Shopping Centers in the Brain

This is the title of revew by Dagher in the Jan 4 issue of Neuron of an article by Knutson et al. in the same issue that tests a neuroeconomic theory that is well suited to investigation by fMRI: that potential gains and losses are evaluated independently (i.e., by different neural systems), and, more specifically, that financial decisions are guided by emotional biases, which are presumably related to neural activity in brain regions involved in the processing of positive and negative emotion.

From the article's abstract: "Consistent with neuroimaging evidence suggesting that distinct circuits anticipate gain and loss, product preference activated the nucleus accumbens (NAcc), while excessive prices activated the insula and deactivated the mesial prefrontal cortex (MPFC) prior to the purchase decision. Activity from each of these regions independently predicted immediately subsequent purchases above and beyond self-report variables. These findings suggest that activation of distinct neural circuits related to anticipatory affect precedes and supports consumers' purchasing decisions."

From Knutson: “It was amazing to be able to see brain activity seconds before a decision and predict whether the person would buy it or not.”

NOTE: I'm not including a graphic of the MRI data from the article, as I have been doing in many posts like this, because they don't give you much you couldn't learn from simply entering the name of brain structures mentioned (insula, nucleus accumbens) in Google Images and getting even more information on their general context.

Another point is that articles like this are trendy and get popular press, but one reasonable reaction is "Well, duh! What did you expect?" Brain changes correlate with behavior changes! Of course, the slicing and dicing of what happens where is a necessary part of describing the machine, and there is a sense of relief that discrete behaviors correlate with discrete regions of brain activity. It could have looked like undifferentiated mush, everything happening everywhere. And, some lists of the multiple areas suggested to be implicated in consciousness begin to look like this.

OK, Materialists, Naturalists, and Humanists, where's the beef?

Looking over the Center for Naturalism website in the previous post nudges me to make a request: I would be grateful for the assistance of blog patrons in assembling a list of alternative-to-conventional-religion sites and organizations to see their take on the following question: can their program generate from a rational basis the emotional intensity and bonding seen in charismatic and pentacostal settings requiring irrational faith, or should they? What might work to provide social support and succor for people without a habit of being critical, who don't have a pedigree of formal education? The excellent three part series in the New York Times this week about the growth and travails of an independent Pentacosal storefront church in west Harlem brings this issue up for me yet again.....

More on the Free Will debate......

I want to relay here a comment from Tom Clark, Center for Naturalism, to my Jan. 4 post on Overbye's NY Times free will article, so that more of you are likely to see the link it includes.

"There were some suggestions in Overbye's article that questioning free will is a *good* thing. Einstein said seeing we don't have free will keeps us humble, and psychologist Dan Wegner suggested it would allow us to understand evil and prompt us to reform people instead of merely paying them back."

"There's a roundup of recent articles on free will, including Overbye's, at http://www.naturalism.org/roundup.htm."

Happiness and human evolution...

I've done some posts on defining happiness and how important social intimacy might or might not be. Several major magazines, including the Economist and the New York Times Magazine, have recently presented articles on research directed towards defining what happiness might in fact consist of, and a number of new university courses have the study of happiness as their main subject (see "Happiness 101, by D.T. Max). The distinction is frequently made between feeling good (the hedonic treadmill) and doing good. The former creates a hunger for more pleasure while the latter is suggested to be more likely to lead to lasting happiness.

My take on the fact that we frequently experience warm feelings after doing good is that we are experiencing the activation of our evolved affiliative neuro-endrocine repertoire, which has components like the release the neuropeptide oxytocin that promotes bonding and trust (see Feb. 13 post). There seems an obvious evolutionary rationale for the pleasure we take in helping others: groups of humans who develop this trait more highly might be more cooperative and effective in competition with other groups of humans whose members treat each other less sweetly. This, like all evolutionary psychology explanations, is hard to test or prove and thus criticized as pseudoscientific hand waving, but I like it. (There does seem to be a consensus that a major engine driving hominid evolution over the past several hundred thousand years has been competition between groups of humans.)

