Evaluating Prefrontal Activation and Its Relationship with Cognitive and Emotional Processes by Means of Hemoencephalography (HEG)

Abstract

The main aim of this study is to determine the efficacy of the method of diagnosis known as hemoencephalography (HEG), which measures hemodynamic changes in the prefrontal cortex by determining differences in oxygen flow to show patterns of neuronal activity. Of the 5 tests designed for this purpose, 2 are strictly cognitive, while the other 3 have primarily emotional or sensitive content. The tests were applied to a sample of 70 university students. The Wilcoxon nonparametric signed rank test was applied to test the paired differences between the HEG baseline result and the HEG result of the task. Results show, first, that the HEG method successfully determines oxygen flow to the prefrontal cortex and clearly differentiates the subject's baseline from HEG activation during the task (Wilcoxon, p < .05); second, that HEG results vary depending on the type of activity, whether cognitive (low emotional load) or emotional (high emotional load) in such a way that cognitive areas, those located higher in the cortex (dorsolateral prefrontal), show less activity during emotional tests and more activity during cognitive tests, thus associating higher areas (dorsolateral prefrontal) with cognition and deeper areas (medial temporal, medial prefrontal, and cingulate) with emotion. The HEG procedure is effective in detecting states or situations of ailment or suffering not always accompanied by evident external manifestations. Furthermore, the procedure can differentiate between cognitive and emotional processing. The HEG method can help diagnosis in clinical settings due to its ability to detect painful-feeling processing independently of both body and verbal language.

Acknowledgments

We thank Natàlia Adell-Calvet of the Unitat d'Assessorament Estadístic (University of Girona) for the statistical analysis. We are indebted to all participants for their invaluable assistance in the research presented here.

Notes

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.

^a Significant difference between HEG baseline and HEG activity during the test by the application of the nonparametric Wilcoxon.