Neurophysiological recordings and neuroimaging data in blind and deaf animals and humans suggest that perceptual functions may be organized differently after sensory deprivation. It has been argued that neural plasticity contributes to compensatory performance in blind humans, such as faster speech processing. The present study employed functional magnetic resonance imaging (fMRI) to map language-related brain activity in congenitally blind adults. Participants listened to sentences, with either an easy or a more difficult syntactic structure, which were either semantically meaningful or meaningless. Results show that blind adults not only activate classical left-hemispheric perisylvian language areas during speech comprehension, as did a group of sighted adults, but that they additionally display an activation in the homologueous right-hemispheric structures and in extrastriate and striate cortex. Both the perisylvian and occipital activity varied as a function of syntactic difficulty and semantic content. The results demonstrate that the cerebral organization of complex cognitive systems such as the language system is significantly shaped by the input available.

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Summary: German belongs to those languages that allow a free permutation of subject, direct object and indirect object in verb final sentences. Five linear precedence (LP) principles have been postulated to describe preference patterns for the different word orders ( Uszkoreit, 1986 ). The present study tested if these rules are valid for meaningful German sentences only or also hold for pseudo-word sentences, i.e., if they are independent of semantic language aspects. Twelve students saw sentences in six different but legal word orders and in one illegal word order, either with normal German words or pronounceable pseudo-words. They had to answer a question focussing on the thematic role of one or more complements. In addition, they rated the acceptability of a subset of sentences in all experimental conditions. The canonical word order was processed fastest and processing times increased the more LP-principles were violated, both for normal and pseudo-word sentences. Moreover, acceptability ratings decreased monotonously with an increasing deviation of the sentences from its canonical word order, again irrespective of the stimulus material. The ungrammatical permutation received the lowest acceptability ruting. These results imply that the LP-principles describe syntactical preferences independent of meaning, at least in isolated sentences.

The present study used functional magnetic resonance imaging to delineate cortical networks that are activated when objects or spatial locations encoded either visually (visual encoding group, n=10) or haptically (haptic encoding group, n=10) had to be retrieved from long-term memory. Participants learned associations between auditorily presented words and either meaningless objects or locations in a 3-D space. During the retrieval phase one day later, participants had to decide whether two auditorily presented words shared an association with a common object or location. Thus, perceptual stimulation during retrieval was always equivalent, whereas either visually or haptically encoded object or location associations had to be reactivated. Moreover, the number of associations fanning out from each word varied systematically, enabling a parametric increase of the number of reactivated representations. Recall of visual objects predominantly activated the left superior frontal gyrus and the intraparietal cortex, whereas visually learned locations activated the superior parietal cortex of both hemispheres. Retrieval of haptically encoded material activated the left medial frontal gyrus and the intraparietal cortex in the object condition, and the bilateral superior parietal cortex in the location condition. A direct test for modality-specific effects showed that visually encoded material activated more vision-related areas (BA 18/19) and haptically encoded material more motor and somatosensory-related areas. A conjunction analysis identified supramodal and material-unspecific activations within the medial and superior frontal gyrus and the superior parietal lobe including the intraparietal sulcus. These activation patterns strongly support the idea that code-specific representations are consolidated and reactivated within anatomically distributed cell assemblies that comprise sensory and motor processing systems.

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