Such a group selection rationale can be applied also to why humans invent religions (which draw caustic blog posts from dry rationalists)...they wage war against other groups of humans more effectively. I do think David Sloan Wilson has it right on the central importance of group selection to human evolution. Have a look at his article "Testing major evolutionary hypothesis about religion with a random sample" which, along with several of this other recent interesting articles can be downloaded in PDF form from his website. I completely fail to understand the objection of the selfish-gene purists to group selection. Their points are now finding some refutation in mathematical models (cf. Bowles) that show how groups with altruistic genes might be better at waging war.

The evolution of cooperation: why the whites of our eyes are large.

Michael Tomasello, co-director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, offers an interesting speculation in a brief essay in the Op-Ed section of the Jan. 13 New York Times. Because the whites of our human eyes are large we can easily detect the direction of another person's gaze even if their head is pointing slightly away from us. In contrast, neither chimpanzees nor any of the other 220 species of nonhuman primates have whites of the eyes that can be easily seen, making it much harder to see if their eyes are looking in a direction other than the one in which their heads are pointing.

Tomasello: "Evolutionary theory tells us that, in general, the only individuals who are around today are those whose ancestors did things that were beneficial to their own survival and reproduction. If I have eyes whose direction is especially easy to follow, it must be of some advantage to me...If I am, in effect, advertising the direction of my eyes, I must be in a social environment full of others who are not often inclined to take advantage of this to my detriment — by, say, beating me to the food or escaping aggression before me. Indeed, I must be in a cooperative social environment in which others following the direction of my eyes somehow benefits me."

"our research team has shown that even infants — at around their first birthdays, before language acquisition has begun — tend to follow the direction of another person’s eyes, not their heads. Thus, when an adult looked to the ceiling with her eyes only, head remaining straight ahead, infants looked to the ceiling in turn. However, when the adult closed her eyes and pointed her head to the ceiling, infants did not very often follow."

"Our nearest primate relatives, the African great apes (chimpanzees, bonobos and gorillas) showed precisely the opposite pattern of gaze following. When the human pointed her eyes only to the ceiling (head remaining straight ahead), they followed only rarely. But when she pointed her head only (eyes closed) to the ceiling, they followed much more often."

"It has been repeatedly demonstrated that all great apes, including humans, follow the gaze direction of others. But in previous studies the head and eyes were always pointed in the same direction. Only when we made the head and eyes point in different directions did we find a species difference: humans are sensitive to the direction of the eyes specifically in a way that our nearest primate relatives are not. This is the first demonstration of an actual behavioral function for humans’ uniquely visible eyes."

"Why might it have been advantageous for some early humans to advertise their eye direction in a way that enabled others to determine what they were looking at more easily? One possible answer, what we have called the cooperative eye hypothesis, is that especially visible eyes made it easier to coordinate close-range collaborative activities in which discerning where the other was looking and perhaps what she was planning, benefited both participants...If we are gathering berries to share, with one of us pulling down a branch and the other harvesting the fruit, it would be useful — especially before language evolved — for us to coordinate our activities and communicate our plans, using our eyes and perhaps other visually based gestures....Infant research, too, suggests that coordinating visual attention may have provided the foundation for the evolution of human language. Babies begin to acquire language through joint activities with others, in which both parties are focused on the same object or task. That’s the best time for an infant to learn the word for the object or activity in question."

More brain enhancement websites

An addendum to my Dec. 27 post on "Brain Fitness." You might want to check out the Smart-Kit website...And this site on "Smart Drugs."

Most popular consciousness articles...

The Association for the Scientific Study of Consciousness keeps an archive of articles on consciousness open for downloading. Here are the most popular downloads for December 2006:

1. Seth, A.K. and Izhikevich, E.I. and Reeke, G.N. and Edelman, G.M. (2006)
*Theories and measures of consciousness: An extended framework.* Proceedings
of the National Academy of Sciences USA, 103 (28). pp. 10799-10804. With
1168 downloads from 23 countries. See: http://eprints.assc.caltech.edu/162/

2. Dehaene, Stanislas and Changeux, Jean-Pierre and Naccache, Lionel
and Sackur, Jérôme and Sergent, Claire (2006) *Conscious, preconscious, and subliminal processing: a testable taxonomy.* Trends in Cognitive Science, 10 (5).
pp. 204-211. With 1017 downloads from 19 countries. See:
http://eprints.assc.caltech.edu/20/

