Biological Bases of Behavior: Comprehensive Study Notes

Imaging Techniques and Neuroimaging

Biopsychologists, behavioral geneticists, physiological psychologists, and behavioral neuropsychologists study the relationships between brain/nervous-system function and behavior. Neuropsychologists are also called biological psychologists.
Studying patients with brain damage links loss of structure with loss of function.
Lesions: precise destruction of brain tissue that enables a more systematic study of the loss of function resulting from surgical removal (ablation), cutting of neural connections, or destruction by chemical applications.
CT scans and MRIs show structure.
Computerized axial tomography (CAT or CT): creates a computerized image using X-rays passed through the brain to show structure and/or the extent of a lesion.
Magnetic resonance imaging (MRI): creates a more detailed computerized image using a magnetic field and pulses of radio waves that cause emission of signals that depend upon tissue density.
EEGs, PET scans, and fMRI speak to brain function.
EEG (electroencephalogram): an amplified tracing of brain activity produced when electrodes positioned over the scalp transmit signals about the brain's electrical activity ("brain waves") to an electroencephalograph machine.
Evoked potentials: EEGs resulting from a response to a specific stimulus presented to the subject.
Positron emission tomography (PET): shows brain activity when radioactively tagged glucose rushes to active neurons and emits positrons.
Functional MRI (fMRI): shows brain activity at higher resolution than the PET scan when changes in oxygen concentration near active neurons alter magnetic qualities.

Nervous System Overview

Central nervous system (CNS): brain and spinal cord.
Peripheral nervous system (PNS): portion of the nervous system outside the brain and spinal cord; includes all of the sensory and motor neurons, and subdivisions called the autonomic and somatic nervous systems.
Autonomic nervous system (ANS): subdivision of the PNS that includes motor nerves that innervate smooth (involuntary) and heart muscle. Its sympathetic nervous system prepares the body for "fight or flight"; the parasympathetic nervous system causes bodily changes for maintenance or rest.
Sympathetic nervous system: subdivision of PNS and ANS whose stimulation results in responses that help your body deal with stressful events.
Parasympathetic nervous system: subdivision of PNS and ANS whose stimulation calms the body following sympathetic stimulation by restoring normal bodily processes.
Somatic nervous system: subdivision of PNS that includes motor nerves that stimulate skeletal (voluntary) muscles.

Brain Structure and Functional Organization

Spinal cord: portion of the CNS below the medulla.
Brain: portion of the CNS above the spinal cord.
Evolutionary model: the brain consists of 3 sections: reptilian brain (medulla, pons, cerebellum); old mammalian brain (limbic system, hypothalamus, thalamus); and the new mammalian brain (cerebral cortex).
Developmental model: the brain consists of 3 slightly different sections: hindbrain (medulla, pons, cerebellum), midbrain (small region with parts involved in eye reflexes and movements), and forebrain (including the limbic system, hypothalamus, thalamus, and cerebral cortex).
Convolutions (gyrification): folding in and out of the cerebral cortex that increases surface area.
Contralaterality: control of one side of the body by the opposite side of the brain.
Medulla oblongata: regulates heart rhythm, blood flow, breathing rate, and digestion; involved in vomiting.
Pons: includes portion of reticular activating system (reticular formation) critical for arousal and wakefulness; sends information to and from the medulla, cerebellum, and cerebral cortex.
Cerebellum: controls posture, equilibrium, and movement.
Basal ganglia: regulates initiation of movements, balance, eye movements, and posture; participates in processing of implicit memories.
Thalamus: relays visual, auditory, taste, and somatosensory information to/from appropriate areas of the cerebral cortex.
Hypothalamus: controls feeding behavior, drinking behavior, body temperature, sexual behavior, threshold for rage behavior, activation of the sympathetic and parasympathetic systems, and secretion of hormones from the pituitary.
Amygdala: influences emotions such as aggression, fear, and self-protective behaviors.
Hippocampus: enables formation of new long-term memories.
Cerebral cortex: center for higher-order processes such as thinking, planning, and judgment; receives and processes sensory information and directs movement.
Association areas: areas of the cerebral cortex that do not have specific sensory or motor functions but are involved in higher mental functions such as thinking, planning, and communicating.

Cortical Organization and Lobes

Geographically, the cerebral cortex can be divided into 8 lobes, four on the left side and four on the right side:
- Occipital lobes: primary area for processing visual information.
- Parietal lobes: front strip is the somatosensory cortex that processes sensory information including touch, temperature, and pain from body parts; association areas perceive objects.

Connections to Foundational Principles and Real-World Relevance

The material ties brain structures to specific functions and behaviors, illustrating localization of function and neural circuitry.
Imaging techniques provide both structural (CT, MRI) and functional (EEG, PET, fMRI) insights that guide clinical diagnosis, intervention, and research.
The autonomic system (sympathetic vs parasympathetic) explains physiological responses to stress and rest, with broad implications for health, psychology, and behavior.
Understanding limbic system components (amygdala, hippocampus) clarifies mechanisms underlying emotion regulation and memory formation.
The cerebral cortex and its association areas emphasize higher-order cognition, planning, and communication, highlighting why damage can disrupt complex behaviors even if primary sensory/motor areas seem intact.

Ethical, Philosophical, and Practical Implications (Note)

Brain imaging technologies raise considerations about safety, privacy, and the interpretation of neural data in clinical and research settings.
Localization and modular views of the brain must be integrated with concepts of distributed processing and plasticity; ethical use requires careful interpretation to avoid overstating causes from imaging alone.
The balance between structural findings (lesions, cortical areas) and functional outcomes underscores the complexity of translating neuroscience into real-world interventions.