Fear and the Human Amygdala
We know that the amygdala plays a role in fear, but there has been little definitive research on humans, because patients with bilateral damage limited to the amygdalas are hard to find. Patient SM is an exception. Although she is normal on tests of IQ, memory, language, and perception, she has trouble recognizing fear in facial expressions and shows no fear around snakes and spiders (even requesting to touch poisonous snakes in a pet store, explaining that she was overcome with curiosity). She also did not experience fear when she was almost killed during an incident of domestic violence, nor when threatened with a gun on one occasion and a knife on another in the crime-ridden neighborhood in which she lives. Her emotions are not blunted; she described feelings of excitement during a haunted house tour—while others in the party were screaming—simiilar to her experience when riding a roller coaster, which she enjoys. The lack of impairment of non-fear emotions is interesting in light of several studies suggesting a broader role for the amygdala; though a single case study has limitations, this one does suggest that, while the amygdala contributes to other emotions, it is not necessary for them. Current Biology, Vol 21, 34-38.
Sports Are Good for Your Heart; Being a Fan Isn't
During the 2006 World Soccer Cup games in Germany, cardiac emergencies tripled among men and almost doubled in women (text, p 236). But it isn't just those crazy soccer fans; American football can have the same effect. During the two weeks after the Pittsburgh Steelers staged a fourth-quarter comeback to beat the Los Angeles Rams, heart-related deaths in Los Angeles shot up 15% among men and 27% among women. Then, in 1984, the Los Angeles Raiders beat the Washington Redskins; this time, the cardiac death rate in L.A. dropped slightly, but only for women and older people. Clinical Cardiology, Vol 34, 102-107.
Roots of Criminal Behavior in Childhood
In a presentation at the annual meeting of the American Associaton for the Advancement of Science, criminologist Adrian Raine described research which indicates that inadequate development of the amygdala during childhood contributes to adult psychopathic and criminal behavior. Adult psychopaths have, on average, an 18% reduction in amygdala volume; in a remarkable study, Raine followed 1800 children who showed impaired fear conditioning at age 3 and found that 20 years later they were much more likely to become criminal offenders. (American Journal of Psychiatry, Vol 167, 56-60). Now taking an unusual direction in his research, Raine is exploring the benefits of omega-3 fatty acid as a dietary supplement, which improves brain cell growth in rats. In studies done by others, giving omega-3 to prisoners reduced serious offending in prison by 30-46%. Raine is conducting a similar study in 11 and 12-year-old children with aggression problems to see if it will help them as well. AAAS 2011 Annual Meeting News
Oxytocin Has Its Downside
Oxytocin may be the "sociability molecule", but the bonding it promotes may come at some expense. In a series of five experiments simulating social situations in which the subjects interacted with virtual in-group members and out-group members, dosing with oxytocin led to greater favorability toward the in-group and derogation of the out-group. Even the "love chemical" apparently wouldn't help with international relations or make you love somebody from the other political party. Proceedings of the National Academy of Sciences, Vol 108, 1262-1266.
The Neurophysiology of Political Orientation
Considering the extreme political divisiveness in the U.S. today, it shouldn't be surprising that some neuroscientists are joining their social science colleagues in the search for the origins of political orientation. While we usually think of political attitudes as environmentally influenced, reports of possible biological influences are turning up from a variety of methodologies. For example, attitudes were more highly correlated between identical twins than fraternal twins on every one of 28 hot-button topics (school prayer, immigration, gay rights, socialism, etc.), suggesting a genetic component. American Political Science Review, Vol 99, 153-167. In a laboratory study, subjects who reacted to loud noises with greater startle and to threatening visual images with higher skin conductance responses were more likely to endorse "socially protective" policies typically associated with a conservative viewpoint, such as favoring defense spending, capital punishment, patriotism, and the Iraq War. Science, Vol 321, 1667-1670. In a study requiring a button press in response to a cue, self-reported liberals were more successful at responding to an additional cue to withhold the response, and this action was accompanied by greater activity in the anterior cingulate cortex, known to be involved in conflict monitoring. Nature Neuroscience, Vol 10, 1246-1247. And an MRI study found that liberals were likely to have more gray matter in the anterior cingulate cortex, while conservatives had more gray matter in the amygdala. Current Biology, Vol 21, 1-4. It is difficult to interpret these results without resorting to value-laden adjectives that reflect one's own views, so I will leave that to the reader. The importance of these studies is their implication that attitudes and values are open to neurophysiological investigation. Do keep in mind that we need to avoid assigning causal explanations to the results, because the studies were correlational.