Biomedical subjects

H L Canoune

Publications and source records attributed to H L Canoune.

3 recordsLinked to original sources

PubMed1997

Modality-specific processing streams in verbal working memory: evidence from spatio-temporal patterns of brain activity.

The present study was concerned with whether there are separate, modality-specific processing "streams" in verbal working memory for information that is heard or read. We used event-related brain potentials (ERPs) recorded from scalp of normal humans to show between-modality differences in spatio-temporal patterns of brain activity during retention in working memory of aurally or visually presented verbal information. The ERP patterns suggested that a sustained, automatically maintained auditory store was activated by auditory presentation and a transient, visual-verbal store was activated by visual presentation. In addition to these modality-specific differences, the ERPs indicated that the phonological loop was activated in both modalities and further suggested that the onset of phonological loop activation was earlier for auditory presentation.

Acoustic Stimulation↗

PubMed1995

Working memory and preparation elicit different patterns of slow wave event-related brain potentials.

Some event-related brain potential (ERP) studies of working memory have used delayed match-to-sample designs in which a stimulus (S1) is held in memory for comparison with a subsequent stimulus (S2). During the S1-S2 interval, ERP slow negatives varied with both the type and amount of material held in working memory. One interpretation is that these slow waves index working memory operations. An alternative explanation is that they only reflect general preparatory processing for the response to S2. To decide between these explanations, we used two visual processing tasks that required similar preparation for S2. In one task, visual memory rehearsal operations were required. During the S1-S2 interval, there were clear differences between the amplitudes, topographies, and the effect of information load on the slow waves in two tasks, thus ruling out preparation only as an explanation.

Adult↗

PubMed1990

Multiple sources of P3b associated with different types of information.

This experiment investigated how the P3a, P3b, and Slow Wave components of the event-related brain potential (ERP) respond to manipulations of the nature, timing, and extent of information delivery. There were two experiments in which the total amount of task information was distributed between pairs of successive stimuli (S1 and S2) within each trail. The task was to predict the relation between S1 and S2. In Experiment 1, the S1 could resolve no, partial, or all uncertainty with respect to the prediction outcome (correct or incorrect). Each S1 delivered three types of information: 1) outcome information--which resolved the subjects' uncertainty about the correctness of their prediction; 2) procedural information--which resolved uncertainty about how much outcome information would be delivered by S1; and 3) memory information--the identity of S1, which had to be stored for subsequent comparison with S2. In Experiment 2, the activity of these components was contrasted in two conditions in which the S1 delivered either memory information alone or both memory and procedural information. P3a and Slow Wave were sensitive only to outcome information. P3b was sensitive to all three types of information, and its scalp topography varied as a function of the type of information. The topographic variations indicate that P3b is not a unitary phenomenon but rather is a composite of activity arising from multiple intracranial sources of bioelectric activity.

Adult↗