutive days, subjects were instructed to indicate recognition of recently learned words. These words were presented along with unlearned words and along with previously learned words which both required a non-recognition response. Recently learned target words as well as previously learned nontarget words elicited a centro-parietal positivity around 500-1000 ms post-stimulus. The size and onset of this late positivity (P300) were affected by the requirement of an overt recognition response. The results suggest that ERPs are sensitive to differences between learned and unlearned words, to some extent independently of the behavioral response. ERPs may therefore be used as indirect measures of recognition memory. In addition, because the present results held for stimuli presented in the auditory modality and because recognition indices were still observed after a one-day interval between learning and testing, this procedure might prove useful in various applications when the integrity of memory is in question.