Computer-automated method to study cardiac conditioning to a chemical cue in young salmon

An apparatus was designed in which young Atlantic salmon (Salmo salar) are rapidly conditioned to reduce heart rate using a chemical-electric shock conditioning procedure. A chemical calibration system permitting efficient stimulus control is described as well as the electronic systems and computer software used to control all events of an experimental session and to quantify cardiac and chemical data. Efficient stimulus control and computer-automated recording techniques minimize inter-trial intervals and the time required for the measurement and analysis of cardiac responses. Data are presented showing that 15-month-old Atlantic salmon can be trained to reduce by 20% their heart rate to the synthetic chemical morpholine within 5 training trials whereas 10-month-old fish did not do so until 15 training trials.