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Fruit flies found to “think” before acting

May 22, 2014
Courtesy of University of Oxford
and World Science staff

Fruit flies “think” be­fore they act, a study sug­gests. 

In ex­pe­ri­ments in which the in­sects had to tell apart ev­er more si­m­i­lar con­centra­t­ions of an odor, re­search­ers found that the flies don’t act in­stinc­tively or im­pul­sive­ly, but seem to ac­cu­mu­late in­forma­t­ion be­fore act­ing. That has been con­sid­ered a sign of high­er in­tel­li­gence.

“Fruit flies have a sur­pris­ing men­tal ca­pa­city,” said Uni­vers­ity of Ox­ford neu­ro­sci­ent­ist Gero Miesen­böck, in whose lab­o­r­a­to­ry the new re­search was per­formed. “Free­dom of ac­tion from au­to­mat­ic im­pulses is con­sid­ered a hall­mark of cog­ni­tion or in­tel­li­gence.” 

The re­search­ers al­so found that a gene called FoxP, ac­tive in a small set of brain cells, facili­tates the choos­ing. 

“Be­fore a de­ci­sion is made, brain cir­cuits col­lect in­forma­t­ion like a buck­et col­lects wa­ter. Once the ac­cu­mu­lated in­forma­t­ion has ris­en to a cer­tain lev­el, the de­ci­sion is trig­gered. When FoxP is de­fec­tive, ei­ther the flow of in­forma­t­ion in­to the buck­et is re­duced to a trick­le, or the buck­et has sprung a leak,” said Ox­ford’s Shamik Das­Gupta, the lead au­thor of the stu­dy.

The re­search­ers watched Dro­soph­i­la fruit flies choose be­tween two con­centra­t­ions of an odor pre­sented to them from op­po­site ends of a nar­row cham­ber, hav­ing been trained to avoid one con­centra­t­ion. When the con­centra­t­ions were very dif­fer­ent and easy to tell apart, the flies usu­ally de­cid­ed quickly and went to the cor­rect end of the cham­ber. When the con­centra­t­ions were very close and hard to tell apart, the flies took much long­er to de­cide and made more mis­takes.

The re­search­ers found that math­e­mat­i­cal mod­els de­vel­oped to de­scribe the mech­a­nisms of de­ci­sion mak­ing in hu­mans and pri­ma­tes al­so matched the fruit fly be­hav­ior. And flies with muta­t­ions in the FoxP gene were par­tic­u­larly in­de­ci­sive. The re­search­ers tracked down the gene’s ac­ti­vity to a small clus­ter of around 200 neu­rons, or brain cells, out of the 200,000 in the fruit fly brain, im­pli­cat­ing these neu­rons in the evidence-gathering pro­cess.

The team re­ports its find­ings in the jour­nal Sci­ence

Fruit flies have one FoxP gene, while hu­mans have four re­lat­ed FoxP genes. Hu­man FoxP1 and FoxP2 have pre­vi­ously been as­so­ci­at­ed with lan­guage and cog­ni­tive de­vel­op­ment. The genes have al­so been linked to the abil­ity to learn fi­ne move­ment se­quences, such as play­ing the pia­no.

“We don’t know why this gene pops up in such di­verse men­tal pro­cesses as lan­guage, de­ci­sion-mak­ing and mo­tor learn­ing,” said Miesen­böck. But “one fea­ture com­mon to all of these pro­cesses is that they un­fold over time.”

“FoxP is not a ‘lan­guage gene,’ a ‘de­ci­sion-mak­ing gene,’” or any more spe­cif­ic cat­e­go­ry, he added. “What FoxP does give us is a tool to un­der­stand the brain cir­cuits in­volved in these pro­cesses. It has al­ready led us to a site in the brain that is im­por­tant in de­ci­sion-mak­ing.”


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Fruit flies “think” before they act, a study suggests. In experiments in which the insects had to tell apart ever more similar concentrations of an odor, researchers found that the flies don’t act instinctively or impulsively, but seem to accumulate information before acting. That has been considered a sign of higher intelligence. “Fruit flies have a surprising mental capacity,” said University of Oxford neuroscientist Gero Miesenböck, in whose laboratory the new research was performed. “Freedom of action from automatic impulses is considered a hallmark of cognition or intelligence.” The researchers also found that a gene called FoxP, active in a small set of around 200 brain cells, is involved in the decision-making. “Before a decision is made, brain circuits collect information like a bucket collects water. Once the accumulated information has risen to a certain level, the decision is triggered. When FoxP is defective, either the flow of information into the bucket is reduced to a trickle, or the bucket has sprung a leak,” said Oxford’s Shamik DasGupta, the lead author of the study. The researchers watched Drosophila fruit flies choose between two concentrations of an odor presented to them from opposite ends of a narrow chamber, having been trained to avoid one concentration. When the concentrations were very different and easy to tell apart, the flies usually decided quickly and went to the correct end of the chamber. When the concentrations were very close and hard to tell apart, the flies took much longer to decide and made more mistakes. The researchers found that mathematical models developed to describe the mechanisms of decision making in humans and primates also matched the fruit fly behavior. And flies with mutations in the FoxP gene were particularly indecisive. The researchers tracked down the gene’s activity to a small cluster of around 200 neurons, or brain cells, out of the 200,000 in the fruit fly brain, implicating these neurons in the evidence-gathering process. The team reports its findings in the journal Science. Fruit flies have one FoxP gene, while humans have four related FoxP genes. Human FoxP1 and FoxP2 have previously been associated with language and cognitive development. The genes have also been linked to the ability to learn fine movement sequences, such as playing the piano. “We don’t know why this gene pops up in such diverse mental processes as language, decision-making and motor learning,” said Miesenböck. But “one feature common to all of these processes is that they unfold over time.” “FoxP is not a ‘language gene,’ a ‘decision-making gene,’” or any more specific category, he added. “What FoxP does give us is a tool to understand the brain circuits involved in these processes. It has already led us to a site in the brain that is important in decision-making.”