Processing deficits for familiar and novel faces in patients with left posterior fusiform lesions.
Bottom Line: Identification of famous faces was found to be compromised in both expressive and receptive tasks.Interestingly, discrimination of faces that varied in terms of feature identity was considerably better in these patients and it was performance in this condition that was related to the size of the length effects shown in reading.These results suggest that the sequential part-based processing strategy that promotes the length effect in the reading of these patients also allows them to discriminate between faces on the basis of feature identity, but processing of second-order configural information is most compromised due to their left pFG lesion.
Affiliation: Research Centre in Brain and Behaviour, Liverpool John Moores University, UK.Show MeSH
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Mentions: Lesions were reconstructed based on high-resolution research MRI or clinical MRI/computed tomography (CT) scans that were available for 17 of 19 participants (scans were unavailable for two UK patients, FW, KW). A lesion region of interest (ROI) was created for each patient using MRIcron software (http://www.cabiatl.com/mricro/mricron/). For research MRI scans, lesions were manually drawn directly on the patients' T1-weighted structural brain images at 1 mm intervals and then normalized to the standard MNI template brain using the lesion volume as a mask during the normalization process (Andersen et al., 2010, Brett et al., 2001). For the clinical CT and MRI scans, lesions were manually drawn onto the standard MNI template brain oriented to match the alignment of the scans (see Andersen et al., 2010, and Roberts et al., 2013 for additional details of our lesion mapping methods). Individual ROIs were subsequently combined to generate the lesion overlap maps. As can be seen in Fig. 2, most patients had damage to left pFG regions that show activation in normal subjects during a reading task. In two cases, imaging revealed additional damage to right medial occipital cortex, but in no cases did the lesions extend to right hemisphere ventral occipito-temporal regions implicated in face processing (i.e., the OFA/FFA). As can be seen in comparison of the lesion overlap maps in Rows 3 and 4 of Fig. 2, damage to the left pFG was more pronounced and consistent for the severe than the mild-moderate groups. Although lesions did extend beyond this region in some patients in both groups, this was not universally the case, and the bottom row of Fig. 2 presents the lesion map for patient 125, who had a relatively small lesion confined to the left fusiform gyrus/occipito-temporal sulcus in the presence of a severe reading impairment (see Fig. 1).
Affiliation: Research Centre in Brain and Behaviour, Liverpool John Moores University, UK.