Biological psychology, also known as biopsychology or psychobiology, is a branch of psychology that focuses on the biological basis of behavior and mental processes. It seeks to understand how biological factors, such as brain structure and function, genetics, neurochemistry, and hormones, influence human cognition, emotions, motivations, and actions.

Key aspects of biological psychology include:

1. Neuroanatomy and Neurophysiology: Biological psychology examines the structure and function of the nervous system, including the brain, spinal cord, and peripheral nervous system. It investigates how neurons communicate with each other through electrochemical signals and how neural circuits give rise to complex behaviors and mental processes.
2. Brain-Behavior Relationships: It explores the relationship between brain activity and behavior, seeking to identify neural correlates of specific cognitive functions, emotions, and behaviors. This includes using techniques such as brain imaging (e.g., MRI, fMRI, PET scans) and electrophysiology (e.g., EEG, ERP) to study brain activity in relation to psychological processes.
3. Genetics and Behavior: Biological psychology investigates the role of genetics in shaping individual differences in behavior and mental traits. It examines how genetic variation influences susceptibility to psychological disorders, personality traits, intelligence, and other aspects of psychological functioning.
4. Neurochemistry and Pharmacology: It explores the role of neurotransmitters, hormones, and other chemical messengers in modulating behavior and mental processes. Biological psychology investigates how alterations in neurochemical systems contribute to psychiatric disorders and how pharmacological interventions can be used to treat mental illness.
5. Endocrine System: Biological psychology examines the role of hormones in regulating physiological and psychological processes, including stress response, reproductive behavior, mood regulation, and metabolism. It investigates how hormonal imbalances can impact mental health and behavior.
6. Evolutionary Psychology: Biological psychology draws insights from evolutionary theory to understand the adaptive functions of behavior and cognition. It explores how natural selection has shaped the structure and function of the brain, as well as psychological mechanisms that promote survival and reproductive success.
7. Developmental Neuroscience: It investigates how biological factors influence brain development across the lifespan, from prenatal development to aging. Biological psychology examines critical periods of brain plasticity, as well as the impact of early experiences and environmental factors on brain development and subsequent behavior.
8. Clinical Applications: Biological psychology has important implications for understanding the etiology and treatment of mental illness. It contributes to the development of biological markers for psychiatric disorders, the discovery of new psychotropic medications, and the refinement of brain stimulation techniques for therapeutic purposes.

Biological psychology integrates principles and methods from neuroscience, genetics, physiology, and psychology to provide a comprehensive understanding of the biological underpinnings of behavior and mental health. It plays a crucial role in advancing our knowledge of brain-behavior relationships and informing interventions for individuals with psychological disorders.