Natural Rationality | decision-making in the economy of nature
Showing posts with label neuroscience. Show all posts
Showing posts with label neuroscience. Show all posts

3/26/08

Nature Neuroscience Special Issue about Decision Neuroscience

The last issue of Nature Neuroscience features 4 great papers on the neuroscience of decision-making:

  • Choice, uncertainty and value in prefrontal and cingulate cortex
    Matthew F S Rushworth and Timothy E J Behrens
  • Risky business: the neuroeconomics of decision making under uncertainty
    Michael L Platt and Scott A Huettel
  • Game theory and neural basis of social decision making
    Daeyeol Lee
  • Modulators of decision making
    Kenji Doya
Enjoy!



2/6/08

A few papers on decision, the brain, and morality

A few papers worth reading:

A study on meta-ethics beleifs (how people see ethical claims):

Important for anyone interested in neuroscience: to a non-expert public, seeing a picture of a brain biases people to give more credibility to a piece of information:

Social cognition: it begins with goal recognition

Jesse Prinz's new book (in a nutshell: morality is emotional and relative to a culture)

Forthcoming in the new journal Neuroethics:

A study on Chimpanzee barter behavior:

  • Brosnan, S. F., Grady, M. F., Lambeth, S. P., Schapiro, S. J., & Beran, M. J. (2008). Chimpanzee autarky, PLoS ONE, 3(1), e1518.




1/28/08

Explaining the Brain

Valerie Gray Hardcastle, a philosopher of mind and neuroscience, reviews Carl F. Craver's Explaining the Brain: Mechanisms and the Mosaic Unity of Neuroscience (Oxford University Press, 2007). It seems like a great book for people interested in neuroscience, not just philosophers.



12/13/07

New draft paper on collective agency

Collective Agency: From Intuitions to Mechanisms (pdf)

Benoît Dubreuil & Benoît Hardy-Vallée

Abstract:

The debate on the nature of collective agency has been at the center of the philosophy of the social sciences for the last century. In recent years, philosophy of language has been the dominant approach to a debate that has often been reduced to the question of the legitimacy of interpreting collective agency on the basis of folk-psychological categories like belief and desire. In this article, we argue that the debate between individualists and collectivists is currently stagnating, but can be revived by a more empirically sensitive approach to agency. Understanding agents, collective or individual, requires an understanding of the mechanisms that bring about and maintain agency. Collective agents, we suggest, are legitimate constructs in social ontology, but their agency is special. Although they implement control mechanisms similar to that of individual agents, they do not have a conscious first-person point of view. Therefore, like individualists, we recognize the ontological salience of individual agency, and like collectivists, we recognize the soundness of collective agents. However, we reject the folk-psychological account of agency (shared by individualists and collectivists) and favor a mechanistic one.



12/12/07

Two New Papers on Natural Rationality

Hardy-Vallée, B. (forthcoming). Decision-Making in the Economy of Nature: Information as Value. In G. Terzis & R. Arp (Eds.), Information and Living Systems: Essays in Philosophy of Biology. Cambridge, MA: MIT Press.

This chapter analyzes and discusses one of the most important uses of information in the biological world: decision-making. I will first present a fundamental principle introduced by Darwin, the idea of an “economy of nature,” by which decision-making can be understood. Following this principle, I then argue that biological decision-making should be construed as goal-oriented, value-based information processing. I propose a value-based account of neural information, where information is primarily economic and relative to goal achievement. If living beings (I focus here on animals) are biological decision-makers, we may expect that their behavior would be coherent with the pursuit of certain goals (either ultimate or instrumental) and that their behavioral control mechanisms would be endowed with goal-directed and valuation mechanisms. These expectations, I argue, are supported by behavioral ecology and decision neuroscience. Together, they provide a rich, biological account of decision-making that should be integrated in a wider concept of ‘natural rationality’.


Hardy-Vallee B. (submitted) Natural Rationality and the Psychology of Decision: Beyond bounded and ecological rationality

Decision-making is usually a secondary topic in psychology, relegated to the last chapters of textbooks. It pictures decision-making mostly as a deliberative task and rationality as a matter of idealization. This conception also suggests that psychology should either document human failures to comply with rational-choice standards (bounded rationality) or detail how mental mechanisms are ecologically rational (ecological rationality). This conception, I argue, runs into many problems: descriptive (section 2), conceptual (section 3) and normative (section 4). I suggest that psychology and philosophy need another—wider—conception of rationality, that goes beyond bounded and ecological rationality (section 5).



10/11/07

Resources on law, neuroscience, and "neurolaw"

From http://lawandneuroscienceproject.org/resources via Neuroethics and Law Blog.

Readings on Law and Neuroscience

Bibliography on Law and Biology

Blog on Neuroethics and Law



9/25/07

My brain has a politics of its own: neuropolitic musing on values and signal detection

Political psychology (just as politicians and voters) identifies two species of political values: left/right, or liberalism/conservatism. Reviewing many studies, Thornhill & Fincher (2007) summarizes the cognitive style of both ideologies:

