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To investigate postoperative changes in fiber tract integrity in patients with temporal lobe epilepsy (TLE) following anterior temporal lobectomy (ATL) and to determine whether postoperative changes are 1) stable vs progressive and 2) related to visual field defects.

To investigate the relationship between white matter tract integrity and language and memory performances in patients with temporal lobe epilepsy (TLE).

Although detection of concordant lesions on MRI significantly improves postsurgical outcomes in focal epilepsy (FE), many conventional MR studies remain negative. The authors evaluated the role of phased array surface coil studies performed at 3 Tesla (3T PA MRI).

The scalp topography of endogeneous potentials was studied during a series of simple cognitive tasks in the auditory modality. P3 and Slow Wave showed the expected task correlates of being larger to rare than to frequent tones, and larger when attended than ignored, but N2 was not clearly measurable due to overlap with P2 and P3. Overall, across all task conditions, P3 was larger at sites over the right hemisphere than the left, particularly for sites near the midline (F3, F4, C3, C4, P3, P4). P3 was present (though smaller) to rare omitted stimuli in a tone series, as well as to tones presented at long, random intervals (3 to 9 s) in a simple counting task. P3 was very large to novel, unique, nontarget auditory stimuli, and had a somewhat different distribution to these stimuli than to targets, suggesting a difference in the underlying intracranial generators. Except for these novel nontarget sounds, P3 showed a consistent topography across tasks in spite of differences in amplitude.

It is generally believed that patients with primary generalized epilepsy have normal cognition and neuroimaging studies.We have previously shown that patients with juvenile myoclonic epilepsy (JME) have impaired visual working memory. In this study we examined relative regional changes in18FDG uptake during a visual working memory paradigm in patients with JME. At rest, there were regional decreases in relative glucose uptake compared to controls. Unlike control subjects, increased activity in the dorsolateral prefrontal cortex was not found during the working memory task. Other regions with increased uptake in controls, such as premotor cortex and basal frontal cortex, also showed no increases, whereas medial temporal structures appeared to play a role in JME but not in control subjects' task performance. The data suggest that JME, a type of primary generalized epilepsy, may suffer from cortical disorganization that affects both the epileptogenic potential and frontal lobe cognitive functioning.

Jackson (Brain 1898; 21: 580–90) observed that seizures arising in the medial temporal lobe may result in a ‘dreamy state’, consisting of vivid memory-like hallucinations, and/or the sense of having previously lived through exactly the same situation (déjà vu). Penfield demonstrated that the dreamy state can sometimes be evoked by electrical stimulation of the lateral temporal neocortex, especially the superior temporal gyrus. Halgren et al. (Brain 1978; 101: 83–117) showed that the dreamy state can be evoked by stimulation of the hippocampal formation and amygdala and Gloor (Brain 1990; 113: 1673–94) has suggested that it is evoked by lateral stimulation only when the resulting after-discharge spreads medially. In order to resolve the relative importance of these areas, we considered the mental phenomena observed in epileptic patients with electrodes stereotaxically implanted into different brain areas for seizure localization prior to surgical treatment. Sixteen patients, all with seizures involving the temporal lobe, experienced the dreamy state either as a result of spontaneous seizures (nine dreamy states in six patients), or due to electrical stimulation (43 in 14) or to chemical activation (five in three). Déjà vu and hallucinations of scenes were often evoked by different stimulations of the same electrode in the same patient. As Jackson had also observed, the dreamy state could occur alone but was often associated with epigastric phenomena and fear, and followed by loss of contact and oro-alimentary automatisms, and then by simple gestural automatisms, all characteristic of partial seizures beginning in the medial temporal lobe. Furthermore, as also emphasized by Jackson, the dreamy state was seldom associated with sensory illusions. Stimulation of either the neocortex (15 occurrences), anterior hippocampus (17) or amygdala (10) could evoke a dreamy state. However, since fewer hippocampal and amygdala leads were stimulated than temporal neocortical, the proportion of medial temporal electrodes where dreamy states could be evoked was much higher than in the neocortex. Most responsive lateral temporal sites were located in the superior temporal gyrus, rather than the middle temporal gyrus which was significantly less responsive. In 85% of dreamy states evoked by medial temporal lobe stimulation, the discharge spread to the temporal neocortex; and in 53% of dreamy states evoked by lateral temporal stimulation, the discharge spread medially. Considering all dreamy states, the amygdala was involved (as the stimulated structure, or as the site of ictal- or after-discharge) in 73% of cases, the anterior hippocampus in 83% and the temporal neocortex in 88%. In every spontaneous seizure where the dreamy state was observed, the amygdala, anterior hippocampus and temporal neocortex were all involved (provided that they were recorded during the seizure). Thus, we conclude that the dreamy state probably depends upon a neuronal network that engages both medial and lateral aspects of the temporal lobe, and that the anterior hippocampus, amygdala and superior temporal gyrus have relatively priviledged access to this circuit.

Multimodal sensory properties of the prefrontal cortex have been extensively studied in monkeys, while little is known of such functions in humans. We report electrophysiological evidence for auditory and visual representations in the dorsolateral prefrontal cortex, as inferred from intracerebral ‘depth’ recordings of focal, sensory-evoked spike-wave complexes (SWC) in an epileptic patient. In addition to clinical monitoring, the patient participated in behavioural evoked potential studies involving auditory and visual discrimination tasks. Inspection of evoked potential recordings from different medial-to-lateral prefrontal sites revealed overlapping, but non-identical topographies of evoked SWC for the two sensory modalities. The maximal activity of sensory-evoked SWC was located 7 mm more medially for visual than for auditory stimuli, and occurred later for visual presentations (mean = III ms following stimulus onset) than for auditory ones (mean = 87 ms). Effects of sensory habituation were seen. Evoked SWC were less likely to occur following repeated presentations of an unchanging tone than when tones alternated in pitch, or when a tone followed an omission in stimulus presentation. Visual hemifield effects were found, with greater prefrontal responsiveness to presentations in the contralateral visual hemifield. These results are consistent with electro-physiological findings in animals indicating overlapping auditory and visual representations in the dorsolateral prefrontal cortex.