A Systems Engineering Based Methodology for Analyzing Human Electrocortical Responses.
Abstract
The objective of this work was to develop a systems engineering based methodology for quantifying and modeling effects of cognitive loading on human electrocortical responses in systems engineering terms. The visual-cortical response was selected as the input-output channel around which the methodology was developed. A steady-state input ( a continuous sum of 10 sine waves) and a transient input (a train of pulses) were used for system stimulation. The human occipital EEG (surface electrodes at Oz and mastoids) was used as the cortical describing functions (gain and phase) and remnant spectra (background EEG). A stimulus parametric investigation indicated that sensitivity to stimulus modulation depth is unequal across frequencies, and that relatively low stimulus intensity and depth of modulation are desirable to reduce response saturation. Comparisons between transient and steady-state simulation revealed that both forms produced functionally related responses, suggesting that the visual-cortical response contains a measurable linear portion. Time domain amplitude changes corresponded to transient and steady-state gain changes. To investigate cognitive loading effects three tasks were utilized: manual tracking, grammatical reasoning, and supervisory control. Changes in visual-cortical response measures related to task loading were observed. With increased cognitive loading, alpha responders generally showed reductions in alpha band gain and remnant, and increases in beta and gain. Non-alpha responders showed increases in beta band gain only.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 20, 1987
- Accession Number
- ADA190809
Entities
People
- Andrew M. Junker
- Richard T. Gill
- William H. Levison
Organizations
- Armstrong Laboratory