Biopsychology and Neuroscience Notes

Biopsychology and the Foundations of Neuroscience

  • Psychology and Biology: Everything psychological is simultaneously biological.
    • Thinking, feeling, or acting requires a body, similar to running with legs.
    • We are bio-psycho-social systems, and understanding behavior requires studying the interaction of biological, psychological, and social systems.

The Brain, The Mind, and Psychology

  • The human brain is the most complex system.
    • Weighs about 3 lbs.
    • About the size of a grapefruit.
    • Pinkish/gray in color.
    • Composed of approximately 100 billion nerve cells.
    • Adults lose about 200,000 nerve cells per day but still retain over 98% of brain cells.

Biopsychology

  • Biopsychology: The specialty in psychology that studies the interaction of biology, behavior, and mental processes; the mind thinking about the mind.
  • Neuroscience: A newer field focusing on the brain and its influence on our behavior.

Innate Abilities

  • Humans are born with innate abilities but must also learn.
  • Evolution: The gradual process of biological change that occurs in a species as it adapts to its environment.

A Wrongheaded Theory

  • Plato correctly located the mind in the head.
  • In the early 1800s, phrenology emerged.
    • Phrenology: Claimed that bumps on the skull could reveal mental abilities and character traits.

The Role of Evolution

  • Evolution has fundamentally shaped psychology by favoring genetic variations that produce adaptive behavior.
  • The evolutionary process links genetics and behavior.

Natural Selection

  • Individuals best adapted to the environment flourish and reproduce, while poorly adapted individuals leave fewer progeny.
  • Accumulation of new traits leads to the formation of new species (Darwin, 1859).

Misconceptions About Evolution

  • Two main misconceptions about evolution:
    1. Darwin did not say humans come from monkeys but suggested a common ancestor millions of years ago.
    2. Behavior does not alter heredity; bigger brains that facilitated communication led to easier survival, making a bigger brain a dominant trait.

Evolution as an Accepted Theory

  • Evolution has been recognized as a valid scientific theory for over a century.
  • Psychology has been slow to accept evolutionary psychology.
  • Some psychologists argue it emphasizes nature (biology) too much and not enough on nurture (learning).

Genetics and Inheritance

  • Genetics plays a role in our basic makeup, including temperament, fears, and behavior patterns.
  • Genetic inheritance is broken into two categories: genotype and phenotype.

Genotype and Phenotype

  • Genotype: An organism’s genetic makeup; the blueprint.
  • Phenotype: An organism’s physical characteristics, including brain chemistry and "wiring."

Heredity and the Environment

  • Heredity never acts alone; it always partners with the environment.
  • Environment includes biological influences like nutrition, disease, and stress.

Chromosomes, Genes, and DNA

  • Every cell carries a complete set of biological instructions for building the organism.
  • Humans have 23 pairs of chromosomes.
    • Each chromosome consists of a long, tightly coiled chain of DNA.
    • DNA holds our unique genetic characteristics.

Genes

  • Genes: Segments of chromosomes that encode directions for inherited physical and mental characteristics.
    • Genes are the “words” that make up the instruction manual.

Chromosomes

  • Chromosomes: Threadlike structures consisting mostly of DNA, along which genes are organized.
  • Chromosomes are like a string of words in a coded sentence, detailing how and when each gene is to be expressed.

Sex Chromosomes

  • Sex chromosomes are represented as "XX" for females and "XY" for males.
  • The mother contributes an "X," and the father's "X" or "Y" determines the biological sex.

Why You Don’t Look Exactly Like Your Siblings

  • You are not exact replicas of your parents due to random shuffling of genes.
  • This variation is the raw material for evolution and genetic differences.

A Debate for the Future

  • Parents can pick the sex of their child with some certainty.
  • Within 25-30 years, it is expected that parents will be able to customize their child's traits, raising ethical questions about genetic manipulation.

How Your Body Communicates

  • The body has two internal communication systems: the fast-working nervous system and the slow-working endocrine system.

