Task-Dependent Modulations of Prefrontal and Hippocampal Activity during Intrinsic Word Production

Autor/inn/en	Whitney, Carin; Weis, Susanne; Krings, Timo; Huber, Walter; Grossman, Murray; Kircher, Tilo
Titel	Task-Dependent Modulations of Prefrontal and Hippocampal Activity during Intrinsic Word Production
Quelle	In: Journal of Cognitive Neuroscience, 21 (2009) 4, S.697-712 (16 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0898-929X
DOI	10.1162/jocn.2009.21056
Schlagwörter	Semantics; Reading Processes; Language Acquisition; Semiotics; Brain Hemisphere Functions; Diagnostic Tests; Oral Language; Associative Learning; Verbal Communication; Task Analysis; Phonology; Role; Neurological Organization; Language Processing + Suchen Sie Ihr Suchwort? Semantik; Leseprozess; Sprachaneignung; Spracherwerb; Semiotik; Diagnostic test; Diagnostischer Test; Oral interpretation; Mündlicher Sprachgebrauch; Aufgabenanalyse; Fonologie; Rollen; Sprachverarbeitung
Abstract	Functional imaging studies of single word production have consistently reported activation of the lateral prefrontal and cingulate cortex. Its contribution has been shown to be sensitive to task demands, which can be manipulated by the degree of response specification. Compared with classical verbal fluency, free word association relies less on response restrictions but to a greater extent on associative binding processes, usually subserved by the hippocampus. To elucidate the relevance of the frontal and medial-temporal areas during verbal retrieval tasks, we applied varying degrees of response specification. During fMRI data acquisition, 18 subjects performed a free verbal association (FVA), a semantic verbal fluency (SVF) task, and a phonological verbal fluency (PVF) task. Externally guided word production served as a baseline condition to control for basic articulatory and reading processes. As expected, increased brain activity was observed in the left lateral and bilateral medial frontal cortices for SVF and PVF. The anterior cingulate gyrus was the only structure common to both fluency tasks in direct comparison to the less restricted FVA task. The hippocampus was engaged during associative and semantic retrieval. Interestingly, hippocampal activity was selectively evident during FVA in direct comparison to SVF when it was controlled for stimulus-response relations. The current data confirm the role of the left prefrontal-cingulate network in constrained word production. Hippocampal activity during spontaneous word production is a novel finding and seems to be dependent on the retrieval process (free vs. constrained) rather than the variety of stimulus-response relationships that is involved. (As Provided).
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Update	2017/4/10