Poster No:
1006
Submission Type:
Abstract Submission
Authors:
Tomoki Uno1,2, Marc Teichmann3, Kouji Takano1, Kimihiro Nakamura1
Institutions:
1National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan, 2Japan Society for the Promotion of Sciences, Tokyo, Japan, 3French National Reference Center for « Rare or Early-Onset Dementias », Pitié-Salpêtrière Hospital, Paris, France
First Author:
Tomoki Uno
National Rehabilitation Center for Persons with Disabilities|Japan Society for the Promotion of Sciences
Tokorozawa, Japan|Tokyo, Japan
Co-Author(s):
Marc Teichmann
French National Reference Center for « Rare or Early-Onset Dementias », Pitié-Salpêtrière Hospital
Paris, France
Kouji Takano
National Rehabilitation Center for Persons with Disabilities
Tokorozawa, Japan
Kimihiro Nakamura
National Rehabilitation Center for Persons with Disabilities
Tokorozawa, Japan
Introduction:
The anterior temporal lobe (ATL) in the left and right hemispheres have been shown to act as a "semantic hub" converging multimodal information (Rice et al., 2015; Lambon Ralph et al., 2017). However, the functional architecture of ATL remains elusive because there are two competing models regarding the hemispheric specialization in semantic processing. On the one hand, the "functional specialization model" assumes that left and right ATLs are specifically involved in verbal and nonverbal semantics, respectively (Mesulam et al., 2014). On the other hand, the "unitary model" posits that the left and right ATLs equally contribute to multimodal semantic processing (Lambon Ralph et al., 2017). Interestingly, each of the two different models has gained empirical support from previous studies using transcranial magnetic stimulation (TMS) (Pobric et al., 2010; Bonni et al., 2015). However, this inconsistency may be attributed to the use of demanding cognitive tasks (i.e., semantic association) of which strong strategic components can cancel out possible differences between verbal and non-verbal semantic processing. The purpose of the present study is to examine whether or not the left and right ATLs are functionally asymmetrical in semantic processing by using repetitive transcranial magnetic stimulation (TMS) with a semantic priming paradigm which taps more implicit and automatic aspects of semantic processing.
Methods:
Eighteen native Japanese speakers participated in the present study (8 females, all right-handed). They made real vs. nonreal judgments about visually presented words (lexical decision (LD)) or objects (object decision (OD)), preceded by semantically related or unrelated primes with short stimulus onset asynchrony (300 ms). Low-frequency ('inhibitory') repetitive TMS was applied prior to the two tasks to the left ATL, the right ATL or the vertex (control).
Results:
For vertex stimulation, we confirmed typical effects of semantic priming in both LD and OD, whereby participants responded faster when targets were preceded by semantically related primes than by unrelated primes. Critically, we observed that semantic priming in LD was eliminated by left ATL stimulation but not by right ATL stimulation, suggesting that verbal semantics is represented in the left ATL. By contrast, semantic priming in OD was impaired by both left and right ATL stimulation, suggesting that the retrieval/analysis of non-verbal semantic information relies on the functional coordination of the left and right ATLs.
Conclusions:
The present TMS data indicate that the left ATL is specialized for verbal semantic processing. This hemispheric asymmetry may be formed via strong structural and functional connections between the ATL and other language areas in the dominant left hemisphere (e.g., left middle-temporal gyrus and inferior frontal gyrus). Our results also showed that non-verbal semantic information is distributed in both hemispheres, probably because semantic analysis of visual objects relies on both the lexicosemantic knowledge in the left hemisphere and the visual shape analysis predominant in the right hemisphere (Seimons et al., 2003). Therefore, the functional coupling between the left and right ATL may play a crucial role in the interhemispheric integration of multimodal information during semantic processing. Taken together, these results partially support the hemispheric specialization model (Mesulam et al., 2014) and extend our understanding of the functional architecture in the anterior temporal semantic hub.
Brain Stimulation:
TMS 2
Language:
Language Comprehension and Semantics 1
Keywords:
Cognition
Cortex
Language
Transcranial Magnetic Stimulation (TMS)
1|2Indicates the priority used for review
Provide references using author date format
Bonni, S. (2015), 'Role of the anterior temporal lobes in semantic representations: Paradoxical results of a cTBS study', Neuropsychologia, vol. 76, pp. 163-169.
Lambon Ralph, M. A. (2017), 'The neural and computational bases of semantic cognition', Nature Reviews Neuroscience, vol. 18, no. 1, pp. 42-55.
Mesulam, M. M. (2014), 'Primary progressive aphasia and the evolving neurology of the language network', Nature Reviews Neurology, vol. 10, no. 10, pp. 554-569.
Pobric, G. (2010), 'Amodal semantic representations depend on both anterior temporal lobes: evidence from repetitive transcranial magnetic stimulation', Neuropsychologia, vol. 48, no. 5, pp. 1336-1342.
Rice, G. E. (2015), 'The roles of left versus right anterior temporal lobes in conceptual knowledge: An ALE meta-analysis of 97 functional neuroimaging studies,' Cerebral Cortex, vol. 25, no. 11, pp. 4374-4391.
Simons, J. S. (2003), 'Neural mechanisms of visual object priming: evidence for perceptual and semantic distinctions in fusiform cortex', Neuroimage, vol. 19, no. 3, pp. 613-626.