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Biomedical subjects

J J Allen

Publications and source records attributed to J J Allen.

33 records · Page 2Linked to original sources
PubMed1996

Event-related potentials as indirect measures of recognition memory.

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 (Allen et al., 1992) 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.

Adolescent↗
PubMed1996

Items for assessing posthypnotic recognition amnesia with the HGSHS:A and the SHSS:C.

A procedure for assessing posthypnotic recognition amnesia is described. A set of items for the Harvard Group Scale of Hypnotic Susceptibility, Form A and for the Stanford Hypnotic Susceptibility Scale, Form C were developed and analyzed for reliability and their ability to discriminate individuals who demonstrate posthypnotic amnesia. Recognition amnesia could be assessed as reliably as recall amnesia, and posthypnotic recognition amnesia identified a select subgroup of high hypnotizable individuals who had higher scores on the screening scales. These items may prove useful for assessing posthypnotic recognition amnesia in conjunction with widely used scales of hypnotic susceptibility.

Adult↗
PubMed1995

An event-related potential investigation of posthypnotic recognition amnesia.

Forty-two individuals selected for high hypnotizability or for low hypnotizability were taught lists of words during hypnosis and assessed for recognition following hypnosis using event-related potential (ERP) procedures, both before and after the cue to reverse amnesia. A subgroup of low-hypnotizable participants were asked to simulate hypnotic behavior. All participants had larger late positive component (LPC) amplitudes to learned than to unlearned words, regardless of whether amnesia was reported. The highly hypnotizable participants who reported recognition amnesia, however, had significant changes in attention-related (P1 and N1) and recognition-related (N400 and LPC) ERP component amplitudes as a function of whether amnesia was reported. These data suggest that posthypnotic amnesia may involve alterations in the processes of attention, selection, and accessibility.

Amnesia↗
PubMed1995

Attention-related electroencephalographic and event-related potential predictors of responsiveness to suggested posthypnotic amnesia.

Higher frequency electroencephalographic (EEG) activity around 40 Hz has been shown to play a role in cognitive functions such as attention. Furthermore, event-related brain potential (ERP) components such as N1 and P1 are sensitive to selective attention. In the present study, 40-Hz EEG measures and early ERP components were employed to relate selective attention to hypnotic response. Participants were 20 low hypnotizable individuals, half assigned as simulators, and 21 high hypnotizable individuals. Each of these groups was subsequently divided into two groups based on recognition amnesia scores. The four groups differed in 40-Hz (36-44 Hz) EEG spectral amplitude recorded during preinduction resting conditions but not in EEG amplitude postinduction. The groups also differed in N1 amplitudes recorded during hypnosis. Regression analysis revealed that these effects only distinguish the high hypnotizable participants who experienced recognition amnesia from all other groups. The findings support the role of selective attention in hypnotic responsiveness, and the utility of subdividing high hypnotizable individuals is discussed.

Adolescent↗
PubMed1992

The identification of concealed memories using the event-related potential and implicit behavioral measures: a methodology for prediction in the face of individual differences.

The development and validation of an event-related potential (ERP) memory assessment procedure is detailed. The procedure identifies learned material with high rates of accuracy, whether or not subjects give intentional responses indicating they had previously learned it. Because the traditional analysis of variance approach fails to provide probabilistic conclusions about any given individual, Bayesian posterior probabilities were computed, indicating the probability for each and every person that material was learned. The method was developed on a sample of 20 subjects, and then cross-validated on two additional samples of 20 subjects each. Across the three samples, the method correctly defined over 94% of learned material as learned, and misclassified 4% of the unlearned material. Additionally, in a simple oddball task performed by the same subjects, the method classified rare and frequent material with perfect accuracy. Finally, combining two implicit behavioral measures--mean reaction time and the number of incorrect responses--in Bayesian fashion yielded classification accuracy that actually exceeded that of the ERP-based procedure overall, but the two methods provided identical accuracy in classifying the most critical material as recognized.

Adult↗
PubMed1987

The measurement of foot preference.

Foot preference has been given only superficial attention in studies of hemispheric lateralization, although it has potential utility for predicting hemispheric dominance. This paper reports the development of a reliable (alpha = 0.89) 11-item behavioral inventory of foot preference. Since footedness and handedness are only partially related, both must be measured reliably to identify individuals who have a consistent right or left side preference. It has yet to be determined whether footedness or handedness has the stronger relationship to other aspects of cerebral lateralization and whether both measures together predict lateralization better than one of them alone.

Brain↗
PubMed1987

Cognitive slippage and depression in hypothetically psychosis-prone college students.

