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The Attention-Allocation Deficit

Pedro

Well-Known Member
The Attention-Allocation Deficit
By Jonah Lehrer September 13, 2010 | 10:57 am | Categories: Frontal Cortex

Attention Deficit/Hyperactivity Disorder is a terribly named disorder. The reason is simple: There is not an actual deficit of attention. We?re used to thinking of illnesses as resulting from a shortage of something ? people with a thyroid disease are missing TSH, just as people with scurvy are missing Vitamin C ? but ADHD doesn?t seem to work like that. Instead, recent evidence suggests that people with ADHD have plenty of attention ? that?s why they can still play video games for hours, or get lost in their Legos, or devote endless attentional resources to activities that they find interesting.

What, then, is the problem in people with ADHD? The disorder is really about the allocation of attention, being able to control our mental spotlight. There?s a new Dana Foundation briefing paper that eloquently explains this new understanding:

Martha Bridge Denckla, M.D., a clinician and scientist at the Kennedy Krieger Institute and Johns Hopkins University, says she faces these kinds of questions regularly from parents who bring their children to the ADHD clinic where she practices. ?I am constantly having to explain to parents that ADHD is not a deficit in the sense of say, a budget deficit or a thyroid deficiency, where you don?t have enough of something. Rather, it?s the control over attention.?

Denckla, who is a member of the Dana Alliance for Brain Initiatives, has found it useful to speak in terms of the allocation of attention when communicating with parents about ADHD. The question, Denckla says, is: ?Where is the child?s attention being allocated? Is it where it needs to be to meet the demands of home, school, and society??
Allocating one?s attention appropriately for success in school requires a degree of willful control?what might be thought of as will power?to turn away from a preferred activity and focus on an activity that may not be as compelling or immediately rewarding.

To understand this model of ADHD, it?s important to understand the anatomy of attention. The story begins with dopamine. While dopamine neurons are relatively rare, they are clustered in very specific areas in the center of the brain, such as the nucleus accumbens and ventral striatum. These cortical parts make up the dopamine reward pathway, the neural system that?s responsible for generating the pleasurable emotions triggered by pleasurable things. It doesn?t matter if we?re having sex or eating sugar or snorting amphetamine: These things fill us with bliss because they tickle these cells.

But the caricature of dopamine as simply the chemical of hedonism is woefully incomplete. For instance, studies have shown that the dopamine reward pathway is also extremely active when people are forced to eat something disgusting, or when a subject is gasping for air after holding their breath. These are intensely unpleasant experiences, and yet our dopamine neurons are pumping out neurotransmitter. This leaves two possibilities: 1) We are all secret masochists, and take pleasure in pain or 2) Dopamine is really about attention and motivation, and is not just the chemical of pleasure and rewards.

I don?t know about you, but I?m betting on hypothesis number two. I think there?s a growing body of evidence suggesting that the real purpose of the dopamine is to help us efficiently assess the outside world. Many dopamine researchers, for instance, refer to the chemical as our ?neural currency,? since it allows us to quickly assign a value to the multitudes of things and ideas we perceive. (In other words, dopamine is the price tag of sensory information, and it attaches hefty prices to things that are delicious, beautiful, or reflect some urgent homeostatic need.) When we see something we want - and it doesn?t matter if it?s a chocolate cupcake or a glass of water ? the mere sight of the object triggers a wave of emotional desire, which motivates us to act. (Emotion and motivation share the same Latin root, movere, which means ?to move.?) The world is full of possibilities, and it is our dopaminergic urges that help us choose between them.

And this returns us to attention and ADHD. There?s a highway of nerves connecting the dopamine reward pathway to the prefrontal cortex, a crucial fold of tissue that controls the spotlight of attention. This makes perfect sense: A sensation or idea that triggers more dopamine release ? it?s deemed worthy of more neural currency ? is more likely to get noticed, and enter the crowded theater of consciousness. In other words, the prefrontal cortex is now paying attention. The chemical has told us what we should notice.*

The problem with ADHD is not that there?s no attention. As I mentioned before, kids with ADHD can still immerse themselves in activities that require focus ? they just tend to require a higher threshold of interest, which is why they don?t pay attention to a boring arithmetic lesson but can easily spend all day on World of Warcraft. Drugs for ADHD, such as the amphetamine-derivatives Ritalin, Adderall, Concerta, etc. work by increasing the amount of dopamine in the synapse. (Like most psychoactive drugs, the exact mechanisms remain unclear, although many think that the drugs work by blocking dopamine transporters, which remove dopamine after it has been released.) Interestingly, some people get a similar boost naturally: studies have linked small coding difference in the genes that underlie dopamine production, such as the COMT Val/Met polymorphism, to variations in ?attentional abilities,? with more neurotransmitter equaling more attention. (Alas, the same mutations that increase dopamine activity in the prefrontal cortex also seem to make us more anxious and sensitive to pain. Needless to say, much more work is needed before this pathway and its implications are fully understood.) In other words, ADHD medications act like a chemical shortcut: Because those dopamine neurons in the midbrain are so excited ? they are suffused with the neurotransmitter ? the world is suddenly saturated with intensely interesting ideas, which get passed along to the prefrontal cortex. Even arithmetic is now compelling enough to notice; the neural currency of long division has been increased, which makes it easier to allocation our attention to the place in the classroom it?s supposed to be allocated. But here?s my point: The drugs haven?t suddenly turned on the spotlight of attention. The spotlight was always there. Instead, they have made it easier for us to point the spotlight in the right direction.

PS. A reader just sent in a marvelous William James anecdote on this subject. When James was told that Benjamin Jowett was absent minded, he gave the following reply: ?No, he is not absent-minded. He is just present minded somewhere else.?

*Interestingly, this system is incredibly ancient. For instance, when honeybees are given small amounts of cocaine instead of nectar ? the insects use a neurotransmitter that is a virtual clone of dopamine ? they begin dancing extremely vigorously. (Honeybees use intricate ?dances? to communicate the location and wealth of the nectar.)

Source/Original article: The Attention-Allocation Deficit | Wired Science*| Wired.com
 

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