Liberals tend to be: against, skeptical of, or cynical about familiar and traditional ideology; open to new experiences; individualistic and uncompromising, pursuing a place in the world on personal terms; private; disobedient, even rebellious rulebreakers; sensation seekers and pleasure seekers, including in the frequency and diversity of sexual experiences; socially and economically egalitarian; and risk prone; furthermore, they value diversity, imagination, intellectualism, logic, and scientific progress. Conservatives exhibit the reverse in all these domains. Moreover, the felt need for order, structure, closure, family and national security, salvation, sexual restraint, and self-control, in general, as well as the effort devoted to avoidance of change, novelty, unpredictability, ambiguity, and complexity, is a well-established characteristic of conservatives. (Thornhill & Fincher, 2007).
In their paper, Thornhill & Fincher presents an evolutionary hypothesis for explaining the liberalism/conservatism ideologies: both originate from innate adaptation to attachement, parametrized by early childhood experiences. In another but related domain Lakoff (2002) argued that liberals and conservatives differs in their methaphors: both view the nation or the State as a child, but they hold different perspectives on how to raise her: the Strict Father model (conservatives) or the Nurturant Parent model (liberals); see an extensive description here). The first one

posits a traditional nuclear family, with the father having primary responsibility for supporting and protecting the family as well as the authority to set overall policy, to set strict rules for the behavior of children, and to enforce the rules [where] [s]elf-discipline, self-reliance, and respect for legitimate authority are the crucial things that children must learn.


while in the second:

Love, empathy, and nurturance are primary, and children become responsible, self-disciplined and self-reliant through being cared for, respected, and caring for others, both in their family and in their community.
In the October issue of Nature Neuroscience, a new research paper by Amodio et al. study the "neurocognitive correlates of liberalism and conservatism". The study is more modest than the title suggests. Subject were submitted to the same test, a Go/No Go task (click when you see a "W" don't click when it's a "M"). The experimenters then trained the subjects to be used to the Go stimuli; on a few occasions, they were presented with the No Go stimuli. Since they got used to the Go stimuli, the presentation of a No Go creates a cognitive conflict: balancing the fast/automatic/ vs. the slow/deliberative processing. You have to inhibit an habit in order to focus on the goal when the habit goes in the wrong direction. The idea was to study the correlation between political values and conflict monitoring. The latter is partly mediated by the anterior cingulate cortex, a brain area widely studied in neuroeconomics and decision neuroscience (see this post). EEG recording indicated that liberals' neural response to conflict were stronger when response inhibition was required. Hence liberalism is associated to a greater sensibility to response conflict, while conservatism is associated with a greater persistence in the habitual pattern. These results, say the authors, are

consistent with the view that political orientation, in part, reflects individual differences in the functioning of a general mechanism related to cognitive control and self-regulation
Thus valuing tradition vs. novelty, security vs. novelty might have sensorimotor counterpart, or symptoms. Of course, it does not mean that the neural basis of conservatism is identified, or the "liberal area", etc, but this study suggest how micro-tasks may help to elucidate, as the authors say in the closing sentence, "how abstract, seemingly ineffable constructs, such as ideology, are reflected in the human brain."

What this study--together with other data on conservatives and liberal--might justify is the following hypothesis: what if conservatives and liberals are natural kinds? That is, "homeostatic property clusters", (see Boyd 1991, 1999), categories of "things" formed by nature (like water, mammals, etc.), not by definition? (like supralunar objects, non-cat, grue emerald, etc.) Things that share surface properties (political beliefs and behavior) whose co-occurence can be explained by underlying mechanims (neural processing of conflict monitoring)? Maybe our evolution, as social animals, required the interplay of tradition-oriented and novelty-oriented individuals, risk-prone and risk-averse agents. But why, in the first place, evolution did not select one type over another? Here is another completely armchair hypothesis: in order to distribute, in the social body, the signal detection problem.

What kind of errors would you rather do: a false positive (you identify a signal but it's only noise) or a false negative (you think it's noise but it's a signal)? A miss or a false alarm? That is the kind of problems modeled by signal detection theory (SDT): since there is always some noise and you try to detect signal, you cannot know in advance, under radical uncertainty, what kind of policy you should stick to (risk-averse or risk-prone. "Signal" and "noise" are generic information-theoretic terms that may be related to any situation where an agent tries to find if a stimuli is present:




Is is rather ironic that signal detection theorists employ the term liberal* and conservative* (the "*" means that I am talking of SDT, not politics) to refer to different biases or criterions in signal detection. A liberal* bias is more likely to set off a positive response ( increasing the probability of false positive), whereas a conservative* bias is more likely to set off a negative response (increasing the probability of false negative). The big problem in life is that in certain domains conservatism* pay, while in others it's liberalism* who does (see Proust 2006): when identifying danger, a false negative is more expensive (better safe than sorry) whereas in looking for food a false positive can be more expensive better (better satiated than exhausted). So a robust criterion is not adaptive; but how to adjust the criterion properly? If you are an individual agent, you must altern between liberal* and conservative* criterion based on your knowledge. But if you are part of a group, liberal* and conservative* biases may be distributed: certains individuals might be more liberals* (let's send them to stand and keep watch) and other more conservatives* (let's send them foraging). Collectively, it could be a good solution (if it is enforced by norms of cooperation) to perpetual uncertainty and danger. So if our species evolved with a distribution of signal detection criterions, then we should have evolved different cognitive styles and personality traits that deal differently with uncertainty: those who favor habits, traditions, security, and the others. If liberal* and conservative* criterions are applied to other domains such as family (an institution that existed before the State), you may end up with the Strict Father model and the Nurturant Parent model; when these models are applied to political decision-making, you may end up with liberals/conservatives (no "*"). That would give a new meaning to the idea that we are, by nature, political animals.


