Distinguishing whether dopamine regulates liking, wanting, and/or learning about rewards.

To determine whether dopamine regulates liking, wanting, and/or learning about rewards during goal-directed behavior, the authors tested genetically engineered dopamine-deficient (DD) mice for acquisition of an appetitive T-maze task with and without endogenous dopamine signaling. Experiment 1 established that DD mice treated with L-dihydroxyphenylalanine (L-dopa [LD]) perform similarly to controls on a T-maze task designed to measure liking, wanting, and learning about rewards. Experiment 2, which tested saline-, caffeine-, and LD-treated DD mice on the T maze, separated performance factors from cognitive processes and revealed that dopamine is not necessary for mice to like or learn about rewards but is necessary for mice to seek (want) rewards during goal-directed behavior.

A critique of Mody, Studdert-Kennedy, and Brady's "Speech perception deficits in poor readers: auditory processing or phonological coding?".

A 1997 article by Mody, Studdert-Kennedy, and Brady claimed that their studies constituted a critical test of two hypotheses concerning students with reading impairment: (a) that they experience speech-specific failure in phonological representation, and (b) they display general deficits in auditory temporal processing. From these studies, the authors concluded that their findings were consistent with the first hypothesis but were not in agreement with the second. A critical analysis of the Mody et al.

More power to them--statistically, that is: a commentary on Studdert-Kennedy, Mody, and Brady's criticism of a critique.

The power analysis discussed above establishes that it was most unlikely that Mody et al. (1997) could make a meaningful test of the Tallal hypothesis because of inadequate n and failure to specify the effect size. Note that this is a best-case scenario, because the power analysis assumes that the analysis of variance assumptions were within reasonable boundaries (e.

Comparative psychology is still alive but may be losing relevance.

Greenberg et al., in their perspective on the current state and fate of comparative psychology, present convincing data that the field is viable and that comparative psychologists are making important contributions to the research literature. The central feature of the field is its emphasis upon evolution.

The role of dopamine in learning, memory, and performance of a water escape task.

Dopamine-deficient (DD) mice have selective inactivation of the tyrosine hydroxylase gene in dopaminergic neurons, and they die of starvation and dehydration at 3-4 weeks of age. Daily injections of L-DOPA (50 mg/kg, i.p.