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Connection with the language network affects object representation in the ventral visual pathway: Evidence from functional and diffusion imaging with patients
Poster Session D, Saturday, October 26, 10:30 am - 12:00 pm, Great Hall 3 and 4
Bo Liu1,3,4, Xiaosha Wang1, Xiaoying Wang1, Yan Li3,4, Yang Han3, Xiaochun Wang3,4, Yanchao Bi1,2; 1Beijing Normal University, Beijing, China, 2Chinese Institute for Brain Research, Beijing, China, 3Shanxi Medical University, Taiyuan, Shanxi Province, China, 4First Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, China
Object knowledge representation enables human understanding of and rich interactions with the world. The current consensus is that object knowledge is grounded in the corresponding cortical regions for which such knowledge is acquired, with higher-order ventral visual cortex (ventral occipital temporal cortex, VOTC) representing the shape and color knowledge of objects. Recent study has identified an additional types of object representation – those derived from language -- in the dorsal anterior temporal lobe (dATL). Regions representing these two types of knowledge are functionally connected during the resting state, but whether the connection between the two systems is critically involved in object representation within either systems and/or object knowledge behavior remain unknown. We here test this question using lesion models, combining diffusion imaging (for white matter structural integrity), fMRI (for functional neural knowledge representation), and neuropsychological assessments (for behavioral integrity) in patients. We first mapped out the white-matter (WM) connections between VOTC and dATL in 33 healthy controls that are age matched with our patients. We then tested in a group of 33 stroke patients the causal relationship between the WM integrity (FA values) of these tracts and the functional neural representation of object color knowledge in VOTC, which was assessed by a fMRI session where the patients received color knowledge of common objects, and between the two neural structures and object color knowledge behavior (both verbal and nonverbal). The impairment of the LdATL-VOTC connection has a significant causal effect on the neural representation of object color in VOTC, and these effects could not be fully explained by potential deficits in the visual perception pathway. The effects of the LdATL-VOTC connection also significantly correlated with object color behavior regardless of task modalities (verbal or nonverbal), and is above and beyond the effects of the related cognitive processes (object recognition and color patch recognition). These two lines of results remained robust when we controlled for a wide range of potential confounding variables, including the broader effects of lesions, patient post-onset duration and cases with special etiologies. In conclusion, our results show that the LdATL-VOTC connection plays a crucial role in the object knowledge representation in the VOTC, and more strongly explain the related behavior than VOTC knowledge representation. That is, in humans knowledge behavior may arise from bridging the sensory derived representation in VOTC and the language derived representation in dATL.
Topic Areas: Disorders: Acquired,