Effect of a single free food presentation on extinction responding in a multiple schedule.

The present study was designed to assess the effect of a single, response-independent food presentation on responding during extinction. Using a two-component multiple schedule, we examined differences in pigeons' extinction responding resulting from a single response-independent food presentation occurring at the beginning of the experimental session (30-s prior to the beginning of the first component). One component presented reinforcement according to a variable interval 45-s schedule and the second presented reinforcement according to a variable interval 180-s schedule. After establishing stable baseline responding we extinguished responding. We systematically manipulated the presence or absence of a single 3-s free food presentation using the food hopper that occurred 30-s prior to the presentation of the first component. We found the single free food presentation increased persistence of responding in extinction. This finding is inconsistent with behavioral momentum theory inasmuch as it assigns a response disruptive role to food presentations occurring outside of the context of the target operant.

Application of impedance threshold devices during cardiopulmonary cerebral resuscitation.

OBJECTIVE: To review the use of impedance threshold devices (ITD) during CPCR, their proposed mechanism of action, and their application in veterinary medicine. DATA SOURCES: Data sources include scientific reviews and original research publications using the PubMed search engine with the following keywords: 'impedance threshold device' and 'resuscitation' and the Veterinary Information Network search function using the keywords 'impedance threshold device.' HUMAN DATA SYNTHESIS: Studies in human medicine have demonstrated that the use of an ITD during CPCR in patients during out-of-hospital cardiac arrest improves coronary perfusion pressure and cerebral perfusion pressure. This improvement in vital organ blood flow results in increased cardiac output and faster return of spontaneous circulation. The use of an ITD has been studied in people and currently holds a class IIb level of recommendation according to the 2010 American Heart Association Guidelines for CPR and Emergency Cardiovascular Care. This device is recommended as a way to improve hemodynamics during CPCR by enhancing venous return and avoiding hyperventilation, thereby increasing the likelihood of a successful resuscitation. VETERINARY DATA SYNTHESIS: Multiple controlled studies using pigs with ventricular fibrillation induced cardiopulmonary arrest have demonstrated increased myocardial and cerebral perfusion with the use of an ITD. These studies have emphasized the importance of decreasing intrathoracic pressures during the decompression phase of CPCR and avoiding hyperventilation in order to maximize vital organ blood flow. CONCLUSIONS: Use of an ITD during CPCR in human and animal studies has demonstrated improved vital organ perfusion and faster return of spontaneous circulation. However, the majority of these studies have been carried out in people during out-of-hospital cardiac arrest and ventricular fibrillation cardiopulmonary arrest pig models. Further studies evaluating the use of an ITD during CPCR in the veterinary hospital setting are warranted.