Behavioural observations in gunn rats

The Gunn rat is a hooded mutant of albino rat with various biochemical defects, including a low UDP-glucuronosyl-transferase activity. As a consequence, about half of their offspring are jaundiced from birth, due to high free bilirubin levels, and develop widespread brain damage. The behaviour of both jaundiced and nonjaundiced Gunn rats was studied in four different tests in a shuttle-box and in a stepthrough passive avoidance situation, and compared with that of normal hooded rats. No differences among groups were found in performance of shuttle responses to a tone in a pseudoconditioning paradigm in which tones and shocks were given at random. However, rats from the two Gunn groups made less shuttlings to the tone in two tests that involved an avoidance contingency (each response cancelled one shock). In addition, nonicteric Gunn rats also performed poorly in a classical conditioning test in the shuttle-box (tones and shocks paired on every trial regardless of responses). This last deficiency of non-icteric Gunn rats may be explained by their higher tendency to freeze in situations involving stimulus-stimulus interactions. They also showed a higher latency than that of the two other groups to enter the dark side of the step-through apparatus on their first exposure to it. All animals seemed to learn the passive-avoidance task to the same extent, however, as shown in a retest carried out 48 h later. Both Gunn groups were hypersensitive to the stereotyped-behaviour-inducing action of apomorphine (0.125–1.0 mg/kg, i.p.), but all groups were about equally sensitive to that of d -amphetamine sulfate (0.5–4.0 mg/kg). Since apomorphine is disposed of by glucuronidation, this might be explained by the low UDP-glucuronosyl-transferase activity known to exist in the Gunn animals. The present results show that additional genetic defects have developed by in-breeding in the Gunn population, which are unrelated to brain damage caused by bilirubin, and which can be well characterized from a behavioural standpoint.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46403/1/213_2004_Article_BF00426881.pd

Integrative thinking is the key : An evaluation of current research into the development of adult thinking

Post-formal relativistic-dialectical thinking has been widely claimed to be a new developmental stage of intellectual development. Other theoretical models come very close to post-formal thinking, with overlapping features such as the study of wisdom and epistemic understanding, as well as models of expertise, critical thinking, and scepticism. No coherent theory exists in the fields of post-formal and relativistic-dialectical thinking, though scholars have claimed that there is some similarity between the models. While empirical evidence of interconnectedness between them exists, a major difficulty lies in the theoretical definition of concepts. We critically assess the definitions of relativism and dialectical thinking and show these to be ambiguous and weakly defined terms. We argue that the notion of “integrative thinking” should be used instead of post-formal or relativistic-dialectical thinking. Integration can be additive or transformative. Transformational integration of various psychological domains seems to be the core component in models of adult cognitive development.peerReviewe