The central nervous system (consisting of the brain and spinal cord) receives and analyzes messages from the peripheral nervous system (consisting of all other nerves), and then sends back a response or action to carry out. Within the peripheral nervous system are two primary systems – somatic and autonomic.

The somatic system consists of nerves that connect to voluntary skeletal muscles and sensory receptors.

• Afferent nerves carry information to the CNS from the PNS.

• Efferent nerves carry information to the PNS from the CNS. 

The autonomic system control automatic, involuntary, visceral functions, like digestion and heart rate, so its nerves connect to organs, vessels, and glands. 

• The sympathetic division mobilizes the body for emergencies, the fight-or-flight response. 

• The parasympathetic conserves bodily resources to save and store energy; "rest and digest"

Neurons are individual cells in the nervous system that receive, integrate, and transmit information.

• • Soma: cell body

  • Dendrites: receive information from other nerve cells

  • Axon: sends information to other nerve cells, muscles, or glands

  • Axon terminals: secrete neurotransmitters

  • Synapse: junction between neurons

  • Myelin sheath: insulates axons and speeds up message transmissions

Glial cells are found throughout the nervous system that provide various types of support for neurons.

• • Remove waste

  • Supply nourishment

  • Provide insulation

Interneurons, exclusively in the brain and spinal cord, process information.

Mirror neurons are those that are activated by performing an action or witnessing an action.

Neural networks

• • interconnected neurons

  • regular connections or routes of communication for different tasks, processes, etc.

  • body/brain “learns” networks over time: “muscle memory” in sports (“practice makes permanent”)

Reflexes: some reactions occur when sensory neurons reach just the spinal cord & spinal cord sends orders

Neurons never actually touch, so messages have to bridge the divide of the synaptic gap to be received by another neuron. To do this, impulses are converted into chemicals, or neurotransmitters, that will then be released by the axon terminals of the pre-synaptic membrane, travel across the synaptic gap, and be absorbed by receptor sites of the postsynaptic membrane of another neuron. Once absorbed by the receiving neuron,  neurotransmitters are re-absorbed by the pre-synaptic membrane in a process known as reuptake.

• Resting Potential: a neuron is stable, with a negative charge as the cell is inactive

• Action Potential: a brief shift in a neuron’s electrical charge that travels along the axon

• Absolute Refractory Period: the minimum length of time after an action potential during which another action potential cannot begin (i.e. “reload”)

• All or None Law: Neurons either send signals or they don’t; there’s no in-between. Furthermore, the strength of the stimulus does not alter the speed or strength of the impulse.

The threshold in a neural impulse is the minimum amount of stimulation required to trigger a neural impulse.

Polarization 🡪 Depolarization 

• opens up portals in axon letting in positive ions (Sodium) which mix with negative ions (Potassium) that are already inside the axon

• process continues down axon to the axon terminal

Neurotransmitters are chemicals that transmit information to one another. An overabundance or lack of these chemicals can cause serious complications.

Agonist: a chemical that mimics the action of a neurotransmitter (nicotine, opiates, etc.)

Antagonist: a chemical that opposes the action of a neurotransmitter (Botox injections)

Excitatory - neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential or “fire”

Inhibitory - neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential or “fire”

Types of Neurotransmitters:

• Acetylcholine (ACh) contributes to regulation of attention, arousal, and memory. A lack of acetylcholine is associated with the memory loss seen in Alzheimer’s disease. 

• Monoamines regulate aspects of everyday behavior. Deficiency of monoamines can lead to schizophrenia, addiction, depressive disorders, mood disorders, and Parkinson’s disease.

Three Types:

• • Serotonin – sleep and wakefulness (deficiency leads to depression)

  • Dopamine – control voluntary movements (excess leads to schizophrenia, deficiency leads to Parkinson's)

  • Norepinephrine – mood and arousal

• GABA (gamma-aminobutyric acid) is a widely-distributed inhibitory transmitter, contributing to the regulation of anxiety and sleep/arousal.

• Glutamate is a widely-distributed excitatory transmitter, involved in learning and memory. 

Deficiencies can lead to anxiety disorders, excess can cause migraines and seizures.

