This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The hypothesis of this protocol is that temporal lobe epilepsy (TLE) is a network disease, involving brain regions anatomically and functionally distant from the seizure focus. The seizure focus can cause dysfunction throughout the network in the interictal state, i.e., between seizures.
The specific aims are as follows: 1) To define the extent and severity of interictal perceptual deficits in 3 sensory modalities using basic psychophysical techniques. 2) To determine the effect of stimulus temporal features, specifically duration, on observed psychophysically-determined perceptual impairments. 3) To document the effect of removing the seizure focus on perceptual abilities. Potential subjects will be prescreened for meeting the inclusion and exclusion criteria by telephone interview with research personnel. Forty patients with unilateral, medically intractable TLE and 20 neurologically normal controls will undergo a battery of neuropsychological and perceptual psychophysical tests. Control subjects will be tested once on all tasks; TLE subjects will be tested three times: 1) baseline assessment while taking their usual anti-epileptic drugs (AEDs, initial test), 2) after substantial or complete AED withdrawal during clinically indicated, inpatient video-EEG monitoring (non-AED test), and 3) 6 months after surgery or 6 months after initial testing for those patients who ultimately do not have surgery (final test). AED levels in TLE subjects will be measured during all three testing sessions, on the first day of testing. All of the psychophysical tests are painless and non-invasive. Visual tasks involve looking at stimuli on a computer screen. Auditory stimuli are presented through high-quality headphones at a comfortable volume. Tactile stimuli are applied to the subject's fingertip with low or moderate force. Primary outcome measures will include comparing performance on the various tests between the following groups: TLE subjects - initial to normal controls, 2) paired final to initial, and 3) paired non-AED to initial. Secondary outcome measures will include initial performance on psychophysical tasks with the hand or ear contra lateral to side of seizure onset compared to hand or ear ipsilateral to side of seizure onset (visual tasks will be performed binocularly).
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