triune brain

the view, now outmoded, that the brain consists of three layers reflecting its evolutionary development. The first and oldest is the archipallium, or R-complex (meaning reptilian complex and including the brainstem and cerebellum); the second is the paleomammalian system, or limbic system; and the most recently evolved is the neopallium, or neocortex, also known as the neomammalian brain. [proposed by U.S. physician and neuroscientist Paul D. MacLean (1913–2007)]

Browse dictionary by letter

a b c d e f g h i j k l m n o p q r s t u v w x y z

Psychology term of the day

February 17th 2025

maze-bright and maze-dull rats

two groups of rats that were separated based on their performance in a standardized maze problem. Those that performed best were bred with each other, as were those that performed most poorly. Over relatively few generations, there was a complete separation in performance, with none of the maze-bright rats overlapping in scores with maze-dull rats. However, the selective breeding appeared to be specific to the maze tests that were used and did not affect learning ability more generally; moreover, maze-dull rats reared in an enriched environment (see enrichment) could perform as well as maze-bright rats.