the science that deals with the biological basis of behavior, thoughts, and emotions and the reciprocal relations between biological and psychological processes. It also addresses topics such as behavior-changing brain lesions, chemical responses in the brain, and brain-related genetics. It includes such fields as behavioral neuroscience, clinical neuroscience, cognitive neuroscience, behavioral endocrinology, and psychoneuroimmunology. Also called biopsychology; physiological psychology; psychobiology.