2006-04-23

Information wants to be free

Scientists find brain cells linked to choice, says a Reuters article in The Scotsman.

"The neurons we have identified encode the value individuals assign to the available items when they make choices based on subjective preferences, a behaviour called economic choice," Padoa-Schioppa said in a statement.


I was left with questions like, "Which neurons? Where? How? Why?" so I looked for the statement at Harvard, found nothing, then checked Nature (the article said findings were published there) and found nothing recent from Dr. Padoa-Schioppa. Turned up an abstract from a Society for Neuroeconomics conference, which revealed it involved the orbitofrontal cortex. Brainmaps.org then underwhelmed me with zero results.

This is the information age? Feh.

I do know how to find stuff, this is just a good example of the bioinformatics infrastructure making it ridiculously difficult. The statement only went to select journalists, Nature wants you to pay lots to read, the Society of Neuroeconomics wants you to travel to a conference, and Brainmaps is a nice initiative but doesn't have access to enough data and has an unintuitive search engine ("hippocampal formation" is in there, but not "hippocampus").

Best results from my brief search: related article by Dr. Padoa-Schioppa in the Journal of Neurophysiology, and Decision Blog on the role of regret in choice.

What I'm wondering about is the overlap between various choice theories and neuropsychological studies. Where do neuroeconomics and neuromarketing (and media theory and sociology) intersect?



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11 Comments:

Blogger Chris said...

Neurons in the orbitofrontal cortex encode economic value

Camillo Padoa-Schioppa, John A. Assad

Economic choice is the behaviour observed when individuals select one among many available options. There is no intrinsically 'correct' answer: economic choice depends on subjective preferences. This behaviour is traditionally the object of economic analysis1 and is also of primary interest in psychology2. However, the underlying mental processes and neuronal mechanisms are not well understood. Theories of human and animal choice1, 2, 3 have a cornerstone in the concept of 'value'. Consider, for example, a monkey offered one raisin versus one piece of apple: behavioural evidence suggests that the animal chooses by assigning values to the two options4. But where and how values are represented in the brain is unclear. Here we show that, during economic choice, neurons in the orbitofrontal cortex5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 (OFC) encode the value of offered and chosen goods. Notably, OFC neurons encode value independently of visuospatial factors and motor responses. If a monkey chooses between A and B, neurons in the OFC encode the value of the two goods independently of whether A is presented on the right and B on the left, or vice versa. This trait distinguishes the OFC from other brain areas in which value modulates activity related to sensory or motor processes19, 20, 21, 22, 23, 24, 25. Our results have broad implications for possible psychological models, suggesting that economic choice is essentially choice between goods rather than choice between actions. In this framework, neurons in the OFC seem to be a good candidate network for value assignment underlying economic choice.



Nature (23 Apr 2006) Letters to Editor

23/4/06 23:42  
Blogger Chris said...

Or just here:
http://www.nature.com/nature/journal/vaop/ncurrent/pdf/nature04676.pdf

23/4/06 23:43  
Blogger Sandra said...

Thanks Chris! A letter to the editor; I wonder why that didn't come up when I searched Nature?

23/4/06 23:46  
Blogger Chris said...

sandra, no problem. I'm in the lab late, and had access to Nature.

By the way, there's a pretty large literature on the role of orbitofrontal cortex and value. Not surprising given its significance in the reward system. Carl Olson and one of his former students have been doing a bunch of work recording neurons in the orbitofrontal cortex, and argue that it often reflects the value of a reward. For example, they've found that neurons in the OFC fire more strongly when there is a short delay before a reward can be received, reflecting, they argue, the value of the reward with the time it takes to receive it taken into consideration (reference below). And Tremblay and Schultz showed several years ago (in a letter to Nature, I think... coincidentally) that activity in the orbitofrontal cortex reflects the relative preference of different rewards. Oh, and Edmund Rolls has done a lot of work on the role of the orbitofrontal cortex in the representation of the value of different tastes (the Padoa-Schioppa & Assad experiments used stimuli with different taste values). Much of the work has been at the individual neuron level. So, not being a neuroscientist myself, I have a hard time figuring out what the value of the Padoa-Schioppa and Assad letter is. What has it added to the discussion? Maybe a neuroscientist who's read the letter can tell me.

Roesch, M.R. & Olson, C.R. (2005). Neuronal activity in primate orbitofrontal cortex reflects the value of time. Journal of Neurophysiology, 94, 2457-2471.

24/4/06 00:28  
Blogger Sandra said...

Hmm, good question. Perhaps for The Neurocritic?

I'm wondering also what applications this info has.

24/4/06 00:35  
Blogger neubrain said...

http://brainmaps.org/index.php?i=orbitofrontal%20cortex

BrainMaps.org has a lot of high-resolution neuroanatomical image data which is in the process of being annotated and associated with keywords. As you found out, there is still considerable work to be done with associating keywords (such as 'orbitofrontal cortex') with image data. However, the raw image data is there to explore, and a lot of orbitofrontal cortex data is there even though 99.9% of it is not currently labeled as such.

27/4/06 00:59  
Blogger Sandra said...

That's great to hear, neubrain. Thanks for the update.

27/4/06 01:02  
Blogger The Neurocritic said...

Yes, I've been meaning to read that article (and to comment on the "Attention Shoppers" press release from Harvard).

29/4/06 22:58  
Blogger Sandra said...

Neurocritic - I hope you do. I'm wondering why they're making the leap from 135 neurons in the orbitofrontal cortex, to how that matters in the supermarket. Practical application? There are a lot of disorders involving decision making and that area of the brain. There's no real cure, and this news doesn't appear to point to one.

Harvard did email with the link to that press release I didn't find with their search engine - for anyone who hasn't seen it, here's the link to Attention Shoppers, and also recent article in Cognition (abstract only, of course...).

30/4/06 04:34  
Blogger The Neurocritic said...

The supplemental material for the Padoa-Schioppa & Assad article in Nature is 27 pages long! [13 pages of single-spaced text and 14 figures]. What ever happened to the 3-4 page Nature paper?? Anyway, one can find out interesting details such as:

"We used the following juices, listed in roughly decreasing order of preference (associated colors in parenthesis): high-sugar lemon Kool-Aid (dark yellow), grape juice (bright green), fruit punch (magenta), apple juice (diluted to 1/2 with water, dark green), cranberry juice (diluted to 1/3 or 1/4 with water, pink), water (white), milk (red), peppermint tea (bright blue), tea (light brown), low-sugar agua frescas Kool-Aid (light red), low-sugar tamarind Kool-Aid (dark brown), slightly salted water (0.60 g/l or 0.65 g/l concentration, light gray)."

At any rate, it'll take a while to slog through it... and to answer Chris's question about whether it's added anything to the literature on "OFC and reward" (176 papers) and "OFC and reward value" (46 papers). See also Rolls ET, orbitofrontal, reward (25 hits) for papers just by Ed Rolls et al. on the topic!

1/5/06 17:26  
Blogger Sandra said...

With the juices, how do they ascribe what the choice corresponds to? Is it the colour, the flavour, the volume, or the effect of the drink (high-sugar Kool-Aid being a quite different substance from water or peppermint tea, of course). Are they looking at mixed reponses in choice like the combination of sweetness and blue or the nurturing associations of a drink like milk? Or in my case, Kool-Aid - but they are presumably not considering the kitsch factor ;)

Why did they use these qualitatively different drinks?

Most importantly, why was the milk red?

1/5/06 21:10  

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