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PubMed2006

Midbrain dopamine neurons encode decisions for future action.

Current models of the basal ganglia and dopamine neurons emphasize their role in reinforcement learning. However, the role of dopamine neurons in decision making is still unclear. We recorded from dopamine neurons in monkeys engaged in two types of trial: reference trials in an instructed-choice task and decision trials in a two-armed bandit decision task. We show that the activity of dopamine neurons in the decision setting is modulated according to the value of the upcoming action. Moreover, analysis of the probability matching strategy in the decision trials revealed that the dopamine population activity and not the reward during reference trials determines choice behavior. Because dopamine neurons do not have spatial or motor properties, we conclude that immediate decisions are likely to be generated elsewhere and conveyed to the dopamine neurons, which play a role in shaping long-term decision policy through dynamic modulation of the efficacy of basal ganglia synapses.

Animals↗
PubMed2004

A model of antipsychotic action in conditioned avoidance: a computational approach.

The selective ability of antipsychotic drugs (APDs) to attenuate conditioned avoidance responding (CAR) has been recognized for over 50 years. However, most efforts to account for this finding have been either neurochemically oriented (focusing on the neuromodulator dopamine) or behavioral, with little effort invested in uniting the two within a computational model. In this paper we propose a computational model, based on concepts from formal reinforcement learning theory, which accounts for the basic finding that noncataleptic doses of APDs disrupt avoidance without disrupting escape. The model formally separates out sensory, motor, and reward processes, and makes novel predictions pertaining to the dose- and time-dependent effects of APDs on response latencies--predictions which we verified in experimental studies using four different APDs (haloperidol, chlorpromazine, risperidone, and clozapine). The APD action in this model is most consistent with an effect on 'expected future reward'--an idea closely linked to motivational drives and consistent with several leading theories of dopamine action.

Animals↗
PubMed2003

Dopamine efflux in nucleus accumbens shell and core in response to appetitive classical conditioning.

Dopamine transmission within the nucleus accumbens has been implicated in associative reinforcement learning. We investigated the effect of appetitive classical conditioning on dopamine efflux in the rat nucleus accumbens shell and core, as dopamine may be differentially activated by conditioned and unconditioned stimuli (CS, US) in these subregions. After implantation of microdialysis cannulae, rats were food restricted and trained for three consecutive days with three acquisition sessions per day. A 10-s noise (CS) was immediately followed by the delivery of two reward pellets (US) for the conditioned group (paired presentation), whereas conditioned stimuli and unconditioned stimuli were presented at random for the control group (unpaired presentation). On the fourth day, all rats were given a further CS + US session and two CS-alone sessions, and extracellular dopamine concentrations were measured (7.5 min/per sample). Behavioural measures (number of nose pokes, latency to nose poke after conditioned stimuli onset, locomotor activity) demonstrated that the paired groups showed a high level of conditioning. CS + US presentation increased dopamine equally in both shell and core of the paired and unpaired groups. CS alone presentation induced a conditioned dopamine release only in the paired groups. No significant difference was found between shell and core. Unlike previous conditioning paradigms involving either a more salient US (foot shock, addictive drug) or a more complex CS, the present paradigm, using normal reward pellets as US and a discrete auditory stimulus as CS, did not lead to differential responses in dopamine efflux in shell and core subregions of the nucleus accumbens.

Animals↗
PubMed2001

The effect of a geriatric education program on emergency nurses.