Related posts
Links
References




9/24/07

Natural Rationality for Newbies



Decision-making, as I routinely argue in this blog, must be understood as entrenched in a richer theoretical framework: Darwin’s economy-of-nature. According to this principle, animals could be modeled as economic agents and their control systems could be modeled as economic devices. All living beings are thus deciders, strategists or traders in the economy of reproduction and survival.

When he suggested that nature is an economy, Darwin paved the way for a stronger interaction between biology and economics. One of the consequences of a bio-economic approach is that decision-making becomes an increasingly important topic. The usual, commonsense construal of decision-making suggests that it is inherently tied to human characteristics, language in particular. If that is the case, then talk of animal decisions is merely metaphorical. However, behavioral ecology showed that animals and human behavior is constrained by economic parameters and coherent with the economy-of-nature principle. Neuroeconomics suggest that the neural processing follow the same logic. Dopaminergic systems drive animals to achieve certain goals while affective mechanisms place goals and action in value spaces. These systems, although they were extensively studied in humans, are not peculiar to them: humans display a unique complexity of goals and values, but this complexity relies partly on neural systems shared with many other animals: the nucleus accumbens and the amygdala, for instance are common in mammals. Brainy animals evolved an economic decision-making organ that allows them to cope with complex situations. As Gintis remarks, the complexity and the metabolic cost of central nervous systems co-evolved in vertebrates, which suggests that despite their cost, brains are designed to make adaptive decision[i].

Hence decision-making should be analyzed similarly as, and occupies an intellectual niche analogous to, the concept of cooperation. Nowadays, the evolutionary foundations, neural substrates, psychological mechanisms, formal modeling and philosophical analyses of cooperation constitutes a coherent—although not unified—field of inquiry [ii]. The nature of prosocial behavior, from kin selection to animal cooperation to human morality, is best understood by adopting a naturalistic stances that highlights both the continuity of the phenomenon and the human specificity. Biological decision-making deserves the same eclecticism.

Talking about biological decision-making comes at a certain conceptual price. As many philosophers pointed out, whenever one is describing actions and decisions, one is also presupposing the rationality of the agent[iii]. When we say that agent A chose X, we suppose that A had reasons, preferences, and so on. The default assumption is that preferences and actions are coherent: the firsts caused the seconds, and the seconds are justified by the firsts. The rationality philosophers are referring to, however, is a complex cognitive faculty, that requires language and propositional attitudes such as beliefs and desires. When animals forage their environment, select preys, patches, or mates, no one presupposes that they entertain beliefs or desires. There is nonetheless a presupposition that “much of the structure of the internal mental operations that inform decisions can be viewed as the product of evolution and natural selection”.[iv] Thus, to a certain degree, the neuronal processes concerned with the use of information are effective and efficient, otherwise natural selection would have discarded them. I shall label these presuppositions, and the mechanisms it might reveal, “natural rationality”. Natural rationality is a possibility condition for the concept of biological decision-making and the economy-of-nature principle. One needs to presuppose that there is a natural excellence in the biosphere before studying decisions and constraints.

More than a logical prerequisite, natural rationality concerns the descriptive and normative properties of the mechanisms by which humans and other animals make decisions. Most concepts of rationality take only the descriptive or the normative side, and hence tend to describe cognitive/neuronal processes without concern for their optimality, or state ideal conditions for rational behavior. For instance, while classical economics considers rational-choice theory either as a normative theory or a useful fiction, proponents of bounded rationality or ecological rationality refuse to characterize decision-making as optimization.[v] Others advocate a strong division of labor between normative and descriptive project: Tversky and Kahneman, for instance, concluded from their studies of human bounded rationality that the normative and descriptive accounts of decision-making are two separate projects that “cannot be reconciled”[vi]

The perspective I suggest here is that we should expect an overlap between normative and descriptive theories, and that the existence of this overlap is warranted by natural selection. On the normative side, we should ask what procedures and mechanisms biological agents should follow in order to make effective and efficient decision given all their constraints in the economy of nature. On the descriptive side, we must assess whether a procedure succeeds in achieving goals or, conversely, what goals could a procedure aim at achieving. If there is no overlap between norms and facts, then either norms should be reconceptualized or facts should be scrutinized: it might be the case that norms are unrealistic or that we did not identify the right goal or value.

This accounts contrasts with philosophers (e.g. Dennett or Davidson) who construe rationality as an idealization and researchers who preach the elimination of this concept because of its idealized status (evolutionary psychologists, for instance[vii]). Thus, rationality can be conceived not as an a priori postulate in economy and philosophy, but as an empirical and multidisciplinary research program. Quine once said that “creatures inveterately wrong in their inductions have a pathetic but praiseworthy tendency to die out before reproducing their kind”[viii]. Whether it is true for inductions is still open to debate, but I suggest that it clearly applies to decisions.

