Category: Human variation

Sleep, Eat, Sex – Orexin Has Something to Say

Blogging on Peer-Reviewed ResearchOrexin is a neuropeptide which is released by the posterior lateral hypothalamus, and is linked to wakefulness and sleep, appetite regulation, and the motivation of sexual and addictive behaviors.  One apt way to think about it is as a hormone in the brain, combining some of the popularly conceived effects of adrenaline and testosterone into one. 

(Don’t get too excited now!  I am just trying to give you a way to think about it, that orexin works to promote arousal and response…)

I am writing a post on the links of orexin to appetitive behavior, particularly addiction, but I’ve generated a lot of material.  So I am going to give you this one first, which summarizes aspects of orexin (also known as hypocretin) and neurological function with respect to sleep, appetite and sex. 
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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! 
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Auditory neurons learning to hear

The Biotechnology and Biological Sciences Research Council’s recent business report (January 2008) had an interesting research report on auditory neurons and the perception of complex sounds. (Science Daily has a short report on the longer piece available here). (The BBSRC is the UK’s principal funder of basic biological research.)

As the BBSRC piece discusses, sound perception is extremely difficult because similar objects often make quite different sounds, and the medium (typically air) through which we hear does not allow for the spatialization or easy decomposition that, say, light allows in vision. The Oxford-based research team is using neural imaging to try to figure out how the brain makes sense of sound, and one thing that they’re finding is that background noise appears to be extremely important to sound processing. The auditory cortex does not simply respond to isolated qualities of specific sounds but to variations in the statistical properties of the entire sound scape. As the article reports: ‘Cortical neurons appear to anticipate this particular level of statistical regularity, and respond best to sounds that vary in pitch and intensity according to this natural rate of ebb and flow, which is found in many natural scenes and most musical compositions.’

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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
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Language and Color

Blogging on Peer-Reviewed ResearchEdge asked prominent scholars a great question, What Have You Changed Your Mind About?

 Lera Boroditsky, in Cognitive Psychology at Stanford, called her post, “Do our languages shape the nuts and bolts of perception, the very way we see the world?”  (And just for the record, I got turned onto this great collection at Edge by kerim’s post, Rethinking Language and Culture, over at Savage Minds, so please check what kerim has to say!)

 Here’s the opening Boroditsky provides us:

 “I used to think that languages and cultures shape the ways we think. I suspected they shaped the ways we reason and interpret information.  But I didn’t think languages could shape the nuts and bolts of perception, the way we actually see the world.  That part of cognition seemed too low-level, too hard-wired, too constrained by the constants of physics and physiology to be affected by language.”

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Puzzles and Cultural Differences

Blogging on Peer-Reviewed ResearchHere’s some interesting research where neuroscientists are using brain scans to show that cultural differences reach down to the level of functional activation in the brain.  Americans had a harder time with visual puzzles that required manipulating objects in context than “East Asians.”  Here a quote from the news article:

 

Neuroscientists Trey Hedden and John Gabrieli of MIT’s McGovern Institute for Brain Research asked Americans and East Asians to solve basic shape puzzles while in a functional magnetic resonance imaging (fMRI) scanner. They found that both groups could successfully complete the tasks, but American brains had to work harder at relative judgments, while East Asian brains found absolute judgments more challenging. Previous psychology research has shown that American culture focuses on the individual and values independence, while East Asian culture is more community-focused and emphasizes seeing people and objects in context. This study provides the first neurological evidence that these cultural differences extend to brain activity patterns.

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