Observations on the design and specification of a wrist-worn human activity monitoring system

Monitoring motor activity provides an important index of sleep, rest, and activity in field studies of sustained operations, shift-work schedules, and sleep deprivation. Poor results with previous methods led to development of a program to design a technologically improved monitoring system. In this 3-year program, specific issues were examined, ranging from the empirical characteristics of the wrist-movement signal and transduction methods to conversion of that signal to a useful index of motility. In this report, we discuss the several design issues encountered as well as observations, conclusions, and resulting specifications. The product of this program is a microprocessor-controlled, self-contained activity recording system, with 16K of digital storage and an operating life of over 30 days. The Walter Reed Activity Monitoring System is designed to examine further the behavioral and physiological correlates of activity.     

身体活动的双系统理论:一种强化学习的视角

以理性决策为基础的锻炼行为理论被认为是理解身体活动的主导体系, 它提供了与身体活动相关的认知构念作为有价值的信息。基于社会生态模型设计的行为干预措施, 因表现出了更好的效果而备受关注。近期研究表明, 积极的运动认知和当前体育环境都没能很好地促进个人锻炼习惯的养成, 因此有必要探索新的理论体系来阐明个人锻炼习惯的形成机制。解释身体活动的最新体系是双系统理论, 由于其考虑了身体活动的无意识和快乐决定因素, 有望提供一个更广泛的动机视角。一方面, 多个有代表性的身体活动双系统模型, 从简单的自发路径, 到情境线索与锻炼习惯, 再到突出自动情感评价作用的复杂概念模型, 阐明了系统1的构建, 结合锻炼行为理论所关注的系统2, 为模型的构建提供了依据。另一方面, 通过对双系统的竞争、协调和层级控制原则的分析, 为模型的控制提供了建议。经典的强化学习框架解释了双系统模型的构建与控制原则:在模型的构建方面, 无模型与基于模型的强化学习分别表示系统1和系统2。在模型的控制方面, Dyna协作架构与分层强化学习, 为身体活动可能是一种相互协作、分层执行的复杂行动组合提供了合理解释。最后提出强化学习视角下锻炼者-体育环境的互动模式, 试图从一个全新的角度探讨锻炼行为。     

Contributions of Psychophysiology to Media Research: Review and Recommendations

Despite the increasing use of psychophysiological measures in various research areas, there is a relative paucity of studies on communication, media, and media interfaces that have taken advantage of this approach. This article provides an overview of the use of psychophysiological measures of attention and emotion in media research with the focus on 3 most commonly used measures: heart rate, facial electromyography, and electrodermal activity. Selected media studies that have used psychophysiological methods to test theory-based predictions regarding the role of attentional and emotional factors in message processing are critically reviewed. The article also highlights some methodological and other issues critical for the successful application of psychophysiological methods to problems in media research. In particular, respiratory sinus arrhythmia (RSA), a selective index of parasympathetic nervous system activity, is introduced as a measure that holds particular promise for media research, given that RSA is highly sensitive to changes in attention.     

An on-line integrator for alpha quantification

A system for the on-line graphic quantification of alpha frequencies (or other frequency bands extracted from EEG signals) is described. Alpha-frequency components (8 to 13 Hz) are actively filtered from complex EEG waveforms and presented to a laboratory-developed solid state integrator. The high-level output of the integrator, which is compatible with all popular EEG and polygraph recorders, is in the form of an ascending analog voltage ramp, reset at a predetermined level, to provide a rapid quantitative determination of alpha activity and variability. The design of the integrator permits an alternate mode of operation where time-synchronized resets, in lieu of voltage-dependent resets, produce variable height voltage ramps, whose amplitude is a direct function of the accumulated alpha activity per unit time. This method of preprocessing and signal conditioning the alpha components of the EEG waveform provides a simple analog registry of on-line real-time correlation of alpha activity with various physiological and behavioral activity.     