Related posts
Notes and references
  • [i] (Gintis, 2007, p. 3)
  • [ii] See for instance how neuroscience, game theory, economic, philosophy, psychology and evolutionary theory interact in (E. Fehr & Fischbacher, 2002; Ernst Fehr & Fischbacher, 2003; Hauser, 2006; Penner et al., 2005).
  • [iii] (Davidson, 1980; Dennett, 1987; Popper, 1994).
  • [iv] (Real, 1994, p. 4)
  • [v] (Chase et al., 1998; Gigerenzer, 2004; Selten, 2001)
  • [vi] (Tversky & Kahneman, 1986, p. s272)
  • [vii][vii] (Cosmides & Tooby, 1994)
  • [viii] (Quine, 1969, p. 126)

References

  • Chase, V. M., Hertwig, R., & Gigerenzer, G. (1998). Visions of Rationality. Trends in Cognitive Science, 2(6), 206-214.
  • Cosmides, L., & Tooby, J. (1994). Better Than Rational: Evolutionary Psychology and the Invisible Hand. The American Economic Review, 84(2), 327-332.
  • Davidson, D. (1980). Essays on Actions and Events. Oxford: Oxford University Press.
  • Dennett, D. C. (1987). The Intentional Stance. Cambridge, Mass.: MIT Press.
  • Fehr, E., & Fischbacher, U. (2002). Why Social Preferences Matter: The Impact of Non-Selfish Motives on Competition, Cooperation and Incentives. Economic Journal, 112, C1-C33.
  • Fehr, E., & Fischbacher, U. (2003). The Nature of Human Altruism. Nature, 425(6960), 785-791.
  • Gigerenzer, G. (2004). Fast and Frugal Heuristics: The Tools of Bounded Rationality. In D. Koehler & N. Harvey (Eds.), Blackwell Handbook of Judgment and Decision Making (pp. 62–88). Oxford: Blackwell.
  • Gintis, H. (2007). A Framework for the Unification of the Behavioral Sciences. Behavioral and Brain Sciences, 30(01), 1-16.
  • Hauser, M. D. (2006). Moral Minds : How Nature Designed Our Universal Sense of Right and Wrong. New York: Ecco.
  • Penner, L. A., Dovidio, J. F., Piliavin, J. A., & Schroeder, D. A. (2005). Prosocial Behavior: Multilevel Perspectives. Annual Review of Psychology, 56(1), 365-392.
  • Popper, K. R. (1994). Models, Instruments, and Truth: The Status of the Rationality Principle in the Social Sciences. In The Myth of the Framework. In Defence of Science and Rationality
  • Quine, W. V. O. (1969). Ontological Relativity, and Other Essays. New York,: Columbia University Press.
  • Real, L. A. (1994). Behavioral Mechanisms in Evolutionary Ecology: University of Chicago Press.
  • Selten, R. (2001). What Is Bounded Rationality ? . In G. Gigerenzer & R. Selten (Eds.), Bounded Rationality: The Adaptive Toolbox (pp. 13-36). MIT Press: Cambridge, MA.
  • Tversky, A., & Kahneman, D. (1986). Rational Choice and the Framing of Decisions. The Journal of Business, 59(4), S251-S278.



9/13/07

Orbitofrontal Cortex Encodes Willingness to Pay in Everyday Economic Transactions

Last week, I discussed the confusion around the notion of valuation. Just to add a little complexity, a new study shows that OFC (also thought to encode economic value) encore the willingness-to-pay:
An essential component of every economic transaction is a willingness-to-pay (WTP) computation in which buyers calculate the maximum amount of financial resources that they are willing to give up in exchange for the object being sold. Despite its pervasiveness, little is known about how the brain makes this computation. We investigated the neural basis of the WTP computation by scanning hungry subjects' brains using functional magnetic resonance imaging while they placed real bids for the right to eat different foods. We found that activity in the medial orbitofrontal cortex and in the dorsolateral prefrontal cortex encodes subjects' WTP for the items. Our results support the hypothesis that the medial orbitofrontal cortex encodes the value of goals in decision making.




Philosophy of neuroscience: two recent papers

Sometimes, philosophers have relevant things to say about science. Here is two papers by two philosophers of (neuro)science I warmly recommend. The first one, by Michael Anderson, proposes a methodology to understand the contribution of different brain areas to cognitive functions (and to make sense of all these studies that say "area X does Z"):

Anderson, M.L. Massive redeployment, exaptation, and the functional integration of cognitive operations. Synthese, forthcoming.

The massive redeployment hypothesis (MRH) is a theory about the functional topography of the human brain, offering a middle course between strict localization on the one hand, and holism on the other. Central to MRH is the claim that cognitive evolution proceeded in a way analogous to component reuse in software engineering, whereby existing components—originally developed to serve some specific purpose—were used for new purposes and combined to support new capacities, without disrupting their participation in existing programs. If the evolution of cognition was indeed driven by such exaptation, then we should be able to make some specific empirical predictions regarding the resulting functional topography of the brain. This essay discusses three such predictions, and some of the evidence supporting them. Then, using this account as a background, the essay considers the implications of these findings for an account of the functional integration of cognitive operations. For instance, MRH suggests that in order to determine the functional role of a given brain area it is necessary to consider its participation across multiple task categories, and not just focus on one, as has been the typical practice in cognitive neuroscience. This change of methodology will motivate (even perhaps necessitate) the development of a new, domain-neutral vocabulary for characterizing the contribution of individual brain areas to larger functional complexes, and direct particular attention to the question of how these various area roles are integrated and coordinated to result in the observed cognitive effect. Finally, the details of the mix of cognitive functions a given area supports should tell us something interesting not just about the likely computational role of that area, but about the nature of and relations between the cognitive functions themselves. For instance, growing evidence of the role of “motor” areas like M1, SMA and PMC in language processing, and of “language” areas like Broca’s area in motor control, offers the possibility for significantly reconceptualizing the nature both of language and of motor control.
In the other paper, Chris Eliasmith presents the Engineering Framework (NEF), a simulation methodology.

Eliasmith, C. How to build a brain: from function to implementation. Synthese, forthcoming.


