Pictorial cognitive task resolution and dynamics of event-related potentials

Effect of iron deficiency on simultaneous measures of behavior, brain activity, and energy expenditure in the performance of a cognitive task

OBJECTIVES

Iron deficiency (ID) - the highly prevalent nutritional deficiency - has been shown to have deleterious effects on measures of cognitive performance and brain activity. Many of these results are suggestive of the impact of ID on neurotransmitter regulation and myelination. A third critical potential effect of ID on brain function is at the level of brain energy expenditure; however, to date there has not been any method for indirectly estimating the impact of ID on energy expenditure in humans in the context of cognitive work.

METHODS

We report here a study comparing ID and iron sufficient (IS) college students in which simultaneous behavioral, encephelographic (EEG), and metabolic data were collected in a task designed as a cognitive analog to standard physical exertion tasks.

RESULTS

We show that increases in cognitive demands produced decrements in behavioral measures of performance, and increases in EEG and metabolic measures of work. Critically, we found that the magnitudes of those changes were directly related to iron levels.

DISCUSSION

We find support for the idea that brain activity mediates the relationship between cognitive demands and energy expenditure, with ferritin and hemoglobin moderating those relationships in distinct ways. Finally, we show that levels of energy expenditure can be indirectly estimated by measures of EEG spectral power.

Brain Network Activation (BNA) reveals scopolamine-induced impairment of visual working memory

The overarching goal of this event-related potential (ERP) study was to examine the effects of scopolamine on the dynamics of brain network activation using a novel ERP network analysis method known as Brain Network Activation (BNA). BNA was used for extracting group-common stimulus-activated network patterns elicited to matching probe stimuli in the context of a delayed matching-to-sample task following placebo and scopolamine treatments administered to healthy participants. The BNA extracted networks revealed the existence of two pathophysiological mechanisms following scopolamine, disconnection, and compensation. Specifically, weaker frontal theta and parietal alpha coupling was accompanied with enhanced fronto-centro-parietal theta activation relative to placebo. In addition, using the characteristic BNA network of each treatment as well as corresponding literature-guided selective subnetworks as combined biomarkers managed to differentiate between individual responses to each of the treatments. Behavioral effects associated with scopolamine included delayed response time and impaired response accuracy. These results indicate that the BNA method is sensitive to the effects of scopolamine on working memory and that it may potentially enable diagnosis and treatment assessment of dysfunctions associated with cholinergic deficiency.

Pictorial cognitive task resolution and expired minute ventilation, oxygen consumption, carbon dioxide production and heart rate

AIMS

To assess the impact of cognitive task solving on respiratory and cardiovascular parameters.

METHODS

The ML870B80 Exercise Physiology System was used to record concurrently with EEG, the cardiorespiratory and metabolic functions of subjects during cognitive activity. The Expired Minute Ventilation (VE), Oxygen Consumption (VO2), Carbon Dioxide Production (VCO2) and Average Heart Rate (BPM) were ascertained for four periods: (1) rest or starting period, (2) reference period, (3) cognitive task solving period and (4) recovery period. Each period was defined by the type of presented visual stimuli and by the prearranged cognitive activity related to visual stimuli. The personality traits of participants were also determined.

RESULTS

The momentary functional state of subject's brain (i.e. the period of the experiment) determined the average values of all measured parameters. During the cognitive task solving period the average VE, VO2 and VCO2 reached the lowest values while the HR behaved reversely--it was the highest in the cognitive task solving period. Further, the average VE, VCO2 and HR values but not VO2 value differed significantly from average values for the same variable measured in the rest period.

CONCLUSION

The changes in respiratory variables during the cognitive task solving period predicate the whole-body metabolic rate rather than the energy metabolism of the brain alone. However, the heart rate related to some personality traits of the subject has a tighter relation to brain's energy metabolic rate during the cognitive task solving--it affects the oxygen supply of the brain.

Pictorial cognitive task solving and dynamics of event--related desynchronization

AIMS

To analyze the event-related desynchronization/synchronization (ERD/ERS) attended with the mental load arising while solving two cognitive tasks. The features of the presented visual stimulus determined the type of cognitive task that should be solved.

METHODS

For each experimental task and everybody's subject FFT Analysis module calculated the total power histograms from a fixed frequency band (3-20 Hz or 8-13 Hz) for each 3-second EEG sample with 50 % overlay and all electrodes. From the histograms the software derived two FFT single values--the average Total Power (TP) and Frequency at Maximum Power (FMP).

RESULTS

It has been shown that during the solution of cognitive tasks the marked changes of ongoing EEG activity appeared. The short lasting and localized amplitude decrease in rhythmic activity (ERD) and the change of EEG frequency were among the most frequent. The ERD extent was determined by an informational content of processed visual stimuli and by the site of scalp-recording electrode. A higher mental load related to the solution of cognitive tasks shifted the average FM to lower frequencies.

CONCLUSION

The suitability of an analysis of ongoing EEG activity to uncover differences in people's brain activation patterns when engaged in performing cognitively demanding tasks was proved.