“Open up your mind and see like me”: Neurocognitive processes for reading Chinese characters

Reading processes require a dynamic integration of visual-orthographic, auditory-phonological and semantic networks. Recent neurolinguistic studies have demonstrated that reading Chinese affects interactions among the usual brain regions specialised for these functions across languages and activates additional areas. Alphabetic word recognition processes are lateralized to the left cerebral hemisphere (LH). In contrast, non-phoneme based Chinese script has long been defined as a visual-to-meaning system, and the visuo-spatial properties of nonlinear writing suggested a holistic right-hemisphere (RH) dominance in reading. Since the majority (over 80%) of modern characters is phonosemantic, it makes them representative of the Chinese language more effectively than other kinds of characters. However, only 36% of all the phonological components are perfectly regular, and representations of semantic radicals have the potential to interfere with each other or be inconsistent, which constrains their phonological and/or semantic recognition. In Chinese character recognition, a RH advantage/bias is recruited for orthographic processing/perception tasks, while a LH is responsible for phonological tasks. Orthographic activation is faster than phonological processing, and holistic processing effect in visual recognition decreases with the level of expertise. “The visual word form area” is bilateral, and the LH middle frontal gyrus – the area specialized for handling visuo-spatial analysis and remembering complex visual patterns – plays a crucial role in Chinese reading, and is larger in Chinese speakers. Reading in alphabetic scripts recruits a “phonological route” connecting Broca’s area and Wernicke’s area, whereas reading in Chinese recruits a neural circuit linking Broca’s area and the supplementary motor area, responsible for planning complex sequential movements.