Mapping brain activity during loss of situation awareness: an EEG investigation of a basis for top-down influence on perception

OBJECTIVE

The objective was to map brain activity during early intervals in loss of situation awareness (SA) to examine any co-activity in visual and high-order regions, reflecting grounds for top-down influences on Level I SA.

BACKGROUND

Behavioral and neuroscience evidence indicates that high-order brain areas can engage before perception is complete. Inappropriate top-down messages may distort perception during loss of SA. Evidence of co-activity of perceptual and high-order regions would not confirm such influence but may reflect a basis for it.

METHOD

SA and bias were measured using Quantitative Analysis of Situation Awareness and brain activity recorded with 128-channel EEG (electroencephalography) during loss of SA. One task (15 participants) required identification of a target pattern, and another task (10 participants) identification of "threat" in urban scenes. In both, the target was changed without warning, enforcing loss of SA. Key regions of brain activity were identified using source localization with standardized low-resolution electrical tomography (sLORETA) 150 to 160 ms post-stimulus onset in both tasks and also 100 to 110 ms in the second task.

RESULTS

In both tasks, there was significant loss of SA and bias shift (p < .02), associated at both 150- and 100-ms intervals with co-activity of visual regions and prefrontal, anterior cingulate and parietal regions linked to cognition under uncertainty.

CONCLUSION

There was early co-activity in high- order and visual perception regions that may provide a basis for top-down influence on perception.

APPLICATION

Co-activity in high- and low-order brain regions may explain either beneficial or disruptive top-down influence on perception affecting Level I SA in real-world operations.

Asymmetric hemispheric contribution to ERPs in associative memory indexes goal relevance and quantity of information

Explicit encoding requires humans to select the information relevant to their goals, yet not all irrelevant information is discarded. The present study addressed how different quantity and relevance of information modulate the electrophysiological activity during the encoding and retrieval phases of a recognition memory task. Subjects learned associations between two semantically unrelated pictures, and then performed a recognition judgment. After recognition, subjects were asked to recall the associated picture by using the recognized image as a cue. Cues yielded either high quantity of information (the cue evoked two associations, only one of them being relevant to the task), or low quantity of information (the cue evoked a single, relevant association). At encoding, a negative peak (400 ms) showed reduced negativity at left sites for the associative trials compared to the non-associative ones, while at right frontal sites the peak was more negative for goal-unrelated associations, compared to goal-related ones. Late right negativity during the test phase (800-1000 ms) discriminated hits followed either by correct or by no recall, but only when the cue evoked multiple associations. Frontal electrophysiological asymmetry at encoding was affected by the behavioral goal, i.e. activity reflected goal-related encoding on the left and goal-unrelated encoding on the right. The late right effect at retrieval suggests a link between this activity during encoding and the evaluation of the higher quantity of information in light of the behavioral goal during retrieval. Overall, the results indicate that different mechanisms and/or neuronal populations are involved in goal-related versus goal-unrelated association.

Accurate memory for object location by individuals with intellectual disability: absolute spatial tagging instead of configural processing?

Using head-mounted eye tracker material, we assessed spatial recognition abilities (e.g., reaction to object permutation, removal or replacement with a new object) in participants with intellectual disabilities. The "Intellectual Disabilities (ID)" group (n = 40) obtained a score totalling a 93.7% success rate, whereas the "Normal Control" group (n = 40) scored 55.6% and took longer to fix their attention on the displaced object. The participants with an intellectual disability thus had a more accurate perception of spatial changes than controls. Interestingly, the ID participants were more reactive to object displacement than to removal of the object. In the specific test of novelty detection, however, the scores were similar, the two groups approaching 100% detection. Analysis of the strategies expressed by the ID group revealed that they engaged in more systematic object checking and were more sensitive than the control group to changes in the structure of the environment. Indeed, during the familiarisation phase, the "ID" group explored the collection of objects more slowly, and fixed their gaze for a longer time upon a significantly lower number of fixation points during visual sweeping.