tryptophan

n. one of the essential amino acids of the human diet. It is a precursor of the neurotransmitter serotonin and of the hormone melatonin and plays a role in general physiological processes. In plants and many animals, it is also a precursor of the B vitamin nicotinic acid. Tryptophan depletion—loss of tryptophan in the brain—may be induced for research purposes.

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Psychology term of the day

January 13th 2025

prima facie

at first sight: on the face of things (Latin, literally: “first face”). Prima facie evidence is evidence that, although not conclusive, is considered sufficiently strong to support an inference of fact in the absence of evidence to the contrary.