Content Objective

  • Vocabulary list: Neuron, Dendrite, Axon, Synapse, Myelin Sheath, Terminal Buttons, Neurotransmitter, Absolute threshold, Action potential, All-or-none principle, Plasticity, Reflex, Neural pathway, Agonist, Antagonist.
  • Students will identify the major parts and functions of neurons and the brain using these terms.

Language Objective

  • Sequencing signal words: First, second, then, next, initially, subsequently, simultaneously.
  • Students will identify the sequence of a neuron firing using sequencing signal words.

Stress and Happiness

  • The nervous and endocrine systems cooperate during stressful and happy situations.

Why Study Them

  • These systems are the biological foundations for all thoughts, emotions, and behaviors.
  • When one system falters, it can significantly affect the brain and mental functions.

Neurons: Our Building Blocks

  • Neurons are specialized cells that receive, process, and transmit information.
  • Bundles of neurons are called nerves.

3 Types of Neurons

  • Neurons are categorized based on location and function:
    • Sensory Neurons
    • Motor Neurons
    • Interneurons

3 Main Tasks of Neurons

  • A neuron exists to:
    1. Receive information.
    2. Carry information down its length.
    3. Pass the information on to the next neuron.

Sensory Neurons

  • Sensory neurons (afferent neurons) carry traffic from sense organs to the brain.
  • They communicate sensory experiences like vision, hearing, taste, touch, smell, pain, and balance.

Motor Neurons

  • Motor neurons (efferent neurons) transport messages from the brain to muscles, organs, and glands.

Interneurons

  • Interneurons relay messages from sensory neurons to other interneurons or motor neurons in complex pathways, making up the majority of our neurons.

How Neurons Work

  • The dendrite, or receiver, accepts incoming messages using branched fibers.

How Neurons Work

  • Dendrites pass the message to the soma, or cell body, which contains the nucleus.
  • The soma assesses all messages and passes on appropriate information at the appropriate time.

How a Neuron Works

  • When the soma decides to pass on a message, it sends it down the axon.
  • The axon is a single transmitter fiber extending from the soma.

Axon

  • The axon is the extension of the neuron through which neural impulses are sent.
  • Axons speak, dendrites listen.
  • Axons vary in length; some are short (brain), others can be 3 feet long (leg).

Action Potential

  • Information travels along the axon as an electrical charge called the action potential.
  • The action potential is the neuron’s “fire” signal, causing neurotransmitters to be released by terminal buttons.

Myelin Sheath

  • The myelin sheath protects the axon and the electric signal, much like insulation on an electrical cord.
  • It is made up of Schwann cells, a glial cell type.

Nodes of Ranvier

  • Nodes of Ranvier are spaces between myelin cells that keep the action potential going through long axons.
  • These spaces prevent the charge from losing intensity.

Action Potential and Resting Potential

  • The axon gets energy from charged chemicals called ions, having a small negative charge called resting potential.
  • When the cell becomes excited, it triggers the action potential, reversing the charge and sending the electrical signal along the axon.

Absolute Threshold

  • The neuron receives excitatory (gas pedal) and inhibitory (brakes) signals.
  • If excitatory signals minus inhibitory signals exceed a minimum intensity (absolute threshold), the action potential is realized.

Refractory Period

  • Each action potential is followed by a recharging refractory period.
  • After this period, the neuron can initiate another action potential.

All or Nothing

  • Once the action potential is released, there is no going back; the axon either fires or it does not (all-or-none principle).
  • A strong stimulus triggers more neurons to fire more often, but not stronger.

Depolarization

  • Depolarization is the initial movement of the action potential from the resting potential in the cell body into the action potential in the axon.

How Cells Connect

  • Neurons do not touch each other; the gap between is called the synapse.
  • The synapse acts as an electrical insulator.

How Cells Connect

  • To pass the synaptic gap/cleft, an electrical message changes in the terminal buttons.
  • This synaptic transmission turns the electrical charge into a chemical message.

How Cells Connect

  • Terminal buttons contain synaptic vesicles, which hold neurotransmitters.
  • When the action potential reaches the vesicles, they rupture and transmitters spill out, fitting into receptors like a key into a lock.

