N-Back auditory test performancein normal individuals

Involvement of executive control in neural capacity related to working memory in aging: an ERP P300 study

Executive control could be involved in neural capacity, which corresponds to the modulation of neural activity with increased task difficulty. Thus, by exploring the P300-an electrophysiological correlate of working memory-we examined the role played by executive control in both the age-related decline in working memory and neural capacity in aging. Event-related potentials (ERPs) were recorded while younger and older participants performed a Sternberg task with two set sizes (2 vs. 6 items), allowing us to calculate a neural capacity index. Participants also completed two control tasks (Stroop and 3-back tests), which were used to calculate a composite executive control index. Results indicated that working memory performance decreased with aging and difficulty. At the neural level, results indicated that the P300 amplitude varied with aging and also with task difficulty. In the low difficulty condition, frontal P300 amplitude was higher for older than for younger adults, whereas in the high difficulty condition, the amplitude of frontal and parietal P300 did not differ between both age groups. Results also suggest that task difficulty led to a decrease in parietal amplitude in both age groups and to an increase in frontal amplitude in younger but not older adults. Both executive control and frontal neural capacity mediated the age-related variance in working memory for older adults. Moreover, executive control mediated the age-related variance in the frontal neural capacity of older adults. Thus, the present study suggests a model for older adults in which executive control deficits with advancing age lead to less efficient frontal recruitment to cope with task difficulty (neural capacity), which in turn has a negative impact on working memory functioning.

The Generation of Involuntary Mental Imagery in an Ecologically-Valid Task

Laboratory tasks (e.g., the flanker task) reveal that incidental stimuli (e.g., distractors) can reliably trigger involuntary conscious imagery. Can such involuntary effects, involving competing representations, arise during dual-task conditions? Another concern about these laboratory tasks is whether such effects arise in highly ecologically-valid conditions. For example, do these effects arise from tasks involving dynamic stimuli (e.g., simulations of semi-automated driving experiences)? The data from our experiment suggest that the answer to our two questions is yes. Subjects were presented with video footage of the kinds of events that one would observe if one were seated in the driver's seat of a semi-automated vehicle. Before being presented with this video footage, subjects had been trained to respond to street signs according to laboratory techniques that cause stimulus-elicited involuntary imagery. After training, in the Respond condition, subjects responded to the signs; in the Suppress condition, subjects were instructed to not respond to the signs in the video footage. Subjects in the Suppress condition reported involuntary imagery on a substantive proportion of the trials. Such involuntary effects arose even under dual-task conditions (while performing the n-back task or psychomotor vigilance task). The present laboratory task has implications for semi-automated driving, because the safe interaction between driver and vehicle requires that the communicative signals from vehicle to driver be effective at activating the appropriate cognitions and behavioral inclinations. In addition, our data from the dual-task conditions provide constraints for theoretical models of cognitive resources.

Pilot Feasibility Study Examining Pupillary Response During Driving Simulation as a Measure of Cognitive Load in Breast Cancer Survivors

OBJECTIVES

To test the feasibility of adding driving simulation tasks to measure visuospatial ability and processing speed to an existing neurocognitive battery for breast cancer survivors (BCSs).

SAMPLE & SETTING

38 BCSs and 17 healthy controls from a cross-sectional pilot study conducted at the University of Kansas Medical Center.

METHODS & VARIABLES

Exploratory substudy measuring pupillary response, visuospatial ability, and processing speed during two 10-minute driving simulations (with or without n-back testing) in a sample of BCSs with self-reported cognitive complaints and healthy controls.

RESULTS

Feasibility of measurement of pupillary response during driving simulation was demonstrated. No between-group differences were noted for pupillary response during driving simulation. BCSs had greater visuospatial ability and processing speed performance difficulties than healthy controls during driving simulation without n-back testing and slower n-back response time.

IMPLICATIONS FOR NURSING

Preliminary evidence showed a possible link between cancer/treatment on visuospatial ability and processing speed in BCSs.

Effects of masker type, sentence context, and listener age on speech recognition performance in 1-back listening tasks

Studies have shown that older listeners with normal hearing have greater difficulty understanding speech in noisy environments than younger listeners even during simple assessments where listeners respond to auditory stimuli immediately after presentation. Older listeners may have increased difficulty understanding speech in challenging listening situations that require the recall of prior sentences during the presentation of new auditory stimuli. This study compared the performance of older and younger normal-hearing listeners in 0-back trials, which required listeners to respond to the most recent sentence, and 1-back trials, which required the recall of the sentence preceding the most recent. Speech stimuli were high-context and anomalous sentences with four types of maskers. The results show that older listeners have greater difficulty in the 1-back task than younger listeners with all masker types, even when SNR was adjusted to produce 80% correct performance in the 0-back task for both groups. The differences between the groups in the 1-back task may be explained by differences in working memory for the noise and spatially separated speech maskers but not in the conditions with co-located speech maskers, suggesting that older listeners have increased difficulty in memory-intensive speech perception tasks involving high levels of informational masking.