前頭葉と頭頂葉を連絡する連合線維束である上縦束 Iを屍体脳において解剖学的に同定することに成功した。また、上縦束 Iが実際のヒト脳において作業記憶に関わることや脳腫瘍による機能再構築の可能性を確認しえた。
これらの知見を踏まえ、従来ではnon eloquent areaあるいはsilent areaと呼称され、脳腫瘍摘出術においては術後の合併症に関してあまり検討されていなかった右前頭葉に位置する脳腫瘍摘出術における作業記憶の障害を解析した。結果、右前頭葉腫瘍において空間性作業記憶が障害されやすいこと、また覚醒下手術により脳機能の再構築を確認しつつ、その予防が可能となることを証明した。
The existence of the association fiber tract between the superior frontal gyrus and parietal lobe was validated for the first time using gross anatomical fiber dissection in post-mortem human brains. This tract corresponds to the superior longitudinal fasciculus I (SLF I) depicted by DTI-tractography in living human brain. The causal role of the supplementary motor area, one of terminations of the SLF I, in verbal working memory and functional reorganization with brain tumor were supported directly with functional mapping during awake surgery for the first time.
Spatial working memory deficits may persist in patient who undergo resection of the tumor located in the right prefrontal brain parenchyma, which has been regarded as a silent area. Injury to the SLF I could play a causal role in the deficits. Awake surgery would be useful to detect the spatial working memory network and its reorganization during tumor exploration located in the right prefrontal region.