To have a fully integrated understanding of neurobiological systems, we must address two fundamental questions: 1. What do brains do (what is their function)? and 2. How do brains do whatever it is that they do (how is that function implemented)? I begin by arguing that these questions are necessarily inter-related. Thus, addressing one without consideration of an answer to the other, as is often done, is a mistake. I then describe what I take to be the best available approach to addressing both questions. Specifically, to address 2, I adopt the Neural Engineering Framework (NEF) of Eliasmith & Anderson [Neural engineering: Computation representation and dynamics in neurobiological systems. Cambridge, MA: MIT Press, 2003] which identifies implementational principles for neural models. To address 1, I suggest that adopting statistical modeling methods for perception and action will be functionally sufficient for capturing biological behavior. I show how these two answers will be mutually constraining, since the process of model selection for the statistical method in this approach can be informed by known anatomical and physiological properties of the brain, captured by the NEF. Similarly, the application of the NEF must be informed by functional hypotheses, captured by the statistical modeling approach.

Together, these two papers provides methodologies that contribute to a better understanding of the brain, its functions and its modelling. Check also their homepage for great papers on philosophy of neuroscience.


Links:




Cognitive Control and Dopamine: A Very Brief Intro

In certain situations, learned routines are not enough. When situations are too uncommon, dangerous and difficult or when they require the overcoming of a habitual response, decisions must be guided by representations. Acting upon an internal representation is referred to, in cognitive science, as cognitive control or executive function[1]. The agent is lead by a representation of a goal and will robustly readjust its behavior in order to maintain the pursuit of a goal. The behavior is then controlled ‘top-down’, not ‘bottom-up’. In the Stroop task, for instance, subject must identify the color of written words such as ‘red’, ‘blue' or ‘yellow’ printed in different colors (the word and the ink color do not match). The written word, however, primes the subject to focus on the meaning of the word instead of focusing on the ink’s color. If, for instance, the word “red” is written in yellow ink, subjects will utter “red” more readily than they say “yellow”. There is a cognitive conflict between the semantic priming induced by the word and the imperative to focus on the ink’s color. In this task, cognitive control mechanisms ought to give priority to goals in working memory (naming ink color) over external affordances (semantic priming). An extreme lack of cognitive control is exemplified in subjects who suffer from “environmental dependency syndrome”[2]: they will spontaneously do what their environment indicates of affords them: for instance, they will sit on a chair whenever they see one, or undress and get into a bed whenever they are in presence of a bed (even if it’s not in a bedroom).

Cognitive control is thought to happen mostly in the prefrontal cortex (PFC),[3] an area strongly innervated by midbrain dopaminergic fibers. Prefrontal areas activity is associated with maintenance and updating of cognitive representations of goals. Moreover, impairment of these areas results in executive control deficits (such as the environmental dependency syndrome). Since working memory is limited, however, agents cannot hold everything in their prefrontal areas. Thus the brain faces a tradeoff between attending to environmental stimuli (that may reveal rewards or danger, for instance) and maintaining representation of goals, viz. the tradeoff between rapid updating and active maintenance [4]. Efficiency requires brains to focus on relevant information and again, dopaminergic systems are involved in this process. According to many researches[5], dopaminergic activity implements a ‘gating’ mechanism, by which the PFC alternates between rapid updating and active maintenance. A higher level of dopamine in prefrontal area signals the need to rapidly update goals in working memory (rapid updating: ‘opening the gate’), while a lower level induces resistance to afferent signals and thus a focus on represented goals (active maintenance: ‘shutting the gate’). Hence dopaminergic neurons select which information (goal representation or external environment) is worth paying attention to. This mechanisms is thought to be implemented by different dopamine receptors, the D1 and D2 being responsive to different dopamine concentration (D1-low, D2-high):


Fig. 1 (From O'Reilly, 2006). Dopamine-based gating mechanism that emerges from the detailed biological model of Durstewitz, Seamans, and colleagues. The opening of the gate occurs in the dopamine D2-receptor–dominated state (State 1), in which any existing active maintenance is destabilized and the system is more responsive to inputs. The closing of the gate occurs in the D1-receptor–dominated state (State 2), which stabilizes the strongest activation pattern for robust active maintenance. D2 receptors are located synaptically and require high concentrations of dopamine and are therefore activated only during phasic dopamine bursts, which thus trigger rapid updating. D1 receptors are extrasynaptic and respond to lower concentrations, so robust maintenance is the default state of the system with normal tonic levels of dopamine firing.

Here is a neurobiological description of the phenomena, with neuroanatomical details:



Fig. 2. (From O'Reilly, 2006). Dynamic gating produced by disinhibitory circuits through the basal ganglia and frontal cortex/PFC (one of multiple parallel circuits shown). (A) In the base state (no striatum activity) and when NoGo (indirect pathway) striatum neurons are firing more than Go, the SNr (substantia nigra pars reticulata) is tonically active and inhibits excitatory loops through the basal ganglia and PFC through the thalamus. This corresponds to the gate being closed, and PFC continues to robustly maintain ongoing activity (which does not match the activity pattern in the posterior cortex, as indicated). (B) When direct pathway Go neurons in striatum fire, they inhibit the SNr and thus disinhibit the excitatory loops through the thalamus and the frontal cortex, producing a gating-like modulation that triggers the update of working memory representations in prefrontal cortex. This corresponds to the gate being open.

Hence it is interesting to note that dopaminergic neurons are involved in basic motivation and reinforcement, and in more abstract operations such as cognitive control.



