Depar t ment of Cel l Phy s i ol ogy Di v i s i on of Aer os pace Medi ci ne
Satoshi Kurihara,Professor and Director Masamichi Sudoh,Associate Professor Hiroko Toshima,Assistant Professor
Gener al Summar y
Our ma i n r e s e a r c h i nt e r e s t s a r e g r a v i t a t i ona l phy s i ol og y ,a e r os pa c e me di c i ne ,a nd s t r e s s r e a c t i on.
Res ear ch Act i v i t i es
Op t o ki ne t i c ny s t ag mus and af t e r ny s t ag mus dur i ng t he 7 day s ʼb e d r e s t
We a na l y z e d t he t i me - de pe nda nt c ha ng e of opt oki ne t i c ny s t a g mus( OKN)a nd opt o- ki ne t i c a f t e r ny s t a g mus( OKAN) ,dur i ng a 7 - da y e x pe r i me nt of 6 - de g r e e he a d- down be d r e s t i n whi c h v a r i ous bi ome di c a l v a r i a bl e s we r e me a s ur e d dur i ng l ong - t e r m a l t e r a t i on of t he di r e c t i on of g r a v i t y . At t he Ts ukuba Spa c e Ce nt e r of t he Na t i ona l Spa c e De v e l op- me nt Ag e nc y of J a pa n( now t he J a pa n Ae r os pa c e Ex pl or a t i on Ag e nc y ) ,6 he a l t hy me n we r e s t udi e d. We c ol l e c t e d OKN a nd OKAN da t a( bot h r i g ht a nd l e f t di r e c t i ons )6 t i me s :i n t he s i t t i ng pos i t i on on t he da y pr e c e di ng be d r e s t ,i n t he s upi ne pos i t i on on t he 1 s t ,3 r d,a nd 5 t h da y s of be d r e s t ,a nd i n t he s i t t i ng pos i t i on a g a i n i mme di a t e l y a f t e r be d r e s t on t he 7 t h da y a nd on t he da y f ol l owi ng be d r e s t . The i nc r e a s e i n OKN ( OKN s l ow- pha s e - v e l oc i t y / s t i mul us s pe e d)t e nde d t o de c r e a s e on t he 1 s t da y of be d r e s t ,ha d r e c ov e r e d g r a dua l l y by t he 5 t h da y ,a nd a f t e r be d r e s t e x c e e de d t he l e v e l be f or e be d r e s t . The g a i n wa s hi g he r whe n t he OKN s l ow pha s e wa s di r e c t e d r i g ht wa r d t ha n whe n i t wa s di r e c t e d l e f t wa r d t hr oug hout t he 6 t i me s . The a ppe a r a nc e r a t e of t he OKAN f i r s t - pha s e de c r e a s e d dur i ng be d r e s t a nd r e c ov e r e d a f t e r be d r e s t t o t he l e v e l be f or e be d r e s t . I n c ont r a s t ,t he a ppe a r a nc e r a t e of t he OKAN s e c ond- pha s e i nc r e a s e d on t he 1 s t da y of be d r e s t ,a nd t he i nc r e a s e wa s ma i nt a i ne d t he r e a f t e r ,s ug g e s t i ng t ha t a n OKAN g e ne r a t or mi g ht di f f e r be t we e n t he f i r s t a nd s e c ond pha s e s . The ma x i mum s l ow- pha s e v e l oc i t y of OKAN de c r e a s e d ma r ke dl y on t he 1 s t da y , but t he r e c ov e r y wa s unc l e a r dur i ng a nd a f t e r be d r e s t . No c l e a r t e nde nc y wa s f ound i n t he t i me - de pe nde nc y of t he OKAN dur a t i on.
We s pe c ul a t e t ha t t he s e t i me - de pe nde nt c ha ng e s obs e r v e d i n t he opt oki ne t i c ⎜ oc ul omot or s y s t e m a r e ba s e d ma i nl y on t he a l t e r na t i on i n g r a v i t y i nf or ma t i on t o t he ot ol i t h or g a n a nd t ha t be d r e s t i s us e f ul f or s t udy i ng l ong - t e r m a da pt a t i on i n t he v e s t i bul a r s y s t e m unde r mi c r og r a v i t y .
St r e s s
1 . The pr oc e s s i ng of s t r e s s i n t he huma n br a i n a nd t he s t r e s s - r e l a t e d di s or de r s We pe r f or me d ne a r - i nf r a r e d opt i c a l t opog r a phy a nd r e c or de d e v e nt - r e l a t e d P3 0 0 pot e n- t i a l s whe n s ubj e c t s f e l t s t r e s s . We t he n i nv e s t i g a t e d i nf or ma t i on pr oc e s s i ng i n t he br a i ns of huma n be i ng s .
201 Research Activities 2007 The Jikei University School of Medicine
2 . Br a i n i ma g i ng i n kar ut a pl a y e r s by me a ns of ne a r - i nf r a r e d opt i c a l t opog r a phy a nd me a s ur e me nt of e v e nt - r e l a t e d pot e nt i a l s
We r e c or de d t he e v e nt - r e l a t e d P3 0 0 pot e nt i a l s a nd pe r f or me d ne a r - i nf r a r e d opt i c a l t opog r a phy of kar ut a pl a y e r s dur i ng a n a udi t or y oddba l l t a s k t ha t i s s i mi l a r t o kar ut a , a nd we i nv e s t i g a t e d i nf or ma t i on pr oc e s s i ng i n t he br a i ns of kar ut a pl a y e r s .
3 . St r e s s f a c i l i t a t e s s pont a ne ous pl a t e l e t a g g r e g a t i on i n he a l t hy y oung pe r s ons Af t e r a r i t hme t i c s t r e s s l oa di ng ,t he c onc e nt r a t i on of nor e pi ne phr i ne wa s s i g ni f i c a nt l y i nc r e a s e d. Spont a ne ous pl a t e l e t a g g r e g a t i on wa s a l s o a c c e l e r a t e d by a r i t hme t i c s t r e s s , whi c h wa s c or r e l a t e d wi t h t he i nc r e a s e i n nor e pi ne phr i ne c onc e nt r a t i on. St r e s s r e l e a s e s nor e pi ne phr i ne f r om s y mpa t he t i c ne r v e t e r mi na l s ,a nd t he bi ndi ng of nor e pi ne phr i ne t o a l pha - 2 a dr e nor e c e pt or s of pl a t e l e t s t r i g g e r s pl a t e l e t a g g r e g a t i on.
Publications
Nomura Y,Igarashi M ,Sudoh M,Hida K, Sekiguchi C,Ishii M,Matsusima M,Kaneita Y, Ikeda M (Nihon Univ).Optokinetic nystagmus
and afternystagmus during the 7days bed rest study.(in Japanese).J J Aerospace Environ Med 2008;45:3‑9.
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