Reuptake

  • Cells are efficient: neurotransmitters not absorbed are reabsorbed by the sending neuron in a process called reuptake.

Some Neurotransmitters and Their Functions

  • Acetylcholine (ACh): Enables muscle action, learning, and memory.
    • Malfunction: Deterioration of ACh-producing neurons in Alzheimer’s.
  • Dopamine: Influences movement, learning, attention, and emotion.
    • Malfunction: Excess dopamine receptor activity linked to schizophrenia; lack of dopamine linked to Parkinson’s.
  • Serotonin: Affects mood, hunger, sleep, and arousal.
    • Malfunction: Undersupply linked to depression; antidepressants raise serotonin levels.
  • Norepinephrine: Helps control alertness and arousal.
    • Malfunction: Undersupply can depress mood.
  • GABA (gamma-aminobutyric acid): Major inhibitory neurotransmitter.
    • Malfunction: Undersupply linked to seizures, tremors, and insomnia.
  • Glutamate: Major excitatory neurotransmitter; involved in memory.
    • Malfunction: Oversupply can overstimulate the brain, producing migraines or seizures.

Neural Communication

  • Chemicals act as agonists (excite) and antagonists (inhibit).
    • Agonists amplify or mimic pleasure; antagonists block absorption.
    • Agonist example: opiates mimicking natural highs.
    • Antagonist example: botulin blocks ACh (muscle action).

Neural Communication

  • Agonists mimic neurotransmitters by exciting receptor sites.
  • Antagonists block neurotransmitters by occupying receptor sites.

Glial Cells

  • Glial cells bind neurons together and provide insulation for the axon.
  • They facilitate communication and may play a role in intelligence.

Content Objective 2/22/10

  • Vocabulary List: Brain stem, Medulla, Pons, Reticular formation, Thalamus, Cerebellum, Cerebral Cortex, Limbic system, Hippocampus, Hypothalamus, Cerebral cortex, Brain lobes, Central nervous system, Peripheral nervous system, Autonomic nervous system, Sympathetic nervous system, Parasympathetic nervous system, Glial cells, Reflex, Plasticity.
  • Students will be able to identify the major parts and functions of the brain and nervous system using the vocabulary words.

Language Objective 2/22/10

  • Correlation words: If…then, As a result of…, One reason for…, Which in turn…, Accordingly…
  • Students will identify cause and effects of injuring different brain regions using correlation words.

The Nervous System

  • Interneurons: CNS neurons that internally communicate and intervene between sensory inputs and motor outputs.
  • Sensory Neurons: (Afferent) carry incoming information from the PNS to the CNS and brain.
  • Motor Neurons: (Efferent) carry outgoing information from the CNS to muscles and glands.

Structures of the Nervous System

  • The nervous system has 2 major components:
    • Central Nervous System (CNS)
    • Peripheral Nervous System (PNS)

The CNS

  • The CNS includes the brain and spinal cord.
  • Encased in bone for protection.

The Peripheral Nervous System

  • The Peripheral Nervous System contains all nerves feeding into the brain and spinal cord.
  • It contains sensory and motor neurons connecting the CNS with the rest of the body.

The Peripheral Nervous System

  • Somatic Nervous System: Controls the body’s skeletal muscles (voluntary movements).
  • Autonomic Nervous System: Controls the glands and muscles of internal organs.
    • Sympathetic Nervous System: Arouses the body, mobilizing energy in stressful situations.
    • Parasympathetic Nervous System: Calms the body, conserving energy.

Sympathetic and Parasympathetic

  • The sympathetic and parasympathetic nervous systems together make up an opponent process system that maintains homeostatic balance.
  • Sympathetic prepares the body for challenges.
  • Parasympathetic calms the body afterward.

Reflexes

  • Reflexes are automatic responses to stimuli.
  • A simple spinal reflex pathway involves a sensory neuron and a motor neuron connected through the spine with an interneuron; this type of response does not involve the brain.

