Temporal binding, binocular rivalry, and consciousness.

Cognitive functions like perception, memory, language, or consciousness are based on highly parallel and distributed information processing by the brain. One of the major unresolved questions is how information can be integrated and how coherent representational states can be established in the distributed neuronal systems subserving these functions. It has been suggested that this so-called "binding problem" may be solved in the temporal domain. The hypothesis is that synchronization of neuronal discharges can serve for the integration of distributed neurons into cell assemblies and that this process may underlie the selection of perceptually and behaviorally relevant information. As we intend to show here, this temporal binding hypothesis has implications for the search of the neural correlate of consciousness. We review experimental results, mainly obtained in the visual system, which support the notion of temporal binding. In particular, we discuss recent experiments on the neural mechanisms of binocular rivalry which suggest that appropriate synchronization among cortical neurons may be one of the necessary conditions for the buildup of perceptual states and awareness of sensory stimuli.     

Daily mood patterns and bulimic behaviors in the natural environment

Objective

Negative affect has been purported to play an important role in the etiology and maintenance of bulimic behaviors. The objective of this study was to identify daily mood patterns in the natural environment exhibited by individuals with bulimia nervosa and to examine the relationship between these patterns and bulimic behaviors.

Method

One hundred thirty-three women aged 18-55 meeting DSM-IV criteria for bulimia nervosa were recruited through clinical referrals and community advertisements. Ecological momentary assessment was used to collect multiple ratings of negative affect, binge eating and purging each day for a two-week period using palmtop computers. Latent growth mixture modeling was used to identify daily mood patterns.

Results

Nine distinct daily mood patterns were identified. The highest rates of binge eating and purging episodes occurred on days characterized by stable high negative affect or increasing negative affect over the course of the day.

Conclusions

These findings support the conclusion that negative mood states are intimately tied to bulimic behaviors and may in fact precipitate such behavior.     

Effect of ecological viewing conditions on the Ames' distorted room illusion

Ecological theory asserts that the Ames' distorted room illusion (DRI) occurs as a result of the artificial restriction of information pickup. According to Gibson (1966, 1979), the illusion is eliminated when binocular vision and/or head movement are allowed. In Experiment 1, to measure the DRI, we used a size-matching technique employing discs placed within an Ames' distorted room. One hundred forty-four subjects viewed the distorted room or a control apparatus under four different viewing conditions (i.e., restricted or unrestricted head movement), using monocular and binocular vision. In Experiment 2, subjects viewed binocularly and were instructed to move freely while making judgments. Overall, the main findings of this study were that the DRI decreased with increases in viewing access and that the DRI persisted under all viewing conditions. The persistence of the illusion was felt to contradict Gibson's position.     

Clamped Corticosterone (B) Reveals the Effect of Endogenous B on Both Facilitated Responsivity to Acute Restraint and Metabolic Responses to Chronic Stress

To determine the effects of both corticosterone (B) and chronic stressors on acute ACTH responses to restraint, young male rats were exposed to streptozotocin-induced diabetes, cold (5-7 degreesC) or intracerebroventricular (icv) neuropeptide Y (NPY) for 5 d and then exposed to restraint within 2 h after lights on. Two groups of rats were studied: intact and adrenalectomized replaced with B pellets that maintained plasma B in the normal mean 24-h range of intact rats. In addition to ACTH and B responses to restraint on d 5, body weight, food intake, fat depots, glucose and other hormones were measured to determine the role of stress-induced elevations in B on energy balance. ACTH responses to restraint were normal in intact rats subjected to diabetes or cold. By contrast, there was no ACTH or B response to restraint in NPY-infused intact rats. All 3 groups of chronically stimulated adrenalectomized rats with clamped B had facilitated ACTH responses to restraint compared to their treatment controls. Overall food intake increased in all groups of stressed rats; however, augmented intake occurred only during the light in intact rats and equally in the light and dark in B-clamped rats. White adipose depot weights were decreased by both diabetes and cold and increased by NPY in intact rats; the decreases with cold and increases with NPY were both blunted and changes in fat stores were not significant in adrenalectomized, B-clamped rats. We conclude that: 1. diabetes- and cold-induced facilitation of restraint-induced afferent input to hypothalamic control of the hypothalamo-pituitary-adrenal (HPA) axis is opposed in intact rats by the elevated feedback signal of B secretion; 2. NPY does not induce facilitation of afferent stress pathways; 3. chronic stimulation of the HPA axis induces acute hyperresponsiveness of hypothalamic neurons to restraint provided that the afferent input of this acute stimulus is not prevented by B feedback; 4. stimulus-induced elevations in B secretion result in day-time feeding; 5. insensitivity of both caloric efficiency and white fat stores to chronic stress in adrenalectomized, B-clamped rats results from loss of normally variable B levels.     

