A genetic variant of a neuron adrenergic receptor that binds neurotransmitter noradrenaline boosts recall of emotionally intense memories.
People with a particular gene variant are better at remembering emotionally laden memories than people with the more common version of the gene, research shows. The gene, called ADRA2B, is involved in detecting brain chemicals related to emotional arousal.
The research highlighted the effect of the gene in stark terms: survivors of the 1994 Rwandan genocide were more likely to harbour persistent memories of the conflict if they had the variant version of the gene. The variant is present in 12% of people of African ancestry and in 30% of Causasians.
The researchers showed Swiss and Rwandan experimental subjects pictures with neutral, emotionally negative, and emotionally positive content. Later they had the subjects write down memories of what they saw in the pictures. The Rwandans were refugees living in Uganda who had seen some terrible things in the intertribal kill-fests in Rwanda.
While more Europeans carry the genetic variant that enhances emotionally laden memory recall the Rwandans who had that genetic variant had better recall of negative emotional events.
The researchers found that, in both groups, people carrying the ADRA2B gene variant were "substantially more likely" to remember both positive and negative pictures than people with other forms of the gene. Neutral images were recalled to the same degree by people with and without the variant.
However, Rwandans with the variant had far higher recall of negative emotional events than the Europeans who carried it – and this was unrelated to whether or not they suffered from post traumatic stress disorder.
The Rwandans might have some other genetic variants that work synergistically with ADRB2B to enhance negative memory recall.
Think about the implications. Groups differ in their average tendency to remember bad memories. Does that make some groups and some individuals more likely to hold grudges, seek revenge, and dwell on past events? Do people who better remember bad and good events try harder to set themselves up for repeats of great past events and to avoid repeats of terrible past events? Does this create different cultures in different parts of the world?
As gene testing costs go down by orders of magnitude we are going to see a flood of reports of genetic variations that influence cognitive function in a large variety of ways. The amount of human behavior ascribed to free will is going to shrink. The amount ascribed to current environmental influences will shrink as well.
|Share |||Randall Parker, 2007 July 31 05:32 PM Brain Genetics|