Biological Bases of Behavior

Biopsychology and the Brain

Biological Psychology

  • Definition:

    • A branch of psychology focused on the connection between the brain and behavior.

Nature vs. Nurture

  • Ancient Debate

  • Evolutionary Psychology

    • Aims to address the nature vs. nurture debate.

    • Some aspects have clear answers, but many remain unresolved.

  • Behavior Genetics

    • Investigates individual differences due to varying genes and environments.

    • Focus on the interaction of heredity and environment.

Interaction of Heredity and Environment

  • Nature vs Nurture

    • Nurture acts on what nature provides.

    • Every psychological event is tied to a biological event.

Evolutionary Psychology

  • Focus

    • Studies what makes us alike by using Darwin's principles.

    • Explains many similarities among humans.

Genetic Legacy

  • Genome Analysis

    • Reflects our genetic similarities.

    • Genetic differences from populations account for 5% of variability in traits.

Behavior Genetics: Predicting Individual Differences

  • Focus Areas

    • Environment: Influences from external factors.

    • Heredity: Genes as a defining factor.

Genes and Their Role

  • Genetic Overview

    • 46 chromosomes containing approximately 20,000 genes.

    • Genes can be active (expressed) or inactive (potentially expressible).

Twin and Adoption Studies

  • Used to determine behavior or mental process influences from nature or nurture.

  • Differentiates between:

    • Monozygotic (identical) twins

    • Dizygotic (fraternal) twins

Gene-Environment Interaction

  • Trait Development

    • Some traits develop uniformly, while others are environment-dependent.

    • Unique traits result from the interplay between genes and experiences.

Epigenetics

  • Studies molecular mechanisms by which environments can influence gene expression.

Communication in the Nervous System

  • Neuronal Communication

    • Neurons are the fundamental units of the nervous system.

Types of Neural Cells

  • Glial Cells:

    • Support neurons by providing nutrients, insulation (myelin), guidance for connections, cleanup of waste, and aiding in learning.

  • Sensory Neurons:

    • Transmit information to the Central Nervous System (CNS).

  • Motor Neurons:

    • Carry commands from the CNS to the muscles and glands.

  • Interneurons:

    • Exist within the brain and spinal cord, facilitating internal communication and processing.

Neural Communication Basics

  • Neuron Structure:

    • Soma: The cell body and control center.

    • Dendrites: Extensions that receive information from other neurons.

    • Axon: Carries the neural impulse/message to target cells.

      • Ends in terminal fibers that release neurotransmitters.

      • Myelin sheath covers the axon to speed up transmission.

Action Potential

  • Neural Impulse:

    • An electrical signal that travels down the axon when initiated.

    • Resting Potential:

      • At rest, the fluid inside the neuron is negatively charged (-70 millivolts).

    • Depolarization:

      • Initiated by a strong signal, creating an action potential in an all-or-none manner.

    • Repolarization:

      • After action potential, ion pumps restore balance.

Communication Between Neurons

  • Chemical Signal Transmission:

    • Action potentials trigger the release of neurotransmitters at terminal endings.

    • These chemicals flow across the synaptic gap to the target neurons.

  • Receiving Signals:

    • Neurotransmitters bind to receptors on receiving neurons’ dendrites, leading to excitation or inhibition, and potential reuptake of leftovers.

Drug Influence on Neural Communication

  • Agonists:

    • Mimic neurotransmitters, sending similar messages.

  • Antagonists:

    • Block neurotransmitter receptors, inhibiting neuron firing.

Addiction and Psychoactive Drugs

  • Psychological Addiction:

    • Craving the effects of substances.

  • Physical Addiction:

    • Body's reliance on the substance to function, leading to withdrawal symptoms.

Tolerance and Addiction Indicators

  • Mild to Severe Addiction:

    • Varies based on behaviors and disruptions in life from drug use.

  • Indicators Include:

    • Diminished control over substance use.

    • Reduced social functioning due to substance use.

    • Continued use despite physical hazards.

Types of Psychoactive Drugs

  • Depressants:

    • Lower neural activity (e.g., Alcohol, Sedatives).

  • Opiates:

    • Pain reduction and lessened neurotransmission (e.g., Morphine, Heroin).

  • Stimulants:

    • Speed up neural activity (e.g., Caffeine, Nicotine).

  • Hallucinogens:

    • Alter perceptions (e.g., LSD, Marijuana).

Nervous System Organization

  • Central Nervous System (CNS):

    • Includes the brain and directs mental processes.

    • Displays neuroplasticity, changing due to experience and usage.

  • Peripheral Nervous System (PNS):

    • Transmits information to and from the CNS.

    • Divided into:

      • Somatic: Connects to sensory receptors and skeletal muscles.

      • Autonomic: Controls involuntary tasks (e.g., heart rate, digestion).

