Authors:

Stamatkis, E., MARSLEN-WILSON, W.D., Tyler, L.K., & Fletcher, P

Reference:

Year of publication:

2004

CBU number:

5780

Abstract:

In recent research using efMRI, we showed that fronto-temporal network (anterior cingulate(ACC), left inferior frontal gyrus(LIFG) & bilateral superior temporal gyrus(STG)), is preferentially activated for the regular past tense, using a task where participants listened to word-pairs and made same/different judgements for real/pseudo regulars and irregulars (Tyler et al., 2003). This may reflect additional processing demands posed by regular inflected forms, requiring modulation of temporal lobe lexican access processes by morpho-phonological parsing functions supported by the LIFG. In a contemporary analysis, we examined this system in terms of inter-regional covariences, an index of functional connectivity. We identified regions where activity was predicted by LIFG and ACC and, critically, by their interaction in the context of the four experimental conditions. These analyses reveal that functional connections between LIFG and RSTG are significantly stronger when processing real vs. pseudo regulars but not for real vs. pseudo irregulars. Additionally, functional connectivity between LIFG and left middle temporal gyrus is positively modulated by activity in ACC and this effect is significantly greater for regulars than irregulars. This three-way interaction suggests three features of the system: a) a positive influence of the LIFG on temporal activity; b) a modulatory influence of the ACC upon this front-temporal connecivity and c) a condition-specificity of this modularity effect such that the ACC influence upon fronto-temporal connectivity is greater when processing regular items. These preliminary findings point to a complex network underlying the processing of spoken words differing in morpho-phonological complexity.