Pavlov's rats? Rodents trained to link rewards to visual cues

January 23, 2013
Source: Johns Hopkins Medicine
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In experiments on rats outfitted with tiny goggles, scientists say they have learned that the brain's initial vision processing center not only relays visual stimuli, but also can "learn" time intervals and create specifically timed expectations of future rewards. The research, by a team at the Johns Hopkins University School of Medicine and the Massachusetts Institute of Technology, sheds new light on learning and memory-making, the investigators say, and could help explain why people with Alzheimer's disease have trouble remembering recent events. 

Results of the study, in the journal Neuron, suggest that connections within nerve cell networks in the vision-processing center can be strengthened by the neurochemical acetylcholine (ACh), which the brain is thought to secrete after a reward is received. Only nerve cell networks recently stimulated by a flash of light delivered through the goggles are affected by ACh, which in turn allows those nerve networks to associate the visual cue with the reward. Because brain structures are highly conserved in mammals, the findings likely have parallels in humans, they say.

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