The first version of Staalhemel was based on a general, averaged measurement of alpha wave levels. In 2010 I’m investigating with researcher Lindsay Brown from Holst Centre in Eindhoven how we can interpret the discrete measurements of the eight individual electrodes on the headset. The electrode positions are named FP1, FP2, F7, F8, C3, C4, O1 and O2.
FP1 covers Brodmann area 10 on the front left side of the frontal lobe. This is part of the prefrontal cortex, that highly developed part of the brain which sets us apart from other mammals since it is responsible for the execution of cognitive tasks. Complex behaviours and simultaneous mental activities need a kind of working memory that keeps track of running tasks in either pending states or executive states. For most cognitive functions information needs to be retrieved after completion of another task. The prefrontal cortex co-ordinates all of this mental traffic and shows clear elevation in beta levels when performing calculative tasks, logical puzzles or other intellectual questions. FP2 covers the right side of the prefrontal cortex.
F7 and F8 cover parts of the frontal cortex. The frontal cortex is involved in integrating sensory information with data retrieval from memory locations. This way new sensory information can be compared with earlier perceptions. Area 45 – which is one part of Broca’s area, a brain centre dedicated to language production – at position F8 is also believed to recover semantic information and to evaluate that information in the light of the current context.
C3 and C4 are located on top of the primary somatosensory cortex, in the parietal part of the cortex. This is a clearly defined strip on top of the brain responsible for processing touch and sensation as well as keeping track of the location of your body parts (proprioception).
The two electrodes at the back of the headset, O1 and O2 for the occipital area of the cortex, cover the secondary visual cortex which is processing information relating to visual association. Cells are tuned to simple properties such as orientation, spatial frequency, and color. Depending on the exact positioning of the headset – which is likely to be slightly different per individual – they might also track the primary visual cortex from which the information is forwarded to the secondary visual cortex. Primary cortex here corresponds to Brodmann area 17 and the secondary to area 18. The connectivity between primary and secondary cortices is important for visual memory.