scholarly journals Electrophysiological evidence for the action of a center-surround mechanism on semantic processing in the left hemisphere

2013 ◽  
Vol 4 ◽  
Author(s):  
Diana Deacon ◽  
John F. Shelley-Tremblay ◽  
Walter Ritter ◽  
Anna Dynowska
2015 ◽  
Vol 6 (1) ◽  
pp. 227-234 ◽  
Author(s):  
Mei Jiang ◽  
Li-Xia Yang ◽  
Lin Jia ◽  
Xin Shi ◽  
Hong Wang ◽  
...  

AbstractObjective: The aim of this study is to evaluate variations in cortical activation in early and late Uygur-Chinese bilinguals from the Xinjiang Uygur Autonomous Region of China. Methodology: During a semantic judgment task with visual stimulation by a single Chinese or Uygur word, functional magnetic resonance imaging (fMRI) was performed. The fMRI data regarding activated cortical areas and volumes by both languages were analyzed. Results: The first language (L1) and second language (L2) activated language-related hemispheric regions, including the left inferior frontal and parietal cortices, and L1 specifically activated the left middle temporal gyrus. For both L1 and L2, cortical activation was greater in the left hemisphere, and there was no significant difference in the lateralization index (LI) between the two languages (p > 0.05). Although the total activated cortical areas were larger in early than late bilinguals, the activation volumes were not significantly different. Conclusion: Activated brains areas in early and late fluent bilinguals largely overlapped. However, these areas were more scattered upon presentation of L2 than L1, and L1 had a more specific pattern of activation than L2. For both languages, the left hemisphere was dominant. We found that L2 proficiency level rather than age of acquisition had a greater influence on which brain areas were activated with semantic processing.


1998 ◽  
Vol 172 (2) ◽  
pp. 142-146 ◽  
Author(s):  
Matthias Weisbrod ◽  
Sabine Maier ◽  
Sabine Harig ◽  
Ulrike Himmelsbach ◽  
Manfred Spitzer

BackgroundIn schizophrenia, disturbances in the development of physiological hemisphere asymmetry are assumed to play a pathogenetic role. The most striking difference between hemispheres is in language processing. The left hemisphere is superior in the use of syntactic or semantic information, whereas the right hemisphere uses contextual information more effectively.MethodUsing psycholinguistic experimental techniques, semantic associations were examined in 38 control subjects, 24 non-thought-disordered and 16 thought-disordered people with schizophrenia, for both hemispheres separately.ResultsDirect semantic priming did not differ between the hemispheres in any of the groups. Only thought-disordered people showed significant indirect semantic priming in the left hemisphere.ConclusionsThe results support: (a) a prominent role of the right hemisphere for remote associations; (b) enhanced spreading of semantic associations in thought-disordered subjects; and (c) disorganisation of the functional asymmetry of semantic processing in thought-disordered subjects.


2020 ◽  
Vol 57 (10) ◽  
Author(s):  
Yue Huang ◽  
Jia Zhao ◽  
Manish Kumar Asthana ◽  
Kun Zuo ◽  
William Edgar Comfort ◽  
...  

2018 ◽  
Vol 32 (6-7) ◽  
pp. 613-623 ◽  
Author(s):  
Shihui Xing ◽  
Ayan Mandal ◽  
Elizabeth H. Lacey ◽  
Laura M. Skipper-Kallal ◽  
Jinsheng Zeng ◽  
...  

Background. In functional magnetic resonance imaging studies, picture naming engages widely distributed brain regions in the parietal, frontal, and temporal cortices. However, it remains unknown whether those activated areas, along with white matter pathways between them, are actually crucial for naming. Objective. We aimed to identify nodes and pathways implicated in naming in healthy older adults and test the impact of lesions to the connectome on naming ability. Methods. We first identified 24 cortical nodes activated by a naming task and reconstructed anatomical connections between these nodes using probabilistic tractography in healthy adults. We then used structural scans and fractional anisotropy (FA) maps in 45 patients with left hemisphere stroke to assess the relationships of node and pathway integrity to naming, phonology, and nonverbal semantic ability. Results. We found that mean FA values in 13 left hemisphere white matter tracts within the dorsal and ventral streams and 1 interhemispheric tract significantly related to naming scores after controlling for lesion size and demographic factors. In contrast, lesion loads in the cortical nodes were not related to naming performance after controlling for the same variables. Among the identified tracts, the integrity of 4 left hemisphere ventral stream tracts related to nonverbal semantic processing and 1 left hemisphere dorsal stream tract related to phonological processing. Conclusions. Our findings reveal white matter structures vital for naming and its subprocesses. These findings demonstrate the value of multimodal methods that integrate functional imaging, structural connectivity, and lesion data to understand relationships between brain networks and behavior.


2007 ◽  
Vol 17 (11) ◽  
pp. 2659-2668 ◽  
Author(s):  
C. Magne ◽  
C. Astesano ◽  
M. Aramaki ◽  
S. Ystad ◽  
R. Kronland-Martinet ◽  
...  

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