三数值加工系统假说：数值加工机制新探

数值加工的机制是数量认知领域的核心科学问题之一。三数值加工系统假说从新的角度阐释了各种数值加工机制的关系, 它认为认知系统通过三种不同的机制来快速分析非符号刺激的数值：感数(subitizing)机制精确地分析1~4个刺激的数值; 数量(numerosity)机制分析密度适中的刺激点阵的数量, 加工误差正比于被分析的数量, 符合韦伯定律; 当刺激的密度超出一定范围时, 密度(density)机制通过分析刺激密度来推断刺激的数量关系, 加工误差正比于被加工数值的平方根。一系列研究证实, 这三种数值加工机制具有不同的行为规律和脑电特征。未来研究需要探讨数量机制是否分别与感数机制、密度机制存在平行激活, 从而阐明三种数值加工机制的作用关系。     

Remembering a location makes the eyes curve away

Working memory is a system that keeps limited information on-line for immediate access by cognitive processes. This type of active maintenance is important for everyday life activities. The present study shows that maintaining a location in spatial working memory affects the trajectories of saccadic eye movements toward visual targets, as the eyes deviate away from the remembered location. This finding provides direct evidence for a strong overlap between spatial working memory and the eye movement system. We argue that curvature is the result of the need to inhibit memory-based eye movement activity in the superior colliculus, in order to allow an accurate saccade to the visual target. Whereas previous research has shown that the eyes may deviate away from visually presented stimuli that need to be ignored, we show that the eyes also curve away from remembered stimuli.     

Nicotinic cholinergic synaptic mechanisms in the ventral tegmental area contribute to nicotine addiction

Tobacco use is a major health problem that is estimated to cause 4 million deaths a year worldwide. Nicotine is the main addictive component of tobacco. It acts as an agonist to activate and desensitize nicotinic acetylcholine receptors (nAChRs). A component of nicotine's addictive power is attributable to actions on the mesolimbic dopaminergic system, which serves a fundamental role in the acquisition of behaviors that are inappropriately reinforced by addictive drugs. Here we show that nicotine, in the same concentration and time ranges as obtained from tobacco, has three main actions that regulate the activity of midbrain dopamine (DA) neurons. Nicotine first activates and then desensitizes nAChRs on the DA neurons. This process directly excites the DA neurons for a short period of time before the nAChRs desensitize. Nicotine also enhances glutamatergic excitation and decreases GABAergic inhibition onto DA neurons. These events increase the probability for synaptic plasticity, such as long-term potentiation. The short-lived direct excitation of the DA neurons coupled with the enhanced glutamatergic afferent activity provides the presynaptic and postsynaptic coincidence necessary to initiate synaptic potentiation. In total, these synaptic events lead to a relatively long-lasting heightened activity of midbrain DA neurons. Consistent with other summarized studies, this work indicates that the synaptic changes normally associated with learning and memory can be influenced and commandeered during the nicotine addiction process.     

Extramarital sex: An examination of the literature

Extramarital sex in the marital system often provides difficult dilemmas for marital therapists in regard to treatment approaches. The authors examine various motivational and perceptual aspects among spouses for engaging in sexual activity outside the marriage. Implications for both research and treatment are discussed.     

Multimodal imaging in psychiatry: the electroencephalogram as a complement to other modalities

The use of different imaging modalities provides the clinician and researcher with different views of anatomy and physiology at unprecedented levels of detail. Multimodal imaging allows for noninvasive measurement of structure and function in humans during complex behavior, and thus provides information about the inner workings of the brain previously unavailable. The present paper examines the various imaging techniques available, and describes their application to the clinic-in the case of epilepsy-and to research-in the case of schizophrenia. Because the electroencephalogram has a dynamic response in milliseconds, it provides the best temporal sensitivity of functional measures of brain activity. When coupled with high-resolution magnetic resonance imaging measures of brain structure, this multimodal approach provides a powerful tool for understanding brain activity. Clinically, the use of multimodal imaging has provided greater precision in localization of the epileptogenic focus. For researchers attempting to determine the underlying causes of schizophrenia, the use of multimodal imaging has helped lead the field away from a specific lesion view to a more distributed system abnormality view of this disorder.     

Adaptive patterns of stress responsivity: a preliminary investigation

The adaptive calibration model (ACM) is an evolutionary-developmental theory of individual differences in stress responsivity. In this article, we tested some key predictions of the ACM in a middle childhood sample (N = 256). Measures of autonomic nervous system activity across the sympathetic and parasympathetic branches validated the 4-pattern taxonomy of the ACM via finite mixture modeling. Moreover, the 4 patterns of responsivity showed the predicted associations with family stress levels but no association with measures of ecological stress. Our hypotheses concerning sex differences in responsivity were only partly confirmed. This preliminary study provides initial support for the key predictions of the ACM and highlights some of the methodological challenges that will need to be considered in future research on this topic.     

Prefrontal cortex regulates inhibition and excitation in distributed neural networks.