Autonomic Nervous System (ANS)

  • Further splits into:

    • Sympathetic: Mobilizes for stress response, encouraging arousal.

    • Parasympathetic: Calms the body and conserves energy.

Function of the Split Brain

  • Hemispheric Specialization:

    • Left hemisphere primarily handles language and analytical skills.

    • Right hemisphere oversees non-verbal tasks like music, art, and spatial recognition.

Brain Structures and Their Functions in Relation to Behavior

Brain Stem

  • Function: Controls essential life functions such as heartbeat, breathing, and consciousness.

  • Behavioral Relevance: Automatic responses are influenced by brain stem activity, impacting reactions to environmental stimuli.

Medulla

  • Function: Regulates vital functions like heart rate and blood pressure.

  • Behavioral Relevance: Affects physical state and responsiveness, crucial for survival during stress responses.

Reticular Formation

  • Function: A network of neurons involved in regulating wakefulness and sleep.

  • Behavioral Relevance: Affects attention and arousal levels, influencing alertness and the ability to focus on tasks.

Reticular Activation System

  • Function: Facilitates selective attention and filters important information from sensory input.

  • Behavioral Relevance: Plays a role in determining what information reaches consciousness, impacting decision-making.

Cerebellum

  • Function: Coordinates voluntary movements and balance.

  • Behavioral Relevance: Influences motor skills and precision in tasks, affecting activities like sports and musical performance.

Thalamus

  • Function: The relay center for sensory information (except smell) to the cerebral cortex.

  • Behavioral Relevance: Impacts perception and consciousness by filtering sensory data that influences behavior.

Hypothalamus

  • Function: Regulates homeostasis, including hunger, thirst, temperature, and sleep cycles.

  • Behavioral Relevance: Connects physiological changes with motivation, influencing behaviors like eating and sleeping.

Pituitary Gland

  • Function: Often referred to as the 'master gland', it regulates hormones affecting various bodily functions.

  • Behavioral Relevance: Influences growth, stress response, and reproduction-related behaviors.

Hippocampus

  • Function: Vital for memory formation and spatial navigation.

  • Behavioral Relevance: Affects learning and memory, impacting decision-making and the ability to recall information.

Amygdala

  • Function: Involved in emotion regulation, particularly fear and pleasure responses.

  • Behavioral Relevance: Plays a key role in emotional processing and influences reactions to threats, impacting social behaviors.

Corpus Callosum

  • Function: Connects the left and right hemispheres, facilitating communication between them.

  • Behavioral Relevance: Affects cognitive processes like reasoning and problem-solving across both hemispheres.

Occipital Lobe

  • Function: Primarily responsible for visual processing.

  • Behavioral Relevance: Visually-driven behaviors such as reading and navigation are influenced by this area.

Visual Cortex

  • Function: Interprets visual data received from the eyes.

  • Behavioral Relevance: Affects perception and response to visual stimuli, impacting how individuals interact with their environment.

Temporal Lobe

  • Function: Involved in processing auditory information and memory.

  • Behavioral Relevance: Influences language comprehension and emotional responses based on sound, affecting social interactions.

Auditory Cortex

  • Function: Processes sound stimuli.

  • Behavioral Relevance: Affects auditory perception and the ability to appreciate music, influencing cultural behaviors.

Wernicke's Area

  • Function: Critical for language comprehension.

  • Behavioral Relevance: Impacts understanding and processing of spoken language, affecting communication skills.

Parietal Lobe

  • Function: Integrates sensory information and is involved in spatial awareness.

  • Behavioral Relevance: Influences perception of touch and proprioception, affecting interactions with the environment.

Somatosensory Cortex

  • Function: Processes sensory input from the body.

  • Behavioral Relevance: Affects the accuracy of responses to tactile stimuli, impacting physical interaction with objects and people.

Frontal Lobe

  • Function: Responsible for higher cognitive functions, including reasoning, planning, and judgment.

  • Behavioral Relevance: Influences decision-making, impulse control, and social behaviors.

Motor Cortex

  • Function: Controls voluntary muscle movements.

  • Behavioral Relevance: Affects physical actions and movement precision, impacting overall physical agility.

Prefrontal Cortex

  • Function: Involved in complex behaviors, decision-making, and moderating social behavior.

  • Behavioral Relevance: Critical for personality expression and managing impulses, vastly influencing social interactions.

Broca's Area

  • Function: Key area for speech production.

  • Behavioral Relevance: Influences verbal communication capabilities, affecting social exchanges and interactions.

Executive Functioning

  • Function: Higher-order cognitive processes such as working memory, flexible thinking, and self-control.

  • Behavioral Relevance: Essential for planning, problem-solving, and adapting to new situations, significantly shaping personal behavior and goal achievement.