Showing papers by "Russell A. Poldrack published in 2008"

Neuroeconomics: Decision making and the brain.

Abstract: American Publishers Award for Professional & Scholarly Excellence (PROSE) Winner-Award for Excellence in Social Sciences (2009) Neuroeconomics is a new highly promising approach to understanding the neurobiology of decision making and how it affects cognitive social interactions between humans and societies/economies. This book is the first edited reference to examine the science behind neuroeconomics, including how it influences human behavior and societal decision making from a behavioral economics point of view. Presenting a truly interdisciplinary approach, Neuroeconomics presents research from neuroscience, psychology, and behavioral economics, and includes chapters by all the major figures in the field, including two Economics nobel laureates. Carefully edited for a cohesive presentation of the material, the book is also a great textbook to be used in the many newly emerging graduate courses on Neuroeconomics in Neuroscience, Psychology, and Economics graduate schools. This groundbreaking work is sure to become the standard reference source for this growing area of research. * Editors and contributing authors represent the acknowledged experts and founders of the field of Neuroeconomics and include Nobel laureates Vernon Smith and Daniel Kahneman, making this the authoritative reference for the field * Presents an interdisciplinary view of the approaches, concepts, and results of the emerging field of neuroeconomics relevant for anyone interested in this area or research * Full color presentation throughout with carefully selected illustrations to highlight key concepts

The Neural Basis of Loss Aversion in Decision-Making Under Risk

Abstract: People typically exhibit greater sensitivity to losses than to equivalent gains when making decisions. We investigated neural correlates of loss aversion while individuals decided whether to accept or reject gambles that offered a 50/50 chance of gaining or losing money. A broad set of areas (including midbrain dopaminergic regions and their targets) showed increasing activity as potential gains increased. Potential losses were represented by decreasing activity in several of these same gain-sensitive areas. Finally, individual differences in behavioral loss aversion were predicted by a measure of neural loss aversion in several regions, including the ventral striatum and prefrontal cortex.

Common Neural Substrates for Inhibition of Spoken and Manual Responses

Abstract: The inhibition of speech acts is a critical aspect of human executive control over thought and action, but its neural underpinnings are poorly understood. Using functional magnetic resonance imaging and the stop-signal paradigm, we examined the neural correlates of speech control in comparison to manual motor control. Initiation of a verbal response activated left inferior frontal cortex (IFC: Broca’s area). Successful inhibition of speech (naming of letters or pseudowords) engaged a region of right IFC (including pars opercularis and anterior insular cortex) as well as presupplementary motor area (pre-SMA); these regions were also activated by successful inhibition of a hand response (i.e., a button press). Moreover, the speed with which subjects inhibited their responses, stop-signal reaction time, was significantly correlated between speech and manual inhibition tasks. These findings suggest a functional dissociation of left and right IFC in initiating versus inhibiting vocal responses, and that manual responses and speech acts share a common inhibitory mechanism localized in the right IFC and pre-SMA.

Selective corticostriatal dysfunction in schizophrenia: examination of motor and cognitive skill learning.

Abstract: It has been suggested that patients with schizophrenia have corticostriatal circuit dysfunction (Carlsson & Carlsson, 1990). Skill learning is thought to rely on corticostriatal circuitry and different types of skill learning may be related to separable corticostriatal loops (Grafton, Hazeltine, & Ivry, 1995; Poldrack, Prabhakaran, Seger, & Gabrieli, 1999). The authors examined motor (Serial Reaction Time task, SRT) and cognitive (Probabilistic Classification task, PCT) skill learning in patients with schizophrenia and normal controls. Development of automaticity was examined, using a dual task paradigm, across three training sessions. Patients with schizophrenia were impaired at learning on the PCT compared to controls. Performance gains of controls occurred within the first session, whereas patients only improved gradually and never reached the performance level of controls. In contrast, patients were not impaired at learning on the SRT relative to controls, suggesting that patients with schizophrenia may have dysfunction in a specific corticostriatal subcircuit.

Automaticity in motor sequence learning does not impair response inhibition

Abstract: We examined the relationship between automaticity and response inhibition in the serial reaction time (SRT) task to test the common assertion that automatic behavior is ballistic. Participants trained for 3 h on the SRT, using blocks of a second-order conditional sequence interleaved with random blocks. Automaticity was measured using a concurrent secondary letter-counting task. Response inhibition was measured using a stop-signal task. RTs decreased with training, with a greater decrease for sequenced versus random blocks. Training correlated with a decreased RT cost to performing the secondary task concurrently with the SRT, indicating the development of automaticity. Crucially, there was no change in the ability to inhibit responses at the end of training, even in individuals who showed no dual-task interference. These results demonstrate that the ability to inhibit a motor response does not decrease with automaticity, suggesting that some aspects of automatic behavior are not ballistic.

