Linda Ann’s Answer
Have you chatted with your academic advisor at your undergraduate program? I would do that for more guidance with the entire process for admission to graduate school. It's a rigorous and competitive process.
Have you perused the website of the American Psychological Association (www.apa.org) and specifically the three divisions within the APA which represent these specialties? I am not a member of these divisions (I hold membership in two others, one of which has information about graduate programs...so there might be something similar for you to peruse):
Division 40: Society for Clinical Neuropsychology provides a scientific and professional forum for individuals interested in the study of the relationships between the brain and human behavior. As such, Division 40 promotes interdisciplinary interaction among various interest areas including physiological cognitive, developmental, clinical rehabilitation, school, forensic and health psychology. The exchange of ideas in facilitated by the Division's encouragement of scientific research, education and practice. Members receive (twice a year) the Society for Clinical Neuropsychology, Newsletter 40, in which pertinent divisional issues and information are published. In addition, the Division presents student awards for distinguished scientific research at the APA annual convention. Visit the website for Division 40: Society for Clinical Neuropsychology (http://www.scn40.org/).
Society for Behavioral Neuroscience and Comparative Psychology
Division 6: Society for Behavioral Neuroscience and Comparative Psychology members are devoted to studying the biology of behavior. Their focus is on behavior and its relation to perception, learning, memory, cognition, motivation, and emotion. Behavioral neuroscientists study the brain in relation to behavior, its evolution, functions, abnormalities, and repair, as well as its interactions with the immune system, cardiovascular system, and energy regulation systems. Comparative psychologists study the behavior of humans and other animals, with a special eye on similarities and differences that may shed light on evolutionary and developmental processes.
Visit the website for Division 6: Society for Behavioral Neuroscience and Comparative Psychology (http://www.apadivisions.org/division-6/index.aspx?_ga=2.225131482.1333862937.1504696292-1798410851.1440699368)
Society for Health Psychology
Division 38: Society for Health Psychology seeks to advance contributions of psychology to the understanding of health and illness through basic and clinical research, education and service activities and encourages the integration of biomedical information about health and illness with current psychological knowledge. The division has a nursing and health group and special interest groups in aging, women, and minority health issues. The division publishes the monthly journal Health Psychology and the quarterly newsletter The Health Psychologist. Division 38 offers a listing of training programs in health psychology and presents an annual student paper award. Visit the website for Division 38: Society for Health Psychology (http://www.apa.org/about/division/div38.aspx).
Have fun looking around. Do speak with your Academic Advisor! Good luck.