OBJECTIVE: In a previous study, emergency nurses gave a high priority to the educational topics of geriatric depression, physical assessment of the elderly, and mental status testing. Our objective was to measure the impact of a 1-day workshop for emergency nurses that addressed these educational needs. METHODS: The workshop consisted of case-based didactic sessions addressing (1) physical assessment of the elderly, (2) delirium, depression, and dementia, and (3) a practical approach to mental status testing in the elderly. The educational program was evaluated using 2 methods: (1) before, and 1 month after, the workshop, participants rated their own practice patterns; and (2) during the course of 2 years, changes in the number of referrals for geriatric assessment and home care from a large emergency department in the study area were monitored. RESULTS: Of 101 ED nurses who attended the 1-day workshop, 51 completed both preworkshop and postworkshop questionnaires (response rate, 50.5%). the most significant self-reported changes in practice 1 month after the workshop were improved screening for depression and altered mental status in older adults (P <.0001 and P <.01, respectively). Other positive changes were noted for inquiring about unplanned weight loss and assistance received at home. A steady increase in the number of referrals for geriatric assessment and home care was noted from the emergency department being monitored. DISCUSSION: Targeted geriatric educational programs can make an impact on the practice of emergency nurses when they are part of an overall, coordinated approach to improving assessment and discharge planning for elderly patients in emergency departments. Mechanisms for reinforcing learning several months after educational events may prove critical to the long-term success of such initiatives.

Aged↗
PubMed2005

Electrophysiological correlates of reward prediction error recorded in the human prefrontal cortex.

Lesion and functional imaging studies have shown that the ventromedial prefrontal cortex is critically involved in the avoidance of risky choices. However, detailed descriptions of the mechanisms that underlie the establishment of such behaviors remain elusive, due in part to the spatial and temporal limitations of available research techniques. We investigated this issue by recording directly from prefrontal depth electrodes in a rare neurosurgical patient while he performed the Iowa Gambling Task, and we concurrently measured behavioral, autonomic, and electrophysiological responses. We found a robust alpha-band component of event-related potentials that reflected the mismatch between expected outcomes and actual outcomes in the task, correlating closely with the reward-related error obtained from a reinforcement learning model of the patient's choice behavior. The finding implicates this brain region in the acquisition of choice bias by means of a continuous updating of expectations about reward and punishment.

Choice Behavior↗
PubMed1995

Speech technology in the year 2001.

This paper introduces the session "Technology in the Year 2001" and is the first of four papers dealing with the future of human-machine communication by voice. In looking to the future it is important to recognize both the difficulties of technological forecasting and the frailties of the technology as it exists today--frailties that are manifestations of our limited scientific understanding of human cognition. The technology to realize truly advanced applications does not yet exist and cannot be supported by our presently incomplete science of speech. To achieve this long-term goal, the authors advocate a fundamental research program using a cybernetic approach substantially different from more conventional synthetic approaches. In a cybernetic approach, feedback control systems will allow a machine to adapt to a linguistically rich environment using reinforcement learning.

Computers↗
PubMed1998

On the culture of student abuse in medical school.

The abuse of students is ingrained in medical education, and has shown little amelioration despite numerous publications and righteous declarations by the academic community over the past decade. The culture of abuse conflicts with the renewed commitments of medical educators and practice professionals to imbue students with a higher degree of professionalism and cultural sensitivity. The authors describe the profiles of student abuse, drawn from recent national surveys of medical students using the AAMC Medical School Graduation Questionnaire, and focus on the most common forms of reported mistreatment--public belittlement and humiliation--that appear to be misguided efforts to reinforce learning. Along with others, the authors believe that the use of aversive methods to make students learn and behave is likely to foster insensitive and punitive behaviors that are passed down from teacher to learner, a "transgenerational legacy" that leads to future mistreatment of others by those who themselves have been mistreated. The undesirable result is compounded when these behaviors are adopted and directed toward patients and colleagues. The authors advocate more concerted action to curtail the abuse of medical students, citing current and proposed accreditation standards that will be employed more stringently by the LCME, and propose a series of more assertive actions that schools should take. The authors stress that the attitudes, behaviors, and values that students acquire in medical school are as much the products of their socialization as the outcomes of curricular design and pedagogy, and implore medical educators to tidy up the environment for learning.

Curriculum↗
PubMed1998

Training future leaders of academic medicine: internal programs at three academic health centers.

