Multimodal encoding in a simplified model of intracellular calcium signaling

Many cells use calcium signaling to carry information from the extracellular side of the plasma membrane to targets in their interior. Since virtually all cells employ a network of biochemical reactions for Ca²⁺ signaling, much effort has been devoted to understand the functional role of Ca²⁺ responses and to decipher how their complex dynamics is regulated by the biochemical network of Ca²⁺-related signal transduction pathways. Experimental observations show that Ca²⁺ signals in response to external stimuli encode information via frequency modulation (FM) or alternatively via amplitude modulation (AM). Although minimal models can capture separately both types of dynamics, they fail to exhibit different and more advanced encoding modes. By arguments of bifurcation theory, we propose instead that under some biophysical conditions more complex modes of information encoding can also be manifested by minimal models. We consider the minimal model of Li and Rinzel and show that information encoding can occur by AM of Ca²⁺ oscillations, by FM or by both modes (AFM). Our work is motivated by calcium signaling in astrocytes, the predominant type of cortical glial cells that is nowadays recognized to play a crucial role in the regulation of neuronal activity and information processing of the brain. We explain that our results can be crucial for a better understanding of synaptic information transfer. Furthermore, our results might also be important for better insight on other examples of physiological processes regulated by Ca²⁺ signaling.     

Effectiveness of a consultation intervention to promote tobacco control policies in Northwest Indian tribes: Integrating experimental evaluation and service delivery

A quasi-experimental replication of an intervention for promoting tobacco control policies in Northwest Indian tribes is described and the process of intervention including issues of collaboration among research institutions and Indian organizations is discussed. The policy intervention was evaluated using a pretest-posttest design wherein 20 tribes that had served as wait-list controls now received the intervention. The intervention comprised a tribal representative attending a kickoff orientation; follow-up visits to the tribes; distribution of tobacco policy workbooks; and phone call consultations. Policy status and stringency were assessed by means of telephone interviews with two key contacts per tribe, and by a count of enacted policies. There were significant pre-post changes in the primary outcome measure, a composite summary score of tobacco policy stringency, and changes were also reflected in enacted policies. The intervention effects observed were similar to those found in the prior randomized trial and suggest a robust, disseminable intervention. Much of the success achieved was attributed to the role of an Indian organization in planning the project and implementing the intervention and evaluation protocols.     

Letter Dyslexia in a Letter-by-Letter Reader

We describe a letter-by-letter patient who produced misreading errors in both letters in isolation and in words. All errors were visual in nature. We hypothesized an access deficit to the abstract visual representation of letters that prevents letter identification. This deficit could account for the patient's letter-by-letter behavior, since each letter constituted a potential identification problem. An access deficit, moreover, could also explain the patient's letter visual errors. In access processing, in fact, the letters sharing common structural features in their abstract representations were the ones more frequently mismatched.     

USE OF EXTINCTION AND REINFORCEMENT TO INCREASE FOOD CONSUMPTION AND REDUCE EXPULSION

Extinction and reinforcement contingencies were used to treat 2 children with feeding disorders. Positive reinforcement and avoidance extinction effectively increased food acceptance but also increased food expulsion. Reduced expulsion and increased swallowing were achieved by repeated presentation of expelled food, a second extinction component.     

Size of the attentional focus and efficiency of processing

By following Eriksen and St. James (1986) the experiments reported in this study focused upon three questions: (a) Can the spatial extent of the attentional focus be made to vary in response to precues? (b) As the area of the attentional focus increases, is there a decrease in processing efficiency for stimuli within the focus? (c) Is the boundary of the focus sharply demarked from the residual field or does it show a gradual dropoff? The results seem to provide answers to these questions: (a) the size of the attentional focus can be adjusted so that it covers areas of the visual field of different size; (b) there is a decrease in processing efficiency when the area of the attentional focus increases; and (c) there is a gradual dropoff in processing efficiency around the attentional focus.     

The management of children''s distress in response to painful medical treatment for burn injuries

The purpose of the current study was to develop an initial assessment of the efficacy of astress-management program designed to reduce the behavioral distress of children undergoing highlypainful medical treatments for their burn injuries. The stress-management program was delivered to 4 male patients, ages 5–12 yr and its effects assessed in a combined multiple-baseline and reversal design. Results indicated that the program was moderately effective at reducing behavioral distress during the burntreatment procedures for 3 of the 4 patients and less effective with the fourth. However, the design also revealed that the presence of a therapist to coach the patient in the use of these techniques was essential and that distress levels rose substantially on days when there was no therapist present. Finally, speculations concerning the factors responsible for the effectiveness of the stress-management program as well as its reduced efficacy with 1 S were discussed.     

Asymmetries in the acquisition of polar adjectives: Linguistic or conceptual?

This study was designed to determine whether the asymmetry in children's acquisition of polar adjective pairs is based on linguistic factors related to differences in adult usage and frequency or on an underlying conceptual difference. 24 children, aged 3;7–4;11, took part in a concept-learning task in which nonsense syllables replaced English words for the positive and negative ends of four dimensions: size, height, length, and thickness. The data indicate that the syllables for the negative end of each dimension have a longer learning period and a greater prelearning error rate. These results support the hypothesis that the asymmetry observed in the acquisition of polar adjectives is based on an underlying conceptual asymmetry.