The Endocrine System

  • The endocrine system is the body’s chemical messenger system, relying on hormones that travel through the bloodstream and affect other tissues.
  • Hormones influence interest in sex, food, and aggression.
  • Major glands include the pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries, and testes.
  • Endocrine messages work slowly but have lasting effects.

Working with Other Systems

  • The nervous system directs endocrine secretions, which then affect the nervous system.
  • In normal conditions, the endocrine system works with the parasympathetic nervous system.
  • In crisis, it supports the sympathetic nervous system by releasing epinephrine (adrenalin), triggering the “fight or flight” response.

The Master Gland

  • The pituitary gland controls all responses of the endocrine system.
  • It is located at the base of the brain and is no larger than a pea.

The Brain

  • The brain is highly complex, with approximately 100 billion neurons, each having roughly 10,000 contacts, resulting in around 1000 trillion synapses.
  • A grain of sand size speck of your brain contains 100,000 neurons and one billion synapses.

The Brain

  • Neurons cluster into work groups called neural networks.
  • Neurons work with close proximity to ensure short, fast connections.
  • Learning occurs as feedback strengthens connections.
  • Neurons that fire together wire together.
  • Inputs are the lessons and practice, while outputs are, for example, beautiful music.

The Brain

  • Creatures with complex brains have three levels: the brain stem, the limbic system, and the cerebral cortex.
  • The brain stem is the part of the brain with the longest ancestry.

The Brain Stem

  • The brain stem is made up of four regions: the medulla, the pons, the reticular formation, and the thalamus.
  • The brainstem is a crossover point where most nerves to and from each side of the brain connect with the body’s opposite side.

The Medulla

  • The medulla regulates basic body functions including breathing, blood pressure, and heart rate automatically.

The Pons

  • The pons relays signals to the cerebellum dealing with movement as well as sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.
  • Pons acts as a “bridge” connecting the brain stem to the cerebellum.

The Reticular Formation

  • The reticular formation is a bundle of nerve cells forming the brain stem’s core.
  • Responsible for keeping the brain awake and alert and monitoring incoming sensory messages.

The Thalamus

  • The thalamus is egg-shaped structures at the top of the brain stem near the center of the brain.
  • It is like the central processing chip of a computer, directing incoming and outgoing sensory and motor traffic (except smell).

The Cerebellum

  • The cerebellum sits at the back of the brain stem and is like a miniature brain.
  • It enables nonverbal learning and memory, helps judge time, regulate emotions, and discriminate sounds and textures.
  • It controls actions we perform without consciously thinking of, such as walking or dancing.

Limbic System

  • The limbic system is the middle layer of brain that wraps around the thalamus; it gives humans/mammals the capability for emotions and memory.

Limbic System

  • The limbic system processes memories, regulates emotions, and is involved in feelings of pleasure, pain, fear, and rage.

Hippocampus

  • The hippocampi (two of them) connect your present with your past memories.

Amygdala

  • The amygdala relates to memory and emotion, playing the largest role in dealing with feelings of pleasure.

Hypothalamus

  • The hypothalamus analyzes blood flow, regulating body temperature, fluid levels, and nutrients.
  • It detects imbalances and tells the body how to respond, such as feeling thirsty or hungry.

Hypothalamus

  • The hypothalamus is organized into neural clusters influencing hunger, thirst, body temperature, and sexual behavior.
  • It has “reward centers.”
  • Addictive disorders could stem from reward deficiency syndrome, leading to cravings.

Cerebral Cortex

  • The cerebral cortex is a thin layer of interconnected neural cells and is the brain’s ultimate control and information-processing center.
  • The larger cortex of mammals enhances capacities for learning and thinking, enabling adaptability.
  • The wrinkles of the brain are made by fissures and folds called Gyri.

Frontal and Parietal Lobes

  • Frontal Lobes: Located behind the forehead, involving the motor cortex and making plans and judgment.
  • Parietal Lobes: Located at the top of the head, used for general processing, especially mathematical reasoning.

Motor Cortex

  • Motor Cortex: Located at the back of the frontal lobe, controls movement of body parts.
  • The right side of the brain controls the left side of the body, and vice versa.
  • Sensory Cortex: Located at the front of the parietal lobe, experiences and processes body touch and movement sensations.
  • The sensory cortex on the right controls sensation on the left side of the body, and vice versa.