The authors review the need for internal programs for leadership training at academic health centers and then describe in detail three programs of this type that have operated during the 1990s: (1) the Allegheny Leadership Institute, founded by the Allegheny Health, Education and Research Foundation, Pittsburgh, Pennsylvania; (2) the Physician Executive Management Development Program (PEMDP) of Saint Louis University School of Medicine; and (3) the University of Nebraska Medical Center Leadership Institute. Educational elements common to these programs include having a small class size and participants from many areas of academic medicine and health care, focusing on educational strategies that draw on participants' experiences and training, conducting the training away from the participants' institutions, having short sessions, using faculty from both within and outside the participants' institutions, and creating strategies to reinforce learning. Lessons learned reflect the unique context of each institution; the authors list the major lessons learned by each of the three programs they surveyed (e.g., leaders of the Saint Louis University PEMDP program believe that it is important to help participants implement desired changes in their work areas once they return to work, and are investigating how to do this). The authors conclude with an extensive list of recommendations to optimize the effects of leadership development training carried out in AHCs' internal programs (e.g., "Focus on specific skills that can be learned, and link the learning experiences to real work situations in health care and higher education") and explain why they think internal leadership institutes have at least three distinct advantages over external programs.

Academic Medical Centers↗
PubMed2005

Teaching the psychosocial aspects of care in the clinical setting: practical recommendations.

Communication skills and the psychosocial dimensions of patient care are increasingly taught in medical schools and generalist residency programs. Evidence suggests they are not reinforced or optimally implemented in clinical training. The authors present the product of an iterative process that was part of a national faculty development program and involved both experts and generalist teachers concerning teaching psychosocial medicine while precepting medical students and residents in clinical settings. Using scientific evidence, educational theory, and experience, the authors developed recommendations, presented them in workshops, and revised them based on input from other experts and teachers, who gave feedback and added suggestions. The results are practical, expert consensus recommendations for clinical preceptors on how to teach and reinforce learning in this area. General skills to use in preparing the trainee for improved psychosocial care are organized into the mnemonic "CAARE MORE": Connect personally with the trainee; Ask psychosocial questions and Assess the trainee's knowledge/attitudes/skills/behaviors; Role model desired attitudes/skills/behaviors; create a safe, supportive, enjoyable learning Environment; formulate specific Management strategies regarding psychosocial issues; Observe the trainee's affect and behavior; Reflect and provide feedback on doctor-patient and preceptor-trainee interactions; and provide Educational resources and best Evidence. The preceptor-trainee teaching skills that are recommended parallel good doctor-patient interaction skills. They can be used during both preceptor-trainee and preceptor-trainee-patient encounters. Important common psychosocial situations that need to be managed in patients include substance abuse, depression, anxiety, somatoform disorder, physical and sexual abuse, and posttraumatic stress disorder. For these problems, where high-level evidence exists, specific psychosocial questions for screening and case finding are provided.

Clinical Medicine↗
PubMedDate not supplied

Computerized training in breast self-examination: a test in a community health center.

Fifty-eight women recruited from a community health center completed either a brief interactive multimedia training program on breast self-examination using a breast model and computer guided feedback on accuracy of lump detection or read a National Cancer Institute pamphlet on breast self-examination and breast lumps. Women using the computer program as compared to the pamphlet group reported a higher sense of self-efficacy for being able to perform a breast self-examination immediately after their educational session and 1 month later. However, the increase in self-efficacy for the computer group diminished over 4 weeks, underscoring the importance of an environment that reminds and reinforces learning for women about the performance of regular breast self-examination. The increase in sense of self-efficacy to perform breast self-examination with roughly 20 minutes of computer-based training and the partial maintenance of that self-efficacy 30 days later suggests the utility of incorporating short, focused interventions in busy primary healthcare settings.

Adult↗
PubMed2025

Asymmetric cortical projections to striatal direct and indirect pathways distinctly control actions.

The striatal direct and indirect pathways constitute the core for basal ganglia function in action control. Although both striatal D1- and D2-spiny projection neurons (SPNs) receive excitatory inputs from the cerebral cortex, whether or not they share inputs from the same cortical neurons, and how pathway-specific corticostriatal projections control behavior remain largely unknown. Here using a G-deleted rabies system in mice, we found that more than two-thirds of excitatory inputs to D2-SPNs also target D1-SPNs, while only one-third do so vice versa. Optogenetic stimulation of striatal D1- vs. D2-SPN-projecting cortical neurons differently regulate locomotion, reinforcement learning and sequence behavior, implying the functional dichotomy of pathway-specific corticostriatal subcircuits. These results reveal the partially segregated yet asymmetrically overlapping cortical projections on striatal D1- vs. D2-SPNs, and that the pathway-specific corticostriatal subcircuits distinctly control behavior. It has important implications in a wide range of neurological and psychiatric diseases affecting cortico-basal ganglia circuitry.

