December 16, 2008
Older Brains Process Negative Pictures Differently

When viewing pictures of negative events older folks did more thinking and less emotional reacting to negative images and they formed fewer memories about negative images.

It turns out there's a scientific reason why older people tend to see the past through rose-coloured glasses.

So then older people share something in common with Eric Idle nailed to a cross singing "Always look on the bright side of life".

A University of Alberta medical researcher, in collaboration with colleagues at Duke University, identified brain activity that causes older adults to remember fewer negative events than their younger counterparts.

"Seniors actually use their brain differently than younger people when it comes to storing memory, especially if that memory is a negative one," said study author Dr. Florin Dolcos, an assistant professor of psychiatry and neuroscience in the Faculty of Medicine & Dentistry.

The study, published online in December in the U.S.-based journal Psychological Science, found age-related changes in brain activity when participants with an average age of 70 where shown standardized images that depicted either neutral or strongly negative events.

The research team asked older and younger participants to rate the emotional content of these pictures along a pleasantness scale, while their brain activity was monitored with a functional magnetic resonance imaging (fMRI) machine, a high-tech device that uses a large magnet to take pictures inside the brain. Thirty minutes later, participants were unexpectedly asked to recall these images. The older participants remembered fewer negative images than the younger participants.

Brain scans showed that although both groups had similar activity levels in the emotional centres of the brain, they differed when it came to how these centres interacted with the rest of the brain.

The older participants had reduced interactions between the amygdala, a brain region that detects emotions, and the hippocampus, a brain region involved in learning and memory, when shown negative images. Scans also showed that older participants had increased interactions between the amygdala and the dorsolateral frontal cortex, a brain region involved in higher thinking processes, like controlling emotions. The older participants were using thinking rather than feeling processes to store these emotional memories.

The greater emotional reaction of younger people probably tends to elicit a bigger behavioral response from younger people. What I wonder: Is the change in the older response due to physical aging or accumulation of learning from experience?

Does the different system of memory encoding occur because the older system is worn out?

Young adults used more of the brain regions typically involved in emotion and recalling memories.

"The younger adults were able to recall more of the negative photos," said Roberto Cabeza, Ph.D., senior author and Duke professor in the Center for Cognitive Neuroscience. If the older adults are using more thinking than feeling, "that may be one reason why older adults showed a reduction in memory for pictures with a more negative emotional content."

"It wasn't surprising that older people showed a reduction in memory for negative pictures, but it was surprising that the older subjects were using a different system to help them to better encode those pictures they could remember," said lead author Peggy St. Jacques, a graduate student in the Cabeza laboratory.

One of my questions about future rejuvenation therapies: How much will rejuvenated minds become youthful in their thought patterns and behavior? Some aspects of youthful function will be restored by rejuvenation. But other aspects might not. We might even need to choose among various youthful patterns of thinking to restore. Restore a stronger tendency to form negative memories? Restore more intense reactions of anger, sadness, or other emotions?

Long time readers know I've argued that the brain is most problematic for rejuvenation because it must be repaired rather than replaced. It is very complex. Repair will be extremely difficult. But the difficulty of brain rejuvenation doesn't just flow from the complexity, size, and need to repair billions of individual cells. We also face the difficult question of deciding which sorts of age-related brain changes to reverse and which to leave in their changed older patterns of functioning.

Share |      Randall Parker, 2008 December 16 10:34 PM  Brain Aging

momochan said at December 17, 2008 1:42 PM:

Could it be that different memory strategies for young versus old may have been selected for? Emotion is clearly involved in burning memories onto the brain, which may help the young who need to attend to salience. The old, however, can draw upon a wealth of memories and experience in utilizing them, so a less emotional approach may be justified.

Randall Parker said at December 17, 2008 7:15 PM:


Yes, maybe some of the changes in old brains have been selected for. Grandmothers boost the number of grandchildren they get when grannie lives longer. So that means selective pressures can act based on how they make granny behave. That means it is not farfetched that selective pressures caused mutations that alter cognitive function in old age to change behavior.

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