"Long before it's in the papers"
January 27, 2015


Scientists ID brain region that helps you make up your mind

Nov. 24, 2013
Courtesy of the University of British Columbia
and World Science staff

One of the small­est parts of the brain is get­ting a sec­ond look af­ter new re­search sug­gests it plays a cru­cial role in de­ci­sion mak­ing.

A study pub­lished Nov. 24 in the jour­nal Na­ture Neu­ro­sci­ence says the lat­er­al ha­ben­u­la, a brain re­gion linked to de­pres­sion and avoid­ance be­hav­iors, has been mis­un­der­stood and may be key to cost-benefit de­ci­sions.

“These find­ings clar­i­fy the brain pro­cesses in­volved in the im­por­tant de­ci­sions that we make on a daily ba­sis, from choos­ing be­tween job of­fers to de­cid­ing which house or car to buy,” said re­searcher Stan Flo­resco of the Uni­vers­ity of Brit­ish Co­lum­bia. “It al­so sug­gests that the sci­en­tif­ic com­mun­ity has mis­un­der­stood the true func­tion­ing of this mys­te­ri­ous, but im­por­tant, re­gion of the brain.”

In the stu­dy, sci­en­tists trained lab rats to choose be­tween a con­sist­ent small re­ward (one food pel­let) or a po­ten­tially larg­er re­ward (four food pel­lets) that ap­peared spo­rad­ic­ally. Like hu­mans, the rats tended to choose larg­er re­wards when cost­s—in this case, the amount of time they had to wait be­fore re­ceiv­ing food—were low, and pre­ferred smaller re­wards when such risks were higher.

Pre­vi­ous stud­ies sug­gest that turn­ing off the lat­er­al ha­ben­u­la would cause rats to choose the larg­er, risk­i­er re­ward more of­ten, but that was­n’t found. In­stead, the rats pick­ed ei­ther op­tion at ran­dom, no long­er show­ing the abil­ity to choose the best op­tion.

The find­ings have im­por­tant im­plica­t­ions for de­pres­sion treat­ment, the re­search­ers said. 

“Deep brain stimula­t­ion—which is thought to in­ac­ti­vate the lat­er­al ha­ben­u­la—has been re­ported to im­prove de­pres­sive symp­toms in hu­mans,” Flo­resco said. “But our find­ings sug­gest these im­provements may not be be­cause pa­tients feel hap­pi­er. They may simply no long­er care as much about what is mak­ing them feel de­pressed.”

Flo­resco, who con­ducted the study with doc­tor­al can­di­date Col­in Stop­per, said more in­ves­ti­ga­t­ion is needed to un­der­stand the com­plete brain func­tions in­volved in cost-benefit de­ci­sion pro­cesses and re­lat­ed be­hav­ior. A great­er un­der­standing of de­ci­sion-mak­ing pro­cesses is al­so cru­cial, they say, be­cause many psy­chi­at­ric dis­or­ders, such as schiz­o­phre­nia, stim­u­lant abuse and de­pres­sion, are as­so­ci­at­ed with im­pair­ments in these pro­cesses.

The lat­er­al ha­ben­u­la is con­sid­ered one of the old­est re­gions of the brain, evolution-wise.

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One of the smallest parts of the brain is getting a second look after new research suggests it plays a crucial role in decision making. A study published Nov. 24 in the journal Nature Neuroscience said the lateral habenula, a region of the brain linked to depression and avoidance behaviors, has been misunderstood and may be key to cost-benefit decisions. “These findings clarify the brain processes involved in the important decisions that we make on a daily basis, from choosing between job offers to deciding which house or car to buy,” said researcher Stan Floresco of the University of British Columbia. “It also suggests that the scientific community has misunderstood the true functioning of this mysterious, but important, region of the brain.” In the study, scientists trained lab rats to choose between a consistent small reward (one food pellet) or a potentially larger reward (four food pellets) that appeared sporadically. Like humans, the rats tended to choose larger rewards when costs—in this case, the amount of time they had to wait before receiving food—were low, and preferred smaller rewards when such risks were higher. Previous studies suggest that turning off the lateral habenula would cause rats to choose the larger, riskier reward more often, but that wasn’t found. Instead, the rats picked either option at random, no longer showing the ability to choose the best option. The findings have important implications for depression treatment, the researchers said. “Deep brain stimulation – which is thought to inactivate the lateral habenula—has been reported to improve depressive symptoms in humans,” Floresco said. “But our findings suggest these improvements may not be because patients feel happier. They may simply no longer care as much about what is making them feel depressed.” Floresco, who conducted the study with doctoral candidate Colin Stopper, said more investigation is needed to understand the complete brain functions involved in cost-benefit decision processes and related behavior. A greater understanding of decision-making processes is also crucial, they say, because many psychiatric disorders, such as schizophrenia, stimulant abuse and depression, are associated with impairments in these processes. The lateral habenula is considered one of the oldest regions of the brain, evolution-wise.