Sources of Intertrial Proactive Interference in Rats’ Short-Term Memory in a Delayed Successive Matching-to-Sample Modality Discrimination

Rats were trained on a delayed successive matching-to-stimulus modality task consisting of onset of chamber lights or a tone for the sample stimulus, S1, and a comparison stimulus, S2. Lever pressing to S1 was reinforced as was lever pressing to its matching S2 (light–light or tone–tone pairs) but not to its mismatching S2 (light–tone, tone–light pairs). The interval between S1 and S2 within a trial, the retention interval (RI), was varied between 1 and 6 s within sessions while the interval between S2 and the next S1, the intertrial interval (ITI), was reduced from 24 to 12 s and finally to 6 s over blocks of sessions. In Experiment 1, where S1 was kept at 2 s and S2 at 10 s, rats’ matching accuracy declined over the longer RI, was slightly disrupted as ITIs were reduced to 6 s only over 1-s RIs, and was generally poorer to the tone than light S1. In Experiment 2, where both stimuli were 10 s increasing RIs caused steeper declines in matching accuracy to the tone S1 than light S1 and decreasing ITIs to 6 s disrupted rats performance over both RIs. Matching accuracy to the tone but not to the light S1 was also poorer when a preceding trial's S2 was a light S2 than when it was a tone S2 only during Experiment 2. Thisintertrial stimulus disagreementeffect was not influenced by ITI duration. These results suggest that intertrial proactive interference in delayed matching tasks consists of two separate and independent processes in rats similar to those found in pigeons (Edhouse & White, 1988).     

Consolidation and translation regulation

mRNA translation, or protein synthesis, is a major component of the transformation of the genetic code into any cellular activity. This complicated, multistep process is divided into three phases: initiation, elongation, and termination. Initiation is the step at which the ribosome is recruited to the mRNA, and is regarded as the major rate-limiting step in translation, while elongation consists of the elongation of the polypeptide chain; both steps are frequent targets for regulation, which is defined as a change in the rate of translation of an mRNA per unit time. In the normal brain, control of translation is a key mechanism for regulation of memory and synaptic plasticity consolidation, i.e., the off-line processing of acquired information. These regulation processes may differ between different brain structures or neuronal populations. Moreover, dysregulation of translation leads to pathological brain function such as memory impairment. Both normal and abnormal function of the translation machinery is believed to lead to translational up-regulation or down-regulation of a subset of mRNAs. However, the identification of these newly synthesized proteins and determination of the rates of protein synthesis or degradation taking place in different neuronal types and compartments at different time points in the brain demand new proteomic methods and system biology approaches. Here, we discuss in detail the relationship between translation regulation and memory or synaptic plasticity consolidation while focusing on a model of cortical-dependent taste learning task and hippocampal-dependent plasticity. In addition, we describe a novel systems biology perspective to better describe consolidation.     

Attentional bias toward threat in contamination fear: overt components and behavioral correlates

Recent research suggests that an attentional bias toward threat may play a causal role in obsessive-compulsive disorder (OCD) with contamination concerns. However, the attentional components involved in this bias, as well as its behavioral correlates, remain unclear. In the present study, eye movements were recorded in individuals high and low in contamination fear (HCF, LCF, respectively) during 30-s exposures to stimulus arrays containing contamination threat, general threat, pleasant, and neutral images. HCF individuals oriented gaze toward contamination threat more often than LCF individuals in initial fixations, and this bias mediated group differences in responding to a behavioral challenge in a public restroom. No group differences were found in the maintenance of gaze on contamination threat, both in terms of initial gaze encounters, as well as gaze duration over time. However, the HCF group made shorter fixations on contamination threat relative to other image types. The implications of these findings for further delineating the nature and function of attentional biases in contamination-based OCD are discussed.     

