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.