A possible social relative reward effect: Influences of outcome inequity between rats during operant responding.

Social interactions/situations have dramatic influences on motivation. Creating animal models examining these influences promotes a better understanding of the psychological and biological underpinnings of social motivation. Rodents are sensitive to social history/experience during associative conditioning and food-sharing tasks. Would reward-oriented operant behavior be sensitive to social influences by showing a negative contrast-like effect when another organism obtains a greater value outcome? We used a side-by-side arrangement of operant response chambers wherein one animal obtained consistently high reward signaled by a discrete cue. The neighboring, experimental rat experienced different combinations of high and low reward trial sequences. Control conditions included distraction from a conspecific in the neighboring chamber (rat distractor) or cue/food dispenser operating without a conspecific (program distractor) in addition to testing subjects alone. Results support an influence of the other animal actively performing the task on the experimental subject's behavior. Primarily, responding was significantly slower for the low reward trials while the neighboring rat was receiving the higher magnitude reward. The lever-press and not food-cup retrieval latency was significantly slower during exposure to a conspecific neighbor performing the operant task. The effect was not obtained in all session sequences and was more pronounced using longer series of consecutive low reward trials. The slowing effect was also obtained with the program-distractor experience in a different trial sequence. These findings suggest a social-induced negative incentive contrast effect in rats possibly mediated by an outcome inequity process that could have key similarities to complex situational-affective effects on motivation involving frustration or jealously.

Asymptomatic strictures in femoro-popliteal vein grafts.

Strictures in saphenous vein grafts represent a preventable cause of graft failure, but these lesions may remain undetected by standard clinical methods until occlusion occurs. A study has been undertaken using intravenous digital subtraction angiography (I.V. DSA) to determine the incidence of asymptomatic strictures in a series of femoro-popliteal vein grafts and all lesions detected have been followed-up without treatment to assess their effect on patency rates. Eighty grafts in 69 asymptomatic patients were examined by I.V. DSA at a variable time postoperatively and again after a mean interval of 13 months. At the first examination a total of 30 strictures were found in 22 grafts (27.5%). At the second examination 5 the 22 strictured grafts (22.7%) had occluded. In contrast, only 4 of the 58 non-strictured grafts (6.9%) had occluded and this difference was statistically significant (chi 2 = 4.0 P less than 0.05). Six new strictures were detected, 2 in previously normal grafts and 4 in already strictured grafts, giving a total of 36 lesions altogether. The finding of a 27.5% stricture rate in asymptomatic patients, carrying a 3-fold increase in occlusion risk leads to the conclusion that screening of these grafts is essential. Sixty-five percent of strictures remained stable and asymptomatic, and this indicates that secondary intervention should be on a selective basis.

The obese child: observations in the gymnasium of the Adelaide Children's Hospital.

This study reviews 107 obese children who were referred to the gymnasium of the Adelaide Children's Hospital. The majority had multiple handicaps. The treatment involved physical activities in small groups associated with counselling of parents (both individually and in groups) by social workers, dietitians, and doctors. A significant number of children were helped by the programme, showing not only a reduction in weight but also improvement in behaviour and attitude. Some children exhibited a hypoactive form of minimal cerebral dysfunction, which is postulated as a new risk factor in the development of childhood obesity. The importance of prevention is emphasized.

The clumsy child: observations in cases referred to the gymnasium of the Adelaide Children's Hospital over a three-year period.

Group treatment of clumsy children is one part of a multidisciplinary management programme which is provided at The Adelaide Children's Hospital for children who have multiple handicaps. This study reviews 176 children who were referred for treatment. Clumsiness was the most common reason for referral. Not all children benefited from group treatment, and those who had significant degrees of mental retardation, or mild spasticity worsening on effort, needed individual handling. Movement training aims mainly to reduce physical clumsiness, and it is hoped that certain nonspecific benefits may result. The greatest improvement occurred in the ability to mix with others. Group counselling of parents, with a social worker as leader, is considered to have played an essential part in the management of these children's problems.