• Endorphins play a role in pain relief and responding to stress. They also contribute to regulation of eating behavior. 

Most recreational drugs are used and abused because they mimic the effects of neurotransmitters. As the drug is used more and more, however, neural receptors are less sensitive to its effects, meaning the user will have to steadily increase their dosage to receive the same effect. 

Increasing one’s “tolerance” to a substance can have damaging effects. 

The brain is the most important component of the nervous system, controlling all thought, movement, and sensation. The brain is divided into two hemispheres, with specialized functions, and operate through contralateral control (left hemisphere controls the right side of the body and vice versa).

Research has found that the brain is “plastic” or malleable. Experiences can shape brain structure. Damage or destruction of brain tissue can lead to neural reorganization. The adult brain can generate new neurons, through neurogenesis. Neuroplasticity is the brain’s ability to reorganize itself by forming new neural connections throughout life. 

• Spinal cord: transmits information between the brain and the rest of the body

• Cerebral Cortex/Cerebrum: folded outer layer; responsible for sensing, thinking, learning, emotion, consciousness, and voluntary movement

• Corpus callosum: bridge between two hemispheres; allows communication between left and right brain

• Association areas are cortical regions that are not directly involved in sensory or motor functions. 

• Frontal: conscious thought, reasoning, planning, problem-solving, speech, movement, and emotion

• Occipital: visual processing

• Parietal: perception of touch, pressure, temperature, and pain

• Temporal: smell, hearing, and memory

• Primary Visual Cortex: visual processing

• Primary Somatosensory Cortex: sense of touch

• Primary Auditory Cortex: auditory processing

• Primary Motor Cortex: movement of muscles

• Wernicke’s area: language comprehension

• Broca’s area: production of speech, moving lips

• Medulla: responsible for unconscious, vital functions like breathing, heart rate, and circulation

• Pons: involved in sleep and arousal, communication between cortex/cerebellum

• Reticular Formation: involved in arousal and ability to focus attention; group of fibers related to sleep and arousal through brainstem

• The relay station for all incoming and outgoing signals; receives sensory information and sends it to appropriate areas of forebrain

• Exception 🡪 smell

• Coordinates voluntary muscle movements, balance, and time management

• If injured, you can have difficulty walking, keeping balance, shaking hands, etc.

The limbic system is a loosely connected network of structures located along the border of the cerebral cortex and deeper sub-cortical areas; the center of emotion.

• Main structures:

  • Hypothalamus: hunger/thirst, body temperature, sexual behavior 🡪 works with endocrine system

  • Amygdala: basic emotions 🡪 primarily, aggression and fear

  • Hippocampus: involved in forming new memories

The most controversial and widely-discussed question in psychology is whether we are born or made.

• • Is it our genes that determine who we are and who we will be? 🡪 Nature

  • Or is it our upbringing, environment, and experiences? 🡪 Nurture

Behavior genetics is the study of the power of genes to shape our actions and personality.

• • Genotype: genetic make-up

  • Phenotype: observable characteristics

  • Polygenic traits are characteristics that are influenced by more than one pair of genes. 

  • Adaptations are inherited characteristics that increased in a population because they helped solve a problem of survival or reproduction. Behavioral adaptations are designed to improve an organism’s chances of reproductive success.

  • Heritability refers to the extent to which trait differences among individuals are attributable to genetic variations.

More often, research is showing that genetics and experience play off each other, and that is what attributes to our behavior and personality. Epigenetics is the study of heritable changes in gene expression that do not involve modifications to the DNA sequence. For example, schizophrenia is not directly inheritable, but your genes have a degree of vulnerability to the condition. This may increase with different experiences, related to stress or trauma. 

Roger Sperry and Michael Gazzinga studied split-brain patients, or those that have had their cerebral hemispheres surgically disconnected by severing the corpus callosum. This radical procedure was used to reduce the severity of epileptic seizures, but had the unexpected side effect of causing disuption in communication between hemispheres.

Brain Imaging Techniques:

• Electroencephalographs (EEGs) monitor the electrical activity of the brain over time by attaching electrodes to the surface of the scalp 🡪 used to diagnose neurological disorders, epilepsy, brain damage, etc.