Notes and references
  1. (Norman & Shallice, 1980; Shallice, 1988)
  2. (Lhermitte, 1986)
  3. (Duncan, 1986; Koechlin, Ody, & Kouneiher, 2003; Miller & Cohen, 2001; O’Reilly, 2006)
  4. (O’Reilly, 2006)
  5. (Montague, Hyman, & Cohen, 2004; O'Donnell, 2003; O’Reilly, 2006)

  • Durstewitz, D., Seamans, J. K., & Sejnowski, T. J. (2000). Dopamine-Mediated Stabilization of Delay-Period Activity in a Network Model of Prefrontal Cortex. Journal of Neurophysiology, 83(3), 1733-1750.
  • Duncan, J. (1986). Disorganization of behavior after frontal lobe damage. Cognitive Neuropsychology, 3(3), 271-290.
  • Koechlin, E., Ody, C., & Kouneiher, F. (2003). The Architecture of Cognitive Control in the Human Prefrontal Cortex. Science, 302(5648), 1181-1185.
  • Lhermitte, F. (1986). Human autonomy and the frontal lobes. Part 11: Patient behavior in complex and social situations: The “environmental dependency syndrome.” Annals of Neurology, 19(4), 335–343.
  • Miller, E. K., & Cohen, J. D. (2001). An integrative theory of prefrontal cortex function. Annual Review of Neuroscience, 24(1), 167-202.
  • Montague, P. R., Hyman, S. E., & Cohen, J. D. (2004). Computational roles for dopamine in behavioural control. Nature, 431(7010), 760.
  • Norman, D. A., & Shallice, T. (1980). Attention to Action: Willed and Automatic Control of Behavior: Center for Human Information Processing, University of California, San Diego.
  • O'Donnell, P. (2003). Dopamine gating of forebrain neural ensembles. European Journal of Neuroscience, 17(3), 429-435.
  • O’Reilly, R. C. (2006). Biologically Based Computational Models of High-Level Cognition Science, 314, 91-94.
  • Shallice, T. (1988). From neuropsychology to mental structure. Cambridge [England] ; New York: Cambridge University Press.



9/10/07

Social Cognition: A Special Issue of Science

The new edition of Science if devoted to Social Cognition. It
(...) explores the adaptive advantages of group life and the accompanying development of social skills. News articles examine clues from our primate cousins about the evolution of sophisticated social behavior and explorations of human behavior made possible by computer-generated realities. Review articles dissect the human capacity for prospection and the links between sociality and brain evolution and fitness. And related podcast segments highlight research on the social abilities of children and chimps and the value of virtual worlds to studies of social science

Four papers you don't want to miss:

Moreover, in the same edition, psychologists Dan Gilbert and Tim Wilson presents a theory of prospection, the anticipation of future events (a subject important for decision-making research:

All animals can predict the hedonic consequences of events they've experienced before. But humans can predict the hedonic consequences of events they've never experienced by simulating those events in their minds. Scientists are beginning to understand how the brain simulates future events, how it uses those simulations to predict an event's hedonic consequences, and why these predictions so often go awry.



8/28/07

The Political Brain

A book review in the NYT of Drew Westen's new book, "The Political Brain".

Stop Making Sense

Published: August 26, 2007

Between 2000 and 2006, a specter haunted the community of fundamentalist Democrats. Members of this community looked around and observed their moral and intellectual superiority. They observed that their policies were better for the middle classes. And yet the middle classes did not support Democrats. They tended to vote, in large numbers, for the morally and intellectually inferior party, the one, moreover, that catered to the interests of the rich.

How could this be?

Serious thinkers set to work, and produced a long shelf of books answering this question. Their answers tended to rely on similar themes. First, Democrats lose because they are too intelligent. Their arguments are too complicated for American voters. Second, Democrats lose because they are too tolerant. They refuse to cater to racism and hatred. Finally, Democrats lose because they are not good at the dark art of politics. Republicans, though they are knuckle-dragging simpletons when it comes to policy, are devilishly clever when it comes to electioneering. They have brilliant political consultants like Lee Atwater and Karl Rove, who frame issues so fiendishly, they can fool the American people into voting against their own best interests. (READ MORE)




8/22/07

Just (don't) do it: The neural correlate of the veto process

A study published in the new edition of the Journal of Neuroscience proposes that the dorsal fronto-median cortex (dFMC) is primarily involved in the inhibition of intentional action. Subjects had to inhibit a simple decision: choosing when to execute a simple key press while observing a rotating clock hand (the design is hence analogue to the famous Ben Libet's experiment on free will where he found out that "subjects perceived the intention to press as occurring before a conscious experience of actually moving". The difference being that this time, researchers have fMRI data (and not just EEG recording) and that subjects must choose and then inhibit. So here is that small piece of gray matter that inhibit you behavior:




(from Brass & Haggard, 2007)

Interestingly, their finding also suggest a top-down mechanisms for action inhibition:

Cognitive models of inhibition have focused on inhibition of prepotent responses to external stimuli (Logan et al., 1984; Cohen et al., 1990). An important distinction is made between "lateral" competitive interaction between alternative representations at a single level (Rumelhart and McClelland, 1986) and inhibitory top-down control signals from hierarchically higher brain areas (Norman and Shallice, 1986). The first idea would be consistent with a general decision process being involved. If the dFMC decides between action and inhibition by a competitive interaction process, then representations corresponding to the possibilities of action and to non-action should initially both be active, leading to activation in both action trials and inhibition trials. Our finding of minimal dFMC activation in action trials (...) argues against a view of endogenous inhibition based on competitive interaction between alternatives and thus is also not consistent with the idea of the dFMC being involved in a general decision process. In contrast, our result is consistent with a specific top-down control signal gating the neural pathways linking intention to action. This view is supported by the negative correlation between dFMC activation and primary motor cortex activation.