Prefrontal cortex provides both inhibitory and excitatory input to distributed neural circuits required to support performance in diverse tasks. Neurological patients with prefrontal damage are impaired in their ability to inhibit task-irrelevant information during behavioral tasks requiring performance over a delay. The observed enhancements of primary auditory and somatosensory cortical responses to task-irrelevant distractors suggest that prefrontal damage disrupts inhibitory modulation of inputs to primary sensory cortex, perhaps through abnormalities in a prefrontal-thalamic sensory gating system. Failure to suppress irrelevant sensory information results in increased neural noise, contributing to the deficits in decision making routinely observed in these patients. In addition to a critical role in inhibitory control of sensory flow to primary cortical regions, and tertiary prefrontal cortex also exerts excitatory input to activity in multiple sub-regions of secondary association cortex. Unilateral prefrontal damage results in multi-modal decreases in neural activity in posterior association cortex in the hemisphere ipsilateral to damage. This excitatory modulation is necessary to sustain neural activity during working memory. Thus, prefrontal cortex is able to sculpt behavior through parallel inhibitory and excitatory regulation of neural activity in distributed neural networks.     

The Integration of a Family Systems Approach for Understanding Youth Obesity,Physical Activity,and Dietary Programs

Rates of overweight in youth have reached epidemic proportions and are associated with adverse health outcomes. Family-based programs have been widely used to treat overweight in youth. However, few programs incorporate a theoretical framework for studying a family systems approach in relation to youth health behavior change. Therefore, this review provides a family systems theory framework for evaluating family-level variables in weight loss, physical activity, and dietary approaches in youth. Studies were reviewed and effect sizes were calculated for interventions that manipulated the family system, including components that targeted parenting styles, parenting skills, or family functioning, or which had novel approaches for including the family. Twenty-one weight loss interventions were identified, and 25 interventions related to physical activity and/or diet were identified. Overall, family-based treatment programs that incorporated training for authoritative parenting styles, parenting skills, or child management, and family functioning had positive effects on youth weight loss. Programs to improve physical activity and dietary behaviors that targeted the family system also demonstrated improvements in youth health behaviors; however, direct effects of parent-targeted programming is not clear. Both treatment and prevention programs would benefit from evaluating family functioning and parenting styles as possible mediators of intervention outcomes. Recommendations are provided to guide the development of future family-based obesity prevention and treatment programs for youth.     

Towards consensus in conceptualizing and operationalizing physical activity maintenance

Recognized challenges in promoting long-term physical activity maintenance may be due to inconsistencies in the conceptualization and operationalization of behavior maintenance terminology in physical activity research. The overall goal of this paper is to propose a framework and agenda for the development of a common set of terms, definitions, and measures for physical activity maintenance concepts that can be widely tested and evaluated. To initiate this effort, this paper (1) provides an overview of conceptual and operational definitions of physical activity maintenance used in the empirical literature, (2) evaluates whether behavior maintenance terms used in addiction science can be translated to physical activity, (3) recommends research directions for developing consensus definitions of physical activity maintenance, and (4) proposes a conceptual model of physical activity maintenance with inflection points that require operational definitions to be decided upon through consensus efforts in the field. Consensus over the conceptualization and operationalization of physical activity maintenance is needed to draw conclusions regarding which policies and programs are best able to promote long-term behavior change.     

Mu rhythm suppression is associated with the classification of emotion in faces

The mirror neuron system (MNS) has been mooted as a crucial component underlying human social cognition. Initial evidence based on functional magnetic resonance imaging (fMRI) suggests that the MNS plays a role in emotion classification, but further confirmation and convergent evidence is needed. This study employed electroencephalography (EEG) to examine modulations in the mu rhythm associated with the inference of emotions from facial expressions. It was hypothesised that mu suppression would be associated with classifying the emotion portrayed by facial expressions. Nineteen participants viewed pictures of facial expressions or emotion words and were asked to either match the stimulus to an emotion word or to passively observe. Mu activity following stimulus presentation was localised using a 3-D distributed inverse solution, and compared between conditions. Subtractive logic was used to isolate the specific processes of interest. Comparisons of source localisation images between conditions revealed that there was mu suppression associated with recognising emotion from faces, thereby supporting our hypothesis. Further analyses confirmed that those effects were not due to activity associated with the motor response or the observation of facial expressions, offering further support for the hypotheses. This study provides important convergent evidence for the involvement of the MNS in the inference of emotion from facial expressions.     

