Category: Medical anthropology

Dopamine and Addiction – Part One

By Daniel Lende 

The Pathway 

In your brain you have a system that comes up from some of the oldest evolved parts of your brain to some of the most recently evolved parts.  Reptile parts to ape parts.  In brain research on addiction, it’s generally called the mesolimbic dopamine pathway or system.  All the main addictive drugs affect this system, making the mesolimbic pathway a core component in addictive behavior.  Addictive experiences—gambling, shopping, eating and sex—also impact the mesolimbic dopamine system. 

In both scientific research and the popular press, the dopamine system is often cast in the role of “bad boy,” a hard-wired brain circuit that has gotten out of control, self-indulging in an orgy of pleasure.  That neat story tells us a lot about how we cast our own morals onto the brain, selectively picking out research to provide a nice scientific sheen.  Hard-wired for hedonism, we have to work even harder at self-control.   

It strikes me as the same sort of story that addicts know how to spin so well.  So let’s be blunt.  Denial! 
Continue reading “Dopamine and Addiction – Part One”

Pets, health and our extended phenotype

There’s a fun piece in The New York Times on The Healing Power of Dogs that discusses a wide range of health effects linked to pet ownership. The article briefly discusses a range of research that has linked pet ownership to health benefits. For example:

One Japanese study found pet owners made 30 percent fewer visits to doctors. A Melbourne study of 6,000 people showed that owners of dogs and other pets had lower cholesterol, blood pressure and heart attack risk compared with people who didn’t have pets. Obviously, the better health of pet owners could be explained by a variety of factors, but many experts believe companion animals improve health at least in part by lowering stress.

This research is fascinating in its own right, especially for a person who’s only recently started to live around animals… a lot of animals (at last count, 8 horses, 1 horse expecting a foal, 2 cats, 2 dogs, innumerable wild birds, kangaroos and wallabies all wandering onto the property). I’ve noticed a huge difference in my health and mood since the change, but it’s hard to separate the effects of having Basil and Roxy (the dogs), Glitz and Glam (the cats), or the bigger monkeys around (the horses). But the research discussed also touches on two issues that I think are of particular importance to those of us interested in neuroanthropology and the biology-culture interface.

Edited version
Continue reading “Pets, health and our extended phenotype”

Mice brains on stress

Blogging on Peer-Reviewed ResearchIn February 2006, a research team at University of Texas and Tufts University published a piece in Science on how experience could modify the structures in the brain that affect the production of dopamine through brain-derived neurotrophic factor (BDNF) (abstract here). The research team used ‘social defeat’ to explore ‘the neurobiological mechanisms through which psychosocial experience alters the activity of the mesolimbic dopamine pathway’; in other words, the malleable system that can induce structural changes in the brains of mice in response to persistent patterns of social interaction.The abstract, while a little thick, suggests all sorts of intriguing possibilities:

Mice experiencing repeated aggression develop a long-lasting aversion to social contact, which can be normalized by chronic, but not acute, administration of antidepressant. Using viral-mediated, mesolimbic dopamine pathway–specific knockdown of brain-derived neurotrophic factor (BDNF), we showed that BDNF is required for the development of this experience-dependent social aversion. Gene profiling in the nucleus accumbens indicates that local knockdown of BDNF obliterates most of the effects of repeated aggression on gene expression within this circuit, with similar effects being produced by chronic treatment with antidepressant. These results establish an essential role for BDNF in mediating long-term neural and behavioral plasticity in response to aversive social experiences.  

Continue reading “Mice brains on stress”

Re-training the damaged brain

There’s a good article today, “Coaching the Comeback,” about an occupational therapist working with patients recovering from traumatic brain injuries.  From physical training, nerve stimulation and direct social interaction (e.g., maintaining eye contact, talking to them), the therapist helps her patients along.  It’s a nice summary of several themes that we’ve said in different ways about brains.  And, the therapist with her collection of skills, her education of families, her moral views on recovery also shows the importance of culture in interaction.  It’s also a nice story in itself…

Autism and Mirror Neurons

Autism has been my latest lens for learning about neuroanthropology. It started with reading claims that autism is linked to mirror neuron disfunction. Mirror neurons are currently used to explain how the brain understands the intentions and emotions of others. Researchers suggest that lack of brain activity in mirroring areas of the brain found in autistic children could explain deficits in social interaction and empathy. A related article on the site links the mirror system to the study of culture: Culture Influences Brain Cells: Brain’s Mirror Neurons Swayed By Ethnicity And Culture. A study compared reactions of subjects to both American and Nicaraguan hand gestures, measuring differences in mirror neuron activity in the brain depending on who was giving the information and whether they were a member of their own ethnic group or a different group.

“We believe these are some of the first data to show neurobiological responses to culture-specific stimuli,” said Molnar-Szakacs. “Our data show that both ethnicity and culture interact to influence activity in the brain, specifically within the mirror neuron network involved in social communication and interaction… An important conclusion from these results is that culture has a measurable influence on our brain and, as a result, our behavior. ” “We are the heirs of communal but local traditions,” said Iacoboni. “Mirror neurons are the brain cells that help us in shaping our own culture. However, the neural mechanisms of mirroring that shape our assimilation of local traditions could also reveal other cultures, as long as such cross-cultural encounters are truly possible. All in all, our research suggests that with mirror neurons our brain mirrors people, not simply actions.”

I’m still trying to wrap my mind around this article—it seems as if it would be a given that culture impacts behavior so am not sure if they discovered something new so much as found a more scientific way of measuring it. Could this possibly be a tool that would indicate whether someone would suffer from culture shock? And linking it back to the first article, would this imply that autistic people would have equal trouble picking up on social cues regardless of who they are with while for others it would depend on whether they share the same cultural background?

Loneliness and Health: Experience, Stress, and Genetics

Blogging on Peer-Reviewed ResearchFeeling lonely?  Well, that might make you sick.  The mechanism?  Well, here’s the surprise.  Patterns of genetic expression.

 Here’s the press release from Genome Biology, “People who experience chronically high levels of loneliness show gene-expression patterns that differ markedly from those of people who don’t feel lonely.”  The study’s lead author, Steven Cole, notes: “In this study, changes in immune cell gene expression were specifically linked to the subjective experience of social distance.  The differences we observed were independent of other known risk factors for inflammation, such as health status, age, weight, and medication use. The changes were even independent of the objective size of a person’s social network. What counts, at the level of gene expression, is not how many people you know, it’s how many you feel really close to over time.”    Continue reading “Loneliness and Health: Experience, Stress, and Genetics”