3. Koch, Christof and Tsuchiya, Nao (2006) *(PART 1) The relationship
between attention and consciousness.* In: 10th annual meeting of the
Association for the Scientific Study of Consciousness, June, Oxford. With
880 downloads from 16 countries. See:
http://eprints.assc.caltech.edu/37/

4. Chai-Youn, Kim and Blake, Randolph (2005) *Psychophysical magic:
rendering the visible 'invisible'.* Trends in Cognitive Science, 9 (8).
pp. 381-8. With 661 downloads from 14 countries. See:
http://eprints.assc.caltech.edu/30/

5. Windt, Jennifer Michelle and Metzinger, Thomas (2006) *The philosophy of
dreaming and self-consciousness: What happens to the experiential subject
during the dream state?* In: The new science of dreaming. Praeger
Imprint/Greenwood Publishers, Estport, CT. With 544 downloads from 13
countries. See: http://eprints.assc.caltech.edu/200/


Also,

- Destrebecqz, Arnaud and Peigneux, Philippe (2005) *Methods for studying
unconscious learning.* In: Progress in Brain Research. Elsevier, pp. 69-80.
See: http://eprints.assc.caltech.edu/170/

- Carter, O and Burr, D and Pettigrew, J and Wallis, G and Hasler, F
and Vollenweider, F (2005) *Using psilocybin to investigate the relationship between
attention, working memory and the Serotonin1A&2A receptors.* Journal of
Consciousness studies, 17 (10). pp. 1497-1508. See:
http://eprints.assc.caltech.edu/5/

- Laureys, Steven (2005) *The neural correlate of (un)awareness: lessons
from the vegetative state.* Trends Cogn Sci, 9. pp. 556-559. See:
http://eprints.assc.caltech.edu/194/

Varieties of Delusion - I'll take the Flying Spagetti Monster

The Jan. 14 issue of the New York Times has a fascinating article on the explosion of faith among pentecostals and similar Christian groups in the U.S. In the spirit of "know your enemy," I'm grateful for their succint summary of some of the major groups (click on the graphic to enlarge it, then your browser's back key to return to post):



For some strange reason the Times doesn't mention another major and growing group, The Church of the Flying Spagetti Monster.

Doonesbury on science - teaching the "controversy"

This cartoon from today's paper is too good not to pass on, so that hopefully more people will see it....(click on image to enlarge it, then on your brower's back key to return to blog.)

Envisioning the future: underlying brain activities

An important component of future-oriented thought involves envisioning oneself participating in a specific future event , a process that might spur the initiation of executive processes to structure behavior. Szpunar et al. report the use of functional neuroimaging to probe brain activity underlying this important mental capacity. To isolate regions particularly important for envisioning the future, they chose a comparison task that did not involve envisioning oneself at a time other than the present. In this task, subjects imagined a familiar individual (Bill Clinton) participating in life-like events with no explicit temporal reference. This condition had neither the aspect of self nor the element of mental time travel.

The authors identified a distributed set of cortical regions that appear to be important for episodic future thought and that are not isolated to regions within frontal cortex. These regions neatly break apart into two sets of regions, each characterized by their pattern of activity across tasks. One set of regions (within left lateral premotor cortex, left precuneus, and right posterior cerebellum) was more active while envisioning the future than while recollecting the past (and more active in both of these conditions than in the task involving imagining another person). These regions have previously been implicated in imagined (simulated) bodily movements. A second set of regions (bilateral posterior cingulate, bilateral parahippocampal gyrus, and left occipital cortex) demonstrated indistinguishable activity during the future and past tasks (but greater activity in both tasks than the imagery control task); similar regions have been shown to be important for remembering previously encountered visual-spatial contexts. Hence, differences between the future and past tasks are attributed to differences in the demands placed on regions that underlie motor imagery of bodily movements, and similarities in activity for these two tasks are attributed to the reactivation of previously experienced visual–spatial contexts. That is, subjects appear to place their future scenarios in well known visual–spatial contexts.

The authors suggest that simulation of bodily actions and reinstatement of visual–spatial context may be particularly relevant to the understanding of the ability to mentally represent a future event.

