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Ch 2 psyc

Chapter 2: Neuroscience: The Brain and Behavior

Chapter 1 Overview

  • Organization of the Nervous System

  • Brain Function

  • Hormones and Behavior

  • Genetic Factors and Behavior

  • Evolutionary History and Current Behavior

Organization of the Nervous System

  • Functions: Facilitates communication within the body and between the body and the outside world.

  • Comprised of NEURONS: basic building blocks found throughout the body.

    • Afferent (sensory) neurons: carry messages to the spinal cord and brain.

    • Efferent (motor) neurons: carry messages from the brain and spinal cord to other body structures.

    • Interneurons: connect sensory and motor neurons.

  • GLIAL cells (90% of brain cells):

    • Provide support, nourishment, and protection for neurons.

    • Contribute to formation of neuronal connections and myelin sheath.

Neurons and Action Potentials

  • Parts of a Neuron:

    • Cell body (with nucleus)

    • Dendrites

    • Axon

    • Axon terminals

  • Action Potential: an electrical current that travels down the axon, triggered when stimulation of a neuron reaches the neuron’s threshold; it is an all-or-none response.

Neurotransmitters

  • Definition: Chemicals stored in synaptic vesicles within axon terminals, released by action potential and move across the synapse to bind with receptor sites on nearby neurons.

  • Synapse: Microscopic space between neurons; action potential releases chemicals into the synapse.

  • Over 50 neurotransmitters identified:

    • Acetylcholine: Involved in skeletal movement and memory; deficiency linked to Alzheimer’s disease.

    • GABA: Reduces anxiety and seizures; linked to alcohol abuse and sleep disorders.

    • Serotonin: Mood regulation; involved in depression and anxiety.

    • Dopamine: Reward feelings, movement, linked to schizophrenia and ADHD.

    • Norepinephrine: Regulates arousal, hunger, and sexual behaviors.

Psychopharmacology

  • Study of how drugs affect behavior.

  • Examples:

    • MDMA (Ecstasy): Massive release of serotonin.

    • L-dopa: Increases production of dopamine.

    • Prozac/Zoloft: Inhibits reuptake of serotonin.

  • Agonists: Chemicals mimicking neurotransmitters.

  • Antagonists: Chemicals opposing neurotransmitter actions.

Structure of the Nervous System

  • Human Nervous System Components:

    • Central Nervous System (CNS): Brain and spinal cord; facilitates two-way communication.

    • Peripheral Nervous System (PNS):

      • Somatic Nervous System: Voluntary actions.

      • Autonomic Nervous System: Involuntary actions, with sympathetic (fight or flight) and parasympathetic (normal functions) branches.

The Brain

  • Three prenatal divisions:

    • Hindbrain: Basic biological and reflex functions.

    • Midbrain: Receives signals from other brain regions.

    • Forebrain: Most complex cognitive functions.

  • Hindbrain Functions:

    • Medulla: Regulates heartbeat and breathing.

    • Pons: Involved in sleep and dreaming.

    • Cerebellum: Balance, coordination, learning and memory for movements.

Midbrain and Forebrain

  • Midbrain: Coordinates reflex movements and regulates temperature.

  • Forebrain Components:

    • Thalamus: Sensory relay station (except smell).

    • Hypothalamus: Regulates eating, drinking, and sexual activity.

    • Limbic System: Involved in emotion, memory, and social behavior.

    • Cerebrum: Largest structure, divided into two hemispheres; connected by corpus callosum.

Four Lobes of the Cerebral Cortex

  • Frontal Lobes: Higher cognitive functions, motor cortex, speech production.

  • Parietal Lobes: Somatosensory area for skin senses.

  • Temporal Lobes: Hearing and memory for speech.

  • Occipital Lobes: Visual processing and memory.

Brain Function Measurement Techniques

  • Methods:

    • Electroencephalogram (EEG)

    • Functional MRI (fMRI)

    • Computerized Tomography (CT)

    • Positron Emission Tomography (PET)

Brain Specialization

  • Split Brain Research:

    • Roger Sperry and Michael Gazzaniga’s findings on individuals post-corpus callosotomy; lateralization of functions across the two hemispheres.

Gender Differences in the Brain

  • Cerebral hemispheres organized differently in men and women, but the differences are small and do not consistently predict performance.

Neural Plasticity and Change

  • Plasticity: Brain's ability to adapt through forming new synapses and changes in neural conduction, influenced by experiences.

Hormones and Behavior

  • Hormones: Chemicals regulating organ activities, produced by endocrine glands (e.g., pituitary, thyroid, adrenal glands).

Genetic Factors and Behavior

  • Genetic Studies:

    • Genetics examines heredity and how traits are transmitted.

    • Nature vs. Nurture: Both biological makeup and environmental experiences influence behavior.

Basics of Genetics

  • Chromosomes: Microscopic DNA strands; 23 pairs in humans.

  • Genes: Functional hereditary units determining traits, can be dominant or recessive.

How Genes Affect Behavior

  • Behavioral Genetics: Studies influence of genetics on behavior, often using twins for comparison.

Epigenetics

  • Examines how gene expression is influenced by external factors, leading to the concept of genetic vulnerability.

Evolutionary History and Current Behavior

  • Evolutionary Psychology: Explains behaviors through the brain's evolutionary development and its implications on modern behaviors; discussions include mate selection and child protection.