Principal component analysis of ion channel splice variant expression patterns for all experimental groups. (a) Colors separate groups based on statistical clustering (k-means clustering) of individuals with similar patterns of ion channel splicing. (b) Colors separate groups based on disease state and brain structure: control TC (blue), mTLE NC (red), AD TC (green), control CB (black), AD CB (yellow). The first principal component explains 43% of the variation in log expression ratios, while the second principal component accounts for 13% of the variation. Separation of clusters along principal components 1 and 2 is, to a large extent, governed by brain structure and disease state.