The devil is in the detail: Zebrafish learn to discriminate visual stimuli only if salient.

Due to their unique characteristics, the zebrafish plays a key role in the comprehension of neurobiology of cognition and its pathologies, such as neurodegenerative diseases. More and more molecular tools for this aim are being developed, but our knowledge about the cognitive abilities of zebrafish remains extremely scarce compared to other teleost fish. We aimed to investigate the complex cognitive abilities of zebrafish using a tracking-based automated conditioning chamber that allowed precise experimental control, avoided potential cueing provided by the observer (Clever Hans phenomenon), and was shown to considerably improve learning in other teleosts.

A psychophysical approach to measuring the threshold for acoustic stimulation in zebrafish (Danio rerio).

Zebrafish are a popular vertebrate animal model for biomedical research including investigations of the auditory system. Responses to acoustic stimulation have been a challenge to carefully measure in zebrafish. Here, the authors have developed a procedure for measuring hearing sensitivity in adult zebrafish using an appetitive automated Go/No Go task.

Differential reinforcement of an approach response in zebrafish (Danio rerio).

Five zebrafish were trained to approach a target using a fully automated training procedure. During a training session, if the distance between the fish and the target was closer than an arbitrarily set distance, the approach response was reinforced by food. The fish continued to respond under this reinforcement contingency and the distance criterion could be shortened up to eighty times within a 1h session.

An automated device for appetitive conditioning in zebrafish (Danio rerio).

An automated device and a procedure for the operant conditioning individual zebrafish were developed. The key feature of this procedure was the construction of a simple, inexpensive feeder that can deliver extremely small amounts of food, thus preventing rapid satiation. This allows the experimenter to run multiple trails in a single test session and multiple sessions in one day.

Localized brain activation related to the strength of auditory learning in a parrot.

Parrots and songbirds learn their vocalizations from a conspecific tutor, much like human infants acquire spoken language. Parrots can learn human words and it has been suggested that they can use them to communicate with humans. The caudomedial pallium in the parrot brain is homologous with that of songbirds, and analogous to the human auditory association cortex, involved in speech processing.

Vocal learning in Budgerigars (Melopsittacus undulatus): effects of an acoustic reference on vocal matching.

Budgerigars were trained to produce specific vocalizations (calls) using operant conditioning and food reinforcement. The bird's call was compared to a digital representation of the call stored in a computer to determine a match. Once birds were responding at a high level of precision, we measured the effect of several manipulations upon the accuracy and the intensity of call production.