Parallel increase of heterochromatic increment threshold and postadaptation thresholds in Parkinson's disease and in neuroleptic treatment

Following reports on a predominant loss of blue/yellow contrast sensitivity in Parkinson's disease, we revisited the physiological phenomenon of transient tritanopia. Normative data were collected from 33 healthy individuals using different colour and time combinations. Stimuli of 440 nm wavelength (blue) proved optimal, if flashed for 50 msec within the early phase of a 2 sec pause in the 600 nm adaptation light. These conditions were then applied to 15 patients with Parkinson's disease. We found a parallel increase of increment threshold (P < 0.001) and postadaptation thresholds (P < 0.01), with little change in the extent of transient tritanopia. The same tendency at a lower significance level was found in 15 psychiatric patients under chronic treatment with depot neuroleptics

Enhancement in dopamine reduces generous behaviour in women.

Generosity is a human behavior common in social contexts. However, humans are not equally generous to everyone alike. Instead, generosity decreases as a function of social distance, an effect called social discounting. Studies show that such social discounting effect depends on diverse factors including personality traits, cultures, stress or hormonal levels. Recently, the importance of the neurotransmitter dopamine in regulating social interactions has been highlighted. However, it remains unclear how exactly dopamine agonist administration modulates generous behavior as a function of social discounting. Here, we investigate the causal effect of dopamine agonist administration on social discounting in a pharmacological intervention study. We employ a randomized, double-blind, within-subject design to investigate the impact of the D2/D3 receptor agonist pramipexole on social discounting by keeping gender constant. We apply hyperbolic social discount model to the data and provide evidence that women under pramipexole become less generous in general, especially towards close others. Our results highlight the crucial role of dopamine in social decision making