Psychobiology is the part of psychology that seeks biological explanations for psychological phenomena; also known as biopsychology, and more or less synonymous with the term physiological psychology. (Dictionary of biological psychology. QP 360 D5 2001).
Psychobiology is a subject that combines the disciplines of Biology and Psychology. It is a relatively new field and it occasionally appears under the rubric of "Biopsychology", or sometimes even "Neuroscience".http://www.southampton.liu.edu/academic/mprogram/socsci/psybio/overview.html
Psychobiology studies the biological basis of thought and behavior. It is the area where psychology overlaps with biology. Psychobiologists study anatomy and physiology, in particular the brain and genetics, as they relate to behavior. http://www.nichols.edu/faculty/davis/py151/LectureNotes01%5C151%20ch%202A.doc