References



8/7/07

Two blogs carnivals: philosophy and neuroscience

But first, what is a blog carnival?

A blog carnival is a type of blog event. It is similar to a magazine, in that it is dedicated to a particular topic, and is published on a regular schedule, often weekly or monthly. Each edition of a blog carnival is in the form of a blog article that contains permalinks links to other blog articles on the particular topic.

There are many variations, but typically, someone who wants to organize a carnival posts details of the theme or topic to their blog, and asks readers to submit relevant articles for inclusion in an upcoming edition. The host then collects links to these submissions, edits and annotates them (often in very creative ways), and publishes the resulting round-up to his or her blog. (From Wikiepdia)

Many carnivals have a home page or principal organizer, who lines up guest bloggers to host each edition. This means that the carnival travels, appearing on a different blog each time.
Two Blog carnival may be of interest for the readers of this blog:



Enjoy !

(other blog carnivals are listed here)



8/1/07

Special issues of the Journal of Neuroscience on decision-making

The new edition of The Journal of Neuroscience features six (!!) Mini-Reviews papers (max 5 pages) on decision-making,:

  • Balleine, B. W., Delgado, M. R., & Hikosaka, O. (2007). The Role of the Dorsal Striatum in Reward and Decision-Making. J. Neurosci., 27(31), 8161-8165.
  • Murray, E. A., O'Doherty, J. P., & Schoenbaum, G. (2007). What We Know and Do Not Know about the Functions of the Orbitofrontal Cortex after 20 Years of Cross-Species Studies. J. Neurosci., 27(31), 8166-8169.
  • Lee, D., Rushworth, M. F. S., Walton, M. E., Watanabe, M., & Sakagami, M. (2007). Functional Specialization of the Primate Frontal Cortex during Decision Making. J. Neurosci., 27(31), 8170-8173.
  • Knutson, B., & Bossaerts, P. (2007). Neural Antecedents of Financial Decisions. J. Neurosci., 27(31), 8174-8177.
  • Corrado, G., & Doya, K. (2007). Understanding Neural Coding through the Model-Based Analysis of Decision Making. J. Neurosci., 27(31), 8178-8180.
  • Wickens, J. R., Horvitz, J. C., Costa, R. M., & Killcross, S. (2007). Dopaminergic Mechanisms in Actions and Habits. J. Neurosci., 27(31), 8181-8183.



A basic mode of behavior: a review of reinforcement learning, from a computational and biological point of view.

The Journal Frontiers of Interdisciplinary Research in the Life Sciences (HFSP Publishing) made its first issue freely available online. The Journal specializes in "innovative interdisciplinary research at the interface between biology and the physical sciences." An excellent paper (complete, clear, exhaustive) by Kenji Doya presents a state-of-the-art review of reinforcement learning, both as a computational theory (the procedures) and a biological mechanism (neural activity). Exactly what the title announces: Reinforcement learning: Computational theory and biological mechanisms. The paper covers research in neuroscience, AI, computer science, robotics, neuroeconomics, psychology. See this nice schema of reinforcement learning in the brain:



(From the paper:) A schematic model of implementation of reinforcement learning in the cortico-basal ganglia circuit (Doya, 1999, 2000). Based on the state representation in the cortex, the striatum learns state and action value functions. The state value coding striatal neurons project to dopamine neurons, which sends the TD signal back to the striatum. The outputs of action value coding striatal neurons channel through the pallidum and the thalamus, where stochastic action selection may be realized

This stuff is exactly what a theory of natural rationality (and economics tout court): plausible, tractable, and real computational mechanism grounded in neurobiology. As Selten once said, speaking of reinforcement learning:

a theory of bounded rationality cannot avoid this basic mode of behavior (Selten, 2001, p. 16)


References



7/26/07

Special issues of NYAS on biological decision-making

The may issue of the Annals of the New York Academy of Sciences is devoted to Reward and Decision Making in Corticobasal Ganglia Networks. Many big names in decision neuroscience (Berns, Knutson, Delgado, etc.) contributed.


Introduction. Current Trends in Decision Making
Bernard W Balleine, Kenji Doya, John O'Doherty, Masamichi Sakagami

Learning about Multiple Attributes of Reward in Pavlovian Conditioning
ANDREW R DELAMATER, STEPHEN OAKESHOTT

Should I Stay or Should I Go?. Transformation of Time-Discounted Rewards in Orbitofrontal Cortex and Associated Brain Circuits
MATTHEW R ROESCH, DONNA J CALU, KATHRYN A BURKE, GEOFFREY SCHOENBAUM

Model-Based fMRI and Its Application to Reward Learning and Decision Making
JOHN P O'DOHERTY, ALAN HAMPTON, HACKJIN KIM

Splitting the Difference. How Does the Brain Code Reward Episodes?
BRIAN KNUTSON, G. ELLIOTT WIMMER

Reward-Related Responses in the Human Striatum
MAURICIO R DELGADO

Integration of Cognitive and Motivational Information in the Primate Lateral Prefrontal Cortex
MASAMICHI SAKAGAMI, MASATAKA WATANABE

