The limbic-reticular coupling theory of memory processing in the brain and its greater compatibility over other theories

The limbic-reticular coupling theory suggests that the hippocampus and amygdala regulate such descending limbic structures as the mammillary bodies, septum, hypothalamus and epithalamus to regulate the ascending noradrenergic, serotonergic, dopaminergic and cholinergic systems, performing declarative memory consolidation and recall. Recent studies have revealed that, less sensitive to familiarity, the hippocampus functions via the fornix, mammillary bodies and hypothalamus for memory recall. Lesions to the thalamic nuclei were complicated with damage to adjacent fornix, stria medullaris and habenula, simultaneously destroying two kinds of structures respectively for familiarity and recall. Furthermore, the orbitofrontal cortex was shown to be clinically irrelevant for memory recall. Electrophysiologically, the hippocampus regulates the raphe nuclei in complex ways, and the hippocampal theta wave activates the dopaminergic cells in ventral tegmental area and cholinergic neurons in basal forebrain, while cholinergic-modulated theta-gamma coupling mediates cortical recall. These concurrent advances support the limbic-reticular coupling theory for elucidation of memory recall.