• Computed Tomography (CT) provide multiple views of the brain, sometimes through contrast imaging 🡪 used to study brain tissue, as well as, injuries or diseases affecting the brain

• Positron Emission Tomography (PET) scans examine brain structures and functions, mapping brain activity 🡪 used to find what areas of the brain are related with certain activities

• Magnetic Resonance Imaging (MRI) scans use radio waves to map 3-D images of brain structure 🡪 used for researching mental disorders

• Functional MRI (fMRI): combines PET and MRI

Some researchers study brain function and activity by testing the abilities of the brain itself.

• Lesioning is the process of destroying part of the brain 🡪used to study and modify behavior

• Electrical Stimulation involves sending weak electric signals into a brain structure to stimulate it 🡪 used in animal research and brain surgery

• Transcranial Magnetic Stimulation is a technique that allows scientists to temporarily enhance or depress activity in specific areas of the brain 🡪 temporary lesions that allow researchers to study the effects of the action

Consciousness is our awareness of ourselves and our environment.

• • Information is collected, enabling us to reflect and plan

  • Ex. Driving, showering

Early psychology was defined as the “description and explanation of states of consciousness”, but the difficulty of studying consciousness led to a focus on behaviorism.

Consciousness enables us to exert voluntary control, while our subconscious collects and responds to information automatically, without commands to do so.

• Ex. Meeting someone new

  • Conscious: talking to them, trying to remember their name and the details they are giving you

  • Subconscious: responding to their gender, age, appearance, voice/accent, etc. 

Biological rhythms are periodic physiological fluctuations controlled by our internal systems, including the following:

• • Annual cycles: once a year occurrences, like hibernation and migration

  • 28-day cycles: female menstruation, causes changes in appetite, behavior, and mood

  • 24-hour cycles: varying and falling levels of alertness, body temperature, and growth hormone secretion

  • 90-minute cycles: stages of sleep

Circadian rhythm is the biological clock that matches the cycle of night and day.

• • Body temperature and alertness fluctuate during the day/night

  • Thinking is sharpest and memory most accurate at your daily peak in arousal (larks vs. owls)

Things that challenge/alter the rhythm:

• • “jetlag”

  • Bright/artificial light

  • DLS

Sleep: periodic, natural, reversible loss of consciousness

Purpose of Sleep:

• Protection: prior to illumination via fire or electricity, stumbling around in the darkness was not a wise move for cavemen

• Recuperation: during sleep, your body will restore tissue and recharge the body after daily exertions

• Growth: during sleep, the pituitary gland secretes growth hormones, which is why we need less sleep as we grow older

While we sleep, we pass through one of the five distinct sleep stages every 90 minutes or so.

• • Awake – relaxed, but aware, alpha waves

  • NREM1 – slipping into sleep, theta wave activity, may experience hallucinations or hypnogogic jerks

  • NREM2 – asleep but easily awoken, “sleep spindles” (bursts of rapid, rhythmic brain activity), possible sleep-talking

  • NREM3 – delta waves, deep sleep

  • REM (Rapid Eye Movement) – a recurring sleep stage during which vivid memories/dreams commonly occur; (a.k.a. paradoxical sleep) muscles are relaxed but other body systems are active, beta waves, as seen when one is awake and alert

Brain Regions Associated with Sleep:

• The reticular formation in the core of your brain stem is important to sleep and wakefulness.

• The ascending reticular activation system (ARAS) consists of the incoming nerve fibers running through the reticular formation that influence physiological arousal; fibers spread to many areas of the cortex. 

• Other structures needed: pons, hypothalamus, thalamus, and medulla. 

Sleep Deprivation:

• Numerous studies have been done on sleep deprivation and restriction, which have a variety of negative effects:

  • Impaired attention, reaction time, cognitive speed and accuracy

  • Decline in performance

  • Limited motor coordination

  • Poor decision-making

  • Increased appetite & obesity

  • Decreased immunity 

• When deprived of REM sleep, you will spend more time in REM in following nights in a rebound effect.

