Epilepsy and Cognitive Neurophysiology Laboratory

Electrophysiological studies to understand the role of intracortical and  thalamocortical networks  in cognition

Published articles

Publications 2018 

Auras localized to the temporal lobe disrupt verbal memory and learning — Causal evidence from direct electrical stimulation of the hippocampus
Authors: Diana Pizarro, Emilia Toth, Auriana Irannejad, Kristen O. Riley, Zeenat Jaisani, Wolfgang Muhlhofer, Roy Martin, Sandipan Pati,
Department of Neurology, University of Alabama at Birmingham, AL, United States of America
Department of Neurosurgery, University of Alabama at Birmingham, AL, United States of America
Epilepsy and Cognitive Neurophysiology Laboratory, University of Alabama at Birmingham, AL, United States of America 


Auras (focal aware seizure; FAS) are subjective ictal events with retained consciousness. Epileptiform activities can disrupt cognitive tasks, but studies are limited to seizures with impaired awareness. As a proof of concept, we examined the cognitive effects of direct electrical stimulation to the left hippocampus which induced a habitual FAS in a patient with left mesial temporal lobe epilepsy. During the induced habitual FAS, verbal memory performance declined significantly as compared to pre-stimulation testing. Tasks measuring auditory working memory and psychomotor processing speed were not affected by the stimulation. The study confirms that FAS can impair episodic verbal memory and learning.

Keywords: Verbal memory, Aura, Focal aware seizure, Learning, Hippocampus, Epilepsy

doi: 10.1016/j.ebcr.2018.07.006

Figure 1 A: Intracranial EEG with recordings from left amygdala–hippocampus, orbitofrontal, insula and lateral temporal regions. Electrical stimulation artifact (highlighted) in hippocampal channels followed by an induced seizure. Co-registered MRI to demonstrate the orthogonal trajectory of left hippocampal depth electrode. B: Serial cognitive test performances in percentile. C: Spectrogram (1–100 Hz) showing seizure in the hippocampal channel and spread to orbitofrontal regions.