Theory of Mind impairment in focal versus generalized epilepsy.

Theory of Mind (ToM) is a critical component of social cognition, and thus, its impairment may adversely affect social functioning and quality of life. Recent evidence has suggested that it is impaired in epilepsy. What is not clear, however, is whether it is related to particular types of epilepsy or other factors. We undertook the present study to explore ToM in patients with focal versus those with generalized epilepsy, the particular pattern of ToM deficits, and the potential influence of antiepileptic medication load. Our sample included 149 adults: 79 patients with epilepsy (34 with generalized epilepsy and 45 with focal epilepsy) and 70 healthy controls. Theory of Mind tasks included a) comprehension of hinting, b) comprehension of sarcasm and metaphor, c) comprehension of false beliefs and deception, d) recognition of faux pas, and e) a visual ToM task in cartoon form. We found significant ToM impairment in the group with focal epilepsy relative to the performance of both the healthy group and the group with generalized epilepsy on all tasks, with the exception of faux pas, on which the group with generalized epilepsy also performed more poorly than the healthy group. Additionally, early age at seizure onset, but not antiepileptic drug (AED) load, was associated with ToM performance. Our findings suggest that focal temporal and frontal lobe, but not generalized, epilepsies were associated with impaired ToM. This may reflect the neuroanatomical abnormalities in the relevant neuronal networks and may have implications for differential cognitive-behavioral interventions based on epilepsy type.

Modality-specific temporal constraints for state-dependent interval timing.

The ability to discriminate temporal intervals in the milliseconds-to-seconds range has been accounted for by proposing that duration is encoded in the dynamic change of a neuronal network state. A critical limitation of such networks is that their activity cannot immediately return to the initial state, a restriction that could hinder the processing of intervals presented in rapid succession. Empirical evidence in the literature consistently shows impaired duration discrimination performance for 100 ms intervals demarked by short auditory stimuli immediately preceded by a similar interval. Here we tested whether a similar interference is present with longer intervals (300 ms) demarked either by auditory or by visual stimuli. Our results show that while temporal estimates of auditory stimuli in this range are not affected by the interval between them, duration discrimination with this duration is significantly impaired with visual intervals presented in rapid succession. The difference in performance between modalities is overall consistent with state-dependent temporal computations, as it suggests that the limits due to slow neuronal dynamics greatly depends on the sensory modality with which the intervals are demarked, in line with the idea of intrinsic, modality-specific neural mechanisms for interval timing.