Sci­en­tists pub­lish method to block fear­ful mem­o­ries

China Daily (Hong Kong) - - CHINA - By WANG HONGYI in Shang­hai wanghongyi@ chi­

Chi­nese sci­en­tists say they’ve found a new way to ef­fec­tively in­hibit a per­son’s fear memory aris­ing from trau­matic events such as do­mes­tic vi­o­lence, sex­ual as­sault and war.

An­i­mal test­ing led by Yu Yongchun, a re­searcher at Fu­dan Univer­sity’s In­sti­tutes of Brain Sci­ence in Shang­hai, found that fear can be ef­fec­tively re­moved by trans­plant­ing a spe­cial kind of nerve cell into the brains of an adult mouse.

The find­ings are ex­pected to shine new light on the treat­ment of se­vere men­tal con­di­tions, such as post-trau­matic stress dis­or­der, or PTSD. The re­sults were pub­lished on­line on Fri­day by Neu­ron, an in­flu­en­tial journal in the field of neu­ro­science.

Yu’s team noted that there are two types of neu­rons in the brain — ex­ci­tory and in­hibitory. Bal­anced ac­tiv­ity be­tween the two types of neu­rons al­lows the brain to func­tion nor­mally.

The part of the brain’s nu­cleus known as the amyg­dala is a key area for pro­cess­ing fear in­for­ma­tion and de­vel­op­ing fear memory.

“When re­ceiv­ing strong stim­u­lus, the amyg­dala will be in a highly ex­cited state, lead­ing to a new ex­ci­tory/ in­hibitory bal­ance that may con­trib­ute to fear memory,” Yu said.

Based on its analy­ses, Yu’s team pro­posed that trans­plant­ing im­ma­ture in­hibitory neu­rons into a highly ex­cited ma­ture amyg­dala could not only in­hibit the overex­cite­ment of the amyg­dala, but also make the adult

When re­ceiv­ing strong stim­u­lus, the amyg­dala will be in a highly ex­cited state.” Yu Yongchun, re­searcher at Fu­dan Univer­sity’s In­sti­tutes of Brain Sci­ence

amyg­dala seem younger, thereby sup­press­ing the re­call of fear memory.

The hy­poth­e­sis has been borne out in a se­ries of ex­per­i­ments on mice, Yu said, but there’s a long way to go be­fore the treat­ment can be tried on hu­mans in a clin­i­cal set­ting.

Yet the re­search is ex­pected to help ex­plore new strate­gies for treat­ing PTSD, which is caused by in­deli­ble and trau­matic mem­o­ries like do­mes­tic vi­o­lence, traf­fic ac­ci­dents, hairy spi­ders, a nasty breakup or mil­i­tary com­bat.

Pa­tients with PTSD of­ten ex­hibit anx­i­ety, de­pres­sion, chronic pain, car­dio­vas­cu­lar dis­ease, meta­bolic dis­or­ders, drug abuse and al­co­hol ad­dic­tion. Statis­tics show that about 80 per­cent of adults have ex­pe­ri­enced a trau­matic event at least once in their life­times, while 5 to 10 per­cent have ex­pe­ri­enced se­vere psy­cho­log­i­cal trauma that can be di­ag­nosed as PTSD.

So far, the treat­ment of PTSD in­volves a com­bi­na­tion of psy­chol­ogy and med­i­ca­tion. How­ever, men­tal symp­toms of­ten re­turn af­ter the treat­ment is stopped.

Wu Yi­wei con­trib­uted to this story.

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