Temporal and Occipital Lobes

  • Temporal Lobes: Involved in auditory processing, semantics in speech and vision, and memory formation through the hippocampus.
  • Occipital Lobes: Located at the back of the brain, responsible for visual functions.

Association Areas

  • These are areas of the cerebral cortex involved in higher-level mental functioning: learning, thinking, memory, and speaking.
  • Damage can cause changes in personality or remove inhibitions.

Aphasia

  • Damage to cortical areas can cause aphasia, or impaired language use.
  • Reading words aloud involves the visual area, angular gyrus (auditory code), Wernicke’s area (understanding), and Broca’s area (motor cortex control).

Plasticity

  • The brain can modify itself after damage, usually through reorganization.
  • Blindness or deafness frees areas for other cognitive tasks.
  • Plasticity is the ability of the nervous system, especially the brain, to adapt or modify itself as a result of experience.

Broca and Wernicke

  • Broca’s Area: Located in the left frontal lobe, involved with expressive language.
    • Damage results in difficulty with spoken language.
    • Area directs muscle movements important to speech production.
  • Wernicke’s Area: Located in the temporal lobe, controls receptive language (understanding what others say).

Damage to Broca’s Area

  • Damage to Broca’s area often results in difficulty with speech (common in stroke patients).

Divided Brains

  • Each hemisphere serves different functions (lateralization).
  • In the past, patients with severe epilepsy were treated with the “split brain” procedure, cutting the corpus collosum.

Myth of the “Two Brains”

  • No activity involves only one hemisphere; logic is not confined to the left hemisphere; creativity or intuition is not exclusive to the right hemisphere; it is impossible to educate one hemisphere at a time; there is no evidence that people are “right-brained” or “left brained.”

Differences in the Hemispheres

  • The left hemisphere is more active during deliberation.
  • The right hemisphere understands simple requests, perceives objects easily, engages in quick, intuitive responses, and is more active when copying drawings, recognizing faces, and perceiving emotions.

The Endocrine System

  • Endocrine System: The body’s “slow” chemical communication system using glands that secrete hormones into the bloodstream.

Techniques for Studying Human Brain Function and Structure

  • Techniques such as EEG, PET, MRI, fMRI, and MEG are used.

EEG (Electroencephalography)

  • Technique: Electrodes placed on the head.
  • What it shows: Summated electrical fields from neuron activity.
  • Advantages: Detects rapid electrical activity changes, allowing analysis of cognitive activity stages.
  • Disadvantages: Poor spatial resolution of the source of activity.

PET (Positron Emission Tomography) SPECT (Single Photon Emission Computed Tomography)

  • Technique: Radioactive substances emit positrons and photons.
  • What it shows: Localization and amount of molecules (neurotransmitters, drugs, tracers) indicating changes in neuronal activity.
  • Advantages: Allows functional and biochemical studies, providing a visual image corresponding to anatomy.
  • Disadvantages: Exposure to low-level radioactivity, limited spatial resolution, and inability to follow rapid changes (faster than 30 seconds).

MRI (Magnetic Resonance Imaging)

  • Technique: The brain is exposed to a magnetic field, and radio-frequency waves are measured.
  • What it shows: High-resolution images of brain anatomy and functional images of blood flow changes.
  • Advantages: No radioactivity exposure, high spatial resolution of anatomical details (<1 mm), high temporal resolution (<1/10 of a second).

fMRI-Functional MRI

  • fMRI stands for functional MRI.
  • It can reveal the brain’s functioning as well as structure.

MEG (Magnetoencephalography)

  • What it shows: Detects magnetic fields produced by electrical currents in neurons.
  • Detects and localizes brain activity, often combined with structural MRI images.
  • Advantages: Detects rapid changes in electrical activity, allowing analysis of cognitive activity stages, and high resolution for surface sources in the cerebral cortex.
  • Disadvantages: Poor spatial resolution below the cortex and very expensive equipment.