To investigate whether VNS can accelerate learning and improve associative memory when learning word pairs, we will investigate the performance of VNS implanted participants on a Verbal Paired-Associate memory task and compare their performance on the words that were learned while paired with VNS in contrast to their performance on the words that were learned while unpaired with VNS and in contrast to their performance on the words that were learned without VNS (i.e. 3 types/groups of words: paired with VNS, unpaired with VNS and without VNS) during the first visit and 1 day,1 week and 1 month after their first visit.