An E.Coli toxin can stimulate learning and memory

Diana et al show (at least for mice) that intracerebral injection of cytotoxic necrotizing factor 1 (CNF1) - a protein toxin from Escherichia coli that constitutively activates Rho GTPases and leads to remodeling of the cerebral actin cytoskeleton - enhances neurotransmission and synaptic plasticity, and improves learning and memory in various behavioral tasks. The effects persist for weeks and are not observed in mice treated with a recombinant CNF1 inactivated by a single amino acid replacement. The results suggest that learning ability can be improved through pharmacological manipulation of neural connectivity.

Two parallel (and sometimes conflicting) brain systems for evaluating others.

The Editor's Choice section of the Jan. 5 Science magazine has a brief review of interesting work by Rydell et al. at Miami University:

"One emerging theoretical view posits two systems of reasoning: a slow-learning system that acquires and classifies associations over long periods of time, and a fast-learning module that emphasizes higher-order conscious cognition. A stimulus--for example, the negatively valenced word "hate"--can be paired in a subliminal fashion with a person's face (for example, Bob's); this association will induce subjects to regard Bob unfavorably, as assessed by their poststimulus choice of positive or negative adjectives, yet they will be unaware of having evolved this implicit attitude. Similarly, written descriptions of Bob's praiseworthy behavior will result in subjects expressing a liking for Bob, where this evaluation reflects a studied and thoughtful appraisal--that is, the formation of an explicit attitude. Rydell et al. show that these mental processes can be accessed separately and appear to operate independently. Not only are subjects capable of developing apparently inconsistent negative implicit attitudes and positive explicit attitudes about the same individual, but they can actually be influenced to invert their preferences by the subsequent presentation of subliminal (positive) words and supraliminal (negative) descriptions."

Attention and consciousness are not the same thing.

I would like to point you to an excellent article by Christof Koch and Naotsugu Tsuchiya in Trends in Cognitive Science arguing that attention and consciousness are two distinct brain processes. They do a much more thorough job than I managed in my "Biology of Mind" book. A PDF form of the article can be obtained from the Koch laboratory web site. Here is their abstract:

The close relationship between attention and consciousness has led many scholars to conflate these processes. This article summarizes psychophysical evidence, arguing that top-down attention and consciousness are distinct phenomena that need not occur together and that can be manipulated using distinct paradigms. Subjects can become conscious of an isolated object or the gist of a scene despite the near absence of top-down attention; conversely, subjects can attend to perceptually invisible objects. Furthermore, top-down attention and consciousness can have opposing effects. Such dissociations are easier to understand when the different functions of these two processes are considered. Untangling their tight relationship is necessary for the scientific elucidation of consciousness and its material substrate.

At the end of their paper the authors comment on the implications their consclusions hold for real life:

It could be contested that top-down attention without consciousness and consciousness with little or no top-down attention are arcane laboratory curiosities that have little relevance to the real world. We believe otherwise. A lasting insight into human behavior – eloquently articulated by Friedrich Nietzsche – is that much action bypasses conscious perception and introspection. In particular, Goodale and Milner isolated highly trained, automatic, stereotyped and fluid visuomotor behaviors that work in the absence of phenomenal experience. As anybody who runs mountain trails, climbs, plays soccer or drives home on automatic pilot knows, these sensorimotor skills – dubbed zombie behaviors – require rapid and sophisticated sensory processing. Confirming a long-held belief among trainers, athletes perform better at their highly tuned skill when they are distracted by a skill-irrelevant dual task (e.g. paying attention to tones) than when they pay attention to their exhaustively trained behaviors.

The history of any scientific concept (e.g. energy, atoms or genes) is one of increasing differentiation and sophistication until its action can be explained in a quantitative and mechanistic manner at a lower, more elemental level. We are far from this ideal in the inchoate science of consciousness. Yet functional considerations and the empirical and conceptual work of many scholars over the past decade make it clear that these psychologically defined processes – top-down attention and consciousness – so often conflated, are not the same. This empirical and functional distinction clears the deck for a concerted neurobiological attack on the core problem – that of identifying the necessary and sufficient neural causes of a conscious percept.

A key to life satisfaction? Lower your expectations.