Mechanisms of Reinforcement Learning and Decision Making in the Primate Dorsolateral Prefrontal Cortex
DAEYEOL LEE, HYOJUNG SEO


Resisting the Power of Temptations. The Right Prefrontal Cortex and Self-Control
DARIA KNOCH, ERNST FEHR

Adding Prediction Risk to the Theory of Reward Learning
KERSTIN PREUSCHOFF, PETER BOSSAERTS

Still at the Choice-Point. Action Selection and Initiation in Instrumental Conditioning
BERNARD W BALLEINE, SEAN B OSTLUND

Plastic Corticostriatal Circuits for Action Learning. What's Dopamine Got to Do with It?
RUI M COSTA

Striatal Contributions to Reward and Decision Making. Making Sense of Regional Variations in a Reiterated Processing Matrix
JEFFERY R WICKENS, CHRISTOPHER S BUDD, BRIAN I HYLAND, GORDON W ARBUTHNOTT

Multiple Representations of Belief States and Action Values in Corticobasal Ganglia Loops
KAZUYUKI SAMEJIMA, KENJI DOYA

Basal Ganglia Mechanisms of Reward-Oriented Eye Movement
OKIHIDE HIKOSAKA

Contextual Control of Choice Performance. Behavioral, Neurobiological, and Neurochemical Influences
JOSEPHINE E HADDON, SIMON KILLCROSS

A "Good Parent" Function of Dopamine. Transient Modulation of Learning and Performance during Early Stages of Training
JON C HORVITZ, WON YUNG CHOI, CECILE MORVAN, YANIV EYNY, PETER D BALSAM

Serotonin and the Evaluation of Future Rewards. Theory, Experiments, and Possible Neural Mechanisms
NICOLAS SCHWEIGHOFER, SAORI C TANAKA, KENJI DOYA

Receptor Theory and Biological Constraints on Value
GREGORY S BERNS, C. MONICA CAPRA, CHARLES NOUSSAIR

Reward Prediction Error Computation in the Pedunculopontine Tegmental Nucleus Neurons
YASUSHI KOBAYASHI, KEN-ICHI OKADA

A Computational Model of Craving and Obsession
A. DAVID REDISH, ADAM JOHNSON

Calculating the Cost of Acting in Frontal Cortex
MARK E WALTON, PETER H RUDEBECK, DAVID M BANNERMAN, MATTHEW F. S RUSHWORTH

Cost, Benefit, Tonic, Phasic. What Do Response Rates Tell Us about Dopamine and Motivation?
YAEL NIV



7/25/07

More than Trust: Oxytocin Increases Generosity

It was known since a couple of years that oxytocin (OT) increases trust (Kosfeld, et al., 2005): in the Trust game, players transfered more money once they inhale OT. Now recent research also suggest that it increases generosity. In a paper presented at the ESA (Economic Science Association, an empirically-oriented economics society) meeting, Stanton, Ahmadi, and Zak, (from the Center for Neuroeconomics studies) showed that Ultimatum players in the OT group offered more money (21% more) than in the placebo group--$4.86 (OT) vs. $4.03 (placebo).
They defined generosity as "an offer that exceeds the average of the MinAccept" (p.9), i.e., the minimum acceptable offer by the "responder" in the Ultimatum. In this case, offers over $2.97 were categorized as generous. Again, OT subjects displayed more generosity: the OT group offered $1.86 (80% more) over the minimum acceptable offer, while placebo subjects offered $1.03.


Interestingly, OT subjects did not turn into pure altruist: they make offers (mean $3.77) in the Dictator game similar to placebo subjects (mean $3.58, no significant difference). Thus the motive is neither direct nor indirect reciprocity (Ultimatum were blinded one-shot so there is no tit-for-tat or reputation involved here). It is not pure altruism, according to Stanton et al., (or "strong reciprocity"--see this post on the distinction between types of reciprocity) because the threat of the MinAccept compels players to make fair offers. They conclude that generosity in enhanced because OT affects empathy. Subjects simulate the perspective of the other player in the Ultimatum, but not in the Dictator. Hence, generosity "runs" on empathy: in empathizing context (Ultimatum) subjects are more generous, but in non-empathizing context they don't--in the dictator, it is not necessary to know the opponent's strategy in order to compute the optimal move, since her actions has no impact on the proposer's behavior. It would be interesting to see if there is a different OT effect in basic vs. reenactive empathy (sensorimotor vs. deliberative empathy; see this post).

Interested readers should also read Neural Substrates of Decision-Making in Economic Games, by one of the author of the study (Stanton): in her PhD Thesis, she desribes many neurpeconomic experiences.

[Anecdote: I once asked people of the ESA why they call their society like that: all presented papers were experimental, so I thought that the name should reflect the empirical nature of the conference. They replied judiscioulsy : "Because we think that it's how economics should be done"...]

References



7/19/07

Beautiful picture of brain areas involved in decision-making

Found yesterday, in a paper by Sanfey (nice review paper, by the way):




"Fig. 2. Map of brain areas commonly found to be activated in decision-making studies. The sagittal section (A) shows the location of the anterior cingulate cortex (ACC), medial prefrontal cortex (MPFC), orbitofrontal cortex (OFC), nucleus accumbens (NA), and substantia nigra (SN). The lateral view (B) shows the location of the dorsolateral prefrontal cortex (DLPFC) and lateral intraparietal area (LIP). The axial section (C; cut along the white line in A and B) shows the location of the insula (INS) and basal ganglia (BG)."
from: