mechanisms sub serving both language and sequential learning. De Vries, Barth, Maiworm, Knecht, Zwitserlood & Flöel found that electrical stimulation of Broca's area enhances implicit learning of an artificial grammar. Direct current stimulation may facilitate acquisition of grammatical knowledge, a finding of potential interest for rehabilitation of aphasia. Petersson, Vasiliki & Hagoort, examine the neurobiological correlates of syntax, the processing of structured sequences, by comparing fMRI results on artificial and natural language syntax. They argue that the "Chomsky hierarchy" is not directly relevant for neurobiological systems through AGL testing. See also Adaptive grammar Grammatical induction References Grammar Language acquisition Computational linguistics