Fig 1.
In addition to the direct connectivity approach (left panel), the connectivity maps approach brings features involving a reference electrode when addressing bi-electrode connectivity.
Adding such an electrode expands the connectivity approach, as the relative changes in connectivity are uncovered.
Fig 2.
Phases of the connectivity maps methodology.
Fig 3.
(A): Connectivity map for healthy subjects, with respect to reference electrode O2 located on the posterior area of the scalp. (B): Connectivity map of schizophrenia patients with respect to the same base electrode, O2. (C): Fisher score for the difference in each electrode’s connectivity with respect to reference electrode O2 between healthy subjects and schizophrenia patients. The location from which significant gaps in the flow of information between healthy subjects and schizophrenia patients originate (with respect to the specific reference electrode) can be determined.
Fig 4.
(A): Connectivity map for healthy subjects with respect to reference electrode P7, located in the posterior area of the scalp. (B): Connectivity map for schizophrenia patients with respect to the same base electrode, P7. (C): Fisher score for the difference in each electrode’s connectivity with respect to reference electrode, P7, between healthy subjects and schizophrenia patients. The location from which significant gaps in the flow of information between healthy subjects and schizophrenia patients (with respect to the specific reference electrode) can be determined.
Fig 5.
(A): Connectivity map for healthy subjects with respect to reference electrode P8 located on the posterior area of the scalp. (B): Connectivity map for schizophrenia patients with respect to the same base electrode, P8. (C): Fisher scores for the difference in each electrode’s connectivity with respect to the reference electrode, P8, between healthy subjects and schizophrenia patients. The location from which significant gaps in the flow of information between healthy individuals and schizophrenia patients (with respect to the specific reference electrode) can be determined.
Fig 6.
A (Top left): The brain activity of healthy subjects 420 ms after the presentation of a stimulus. Fig 6B (Top right): The brain activity of schizophrenia patients 420 ms after the presentation of a stimulus. Fig 6C (Bottom left): The connectivity features obtained 420 ms after the presentation of a stimulus for healthy subjects. Fig 6D (Bottom right): The connectivity features obtained 420 ms after the presentation of a stimulus for schizophrenia patients. Strong connectivity can be observed within the healthy subjects, and weak connectivity can be observed within the schizophrenia patients, even though the general brain activity level is similar in both populations.
Fig 7.
Connectivity maps showing electrode connectivity from posterior sources to frontal destinations with Fisher scores of at least >0.6, zoomed in to the relevant interval.
Fig 8.
The Fisher score for each electrode based on the average score of the top five maximal connections in which it is involved.
There is a significant fall in the aggregated Fisher score in the prefrontal area from 0.4 to 2.
Table 1.
Discrimination accuracy for each tested methodology.