Challenge-driven attention: interacting frontal and brainstem systems.

Abstract: The world is an unpredictable place, presenting challenges that fl uctuate from moment to moment. However, the neural systems for responding to such challenges are far from fully understood. Using fMRI, we studied an audiovisual task in which the trials' diffi culty and onset times varied unpredictably. Two regions were found to increase their activation for challenging trials, with their activities strongly correlated: right frontal cortex and the brainstem. The frontal area matched regions found in previous human studies of cognitive control, and activated in a graded manner with increasing task diffi culty. The brainstem responded only to the most diffi cult trials, showing a phasic activity pattern paralleling locus coeruleus recordings in monkeys. These results reveal a bridge between animal and human studies, and suggest interacting roles for the brainstem and right frontal cortex: the brainstem may signal that an attentional challenge is occurring, while right frontal cortex allocates cognitive resources in response.

Neural Substrates for Reversing Stimulus–Outcome and Stimulus–Response Associations

Abstract: Adaptive goal-directed actions require the ability to quickly relearn behaviors in a changing environment, yet how the brain supports this ability is barely understood. Using functional magnetic resonance imaging and a novel reversal learning paradigm, the present study examined the neural mechanisms associated with reversal learning for outcomes versus motor responses. Participants were extensively trained to classify novel visual symbols (Japanese Hiraganas) into two arbitrary classes ("male" or "female"), in which subjects could acquire both stimulus-outcome associations and stimulus-response associations. They were then required to relearn either the outcome or the motor response associated with the symbols, or both. The results revealed that during reversal learning, a network including anterior cingulate, posterior inferior frontal, and parietal regions showed extended activation for all types of reversal trials, whereas their activation decreased quickly for trials not involving reversal, suggesting their role in domain-general interference resolution. The later increase of right ventral lateral prefrontal cortex and caudate for reversal of stimulus-outcome associations suggests their importance in outcome reversal learning in the face of interference.

The Interface Between Neuroscience and Psychological Science

Abstract: Neuroscience and psychological science have a long history of mutual interest and influence. Yet, while neuroscientists played a critical role in the founding of psychological science (Gardner, 1984), throughout much of the first century of experimental psychology, neuroscience was relegated to a relatively minor role. At the same time, the sophisticated psychological models developed during this period were often overlooked by neuroscientists seeking to understand how the brain gives rise to thought and behavior. Exciting developments over the past two decades have changed all of this. For example, the founding of the Cognitive Neuroscience Society in 1992 marked an emerging perspective that neuroscientific approaches can play a central role in psychological theorizing, and over the past 15 years the complementary power of neuroscientific evidencehas been increasingly apparent. At the same time, one need only attend the annual meeting of the Society for Neuroscience to appreciate the fundamental role that psychological theory now plays in advancing neuroscience. Another way to assess how things have changed is to examine the evolution in the fields’ textbooks over this period. For example, in its first edition in 1980, John Anderson’s Cognitive Psychology and Its Implications (Anderson, 1980) contained few references to the neuroscience literature and limited discussion of how neuroscience data might inform psychological theorizing. The contrast with the 2005 edition (Anderson, 2005) is striking, as this newest edition has a rendering of Brodmann’s map of brain areas on the inside cover, and nearly every chapter has substantial discussion of neuroscience data and its relation to psychological processes. Consideration of one of neuroscience’s canonical texts, Principles of Neural Science by Kandel, Schwartz, and Jessell (2000), reveals a similar transformation, with increasing integration of psychological models. Technological developments have propelled the increased cross-fertilization between neural and psychological science. For example, when we were beginning graduate students in the early 1990s, the central methods available to cognitive neuroscientists studying humans were behavioral studies, computational modeling, electroencephalography, and patient studies. However, during our time as students, the field rapidly shifted with the development and dissemination of functional neuroimaging techniques, particularly functional magnetic resonance imaging (fMRI). Researchers now had the ability to non-invasively characterize the neural correlates of psychological processes with high spatial resolution. Since the development of fMRI in the early 1990s, its adoption has been nothing less than explosive; from 9 papers in 1993 to 2,139 papers in 2007, the growth of publications using fMRI has closely followed an exponential function and shows no evidence of slowing down. The aim of this special issue of Current Directions in Psychological Science is to highlight just how intimate the dialog between psychological and neural science has become. The papers in this special issue demonstrate the breadth with which neuroscientific methods and data have penetrated psychology, as well as the ways in which psychological theory has served to foster neuroscientific advances. From these articles, it is apparent how the interplay between neuroscience and psychological science has produced new insights into fundamental theoretical problems and at the same time has highlighted new questions that await answers.