J Korean Med Sci.  2014 Oct;29(10):1416-1424. 10.3346/jkms.2014.29.10.1416.

Neural Substrates of Hanja (Logogram) and Hangul (Phonogram) Character Readings by Functional Magnetic Resonance Imaging

• Cho ZH
• Kim N
• Bae S
• Chi JG
• Park CW
• Ogawa S
• Kim YB

• KMID: 2129634
• DOI: http://doi.org/10.3346/jkms.2014.29.10.1416

Abstract

The two basic scripts of the Korean writing system, Hanja (the logography of the traditional Korean character) and Hangul (the more newer Korean alphabet), have been used together since the 14th century. While Hanja character has its own morphemic base, Hangul being purely phonemic without morphemic base. These two, therefore, have substantially different outcomes as a language as well as different neural responses. Based on these linguistic differences between Hanja and Hangul, we have launched two studies; first was to find differences in cortical activation when it is stimulated by Hanja and Hangul reading to support the much discussed dual-route hypothesis of logographic and phonological routes in the brain by fMRI (Experiment 1). The second objective was to evaluate how Hanja and Hangul affect comprehension, therefore, recognition memory, specifically the effects of semantic transparency and morphemic clarity on memory consolidation and then related cortical activations, using functional magnetic resonance imaging (fMRI) (Experiment 2). The first fMRI experiment indicated relatively large areas of the brain are activated by Hanja reading compared to Hangul reading. The second experiment, the recognition memory study, revealed two findings, that is there is only a small difference in recognition memory for semantic transparency, while for the morphemic clarity was much larger between Hanja and Hangul. That is the morphemic clarity has significantly more effect than semantic transparency on recognition memory when studies by fMRI in correlation with behavioral study.

Keyword

Neural Substrates of Language; Functional Magnetic Resonance Imaging; Functional Neuroimaging; Hanja and Hangul

MeSH Terms

Adult
Brain/*physiology
Brain Mapping/*methods
Brain Waves/*physiology
Female
Humans
Magnetic Resonance Imaging
Male
Neurolinguistic Programming
Recognition (Psychology)/physiology
Writing

Figure

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  Fig. 1 Neural hypothesis of the character processing of logographic and non-logographic languages. ILF, inferior longitudinal fasciculus; SLF, superior longitudinal fasciculus; IFO, inferior fronto-occipital fasciculus; SFO, superior fronto-occipital fasciculus.

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  Fig. 2 A set of Hanja and Hangul scripts used in the word recognition experiment. The left panel illustrates a Hanja set and at the right a Hangul set. Within each activation block, a word was displayed for 1 sec, resulting a total of 30 sec for 30 words given per block.

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  Fig. 3 Experimental sequence of the functional MRI recognition memory study. Names were categorized according to morphemic clarity and semantic transparency (e.g., HT-HMC, LT-HMC, HT-LMC, and LT-LMC) and presented in random order. Each block was composed of three phases: reading (2 sec), rehearsal (4 sec) and button press (2 sec).

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  Fig. 4 Experiment 1: Two sets of experimentally obtained images demonstrating the two potential pathways; the grapheme and phoneme dorsal pathways. Illustrations (A) and (B) depict Hangul>Baseline and Hanja>Baseline results. Illustration (C) is Hangul>Hanja where the angular gyrus (AG) is activated with Hangul (Hangul>Hanja), suggesting the involvement of this area for grapheme to phoneme conversion, while in (D) shows the case of Hanja>Hangul and depicts hypothetical pathway which involves both Broca's area (BA) and premotor area (PM) for Hanja reading.

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  Fig. 5 Experiment 2: Behavioral results of recognition memory. Recognition memory data of the four cases (HT-HMC, LT-HMC, HT-LMC, and LT-LMC) was collected 1 min (at the left), 10 min (at the middle), and 120 min (at the right) after the fMRI experiment. As seen, the difference between the transparency groups (HT-HMC to LT-HMC) was small, while the difference between the morphemic clarity (MC) groups (HT-HMC to HT-LMC and LT-HMC to LT-LMC) was large.

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  Fig. 6 Experiment 2: Comparison of cortical activation during Hanja vs Hangul names encoding. Results from the fMRI study are shown in three axial view images (A, B, and C), one sagittal (D) and one coronal (E), respectively. The areas most activated with Hanja are the left parahippocampal area (A, B, D, and E), posterior temporal cortex (C) and the lateral superior parietal cortex (LSPC) (D). This result is consistent with the notion that better long-term memory recognition for Hanja is supported by increased activation of the hippocampal area.

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