LANGUAGE-RELATED FIELD POTENTIALS IN THE ANTERIOR-MEDIAL TEMPORAL-LOBE .2. EFFECTS OF WORD TYPE AND SEMANTIC PRIMING

Field potentials were recorded from intracranial electrodes in humans to study the role of the anterior medial temporal lobe (AMTL) in langu age-related processing. Subjects viewed lists of words in which orthog raphy and word type varied, or in which words were primed by semantic associates. Large negative field potentials were elicited within the A MTL by isolated words. The amplitude and intracranial distribution of these AMTL field potentials were consistent with those in our previous study in which anomalous sentence-ending words were used as stimuli ( McCarthy et al., in press). The neocortex, in the region of the collat eral sulcus and anterior fusiform gyrus, was identified as the likely neural generator of this field potential. The AMTL field potential was diminished by semantic priming, and was larger for words with semanti c content than for words serving grammatical function. Orthographicall y illegal nonwords did not elicit this field potential. The N400 scalp event-related potential (ERP) has been shown to respond in the same m anner to these task manipulations (Nobre and McCarthy, 1994), and, thu s, the AMTL field potential was proposed to contribute to the generati on of N400. The possible roles in language processing reflected by the AMTL field potential were considered.