Human Medial Forebrain Bundle (MFB) and Anterior Thalamic Radiation (ATR): Imaging of Two Major Subcortical Pathways and the Dynamic Balance of Opposite Affects in Understanding Depression

The medial forebrain bundle (MFB), a key structure of reward-seeking circuitry, remains inadequately characterized in humans despite its vast importance for emotional processing and development of addictions and depression. Using Diffusion Tensor Imaging Fiber Tracking (DTI FT) the authors describe potential converging ascending and descending MFB and anterior thalamic radiation (ATR) that may mediate major brain reward-seeking and punishment functions. Authors highlight novel connectivity, such as supero-lateral-branch MFB and ATR convergence, caudally as well as rostrally, in the anterior limb of the internal capsule and medial prefrontal cortex. These anatomical convergences may sustain a dynamic equilibrium between positive and negative affective states in human mood-regulation and its various disorders, especially evident in addictions and depression.