Journal Article↗
PubMed1990

The Moving Children Project: a conceptual, process-oriented model for skills development in children.

The Moving Children: Healthy Children (Moving Children) Project is a multidimensional conceptual model that provides elementary teachers a structure to incorporate mental and social concepts into a physical education program. The Moving Children Model focuses on four physical concepts which cover the full range of physical activity: body movement, object control, implement control, and game structure. The model helps children apply physical, mental, and social concepts to everyday situations. This objective is implemented by structuring the lesson to the environment and facilitating communication with follow-up classroom dialogue and journal assignments. As a result, successful, experimental learning reinforces a life-long attachment to movement and principles of health promotion.

Child↗
PubMed2005

Getting to know you: reputation and trust in a two-person economic exchange.

Using a multiround version of an economic exchange (trust game), we report that reciprocity expressed by one player strongly predicts future trust expressed by their partner-a behavioral finding mirrored by neural responses in the dorsal striatum. Here, analyses within and between brains revealed two signals-one encoded by response magnitude, and the other by response timing. Response magnitude correlated with the "intention to trust" on the next play of the game, and the peak of these "intention to trust" responses shifted its time of occurrence by 14 seconds as player reputations developed. This temporal transfer resembles a similar shift of reward prediction errors common to reinforcement learning models, but in the context of a social exchange. These data extend previous model-based functional magnetic resonance imaging studies into the social domain and broaden our view of the spectrum of functions implemented by the dorsal striatum.

Caudate Nucleus↗
PubMedDate not supplied

Dynamics of betting behavior under flat reward condition.

One of the missions of the cognitive process of animals, including humans, is to make reasonable judgments and decisions in the presence of uncertainty. The balance between exploration and exploitation investigated in the reinforcement-learning paradigm is one of the key factors in this process. Recently, following the pioneering work in behavioral economics, growing attention has been directed to human behaviors exhibiting deviations from the simple maximization of external reward. Here we study the dynamics of betting behavior in a simple game, where the probability of reward and the magnitude of reward are designed to give a "zero" expected net reward ("flat reward condition"). No matter how the subject behaves, there is on average no change in one's resources, and therefore every possible sequence of action has the same value. Even in such a situation, the subjects are found to behave not in a random manner, but in ways showing characteristic tendencies, reflecting the dynamics of brain's reward system. Our results suggest that brain's reward system is characterized by a rich and complex dynamics only loosely coupled with external reward structure.

Adult↗
PubMed2006

Basal ganglia orient eyes to reward.

Expectation of reward motivates our behaviors and influences our decisions. Indeed, neuronal activity in many brain areas is modulated by expected reward. However, it is still unclear where and how the reward-dependent modulation of neuronal activity occurs and how the reward-modulated signal is transformed into motor outputs. Recent studies suggest an important role of the basal ganglia. Sensorimotor/cognitive activities of neurons in the basal ganglia are strongly modulated by expected reward. Through their abundant outputs to the brain stem motor areas and the thalamocortical circuits, the basal ganglia appear capable of producing body movements based on expected reward. A good behavioral measure to test this hypothesis is saccadic eye movement because its brain stem mechanism has been extensively studied. Studies from our laboratory suggest that the basal ganglia play a key role in guiding the gaze to the location where reward is available. Neurons in the caudate nucleus and the substantia nigra pars reticulata are extremely sensitive to the positional difference in expected reward, which leads to a bias in excitability between the superior colliculi such that the saccade to the to-be-rewarded position occurs more quickly. It is suggested that the reward modulation occurs in the caudate where cortical inputs carrying spatial signals and dopaminergic inputs carrying reward-related signals are integrated. These data support a specific form of reinforcement learning theories, but also suggest further refinement of the theory.

Animals↗