Neural basis of hierarchical visual form processing of Japanese Kanji characters

Abstract

IntroductionWe investigated the neural processing of reading Japanese Kanji characters, which involves unique hierarchical visual processing, including the recognition of visual components specific to Kanji, such as “radicals.”MethodsWe performed functional MRI to measure brain activity in response to hierarchical visual stimuli containing (1) real Kanji characters (complete structure with semantic information), (2) pseudo Kanji characters (subcomponents without complete character structure), (3) artificial characters (character fragments), and (4) checkerboard (simple photic stimuli).ResultsAs we expected, the peaks of the activation in response to different stimulus types were aligned within the left occipitotemporal visual region along the posterior–anterior axis in order of the structural complexity of the stimuli, from fragments (3) to complete characters (1). Moreover, only the real Kanji characters produced functional connectivity between the left inferotemporal area and the language area (left inferior frontal triangularis), while pseudo Kanji characters induced connectivity between the left inferotemporal area and the bilateral cerebellum and left putamen.ConclusionsVisual processing of Japanese Kanji takes place in the left occipitotemporal cortex, with a clear hierarchy within the region such that the neural activation differentiates the elements in Kanji characters' fragments, subcomponents, and semantics, with different patterns of connectivity to remote regions among the elements.

Relationship between Motor Coordination, Cognitive Abilities, and Academic Achievement in Japanese Children with Neurodevelopmental Disorders

“…The acquisition of literacy skills varies according to writing systems (Koyama, Hansen, & Stein, 2008). While alphabetic or syllabic scripts such as the English alphabet employ phonographic systems in which a symbol is mapped onto a sound unit (Shaywitz, Shaywitz, Fletcher, & Escobar, 2015), the Japanese writing system uses not only phonographic but also logographic systems in which a symbol is mapped onto either a word or a meaningful unit, such as in Chinese (Higuchi et al, 2015;Koyama et al, 2008;Uno Wydell, Haruhara, Kaneko, & Shinya et al, 2009). In addition, logographic Japanese characters have visual forms that are different from alphabetic letters.…”

www.kanjidatabase.com: a new interactive online database for psychological and linguistic research on Japanese kanji and their compound words

“…Likewise, Tamaoka and Kiyama (2013) showed that visually complex kanji with low frequency elicited a heavier cognitive load within single kanji processing. Because visual complexity is an important factor when recognizing kanji (see also : Higuchi, Moriguchi, Murakami, Katsunuma, Mishima, & Uno, 2016), stroke counts must be controlled for conditions within experiments involving kanji.…”