Abstract
Objective: The medial temporal lobe (MTL) encodes and recalls memories and can be a predominant site for interictal spikes (IS) in patients with focal epilepsy. It is unclear whether memory deficits are due to IS in the MTL producing a transient decline. Here, we investigated whether IS in the MTL subregions and lateral temporal cortex impact episodic memory encoding and recall. Methods: Seventy-eight participants undergoing presurgical evaluation for medically refractory focal epilepsy with depth electrodes placed in the temporal lobe participated in a verbal free recall task. IS were manually annotated during the pre-encoding, encoding, and recall epochs. We examined the effect of IS on word recall using mixed-effects logistic regression. Results: IS in the left hippocampus (odds ratio [OR] =.73, 95% confidence interval [CI] =.63–.84, p <.001) and left middle temporal gyrus (OR =.46, 95% CI =.27–.78, p <.05) during word encoding decreased subsequent recall performance. Within the left hippocampus, this effect was specific for area CA1 (OR =.76, 95% CI =.66–.88, p <.01) and dentate gyrus (OR =.74, 95% CI =.62–.89, p <.05). IS in other MTL subregions or inferior and superior temporal gyrus and IS occurring during the prestimulus window did not affect word encoding (p >.05). IS during retrieval in right hippocampal (OR =.22, 95% CI =.08–.63, p =.01) and parahippocampal regions (OR =.24, 95% CI =.07–.8, p <.05) reduced the probability of recalling a word. Significance: IS in medial and lateral temporal cortex contribute to transient memory decline during verbal episodic memory.
Original language | English (US) |
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Pages (from-to) | 2325-2337 |
Number of pages | 13 |
Journal | Epilepsia |
Volume | 63 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2022 |
Externally published | Yes |
Keywords
- CA1
- dentate gyrus
- episodic memory
- interictal epileptiform discharges
- intracranial EEG
- lateral temporal cortex
- medial temporal lobe
ASJC Scopus subject areas
- Neurology
- Clinical Neurology