Why do citizens of Denmark have score higher than any other Western country on measures of life satisfaction? A brief article in today's Science section of the New York Times points to a study suggesting an answer: the country’s secret is a culture of low expectations. "...on surveys, Danes continually report lower expectations for the year to come, compared with most other nations... If you’re a big guy, you expect to be on the top all the time and you’re disappointed when things don’t go well. But when you’re down at the bottom .. you hang on, you don’t expect much, and once in a while you win, and it’s that much better....year after year, they are pleasantly surprised to find that not everything is getting more rotten in the state of Denmark,”

Become an Evo Warrior

From the Jan. 5 issue of Science Magazine:

What can you do if your local school board proposes a curriculum that downplays evolution? Or if your hometown newspaper runs an editorial supporting "intelligent design"?

This new site from the Federation of American Societies for Experimental Biology in Rockville, Maryland, offers advice and resources for scientists who want to defend Darwinism. Downloadable documents provide pointers on meeting with public officials, testifying at school board hearings, and related topics. Much of the advice is common sense, but some of it may be counterintuitive for scientists. For example, although you want your papers to run in prestigious journals, an op-ed will probably have more impact if it appears in the local paper than if it's accepted by The Wall Street Journal. The site also furnishes PowerPoint files on topics such as the importance of learning about evolution.

Movement errors can rise in the brain before the movement starts.

Churchland et al report in Neuron Magazine that variations in firing of the motor cortical neurons that plan and preceed trained skilled physical movement (like throwing a dart at a dart board) are responsible for a large fraction of the variability of the movement. This contradicts our usual assumption that something goes wrong during the movement. Recording from monkey motor and pre-motor cortex neurons, they found that variations in the velocity of trained reaches correlated with fluctuations in brain activity during the preparatory period — hundreds of milliseconds before the movement started.

Constructive memory a tool for anticipating futures.

Daniel Schacter writes a brief essay in the Jan. 4 issue of Nature Magazine on why our memory is not a literal reproduction of the past, but is instead constructed by pulling together pieces of information from different sources.

"One clue comes from studies indicating that memory errors can reveal the operation of adaptive rather than defective processes. For example, consider the following words: tired, bed, awake, rest, dream, night, blanket, doze, slumber, snore, pillow, peace, yawn and drowsy. When asked whether 'blanket'; was on the list (a few minutes after seeing the words), most people correctly recognize that it was; when asked about 'point';, they correctly remember that it was not. When asked about 'sleep';, most people confidently remember having seen it — but they are wrong. They falsely recognize 'sleep'; because they remember that many associated words were present, and mistakenly rely on their accurate memory for the general theme of the list."

"Future events are not exact replicas of past events, and a memory system that simply stored rote records would not be well-suited to simulating future events. A system built according to constructive principles may be a better tool for the job: it can draw on the elements and gist of the past, and extract, recombine and reassemble them into imaginary events that never occurred in that exact form. Such a system will occasionally produce memory errors, but it also provides considerable flexibility."

"Taken together, neurological and neuroimaging studies suggest that false-recognition errors reflect the healthy operation of adaptive, constructive processes supporting the ability to remember what actually happened in the past. Many researchers believe that remembering the gist of what happened is an economical way of storing the most important aspects of our experiences without cluttering memory with trivial details. We agree. But we also see another important function for constructive memory, one that emerges from an idea that a growing number of researchers are embracing — that memory is important for the future as well as the past."

Watching the brain make up its mind about an ambiguous stimulus.

On looking at an ambiguous visual stimuli, we can experience frequent spontaneous transitions between two competing percepts while physical stimulation remains unchanged (see example in the top section of Figure 1)... a key question has remained unresolved: Does perceptual rivalry result merely from local bistability of neural activity patterns in sensory stimulus representations (i.e. mainly in posterior visual cortical areas), or do higher-order areas (i.e. frontal cortex) play a causal role by shifting inference and, thus, initiating perceptual changes? Sterzer and Kleinschmidt have used functional MRI to measure brain activity while human observers reported successive spontaneous changes in perceived direction for an ambiguous apparent motion stimulus (Fig 1, top). In a control condition, the individual sequences of spontaneous perceptual switches during bistability were replayed by using a disambiguated version of the stimulus (Fig. 1, bottom).