Contribution of Leisure-Time Physical Activity on Psychological Benefits Among Elderly Immigrants

Research provides evidence that leisure-time physical activity engagement promotes health and well-being among older adults. In this study, using data released from the Health and Retirement Study (HRS) in 2008, we focused on the exploration of the relationship between leisure-time physical activity and psychological benefits such as positive affect, optimism, psychological well-being, and life satisfaction among elderly immigrants. The results of this study demonstrated that leisure-time physical activities play an important role in gaining psychological benefits. This finding provided further evidence that leisure-time physical activities provides rich opportunities for elderly immigrants to experience psychological benefits, which may contribute to quality of life and successful aging.     

Hippocampal regulation of context-dependent neuronal activity in the lateral amygdala

Pavlovian fear conditioning is a robust and enduring form of emotional learning that provides an ideal model system for studying contextual regulation of memory retrieval. After extinction the expression of fear conditional responses (CRs) is context-specific: A conditional stimulus (CS) elicits greater conditional responding outside compared with inside the extinction context. Dorsal hippocampal inactivation with muscimol attenuates context-specific CR expression. We have previously shown that CS-elicited spike firing in the lateral nucleus of the amygdala is context-specific after extinction. The present study examines whether dorsal hippocampal inactivation with muscimol disrupts context-specific firing in the lateral amygdala. We conditioned rats to two separate auditory CSs and then extinguished each CS in separate and distinct contexts. Thereafter, single-unit activity and conditional freezing were tested to one CS in both extinction contexts after saline or muscimol infusion into the dorsal hippocampus. After saline infusion, rats froze more to the CS when it was presented outside of its extinction context, but froze equally in both contexts after muscimol infusion. In parallel with the behavior, lateral nucleus neurons exhibited context-dependent firing to extinguished CSs, and hippocampal inactivation disrupted this activity pattern. These data reveal a novel role for the hippocampus in regulating the context-specific firing of lateral amygdala neurons after fear memory extinction.     

Operant conditioning and discrimination of alpha: some methodological limitations inherent in response-discrimination experiments

Studies on the operant conditioning of central nervous system activity have produced results interpreted as demonstrating that responses, certain properties of responses, or response-produced stimuli can function as discriminative stimuli. It is assumed that the feedback stimulus in biofeedback makes the subject aware of the internal response and that by becoming aware of the response, the subject can acquire voluntary control over it. In this context, awareness is operationally defined as the ability to use the response as a discriminative stimulus. Since direct evidence for the assumed relationship between control and discrimination is lacking, an attempt was made to test the hypothesis that discrimination of a response automatically leads to control over that response. The discriminative stimuli were the presence and absence of occipital alpha electroencephalograph (EEG) activity. Data from two experiments are reported. The first study, employing naive subjects, was designed to answer the following questions: (a) Since pilot data indicated that subjects seemed to match their responses to the more probable type of trial, would increases in the probability of a correct response result when the probabilities of alpha and nonalpha trials were held near .50? (b) If correct responding does increase, would performance of these subjects in an alpha feedback task be enhanced relative to that of subjects not previously given discrimination training? and (c) If subjects could not learn the discrimination task, would feedback training enhance their performance in a subsequent discrimination task? Results from this study indicate that holding the probabilities of alpha and nonalpha discrimination trials near .50 results in an absence of learning curves, but leaves open the possibility that sophisticated subjects are capable of discriminating alpha and nonalpha activity. The second study deals with two questions: (a) Can sophisticated subjects learn to discriminate occipital alpha activity from nonalpha activity? and (b) Does the procedure of providing subjects with salient stimuli, contingent on the presence and absence of alpha activity, establish stimulus control of the presence and absence of alpha activity? Results indicate that it is not possible to conclude that subjects can learn to discriminate alpha and nonalpha activity. However, learning to increase percent-time nonalpha or decrease percent-time alpha with respect to baseline levels by means of EEG-contingent stimulation provides subjects with the ability to suppress percent-time alpha in the absence of feedback. Information gained in both studies through subject interviews indicates that subjects most often acquired their control of alpha activity during feedback by a specific strategy and then used the strategy during the stimulus-control tests.     

A NEURAL SYSTEM FOR ERROR DETECTION AND COMPENSATION

Abstract— Humans can monitor actions and compensate for errors. Analysis of the human event-related brain potentials (ERPs) accompanying errors provides evidence for a neural process whose activity is specifically associated with monitoring and compensating for erroneous behavior. This error-related activity is enhanced when subjects strive for accurate performance but is diminished when response speed is emphasized at the expense of accuracy. The activity is also related to attempts to compensate for the erroneous behavior.