Authors:

HORNER, A.J. & HENSON, R.N.A.

Reference:

Year of publication:

2009

CBU number:

6953

Abstract:

Prior exposure to a stimulus can facilitate its subsequent identification and classification. This behavioural facilitation is usually accompanied by a reduction in neural response within distinct cortical regions (Repetition Suppression - RS) (Grill-Spector, Henson, & Martin, 2006). Despite previous research suggesting RS within Occipital/Temporal regions reflects repetition of perceptual and/or conceptual processes (Henson et al., 2003; Horner & Henson, 2008; Race, Shanker, & Wagner, in press) delineating these two possible contributions has not yet been possible. Previous research has suggested RS within left, as opposed to right, Fusiform cortex is less sensitive to changes in view-point (Vuilleumier, Henson, Driver, & Dolan, 2002) and exemplar (Koutstaal et al., 2001). Although these data suggest RS within the left Fusiform may reflect repetition of conceptual processes to a greater degree than right Fusiform it is also possible that such effects are attributable to the repetition of more high-level perceptual processes (e.g., the extraction of three-dimensional object properties). To control for such a possibility we visually presented the names of concrete objects at Study whereas we presented object pictures at Test. Results from two fMRI experiments demonstrate significant RS within left Fusiform and left Lateral Occipital cortex. Furthermore, RS within the equivalent right hemisphere regions do not demonstrate significant RS (indeed, a significant Region-by-RS interaction is present). These results suggest that RS within left Fusiform and Lateral Occipital cortex can result from the repetition of conceptual processes, whereas RS within the equivalent right hemisphere regions is primarily driven by the repetition of perceptual processes.