| This study followed patients with temporal lobe epilepsy from pre to post-surgical status in order to investigate neuroplasticity and recovery of memory function. Functional changes were characterized using BOLD fMRI acquisition during a scene memory encoding task. Neuropsychological testing provided a means of investigating memory function over time. Twenty patients, who were included in a prior investigation, were entered into this study before surgery, those who completed surgery (N=14) and were eligible were studied at one time-point after surgery and a cohort of those patients (N=11) were studied at an additional time-point after surgery. Fifteen controls were studied, with ten controls returning for a second scanning session. Patterns of functional activation were examined over time throughout the whole brain, as an asymmetry score between the posterior temporal lobe on the ipsilesional and contralesional side, and within the hippocampus and parahippocampus on the contralesional side. Age of onset, side of seizure and neuropsychological outcome were examined as factors contributing to neural plasticity. Subjects with a late age of onset showed declines on more neuropsychological measures than those with an early age of onset. Control HPF asymmetries remained relatively stable across time, while the subjects with TLE showed increases in asymmetry post-surgically. Whole brain activation pattern changes were evident in the posterior temporal lobes in both right and left-side seizure groups from the pre to first post-surgical scan. The right-side seizure group showed a reversal of change in activation at the second post-surgical time-point, as well as an effect of age of onset which included medial frontal activation for the early onset group. The right-side seizure subjects consistently showed more contralateral (left-side) activation, compared to subject with left-side seizure. The HPF asymmetries became larger after surgery for both groups combined. Right and left-side seizure groups showed negative correlations between change in visual memory and post-surgical contralateral activation and positive correlations between change in verbal memory measures and post-surgical contralateral activation. Overall, subjects with TLE showed both functional and dysfunctional changes in activation from the pre to post-surgical time-points. |