Fig. 1. Stimulus display. Ambiguous and disambiguated versions of the apparent motion quartet used in the rivalry and replay conditions, respectively, are shown. The single frames alternated at 4 Hz. When looking at the rivalry stimulus, perception is bistable and fluctuates spontaneously between periods of horizontal and vertical apparent motion perception. Disambiguated versions of the stimulus were used to change participants' perception of apparent motion with the same temporal sequence as during the rivalry condition.


Fig. 2. Transient activation during perceptual switches. (A) Regions commonly activated in response to both spontaneous and stimulus-driven perceptual switches are rendered in blue onto a standard anatomical template image Numbers 1–6 indicate the regions that were subsequently used for detailed analyses of signal time courses. (B) Greater response amplitudes during spontaneous as opposed to stimulus-driven switches were observed in bilateral inferior frontal regions and are shown in red. (C) Earlier responses during spontaneous as opposed to stimulus-driven switches were observed in the right inferior frontal gyrus.

Greater activations during spontaneous compared with stimulus-driven switches were observed in inferior frontal cortex bilaterally. Subsequent chronometric analyses of event-related signal time courses showed that, relative to activations in motion-sensitive extrastriate visual cortex, right inferior frontal cortex activation occurred earlier during spontaneous than during stimulus-driven perceptual changes. The temporal precedence of right inferior frontal activations suggests that this region participates in initiating spontaneous switches in perception during constant physical stimulation. Their findings can thus be seen as a signature of when and where the brain "makes up its mind" about competing perceptual interpretations of a given sensory input pattern.

Brain correlates of "flashbulb memory" of 9/11

The term "flashbulb memory" is used to describe the recall of shocking, consequential events such as hearing news of a presidential assassination. Sharot et al test the idea that the vivid detail of such memories results from the action of a unique neural mechanism. They study personal recollections of the terrorist attacks of September 11, 2001 (9/11) in New York City, combining behavioral and brain imaging techniques, with two goals: (i) to explore the neural basis of such memories and (ii) to clarify the characteristics of the emotional events that may give rise to them. Three years after the terrorist attacks, participants were asked to retrieve memories of 9/11, as well as memories of personally selected control events from 2001. At the time of the attacks, some participants were in Downtown Manhattan, close to the World Trade Center; others were in Midtown, a few miles away. The Downtown participants exhibited selective activation of the amygdala as they recalled events from 9/11, but not while they recalled control events. This was not the case for the Midtown participants. Moreover, only the Downtown participants reported emotionally enhanced recollective experiences while recalling events from 9/11, as compared with control events. These results suggest that close personal experience may be critical in engaging the neural mechanisms that underlie the emotional modulation of memory and thus in producing the vivid recollections to which the term flashbulb memory is often applied.

Figure: Blood oxygen level-dependent (BOLD) response and proximity to the WTC. (a) Coronal slice of the structurally defined left amygdala (outlined in red) that includes the peak active voxel. (b) Mean percentage signal change from the peak active voxel in the left amygdala, revealing a two-way interaction of trial type (9/11 vs. summer) x group (Downtown vs. Midtown). (c and d) ANCOVA contrasting activation during 9/11 trials vs. summer trials, with participants' distance from the WTC as a covariate, in voxels within the structurally defined amygdala (c) and posterior parahippocampal cortex (d). Warm colors indicate positive correlation, and cool colors indicate negative correlation. Participants who were closer to the WTC showed decreased activation in the posterior parahippocampal cortex and increased activation in the amygdala bilaterally during retrieval of 9/11 memories relative to summer memories.

Being happy broadens your scope of attention.

Rowe et. al. have measured the "effect of positive mood states ... in two different cognitive domains: semantic search (remote associates task) and visual selective attention (Eriksen flanker task). In the conceptual domain, positive affect enhanced access to remote associates, suggesting an increase in the scope of semantic access. In the visuospatial domain, positive affect impaired visual selective attention by increasing processing of spatially adjacent flanking distractors, suggesting an increase in the scope of visuospatial attention. During positive states, individual differences in enhanced semantic access were correlated with the degree of impaired visual selective attention. These findings demonstrate that positive states, by loosening the reins on inhibitory control, result in a fundamental change in the breadth of attentional allocation to both external visual and internal conceptual space."