Transient epileptic amnesia (TEA) is an underdiagnosed sub-type of temporal lobe epilepsy, associated with recurrent amnestic episodes, and more persisting memory dysfunction in the form of accelerated long-term forgetting and autobiographical amnesia. EEG investigations form part of the diagnostic work-up but can often be inconclusive. The current research investigated whether resting state EEG analysis using quantitative EEG and connectivity analysis could provide new insight into the underlying causes of memory dysfunction in TEA. To date, no research has utilised connectivity in resting-state EEG  to investigate functional and effective connectivity within TEA.
Resting-state EEG recordings were acquired from the medical records of 28 patients diagnosed with TEA and compared to age and sex matched healthy controls. Pre-processing and initial analysis were undertaken using MATLAB, EEGLAB. Connectivity analysis was undertaken using three connectivity measures: imaginary coherence, weighted phase lag index and phase transfer entropy. All connectivity analysis was performed using Brainstorm.
The results showed functional connectivity alterations across frontal and temporal, frontal and parietal, and temporal and parietal networks within beta, alpha and theta bands. Dysfunction of effective connectivity affecting theta frequencies affecting was seen across all inter-regional networks  inter-regionally for theta frequencies. Finally, we confirmed that inter-ictal abnormalities were seen more frequently seen in an independent bi-temporal distribution and were more prevalent during non-REM sleep.
Our research has provided new evidence regarding functional and effective connectivity disturbances in TEA. We have demonstrated clear and consistent dysfunction of connectivity, both within memory areas of the temporal lobes, and within memory networks extending within the cortex. The evidence supports the hypothesis that memory consolidation and recall networks are affected in TEA.