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:12/15/2016)... 2016  There is much more to innovative access ... engine. Continental will demonstrate the intelligence of today,s solutions ... . Through the combination of the keyless entry and ... elements, the international technology company is opening up new ... "The integration of biometric elements brings our ...
(Date:12/12/2016)... , Dec. 12, 2016  Researchers at Trinity ... for graphene by combining the material with Silly ... sensitive pressure detector able to sense pulse, blood ... small spider.  The research team,s ... be read here:  http://science.sciencemag.org/content/354/6317/1257 ...
(Date:12/8/2016)... 8, 2016  Singulex, Inc., the leader in Next ... into a license and supply agreement with Thermo Fisher ... provides Singulex access to Thermo Scientific BRAHMS PCT (Procalcitonin), ... is used to diagnose systemic bacterial infection and sepsis ... to aid in assessing the risk of critically ill ...
Breaking Biology News(10 mins):
(Date:1/19/2017)... Research and Markets ... has announced the addition of the "Implantable Biomaterials ... report to their offering. Report Highlights: ... detailed analysis on current and future market trends to identify the investment ... as the base numbers Key market trends across the ...
(Date:1/19/2017)... ... January 19, 2017 , ... ... vigilance software to leading biopharmaceutical and medical device manufacturers and regulators, is proud ... 21 CFR Part 11-compliant email client designed to provide product vigilance departments with ...
(Date:1/19/2017)... Calif. , Jan. 19, 2017  ArmaGen, ... Mathias Schmidt , Ph.D., as chief executive officer, ... of directors. Dr. Schmidt brings to ArmaGen more than ... the research and development of biotherapeutics and pharmaceuticals. ... executive with the diverse experience and skillset necessary ...
(Date:1/19/2017)... ... 18, 2017 , ... The American Medical Informatics Association (AMIA) ... Sharing Policy. Specifically, the nation’s leading informatics experts, said data sharing plans should ... AMIA recommended that NIH earmark funding for researchers to produce and execute data ...
Breaking Biology Technology: