Coccia et al., 2004

Foxit PDF readerでいい感じに書き込みしながら読んでたら最後の最後に保存して終了するのを忘れた。すげーブルーだ。

Coccia et al., 2004 Semantic memory is an amodal, dynamic system: Evidence from the interaction of naming and object use in semantic dementia.

意味認知症(semantic dementia: SD)のlongitudinal study.

意味認知症についておさらいすると物事の意味全般が失われていく障害で、左右大脳皮質の前側頭葉(anterior temporal lobe)の萎縮によってこれが起こるのではないかと近年主張されている。治療法はできていない。



This research made scruitinies of two SD patients over 4 years.

Patient E. and D. both presented hypoperfusion (還流低下) in left lateral temporal cortex.

The authors used general semantics and object-use/naming test batteries.
Both batteries had item consistency. Same 42 items from animate and manmade cotegories were involved in all general semantics tests. Same 20 manmade objects were used for all object-use/naming tests.

1. General semantics and object-use ability goes down in parallel.

2. Object-use was relatively preserved compared to naming them.

3. Naming object was improved during demonstrating use of it (actual using or pantomiming).

Result 1 supports unitary semantic system hypothesis.

Result 2 might seem to be indicating separate semantic systems for verbal and non-verbal processes.This can be, however, explained within unitary semantic system hypothesis taking into account at least two differences between naming and using objects.
(ⅰ)Names are more abstractly connected to meaning, while object-structure and use are rather systematically connected.
(ⅱ)Object-use can be supported by both ventral and dorsal visual-to-action streams
(Milner and Goodale, 1995).

Result 3 would be the striking result in this research. it can be explained by the theories that assume semantic representations are dynamic.
Semantic activation can be facilitated by one or more modality-specific aspect of it
Presenting contextual information actually makes naming of items more accurate (Lambon Ralph and Howard, 2000). Extending this notion, all aspect of correct object use can facilitate the amodal representation of the object.

memo for (ⅰ)
Thus naming is much more vulnerable to the degradation of amodal semantic hub. Some clinical studies already highlighted this explanations for poor verbal performances in SD (Caramazza et al., 1990; Rapp et al., 1993). PDP researches also demonstrated that semantic activation i smore accurate for systematic than arbitrary mappings (Lambon Ralph & Howard, 2000; Plaut, 1999; Rogers et al., ).

Lambon Ralph and Howard, 2000 Gogi aphasia or semantic dementia? Evidence from concept definitions by patients with semantic dementia. Brain and Lanbuage, 7-, 309-335.
Patient IWとConputational modelの論文

Lembon Ralph et al., 1999 Is a picture worth a thousand words? Simulating and assessing poor verbal comprehension in a case of progressive fluent aphasia. Cog. NeuroPsy. 17, 437-466.
Picture presentationでの命名のほうが言語的記述からの命名よりも簡単といってる研究(のはず)

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