Navigation Links
Reward linked to image is enough to activate brain's visual cortex
Date:3/21/2013

Once rhesus monkeys learn to associate a picture with a reward, the reward by itself becomes enough to alter the activity in the monkeys' visual cortex. This finding was made by neurophysiologists Wim Vanduffel and John Arsenault (KU Leuven and Harvard Medical School) and American colleagues using functional brain scans and was published recently in the leading journal Neuron.

Our visual perception is not determined solely by retinal activity. Other factors also influence the processing of visual signals in the brain. "Selective attention is one such factor," says Professor Wim Vanduffel. "The more attention you pay to a stimulus, the better your visual perception is and the more effective your visual cortex is at processing that stimulus. Another factor is the reward value of a stimulus: when a visual signal becomes associated with a reward, it affects our processing of that visual signal. In this study, we wanted to investigate how a reward influences activity in the visual cortex."

To do this, the researchers used a variant of Pavlov's well-known conditioning experiment: "Think of Pavlov giving a dog a treat after ringing a bell. The bell is the stimulus and the food is the reward. Eventually the dogs learned to associate the bell with the food and salivated at the sound of the bell alone. Essentially, Pavlov removed the reward but kept the stimulus. In this study, we removed the stimulus but kept the reward."

In the study, the rhesus monkeys first encountered images projected on a screen followed by a juice reward (classical conditioning). Later, the monkeys received juice rewards while viewing a blank screen. fMRI brain scans taken during this experiment showed that the visual cortex of the monkeys was activated by being rewarded in the absence of any image.

Importantly, these activations were not spread throughout the whole visual system but were instead confined to the specific brain regions responsible for processing the exact stimulus used earlier during conditioning. This result shows that information about rewards is being sent to the visual cortex to indicate which stimuli have been associated with rewards.

Equally surprising, these reward-only trials were found to strengthen the cue-reward associations. This is more or less the equivalent to giving Pavlov's dog an extra treat after a conditioning session and noticing the next day that he salivates twice as much as before. More generally, this result suggests that rewards can be associated with stimuli over longer time scales than previously thought.

Why does the visual cortex react selectively in the absence of a visual stimulus on the retina? One potential explanation is dopamine. "Dopamine is a signalling chemical (neurotransmitter) in nerve cells and plays an important role in processing rewards, motivation, and motor functions. Dopamine's role in reward signalling is the reason some Parkinson's patients fall into gambling addiction after taking dopamine-increasing drugs. Aware of dopamine's role in reward, we re-ran our experiments after giving the monkeys a small dose of a drug that blocks dopamine signalling. We found that the activations in the visual cortex were reduced by the dopamine blocker. What's likely happening here is that a reward signal is being sent to the visual cortex via dopamine," says Professor Vanduffel.

The study used fMRI (functional Magnetic Resonance Imaging) scans to visualise brain activity. fMRI scans map functional activity in the brain by detecting changes in blood flow. The oxygen content and the amount of blood in a given brain area vary according to the brain activity associated with a given task. In this way, task-specific activity can be tracked.


'/>"/>

Contact: Wim Vanduffel
wim.vanduffel@med.kuleuven.be
32-016-330-666
KU Leuven
Source:Eurekalert

Related biology news :

1. Pavlovs rats? Rodents trained to link rewards to visual cues
2. Stress-resilience/susceptibility traced to neurons in reward circuit
3. Prenatal testosterone levels influence later response to reward
4. NIH New Innovator Award helps Sanford-Burnham scientist pursue high-risk, high-reward project
5. Rewarding work for butterflies
6. Risks and rewards of quantifying natures ecosystem services
7. Kids consumption of sugared beverages linked to higher caloric intake of food
8. Prenatal exposure to pesticide DDT linked to adult high blood pressure
9. 2 new genes linked to amyotrophic lateral sclerosis and related disorders
10. MBL scientists find genes linked to human neurological disorders in sea lamprey genome
11. Signaling pathway linked to fetal alcohol risk
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/20/2016)... 20, 2016  Synaptics Incorporated (NASDAQ: SYNA ... today announced sampling of S1423, its newest ClearPad ... small screen applications including smartwatches, fitness trackers, and ... and rectangular shapes, as well as thick and ... moisture on screen, while wearing gloves, and supports ...
(Date:1/15/2016)... JUAN, Puerto Rico , Jan. 15, 2016 /PRNewswire/ ... companies big and small to find new ways to ... driven culture. iOS and Android ... device based on biometrics, transforming it into a hardware ... request that users swipe their fingerprint on their KodeKey ...
(Date:1/13/2016)... 13, 2016 ... of the  "India Biometrics Authentication & ... (2015-2020)"  report to their offering.  ... announced the addition of the  "India ... Estimation & Forecast (2015-2020)"  report ...
Breaking Biology News(10 mins):
(Date:2/10/2016)... , Feb. 10, 2016  The Maryland House ... , has announced that University of Maryland School of ... MBA and University of Maryland Medical System President and ... the "Speaker,s Medallion," the highest honor given to the ... Delegates. Dean Reece and Mr. Chrencik ...
(Date:2/10/2016)...  Allergan plc (NYSE: AGN ) a leading ... , Allergan,s CEO and President, will be featured as ... the RBC Capital Markets Healthcare Conference on Tuesday, February ... York Palace Hotel in New York, NY ... can be accessed on Allergan,s Investor Relations web site ...
(Date:2/10/2016)... NC (PRWEB) , ... February 10, 2016 , ... ... anticipated expansion to their comprehensive training and support program, Sonalinkā„¢ remote monitoring. The ... HIFU procedures performed on Friday, February 5th, connecting Dr. Samuel Peretsman to a ...
(Date:2/10/2016)... ... February 09, 2016 , ... Creation Technologies, ... of the Highest Overall Customer Rating Award from Circuits Assembly , today announced ... across the USA, Canada, Mexico and China. , The EMS provider, known in ...
Breaking Biology Technology: