Training protocol for touchscreen-based visual discrimination in mice

Automated touchscreen-based tasks are increasingly being used to explore a broad range of issues in learning and behavior in mice. Researchers usually report how they train mice before acquiring the target task concisely, and shaping protocols at this stage are typically flexible. In this report, we described a training protocol, developed in our laboratory, for mice acquiring a simultaneous discrimination performance using visual stimuli. C57BL/6N mice were first given magazine training. Nosepoke responses were then authoshaped and maintained on a continuous reinforcement schedule. Self-start response was then introduced in order to measure response time to complete each trial. The stimulus position was also varied across trials. We finally examined the contrast discrimination performance. Mice were tested with four different contrast ratios. Target stimuli were white and black targets and the brightness of distractors had values between targets and background. All mice successfully went through all training stages, confirming that this training protocol is promising for shaping appropriate discriminative behaviors in mice.

The Fish Stick: An Easy-to-Use Classroom Training Apparatus for Fish

The fish stick is an easy-to-use device for conditioning fish under classroom conditions. It is constructed from inexpensive plastic pipe available at most hardware stores and uses electronic components available at retail electronics outlets. Fish press a nipple for baby food which can be brought under stimulus control using lights, vibratory cues, or both. The fish stick is suitable for inquiry-based experiences in courses on the psychology of learning or comparative psychology. Data are presented using a continuous reinforcement schedule and discrimination learning. Students report that the fish are easy to train and enjoy the hands-on experience.

Intracranial self-stimulation motivates weight-lifting exercise in rats

The purpose of this study was to determine the feasibility of using a positive reinforcement protocol to motivate weight-lifting exercise in rats. Intracranial self-stimulation was used to induce weight-lifting exercise. Bipolar electrodes were implanted in the ventral tegmental area of rats, and the animals were trained to bar press on a continuous reinforcement schedule for electrical brain stimulation. Animals with response rates of 1,200–1,500 presses/h were then trained with a discriminative light stimulus to alternate between a normally positioned bar and an elevated bar that could be reached only by standing on the hindlimbs. The animals were fitted with a weighted jacket at a starting resistance of 5–10% of their body weight. Weight-training sessions were conducted 5 days/wk for 10 wk. Training consisted of 600 presses/session, alternating every 15 presses between the low and high bars. At the beginning of each subsequent week, the resistance was progressively increased, with some animals eventually training at resistances greater than 50% of their body weight. At the end of the training period, the rats were lifting over 550% of the starting weight. Gastrocnemius size and mean fiber diameter were increased in the weight-lifting animals. This model combines exercise with positive incentive and has the advantages of being relatively easy to implement and not producing any apparent physical or mental trauma in the animal.

The Influence of Partial Reinforcement on Serial Autoshaping with Pigeons

The effect of partial reinforcement on the rate of responding during the first element of a serial compound was investigated using autoshaping in pigeons. Experiment I employed the illumination of a response key by two different colours as the elements of the compound. Responding during the first element was faster when this stimulus was intermittently paired with the second element and the unconditioned stimulus than when a continuous reinforcement schedule was employed. Experiment II demonstrated that this effect of partial reinforcement is unaffected by maniuplating the associative strength of the second element at the outset of compound conditioning. A similar effect of partial reinforcement was also found in Experiment III which used a tone as the first element of the serial compound.

Changes in core temperature and feeding in rats by levorphanol and dextrorphan

Male Sprague–Dawley rats received saline for 5 days before and 5 days after daily subcutaneous injections of levorphanol or dextrorphan tartrate (8 mg base/kg) for 10 days. Core temperatures, measured by telemetry, and acquisition of food pellets on a continuous reinforcement schedule were monitored simultaneously and recorded every 30 min for each rat throughout the experiment. After the first levorphanol injections signs of acute intoxication were apparent, and a mild but delayed hyperthermia was observed and food intake declined. With repeated injections of levorphanol peak hyperthermia increased and occurred with a shorter latency after administration, as did a phase of 'stimulated' feeding activity. This phase of vigorous feeding during light hours markedly disrupted the characteristic diurnal pattern of daily food intake. During withdrawal temperatures decreased, feeding became more intermittent, and signs of increased irritability were evident in the levorphanol group. Patterns during daily injections of dextrorphan, and after its withdrawal, were similar to those in the saline control period. These results indicate that the patterns of change in temperature and feeding responses to levorphanol are similar to those found earlier with heroin, codeine, and morphine, and that these changes involve stereospecific receptors.

Food deprivation increases oral and intravenous drug intake in rats

Rats given continuous access to etonitazene hydrochloride in their drinking water (5 micrograms per milliliter) more than doubled their drug intake while deprived of food. Another group of rats with implanted jugular catheters self-administered etonitazene (10 micrograms per kilogram) intravenously on a continuous reinforcement schedule, and the number of infusions increased significantly on days when they were deprived of food. These results suggest that feeding condition may be a powerful determinant of drug-reinforced behavior.

Overtraining Extinction Effect Using a Free-Operant Procedure

The effects of five levels of training (210, 490, 1470, 2450, 3430 reinforced responses) on extinction performance were investigated. A free-operant bar-press paradigm was employed. A continuous reinforcement schedule was used with .12 ml. of 64% sucrose. Number of bar-presses and duration of time to reach a 1-min. non-response criterion showed that resistance to extinction was an increasing function of the number of reinforcements during training. However, the amount of time required to reach a 5-min. criterion showed the opposite relationship. It was concluded that different criteria reflected different patterns of extinction behavior and that the overtraining extinction effect (decreased resistance to extinction following extended training) could be demonstrated in a free-operant situation if the appropriate criteria were selected.