Advancing age progressively affects obstacle avoidance skills in the elderly

The ability to adequately avoid obstacles while walking is an important skill that allows safe locomotion over uneven terrain. The high proportion of falls in the elderly that is associated to tripping over obstacles potentially illustrates an age-related deterioration of this locomotor skill. Some studies have compared young and old adults, but very little is known about the changes occurring within different age groups of elderly. In the present study, obstacle avoidance performance was studied in 25 young (20-37 years) and 99 older adults (65-88 years). The participants walked on a treadmill at a speed of 3 km/h. An obstacle was dropped 30 times in front of the left foot at various phases in the step cycle. Success rates (successful avoidance) were calculated and related to the time available between obstacle appearance and the estimated instant of foot contact with the obstacle (available response times or ARTs ranging from 200 to more than 350 ms). In addition, latencies of avoidance reactions, the choice of avoidance strategies (long or short step strategy, LSS or SSS), and three spatial parameters related to obstacle avoidance (toe distance, foot clearance, and heel distance) were determined for each participant. Compared to the young, the older adults had lower success rates, especially at short ARTs. Furthermore, they had longer reaction times, more LSS reactions, smaller toe and heel distances, and larger foot clearances. Within the group of elderly, only the 65-69 year olds were not different from young adults with respect to success rate, despite marked changes in the other parameters measured. In particular, even this younger group of elderly showed a dramatic reduction in the amount of SSS trials compared to young adults. Overall, age was a significant predictor of success rates, reaction times, and toe distances. These parameters deteriorated with advancing age. Finally, avoidance success rates at short ARTs were considerably worse in elderly participants who sustained recurrent falls in the six-month period prior to the assessment compared to those who sustained no or only one fall. An exercise program has been shown to improve avoidance success rates, especially at short ARTs, but the training effects on the determinants of success still need to be assessed.     

Discrete and contextual cue alterations eliminate the instrumental appetitive-to-aversive transfer impairment in phenytoin-treated rats

We have shown previously that the antiepileptic phenytoin impairs transfer in an instrumental learning task (Banks et al., 1999). The present study examined the effects of contextual alterations on appetitive-to-aversive transfer performance of rats treated with either phenytoin or tang. Adult rats were tested in tone-signaled appetitive and aversive instrumental tasks, where the animal bar-pressed to obtain a food reward (sugar pellet) or to avoid shock. Rats were trained on the appetitive task for 31 days. Beginning on the twenty-first day, rats were gavaged with either phenytoin or tang twice daily. Animals were then transferred to aversive training, with the phenytoin or tang treatment continuing throughout the 25 testing days. For some animals, contextual changes were introduced as they shifted from appetitive to aversive training, while for other animals these changes were not made. Phenytoin-treated rats that were presented with changes in context as they transferred from the appetitive to the aversive task learned the avoidance response to levels substantially higher than drug-treated rats not presented with the contextual changes. These results indicate that phenytoin impairs avoidance learning following transfer from the appetitive task, and that this impairment can be eliminated by introducing changes in context at the point of transfer. In the tang-treated control subjects, on the other hand, there was no improvement in transfer learning performance associated with the changes in contextual cues. This pattern of results suggests that contextual encoding processes in rats being trained in an instrumental appetitive-to-aversive paradigm are dramatically affected by phenytoin.     

The neurobiology of adaptive learning in reading: A contrast of different training conditions

fMRI was used to investigate the separate influences of orthographic, phonological, and semantic processing on the ability to learn new words and the cortical circuitry recruited to subsequently read those words. In a behavioral session, subjects acquired familiarity for three sets of pseudowords, attending to orthographic, phonological, or (learned) semantic features. Transfer effects were measured in an event-related fMRI session as the subjects named trained pseudowords, untrained pseudowords, and real words. Behaviorally, phonological and semantic training resulted in better learning than did orthographic training. Neurobiologically, orthographic training did not modulate activation in the main reading regions. Phonological and semantic training yielded equivalent behavioral facilitation but distinct functional activation patterns, suggesting that the learning resulting from these two training conditions was driven by different underlying processes. The findings indicate that the putative ventral visual word form area is sensitive to the phonological structure of words, with phonologically analytic processing contributing to the specialization of this region.     

Pastoral counseling among Chinese churches: a Canadian study

This article reports the results of a survey of Canadian Chinese pastors (N 20) regarding their experiences and attitudes related to pastoral counseling. It identifies common concerns encountered during pastoral counseling, as well as key areas of church concerns. Results of the survey indicate that pastoral counseling may be more important than is currently recognized by Chinese pastors, particularly in key areas of marriage, family life, and general relationship issues. The authors discuss possible implications of the survey relative to training and equipping Chinese pastors to engage more in pastoral counseling as an integral part of their parish ministry.     

Direct and Nondirect Communication of Maternal Beliefs to Adolescents: Adolescent Motivations for Premarital Sexual Activity1

Communication between mothers and adolescents about premarital sexual intercourse was studied in the context of a model of maternal influence on the formation of adolescent beliefs about sexual behavior. Two different forms of maternal influence were explored: (a) direct communication, and (b) indirect transmission of maternal orientations. Respondents were 751 inner-city, African American adolescents (ages 14 to 17) and their mothers. Results indicated that adolescent motivations were related to their sexual behavior, and that maternal beliefs about sex were predictive of those motivations, independent of reports of the amount of communication that had taken place. These data are consistent with a model that underscores multiple mechanisms by which parents influence adolescent sexual behavior over and above direct communication.     

Detecting phonemes and letters in text: Interactions between different types and levels of processes

In six experiments, subjects detected phonemes or letters in text presented auditorily or visually. Experiments 1 and 2 provided support for the hypothesis that a mismatch between the phoneme and letter representations of a target leads to detection errors. In addition, visual word unitization processes were implicated. Experiments 3 and 4 provided support for the hypothesis that the Gestalt goodness of pattern affected detection errors when subjects searched for letters. Experiments 5 and 6 demonstrated that the effects of unitization on the detection of letters in common words were decreased by altering the familiar configuration of the test words. The combined results of all six experiments lead to the conclusion that both visual and phonetic processes influence letter detection, that these processes communicate through a type of cross-checking, and that there are at least two levels of visual (and perhaps of phonetic) processing involved in the letter detection task.     

Seeking harmony in Chinese families: A dyadic analysis on Chinese parent‒child relations

Based on Leung, Koch, and Lu’s (2002) dualistic harmony model, we examined the relations of two harmony‐seeking behaviors—harmony enhancement and disintegration avoidance—to family functioning among 177 Hong Kong Chinese adolescent?parent dyads. Structural equation modeling results showed that adolescent‐rated harmony enhancement was positively related to adolescent‐rated family functioning whereas parent‐rated harmony enhancement was positively related to parent‐rated family functioning. Disintegration avoidance, however, was not related to family functioning in the two samples. Furthermore, no significant cross‐path association between harmony‐seeking behaviors and family functioning was identified, meaning that the harmony‐seeking behaviors of adolescents and their parents did not relate to each other’s perception of family functioning. Implications of these findings to our understanding of family in Chinese culture are discussed.