Clinical Predictors of Depression in Patients with Low-Grade Brain Tumors: Consideration of a Neurologic Versus a Psychogenic Model

Few studies have examined quality of life issues in patients with brain tumors, though coping with cancer is stressful and is associated with heightened levels of depression. We used regression to examine the clinical factors that might predict depression in a group of 57 adults with low-grade brain tumors after surgery but prior to radiotherapy and chemotherapy. A neurological model comprised of tumor characteristics and treatment was compared with a psychogenic model comprised of both psychosocial and psychodynamic variables. Demographic variables and level of fatigue were also included. A model consisting primarily of fatigue (also clinically elevated) and secondarily of tumor location and aggressiveness of surgical treatment accounted for 33% of the depression score. In a small group at a later follow-up when patient depression was clinically elevated (4–6 years after baseline), fatigue, female sex, cognitive dysfunction, increased family support, and increased report of physical symptoms were associated with depression. The late out findings remain exploratory because of the small sample size, but they suggest that depression develops over time and results from a combination of neurological and psychosocial problems that ensue initial treatments. Treating these collateral problems may reduce the complications from depression.     

A Critical Review of the Clinical Effects of Therapeutic Irradiation Damage to the Brain: The Roots of Controversy

We critically examined the damaging affects of therapeutic irradiation by comparing results from cross-disciplinary studies of early- and late-delayed radiotherapy effects. Focus is attained by concentrating on clinical treatment issues (volume of brain, dose, timing of effects, age, modality types, and stereotactic treatment techniques), rather than on methodological means or problems, which is necessary to understand the mechanisms and characteristics of radiotherapy-induced behavioral dysfunction including cognition. We make observations and hypotheses about the actual risks from radiotherapy that could be informative in the treatment decision process, and which may lessen the concerns of some patients and their families about the risks they take when receiving radiation. Conditions that predispose to radiation injury are reviewed: (1) higher doses even to part of the brain versus lower doses to the whole brain, (2) combined treatment modalities, (3) malignancy itself, (4) radiation early during postnatal brain development, and (5) late-delayed effects (more than 3 years posttreatment). Current neurocognitive frameworks for understanding cognitive change over time in children and adults are summarized, along with the literature on effects of brain tumors and treatment on depression. No studies have as yet identified candidate brain regions that are more sensitive to radiotherapy. Two studies have provided early, preliminary evidence for a specific vulnerability of visual attention/memory to the early stage of late radiation damage. Furthermore, radiation effects appear severe only in a minority of patients. Risk is related to direct and indirect effects of cancer type, concurrent clinical factors, and premorbid risk factors.     

Faces as forms in the world of the newborn

A number of recent studies have indicated that newborns can learn to recognize mother's face within a few hours of birth. Two of the present authors suggested that a simple auto-associative net might explain that rapid learning. This paper reports three experiments in which the newborn's ability to recognize a learned face over three transformations was tested. The transformations were: (1) a photonegative transformation, (2) a size change and (3) rotation in the third dimension of visual space. Existing auto-associative nets cannot maintain identification across these transformations. The newborns succeeded with all three. An alternative proposal based on the idea that there is a built-in specification of the true shape of a face in the frontal parallel plane is outlined. These data present a challenge not only to associationist theories but also to their main rival, differentiation theory.     

The Draw-A-Person Test and Process-Reactive Schizophrenia

The Draw-A-Pcrson test was administered to three matched groups of 32 male Ss each: reactive schizophrenics, process schizophrenics, and normal control subjects. Patients were rated for prognosis using the Premorbid Subscale of the Phillips Scale. Drawings were rated by two judges on 80 diagnostic signs culled from the literature. No signs were found to significantly differentiate reactive and process schizophrenics, and only three signs significantly differentiated normals from schizophrenics. It was concluded that a sign approach to the DAP is insensitive to the reaction-process dimension of schizophrenia, and of only limited value in differentiating between normals and schizophrenics in general.     

Carrying the Burden: Perspectives of African American Pastors on Peer Support for People with Cancer

For African Americans facing advanced cancer, churches are trusted sources of support and ideal settings to improve access to supportive care. The Support Team model enhances community support for practical, emotional, and spiritual caregiving. We report on focus groups with pastors of 23 Black Churches and explore their perspective on the Support Team model for church members with cancer. Pastors describe the needs of church members facing cancer from a holistic perspective and recognize opportunities for synergistic faith–health collaboration. The results of this study indicate potential benefits of the Support Team model in Black Churches to reduce silent suffering among individuals facing cancer.