Subjects who scored deviantly high on the combined Perceptual Aberration-Magical Ideation (Per-Mag) Scale and subjects who scored low on the scale were compared on two putative measures of cognitive slippage--a continued word association task and a task of referential communication. The Per-Mag subjects performed more deviantly than did the control subjects on both tasks, but those Per-Mag subjects who also scored above the mean on the General Behavior Inventory (GBI) depression subscale were most deviant. The Per-Mag Scale and the GBI are recommended for concurrent use in mass screening to identify a group of individuals who exhibit signs of cognitive slippage and who may, therefore, be at risk for the development of severe psychopathology.

Depressive Disorder↗
PubMed1985

Functional consequences of zinc deficiency.

Zinc is an essential trace element necessary for over 200 zinc metalloenzymes and required for normal nucleic acid, protein, and membrane metabolism. During the past two decades there has been a rapid expansion of knowledge concerning zinc metabolism in both normal and disease situations, including mechanisms for zinc absorption, excretion and internal redistribution of zinc after stress or trauma. Acrodermatitis enteropathica has been recognized to be a disease of impaired zinc absorption in man. A host of disease processes now are recognized to be complicated by zinc deficiency including alcoholic liver disease, sickle cell anemia, protein calorie malnutrition, and a variety of intestinal diseases including Crohn's disease, sprue, short bowel syndrome and after jejunal ileal bypass. Zinc has proved to be an extremely interesting mineral to nutritionists and physicians because of its importance in normal physiology and biochemistry and because of the diverse presenting features of zinc deficiency. This paper reviews ten functional consequences of zinc deficiency and emphasizes certain consequences in which there have been new discoveries concerning their mechanism (e.g., anorexia) or their clinical importance (e.g., immune dysfunction).

Acrodermatitis↗
PubMed1980

Ethnic differences in drug response.

People from different ethnic or environmental backgrounds may respond differently to psychotropic drugs. The underlying psychogenic or biochemical cause of mental illness may vary in different cultures and cause differences in the presenting symptomatology. The psychotropic effect of drugs may then differ or be interpreted differently. Also, the pharmacokinetics of drugs, particularly rates of metabolism, may differ on account of genetic and/or environmental factors. The relevance of such differences to general clinical treatment will depend on the type of drug. If the margin of safety of a particular compound is small, then variation due to ethnic origin may be an important factor. For relatively safe drugs this is not so crucial but, in psychiatry particularly, unpleasant drug-induced side effects are common and it is desirable to find the preparation most acceptable to the individual. Clinical findings should not be extrapolated from one culture to another without examination of the relevant ethnic groups.

Asia↗
PubMed1975

The Lynfield Obsessional/Compulsive Questionnaires.

The need for adequate methods of measuring symptoms in obsessional disorders is stressed, particularly since, owing to the comparative rarity of the condition, a multicentre approach will be necessary if controlled studies are envisaged. A new method of measurement, the Lynfield Obsessional/Compulsive Questionnaire, is described. The questionnaire is derived from the Leyton Obsessional Inventory and may be of value in showing response to treatment.

Humans↗
PubMed1975

Changes in obsessive/compulsive patients as measured by the Leyton Inventory before and after treatment with clomipramine.

The Leyton Obsessional Inventory has been found to be a useful measure in assessing patients before and after treatment with clomipramine. Mean scores for symptoms and interference altered significantly during the course of treatment. The Leyton Obsessional Inventory, however, lacks external validation owing to the absence of some valid alternative quantification. In the absence of such external validation it seems justifiable to use the mean Leyton score diagnostically but not as a sole indication of severity or response to treatment.

Clinical Trials as Topic↗
PubMedDate not supplied

Regional electroencephalographic asymmetries in bipolar seasonal affective disorder before and after exposure to bright light.

Electroencephalographic (EEG) asymmetries found in nonseasonal depression were examined in seasonal affective disorder before and after bright-light exposure. Subjects with seasonal depression demonstrated the expected pattern of frontal asymmetry both when depressed and following light-induced remission. Right-hemisphere EEG coherence, by contrast, served as a state-dependent indicator of seasonal depression.

Analysis of Variance↗
PubMedDate not supplied

Seclusion and restraint of children: a literature review.

TOPIC: Nurses' attitudes toward the use of seclusion and restraint with children. PURPOSE: To review recent literature concerning these controversial interventions, and to examine possible alternative therapeutic interventions. SOURCES: Selected published nursing and psychiatric literature 1987 to 1998. CONCLUSIONS: Staff have a positive attitude toward the use of seclusion and restraint. A theory of power and control may explain their use when many alternative, less restrictive interventions are available.

Attitude of Health Personnel↗