Rationale:
Emotional deficits in temporal lobe epilepsy (TLE) often present as a complex array of cognitive differences compared to healthy individuals. However, the impact of the lateralization of the epileptogenic zone on emotional perception remains generally underexplored. This study determines whether lateralized differences exist in emotional perception using two recognition tasks Reading the Mind Through the Eyes (RMTE) and the Emotion Recognition Task (ERT) in TLE patients. Based on available literature in broader neurologic and psychiatric populations, we hypothesized that right TLE patients would be more impaired than the left, and that both groups would score worse than healthy controls (HCs). We also explored whether deficits in this emotional construct contribute to seizure onset confirmation.
Methods:
The study involved 28 TLE patients (14 right/14 left) and 17 HCs with no neurological or psychiatric conditions from the Atlanta metropolitan area. Emotional perception was assessed using RMTE and ERT, alongside three self-report measures: Beck Depression Inventory, Beck Anxiety Inventory, and the Social Connectedness scale to explore potential psychiatric comorbidities.Results:
An ANOVA revealed significant differences between TLE patients and HCs across RMTE, ERT, and all self-report measures, with the left TLE patients performing worse than either group on emotional recognition tests contrary to our hypothesis. Both RMTE and ERT distinguished between left and right-sided TLE patients (F[1, 99] = 5.84, p=.023; F[1, 99] = 6.54, p=.017). Logistic regression indicated performance on RMTE and ERT could predict lateralization of the seizure onset zone, with the model being statistically significant (χ² (2) = 8.64, p=.021) and explaining 35.4% (Nagelkerke R²) of the variance in diagnostic group, correctly classifying 71.4% of cases. However, neither task alone fully explained the model's significance, suggesting other contributing factors. While the model accurately identified left TLE and HCs, it struggled to differentiate right TLE cases from HCs. These results were independent of education, age, biological sex, psychiatric status, or baseline language function.Conclusions:
Our findings suggest that emotional perception in TLE is influenced by the lateralization of the seizure onset zone, which has critical implications for diagnostic analysis and treatment planning. Left-sided TLE patients showed significantly poorer performance on emotional perception tasks compared to right TLE patients, with both groups performing worse than HCs. These findings are contrary to the hypothesis that the right hemisphere is more specialized for emotional recognition and may suggest that potential disruption of such function by the seizure networks of TLE patients differs from the structural effects of other diseases (e.g., stroke, tumor) or that the theoretical model is more complex than currently proposed. Models exist suggesting bilateral involvement of TL structures in emotional recognition, including differences in valence of stimuli, and our data appear more supportive of bilateral involvement.Funding:
This project was funded by NIH/NINDS grants awarded to Dr. Drane (R01 NS088748, K02 NS070960).