• Insomnia: recurring problems falling and/or staying asleep

• Sleep apnea: temporary cessations in breathing during sleep

• Narcolepsy: a sleep disorder characterized by uncontrollable “sleep attacks”; sufferers may lapse directly into REM sleep

• Nightmares: anxiety-arousing dreams that lead to awakening, usually from REM sleep

• Night terrors: abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic

• Somnambulism: sleepwalking (more common in children)

• REM Sleep Behavior Disorder (RBD): potentially troublesome dream enactments during REM – talking, yelling, flailing, leaping, etc. 

Facts of Dreams:

• Not as bizarre as widely assumed, though we are more tolerant of logical discrepancies and implausible scenarios than we are while awake.

• Dreams can occur in stages other than REM sleep.

• Dreams are typically self-centered.

• Unless you wake up during or shortly after your dream, you’ll forget it.

• The most common dreams involve sex, aggression, or misfortune.

• Your dreams are affected or influenced by the occurrences of your daily lives, identified by Freud as “day residue”.

• Stimuli detected during sleep can also impact the nature of dreams (ex. water, alarm).

• While Western cultures write-off dreams as fantastical visions, many other cultures believe dreams provide information about oneself, the future, and/or the spiritual world. 

• Lucid dreams are those in which people can think clearly about the circumstances of waking life and the fact that they are dreaming, yet they remain asleep in the midst of a vivid dream.

• Sleep paralysis is a feeling of being conscious but unable to move. It occurs when a person passes between stages of wakefulness and sleep. During these transitions, you may be unable to move or speak for a few seconds up to a few minutes.

Common Dreams:

1. Being chased

2. Sex

3. Falling

4. School, teachers, studying

5. Arriving late

6. Being on the verge of falling

7. Someone alive is dead

8. Trying repeatedly to do something

9. Flying

10. Vividly sensing a presence in the room

Theories of Dreaming:

• Rosalind Cartwright – Problem-Solving

  • Dreams provide the opportunity to work through everyday problems and emotional issues in one’s life.

• Sigmund Freud – Wish Fulfillment

  • The purpose of dreams is to fulfill unconscious urges and unmet needs through wishful thinking.

    • Manifest vs. latent content

• J. Allan Hobson – Activation-Synthesis

  • Dreams are side effects of neural activation; the cortex takes the random signals received lower brain centers and constructs a dream to make sense of these signals. 

Austrian physician Franz Mesmer claimed to use the power of “animal magnetism” to “heal” various afflictions. Although many patients found themselves cured of ailments, it was due to the power of suggestion. His practice was written off as a fraud, and gave us the term “mesmerized”, but did lead to an in-depth look at the use of suggestion and hypnotism. 

Hypnosis is a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur. Hypnosis is also described as a systematic procedure that typically produces a heightened state of suggestibility. 

• Analgesia: treatment of acute and chronic pain (used by dentists/doctors as a substitute for anesthetic)

• Sensory distortions and hallucinations: sensing things that are not present, or failing to sense things that are

• Disinhibition: effect of hypnosis that removes boundaries that would typically prevent subject from performing specific actions (social norms, illegal acts, etc.)

• Posthypnotic amnesia: supposed inability to recall what one experienced during hypnosis; induced by the hypnotist’s suggestion

• Posthypnotic suggestion: a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to control undesired symptoms or behaviors

Hypnosis works based on the subject’s susceptibility. It cannot provide a subject with skills or abilities they do not already possess or have the power to possess. Hypnosis can help recall some memories, but not to the extent people think. It can also relieve pain and treat some health conditions.

Dissociation: a split in consciousness which allows some thoughts and behaviors to occur simultaneously with others 🡪 distraction

Theories of Hypnosis:

• Role Playing: People “play along” with how hypnotized people are supposed to act; role expectations are what produce hypnotic effects, rather than a trance-like state

• Altered State of Consciousness: Divided consciousness (Dissociation); Role-playing doesn’t explain abandoning previous fears, rules, etc.

Meditation refers to a family of practices that train attention to heighten awareness and bring mental processes under greater voluntary control.

• Focused attention: attention is concentrated on a specific object/image/sound/sensation

• Open monitoring: attention is directed to the contents of one’s moment-to-moment experience in a nonjudgmental and nonreactive way