An interactive introduction to common EEG regions of interest in FPVS research.
From electrodes to regions
EEG records tiny voltage changes at many points on the scalp. Instead of interpreting every electrode separately, researchers often combine neighboring electrodes into a region of interest (ROI) and summarize their responses. In FPVS, this can make a response shared across nearby electrodes easier to describe and can reduce the number of separate statistical comparisons.
An ROI is an analysis choice, not a sharp boundary in the brain. Electrical activity spreads through the head, and the electrodes included in an ROI can change with the montage, stimuli, research question, and previous evidence. Each highlighted group below reproduces one published FPVS definition, but none is a universal definition.
Interactive scalp map · BioSemi 64
Explore a region of interest
Choose a map view, then select a region name or one of its colored electrodes. The nose is at the top of the map.
64scalp electrodes
Map view
The interactive electrode map requires JavaScript. The ROI explanations and electrode lists remain available below.
↑ Front of head · Left side of the map = left side of the head
P9, P10, and Iz sit outside the circular head-equator outline because BioSemi places them below that plane.
Selected ROI · left hemisphere
Left occipito-temporal (LOT)
Electrodes: PO3, P7, PO7, P9, O1
Left occipito-temporal electrodes often capture category-selective visual responses. Quek and de Heering used this exact group to summarize FPVS responses that distinguished faces and birds from the rapidly presented background category.
This published LOT includes O1. The same electrode can belong to more than one reasonable ROI when the groupings answer different analysis questions.
Right occipito-temporal electrodes are commonly used for category-selective FPVS responses, especially in face paradigms. Quek and de Heering used this exact group alongside LOT to compare face- and bird-selective signals.
This ROT includes O2, mirroring the inclusion of O1 in LOT. A stronger response on one side of the map does not by itself identify the neural source beneath that electrode group.
Central ROIs are less common than posterior visual ROIs in FPVS. Coll and colleagues used this exact six-electrode group in a supplementary analysis of responses to fixed- and mixed-expression face sequences.
The experimental pattern differed between their central and occipital groups, showing why ROI choice should follow the research question. This scalp label does not identify one “central” brain area.
Nijhof and colleagues used this exact fronto-central group in an FPVS study of responses to a person's own face and name. In this cluster, responses were larger for faces than names, and own-face responses were larger than responses to close-other and stranger faces.
The authors selected these electrodes with a collapsed localizer, so this is a study-specific published example rather than a universal frontal preset. Cz also belongs to the central example on this map; when either overlapping ROI is selected, Cz takes that ROI's color.
Parieto-occipital ROIs sample lateral posterior scalp sites. Valentini and Gyimes used this exact group for the 1-Hz deviant response to periodically presented threatening or non-threatening scenes.
Notice that this example overlaps with LOT. The different name reflects a different analysis question—not a sharp border between two pieces of cortex.
Right parieto-occipital groups provide a matching posterior region in the right hemisphere. Valentini and Gyimes used this exact group with its left-hemisphere counterpart for the 1-Hz deviant response to rapidly presented scenes.
As with LPO, the label describes an electrode grouping. It does not prove that the measured signal originated directly beneath those electrodes.
Occipital ROIs commonly summarize the response to the rapid visual stimulation itself. Quek and de Heering used this exact group because the common 6-Hz visual response was expected to be strongest there.
O1 and O2 also appear in their LOT and ROT definitions. This overlap is intentional: the occipital group addressed the common visual response, while the lateral groups addressed category-selective responses.
Common ROI set shown. Left occipito-temporal ROI selected.
Reading the map carefully
The map uses the official BioSemi standard headcap coordinates for the 64 scalp channels. BioSemi also uses two additional electrodes, CMS and DRL, to operate the recording system; they are not part of the 64 scalp channels shown here.
The selected electrode sets reproduce the definitions used in the FPVS papers cited on their cards. They can overlap, and other studies may use different boundaries or choose electrodes from an independent localizer. Before using an ROI in an analysis, researchers should define it from a prior study, an independent dataset, or a clearly documented analysis plan—not simply choose the electrodes that produce the preferred result.