The Ash Twins Blog

Immigrant Elephants Stick Together:

[S]cientists in California got to wondering how elephants, which are highly social creatures, handle making themselves at home when they get to a new neighborhood.

It turns out they form enclaves that are the elephant equivalent of a ghetto, where the new pachyderms in the park associate with one another and with other immigrant elephants. Then, once the transplants have been around for a year, they get friendly with the locals.

The Amnesia Gene:

In healthy subjects events that are emotionally charged—and it doesn’t matter if the emotions are positive or traumatic—tend to be much better remembered than emotionally neutral events. This psychological tendency comes with a glaring exception, however: in some individuals, extremely stressful or traumatic events can induce amnesia, so that they lose the ability to remember what happened. In some instances this loss can lead to the erasure of a vast amount of memory, so that people even forget basic facts about their identity, such as where they live or what their name is.

Amnesia induced by negative emotions is considered a psychological defense mechanism that protects the organism from the consequences of extreme trauma and catastrophic fear…

This new study, by the neuroscientist Bryan Strange and colleagues at the Wellcome Trust Center for Neuroimaging in London, examined the role of serotonin transporter genes (5-HTTLPR) in the development of emotion induced amnesia. (Such transporter genes influence the availability of the serotonin transporter, a key regulator of serotonin transmission between brain cells.) Serotonin transporter genes have been extensively investigated for their role in stress induced psychiatric disorders, such as post-traumatic stress disorder (PTSD). In recent years, scientists have found that subjects with 5-HTTLPR short variant genotype are more likely to get depressed after stressful life events and are also at increased risk for PTSD. Furthermore, this short variant genotype is associated with anxiety related traits that have also been implicated in the susceptibility to anxiety and depression.

In the experiment, the authors demonstrate that subjects with the 5-HTTLPR short variant genotype had difficulty remembering a series of neutral words (harvest, kid, thought, and so on) that were presented prior to the presentation of emotionally charged words (such as rape, abortion, tumor), at least when compared with subjects who have the 5-HTTLPR long variant genotype. It’s important to note, however, that these genes did not affect memory for emotional words. Thus, the data suggest that the contribution of 5-HTTLPR to disturbances in emotional memory may be specific to emotion-induced retrograde amnesia, which occurs when subjects are unable to remember what happened before the traumatic event. In contrast, other serotonergic genes, or genes linked with other neurotransmitter systems, might influence memory for emotional words…

At a modest level of activation, the amygdala seems to augment the function of the hippocampus, a brain region involved in the formation of long-term memory. When the amygdala is greatly excited, as during traumatic events, however, hippocampal function is inhibited and memory impairment is triggered.  Other studies have demonstrated that subjects with the 5-HTTLPR short variant genotype have enhanced amygdala reactivity to emotional stimuli. The hyperactive amygdala in these individuals may, at least in part, explain why they are more susceptible to emotion-induced memory loss.

E-prescribing leads to more generics:

Massachusetts physicians who used an e-prescribing system increased their use of generics by 6 percent—from 55 percent to 61 percent of all prescriptions they filled—compared with when they wrote them out by hand the old-fashioned way, according to a study in this week’s Archives of Internal Medicine.