Plastic reorganization of neural systems for perception of others in the congenitally blind.

Recent evidence suggests that the function of the core system for face perception might extend beyond visual face-perception to a broader role in person perception. To critically test the broader role of core face-system in person perception, we examined the role of the core system during the perception of others in 7 congenitally blind individuals and 15 sighted subjects by measuring their neural responses using fMRI while they listened to voices and performed identity and emotion recognition tasks. We hypothesised that in people who have had no visual experience of faces, core face-system areas may assume a role in the perception of others via voices. Results showed that emotions conveyed by voices can be decoded in homologues of the core face system only in the blind. Moreover, there was a specific enhancement of response to verbal as compared to non-verbal stimuli in bilateral fusiform face areas and the right posterior superior temporal sulcus showing that the core system also assumes some language-related functions in the blind. These results indicate that, in individuals with no history of visual experience, areas of the core system for face perception may assume a role in aspects of voice perception that are relevant to social cognition and perception of others' emotions.

The brain network underlying serial visual search: comparing overt and covert spatial orienting, for activations and for effective connectivity.

We used functional magnetic resonance imaging (fMRI) to investigate the brain basis of overt and covert forms of attention during search, while employing stringent control of both eye movements and attentional shifts. A factorial design compared overt and covert forms of goal-directed serial search versus stimulus-driven tracking. To match ocular changes and the number and magnitude of attention shifts across cells in the design, stimulus-driven tracking involved trial-specific "replay" of previous goal-directed eye movements. We found that, in terms of cortical activations, engagement of the dorsal fronto-parietal network by goal-directed attention did not depend on oculomotor requirements, being found similarly for covert attention, in accord with other work. However, analyses of effective connectivity (or "functional coupling") revealed that information flow within this network changed significantly as a function of both the task (goal-directed or stimulus-driven) and the overt versus covert form of attention. Additionally, we observed a distinct set of subcortical regions (pulvinar and caudate nucleus) engaged primarily during the covert form of goal-directed search. We conclude that dynamics within the dorsal fronto-parietal attentional system flexibly reorganize to integrate task demands and oculomotor requirements.

Spatial attention can modulate audiovisual integration at multiple cortical and subcortical sites.

The role of attention in multisensory integration (MI) is presently uncertain, with some studies supporting an automatic, pre-attentive process and others suggesting possible modulation through selective attention. The goal of this functional magnetic resonance imaging study was to investigate the role of spatial attention on the processing of congruent audiovisual speech stimuli (here indexing MI). Subjects were presented with two simultaneous visual streams (speaking lips in the left and right visual hemifields) plus a single central audio stream (spoken words). In the selective attention conditions, the auditory stream was congruent with one of the two visual streams. Subjects attended to either the congruent or the incongruent visual stream, allowing the comparison of brain activity for attended vs. unattended MI while the amount of multisensory information in the environment and the overall attentional requirements were held constant. Meridian mapping and a lateralized 'speaking-lips' localizer were used to identify early visual areas and to localize regions responding to contralateral visual stimulations. Results showed that attention to the congruent audiovisual stimulus resulted in increased activation in the superior temporal sulcus, striate and extrastriate retinotopic visual cortex, and superior colliculus. These findings demonstrate that audiovisual integration and spatial attention jointly interact to influence activity in an extensive network of brain areas, including associative regions, early sensory-specific visual cortex and subcortical structures that together contribute to the perception of a fused audiovisual percept.

Functional MRI in NPSLE patients reveals increased parietal and frontal brain activation during a working memory task compared with controls.

OBJECTIVES: Anatomical MRI brain scans may not reflect neurological dysfunction in patients with NPSLE. We used blood-oxygen-level-dependent functional MRI (BOLD-fMRI) to investigate working memory function in NPSLE patients. METHODS: Twenty-seven females took part: nine NPSLE patients (mean age 40 yrs; SLEDAI 10.9); nine RA patients and nine healthy controls. Subjects were tested using the n-back paradigm for working memory, where patients indicate when a stimulus matches one presented n trials previously. Functional scans used 3 mm slices x 30, repetition time 2570 ms, echo time 50 ms. Echo planar images were superimposed onto T1w anatomical images (Siemens 1.5 T). Data analysis used Brain Voyager QX Version 1.7. RESULTS: During the memory task, there was activation in areas serving working memory, executive function and attention in all groups. Nine regions of interest were selected for activation during working memory (N-back task vs fixation, P < or = 0.005). In six out of nine regions, there was greater activation in the NPSLE group. This reached significance in three regions: the posterior inferior parietal lobules of both hemispheres [Brodmann area (BA) 7] separately and combined (P = 0.014, 0.016 and 0.004, respectively), and the supplementary motor area (mid-line frontal lobe) (BA32/6; P = 0.032). CONCLUSIONS: NPSLE patients showed greater frontoparietal activation than the other groups during the memory task, suggesting a greater need to recruit extra cortical pathways, possibly to supplement impaired function of standard pathways.