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We previously reported the neuropsychological consequences of a lesion confined to the middle and posterior part of the right fusiform gyrus (case JA) causing a partial loss of knowledge of visual attributes of concrete entities in the absence of category-selectivity (animate versus inanimate). We interpreted this in the context of a two-step model that distinguishes structural description knowledge from associative-semantic processing and implicated the lesioned area in the former process. To test this hypothesis in the intact brain, multi-voxel pattern analysis was used in a series of event-related fMRI studies in a total of 46 healthy subjects. We predicted that activity patterns in this region would be determined by the identity of rather than the conceptual similarity between concrete entities. In a prior behavioral experiment features were generated for each entity by more than 1000 subjects. Based on a hierarchical clustering analysis the entities were organised into 3 semantic clusters (musical instruments, vehicles, tools). Entities were presented as words or pictures. With foveal presentation of pictures, cosine similarity between fMRI response patterns in right fusiform cortex appeared to reflect both the identity of and the semantic similarity between the entities. No such effects were found for words in this region. The effect of object identity was invariant for location, scaling, orientation axis and color (grayscale versus color). It also persisted for different exemplars referring to a same concrete entity. The apparent semantic similarity effect however was not invariant. This study provides further support for a neurobiological distinction between structural description knowledge and processing of semantic relationships and confirms the role of right mid-posterior fusiform cortex in the former process, in accordance with previous lesion evidence. publisher: Elsevier articletitle: Right fusiform response patterns reflect visual object identity rather than semantic similarity journaltitle: NeuroImage articlelink: http://dx.doi.org/10.1016/j.neuroimage.2013.05.128 content_type: article copyright: Copyright © 2013 Elsevier Inc. All rights reserved. ispartof: NeuroImage vol:83 pages:87-97 ispartof: location:United States status: published

Item does not contain fulltext Previous studies using explicit semantic tasks, such as category or similarity judgments, have revealed considerable neuroanatomical overlap between processing of the meaning of words and pictures. This result may have been influenced by the semantic executive control required by such tasks. We examined the degree of overlap while minimizing semantic executive demands. In a first fMRI experiment (n = 28), we titrated word (35.3 ms, SD = 9.6) and picture presentation duration (50.7 ms, SD = 15.8) such that conscious stimulus identification became a stochastic process, with a 50% chance of success. Subjects had to indicate by key press whether or not they had been able to identify the stimulus. In a second fMRI experiment (n = 19), the identification runs were followed by a surprise forced-choice recognition task and events were sorted on the basis of subsequent memory retrieval success rather than a subjective consciousness report. For both words and pictures, when stimulus processing exceeded the conscious identification threshold, the left occipitotemporal sulcus (OTS), intraparietal sulcus, inferior frontal junction, and middle third of the inferior frontal sulcus (IFS) were more active than when subjects had been unable to identify the stimulus. For both words and pictures, activity in two of these regions, IFS and OTS, predicted subsequent memory retrieval success. A Bayesian comparison revealed that the effective connectivity between IFS and the word- or picture-specific systems was mainly mediated via its connections with OTS. The amodal nature of left OTS and IFS involvement in word and picture processing extends to tasks with minimal semantic executive demands. 13 p.

Contains fulltext : 127510.pdf (Publisher’s version ) (Closed access) The involvement of neural motor and sensory systems in the processing of language has so far mainly been studied in native (L1) speakers. In an fMRI experiment, we investigated whether non-native (12) semantic representations are rich enough to allow for activation in motor and somatosensory brain areas. German learners of Dutch and a control group of Dutch native speakers made lexical decisions about visually presented Dutch motor and non-motor verbs. Region-of-interest (ROI) and whole-brain analyses indicated that 12 speakers, like L1 speakers, showed significantly increased activation for simple motor compared to non-motor verbs in motor and somatosensory regions. This effect was not restricted to Dutch-German cognate verbs, but was also present for non-cognate verbs. These results indicate that L2 semantic representations are rich enough for motor-related activations to develop in motor and somatosensory areas. 16 p.