Neuronal assemblies: necessity, signature and detectability

The ease with which highly developed brains can generate representations of a virtually unlimited diversity of perceptual objects indicates that they have developed very efficient mechanisms to analyse and represent relations among incoming signals. Here, we propose that two complementary strategies are applied to cope with these combinatorial problems. First, elementary relations are represented by the tuned responses of individual neurons that acquire their specific response properties (feature selectivity) through appropriate convergence of input connections in hierarchically structured feed-forward architectures. Second, complex relations that cannot be represented economically by the responses of individual neurons are represented by assemblies of cells that are generated by dynamic association of individual, featureselective cells. The signature identifying the responses of an assembly as components of a coherent code is thought to be the synchronicity of the respective discharges. The compatibility of this hypothesis is examined in the context of recent data on the dynamics of synchronization phenomena, the dependence of synchronization on central states and the relations between the synchronization behaviour of neurons and perception.     

Evaluation of self-contained training procedures for the Time-Sample Behavioral Checklist

The comparative effectiveness of two time-limited modes of training observers to code the behavior of clients in residential treatment programs on the Time-Sample Behavioral Checklist (TSBC) was evaluated. The susceptibility of training procedures to consensual observer drift and the predictability of TSBC mastery from trainee characteristics were also examined. Two equated groups of undergraduate students (N=15 each) participated in full-time training on the TSBC and another instrument for 27 days, followed by criterion testingin vivo and on videotapes. One group was trained by experienced personnel using procedures known to be effective but potentially subject to consensual observer drift. The other group was trained using a previously untested set of written and videotape procedures that do not rely on experienced personnel. Comparative effectiveness and observer drift were evaluated by multivariate and univariate ANOVAs on mastery scores reflecting both pattern agreement and level differences between each trainee and criterion codings. The new, more efficient training procedures were found to be as effective as the original training procedures in the degree of mastery achieved by trainees. Original training procedures were found to be resistant to consensual observer drift, with such a phenomenon appearing in only 1 instance of 156 opportunities. The high degree of mastery achieved by trainees during the time-limited training period was comparable to that previously achieved with the original training procedures. No meaningful predictions of coding mastery were found, with only one trainee characteristic being significantly related to one of six mastery criteria. The results document procedures that are both efficient and resistant to invalidity for training observers in the use of multidimensional observational systems, as well as providing guidelines for the development of standardized procedures.This article is based on a thesis submitted to the Graduate College of the University of Illinois at Urbana-Champaign in partial fulfillment of the requirements for the Ph.D. degree in psychology by the first author and under direction of the second author. The third and fourth authors also participated as supervisors. Appreciation is extended to other members of the thesis committee, Fred Kanfer, Ross Parke, and Julian Rappaport, and to John Gottman and W. Robert Nay for their comments and recommendations. This study was partially supported by Public Health Service Grants MH-25464 and MH-14257 from the National Institute of Mental Health and by grants from the Joyce Foundation, the MacArthur Foundation, and the Illinois Department of Mental Health and Developmental Disabilities.     

The comparative effectiveness of two modes of observer training on the Staff-Resident Interaction Chronograph

The comparative effectiveness of two time-limited modes of training observers to code activity on the Staff-Resident Interaction Chronograph (SRIC) in residential treatment programs for mentally disabled adults was evaluated. The susceptibility of training procedures for consensual observer drift was also examined, as was the predictability of SRIC mastery from trainee characteristics. Two equated groups of undergraduate student trainees (N=15 each) participated in full-time training for 27 days, followed by two weeks of criterion testing in vivo and on videotapes. One group received training by experience personnel using procedures known to be effective (original method). The other group received training via a previously untested set of written and videotaped procedures that do not rely on experienced personnel (package method). Multivariate and univariate analyses of variance found both methods to be equally effective in the degree of mastery achieved by trainees, without evidence of observer drift. No meaningful predictions of coding mastery were found, but conceptual mastery was predictable from individual characteristics. Differences were obtained for both groups between in vivo versus videotaped criterion tests. The results document procedures that are both efficient and resistant to invalidity for complex observational methodology as well as feasible for standardizing assessment of staff functioning across residential settings.This article is based on a thesis submitted to the Graduate College of the University of Illinois at Urbana-Champaign in partial fulfillment of the requirements for the Ph.D. degree in psychology by the first author under direction of the second author. The third and fourth authors also participated as supervisors. Appreciation is extended to other members of the thesis committee, Fred Kanfer, W. Robert Nay, Julian Rappaport, and James Wardrop, for their comments and recommendations. This study was partially supported by Public Health Service Grants MH-25464 and MH-14257 from the National Institute of Mental Health, and by grants from The Joyce Foundation and the Illinois Department of Mental Health and Developmental Disabilities.     

Electroencephalographic and blood pressure correlates of operantly conditioned heart rate in the restrained monkey

Each of four monkeys was trained to slow its heart rate and to speed its heart rate. Mean blood pressure was positively correlated with heart rate during speeding and during slowing. These correlations increased from early training to late training for all animals during slowing; however, they did not change during speeding. High voltage in the 8–14 Hz band of the EEG was correlated negatively with heart rate; however, the correlations were insignificant or low. The correlations between EEG changes and heart rate changes increased (became more negative) during the late phase of slow training but did not change reliably during speeding training. Baseline levels in all physiological functions changed as a function of stage of training. Response patterns during escape behavior indicate dissociation of heart rate and blood pressure, whereas response patterns during avoidance behavior show correlation of heart rate and blood pressure. The findings indicate that the physiological effects of heart rate slowing and heart rate speeding are different and not merely mirror images of one another.