Topographic analysis of the rat's bar behaviour in the Skinner box

Protocols for the Evaluation of Neurodevelopmental Alterations in Rabbit Models In Vitro and In Vivo

The rabbit model is gaining importance in the field of neurodevelopmental evaluation due to its higher similarity to humans in terms of brain development and maturation than rodents. In this publication, we detailed 14 protocols covering toxicological relevant endpoints for the assessment of neurodevelopmental adverse effects in the rabbit species. These protocols include both in vitro and in vivo techniques, which also cover different evaluation time-points, the neonatal period, and long-term examinations at postnatal days (PNDs) 50–70. Specifically, the protocols (P) included are as follows: neurosphere preparation (GD30/PND0; P2) and neurosphere assay (P3), behavioral ontogeny (PND1; P4), brain obtaining and brain weight measurement at two different ages: PND1 (P5) and PND70 (P12), neurohistopathological evaluations after immersion fixation for neurons, astrocytes, oligodendrocytes and microglia (PND1; P6-9) or perfusion fixation (PND70; P12), motor activity (P11, open field), memory and sensory function (P11, object recognition test), learning (P10, Skinner box), and histological evaluation of plasticity (P13 and P14) through dendritic spines and perineuronal nets. The expected control values and their variabilities are presented together with the information on how to troubleshoot the most common issues related to each protocol. To sum up, this publication offers a comprehensive compilation of reliable protocols adapted to the rabbit model for neurodevelopmental assessment in toxicology.

Mediation of timing accuracy by operant behavior

We attempted to demonstrate that timing performance on a temporal discrimination would be enhanced if rats were required to fill a duration with behavior than when they were not required to respond. Six rats were trained to discriminate between a 3- and 9-s stimulus in a symbolic-matching-to-sample task. In two conditions, a tone was used to signal the sample, and in the other two conditions, a light was used to signal the sample. In two conditions, the rats were required to respond on a lever mounted on the rear wall of the experimental chamber before making their discriminative response to one of the two levers mounted on the front wall of the experimental chamber. In the other two conditions, the rear lever was not presented during sample presentation, and no response was required. Consistent with our predictions, timing performance was significantly better when a lever-response was required during sample presentation than when no response was required.