NOTE: Unit 1 Biology of Behavior (copy)

Nervous System

Central Nervous System - Brain and spinal cord

• 2 types of cells in the brain: neurons & glial cells

Peripheral Nervous System - sensory and motor neurons connecting the CNS to the rest of the body

• Somatic - voluntary control of skeletal muscles

• Autonomic - involuntary control of glands and internal organs

Sympathetic Nervous System - responds to stressful or dangerous situations

Parasympathetic Nervous System - responsible for the body's rest and digestion response when the body is relaxed, resting, or feeding

Nerves, Neurons, Neural firing

Nerves - electrical cables formed from bundles of axons, linking the CNS with the body's sensory receptors, muscles, and glands

Sensory Neurons - neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord

Motor neurons - neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Interneurons - neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs

Reflex - simple, automatic response to a sensory stimulus

The Neuron

Dendrites - receive messages from other cells

Soma (cell body) - cell's life support center

Axon - passes messages away from cell body to terminal branches

Myelin Sheath - covers the axon, helps speed up neural impulses

Axon Terminal Branches - form junctions with dendrites of other neurons

Axon Terminal Buttons - convert electrical impulses into chemical messages (neurotransmitters)

Synapse - the meeting point between neurons

The Synapse

Sending neuron (terminal branch)

Synaptic vesicles - store and release neurotransmitters

Receptor sites - places where receiving neuron accept neurotransmitters

Receiving neuron (dendrite)

Neurotransmitters & Hormones

Hunger Regulation

Grelin - Hunger-arousing hormone, produced by empty stomach

• Lack of sleep and restricting calorie intake →oversupply causes overeating and weight gain

• Sleeping and eating high protein foods →undersupply causes decreased appetite, unintended weight loss

Leptin - Hunger-repressing hormone, secreted by fat cells

• Oversupply causes leptin resistance, leading to overeating and potential obesity

• Undersupply causes difficulty in regulating weight → excessive hunger and weight gain

Arousal and Stress Reactions

Norepinephrine - Produces fight or fight response by increasing heart rate, blood pressure, and blood sugar for more energy

• Oversupply causes high blood pressure, irregular heartbeat, excessive sweating, anxiety

• Undersupply causes lack of energy and concentration, ADHD symptoms, feeling unmotivated

Adrenaline (Epinephrine)- Produced by adrenal glands, response to stress or excitement, prepares body for fight or flight by increasing heart rate and energy

• Oversupply causes muscle cramps, increased heart rate, excessive salivation, nausea, sweating, difficulty sleeping, stress-related disorders

• Undersupply causes memory issues, decreased attention span, fatigue, decreased heart rate

Learning and Curiosity

Acetylcholine (ACh) - Involved in muscle activation, learning, memory, facilitating communication between nerve cells, and muscles

• Oversupply causes muscle cramps, muscle weakness, severe cases can cause paralysis

• Undersupply linked to memory issues learning difficulties, may contribute to conditions like Alzheimer's disease and muscle weakness

Glutamate - Brain's most abundant excitatory neurotransmitter, involved in memory and learning

• Oversupply can lead to excitotoxicity, damages nerve cells, and associated with conditions like Alzheimer's and ALS

• Undersupply impairs cognitive functions like memory and learning

Happy Feelings

Endorphine - Natural opiate-like transmitter, distraction from pain (and pleasure)

• Oversupply causes reduces pain

• Undersupply causes mood issues and difficulty managing stress

Oxytocin - 'Love hormone’ invovled in social bonding, sexual reproduction, childbirth, increased feelings of trust and empathy

• Oversupply causes to social cues, anxiety, and overattachment

• Undersupply causes difficulties in making social bonds, lower trust, loneliness or depression and low motivation

Dopamine - Involved in reward, motivation, pleasure, and plays a role in motor control and cognitive function

• Oversupply is linked to schizophrenia, hallucinations and delusions, and addictive behaviors due to overactivation of dopamine receptors

• Undersupply is linked to Parkinson's disease, PD tremors, difficulty motor control, and depression

Serotonin - Regulates mood, appetite, and sleep, contributes to feelings of well-being and happiness

• Oversupply causes mania and serotonin syndrome, leading to confusion, agitation high blood pressure

• Undersupply is linked to mood disorders like depression, anxiety, and sleep disturbances

Miscellaneous

Melatonin - Produced by pineal gland, regulates sleep-wake cycle by promoting sleepiness in response to darkness

• Oversupply causes excessive drowsiness, lethargy, and concentration problems. May disrupt circadian rhythm

• Undersupply causes insomnia, difficulty falling asleep, may impair immune function

GABA - Main inhibitory neurotransmitter in the brain, helps calm the NS and promote relaxation

• Oversupply causes excessive relaxation, drowsiness, impaired motor coordination, sluggishness

• Undersupply causes anxiety, insomnia, restlessness, and epilepsy due to lack of inhibitory signals in brain

Substance P - Involved in transmitting pain signals to the brain, plays a role in body’s response to pain and inflammation

• Oversupply linked to increased perception of pain and chronic pain conditions

• Undersupply causes reduced pain perception, which can be dangerous if injuries go unnoticed

Psychoactive Drugs & Substance use

DSM 5 criteria of Substance Use Disorder -

Continued drug use despite significant life disruption. Brain changes can persist after quitting use, which causes strong cravings. Indicators:

• Diminished Control

  • Uses more substance, or for longer, than intended

  • Cannot regulate use of substance

  • Lots of time getting, using, or recovering from substance

  • Craving of substance

• Diminished Social Functioning

  • Disrupts commitments at work, school, or home

  • Continues use despite social problems

  • Reduced social, recreational, and work activities

• Hazardous Use

  • Continues use despite hazards

  • Continues use despite worsening physical or psychological problems 

• Drug Action

  • Experiences tolerance

  • Experiences withdrawal when attempting to end use

Psychoactive Drugs - Chemicals that change perceptions and moods

States of Consciousness (Sleep)

Sleep patterns

• Circadian rhythm - (Latin circa “about” and diem “day”) 24 hour cycle of bodily rhythms, biological clock based on the sun and moon / when light and dark hits our eyes

• Suprachiasmatic nucleus - pair of cell clusters in the hypothalamus that control circadian rhythm

• Stages of sleep - 90 minute cycles

  • Stage 1-3/4 to 2 to REM every 90 mins

  • Deep sleep occurs during stages 3-4: Immune system restores, muscles restore, process memories

  • REM sleep is when you dream

Sleep cycle

• Stage 1 NREM

  • light sleep

  • 5% of sleep

  • hallucinations and hypnagogic sensations (feeling like falling)

  • theta waves

• Stage 2 NREM

  • light sleep

  • 45-50% of sleep

  • easy to wake, more relaxed

  • sleep spindles and K-complexes

• Stage 3-4 NREM

  • deep sleep

  • 5-10% of sleep

  • difficult to wake, muscle restoration, consolidation of learning (latent learning - consolidation of learning during sleep; subconscious retention of information without reinforcement or motivation), release of growth hormone

  • delta waves

• REM

  • deep sleep

  • 20-25% of sleep

  • paradoxical, muscle atonia, dreaming

  • similar to wakefulness (alpha waves)

Sleep theories - why do we sleep?

• Protection - darkness & hunting/gathering (evolutionary)

• Recuperation - immune system & brain repair

• Restoration & rebuilding - consolidating memories, reactivates recent experiences for cortex

• Inspiration for creativity - problem-solving, innovation, boosting insight

• Supporting growth - pituitary gland releases HGH for muscle development

Sleep deprivation

“The brain keeps an accurate count of sleep debt for at least 2 weeks”

• More conflict in friendships and relationships

• Predictor of anxiety & depression, increases cortisol

• Contributes to weight gain, increases ghrelin and decreases leptin

• Decreased ability to focus attention, process, and store memories

• Decreased production of immune cells, increased risk of viral inflections

• Increase inflammation, reduces muscle strength and slower reaction time

Dreams

• Wish-fulfillment - Sigmund Freud, psychodynamic theory; dreams express otherwise unacceptable feelings

  • Latent content: underlying or hidden meaning behind meaning; pertains to unconscious wants, desires, or fears (more prevalent)

  • Manifest content: actual dream content remembered in day

• Information processing - filing memories, sorting the day’s events

• Physiological functions - developing & preserving neural pathways (REM sleep promotes brain stimulation)

• Activation-synthesis theory - making sense of neural static (triggered by REM), evoking random visual memories and creating stories

• Cognitive development - stimulates life, reflect individual cognitive development

Sleep disorders

Insomnia - recurring problems in falling or staying asleep

• stressful life event, birth of a child, death of a loved one, hustle culture, naturally being a night owl

• evolutionary: we need both night owls and early birds

Narcolepsy - characterized by attacks of overwhelming sleepiness

• may lapse directly into REM sleep, often at inopportune times

• cataplexy - brief bouts of muscle weakness or paralysis

Sleep apnea - characterized by temporary stopping of breathing during sleep and repeated momentary awakenings

• fatigue and depression, as a result of slow-wave sleep deprivation

• associated with obesity, especially among men

Night terrors - characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep

• within two or three hours of sleep

• usually not remembered

Sleep walking/sleep talking - doing normal activities (sitting up, walking, speaking) while asleep

• sleep talking can occur during any sleep stage

• sleep walking (also somnambulism) occurs in NREM-3 sleep

Electroencephalogram (EEG) used to study sleep

Brain Structures and Function

Cerebral Cortex - control center

Cerebrum

Frontal lobe - Broca's area

• Includes prefrontal cortex

  • making judgments, executive functions, rational decisions

• Speaking, muscle movement

Parietal lobe

• Includes somatosensory cortex

  • Processing information from the body’s senses

  • Touch, temperature, pain

• Association areas

• Behind frontal lobe

Occipital lobe

• Interpreting incoming visual information

• In the back

Temporal lobe - Wernicke's area

• Auditory information

• Above ears

Cerebellum

• Voluntary bodily movement and balance

• Under occipital and temporal lobes

• Dependent on GABA, sensitive to alcohol - loses balance

Limbic System

Thalamus

• Relays information of senses (except olfactory), before being sent to cerebral cortex

Hypothalamus

• Maintenance functions like eating and sleeping

• Homeostasis

Pituitary gland

• Makes, stores, and releases hormones

• Puberty

Hippocampus

• Where memories are stored

• If needed important/long-term, moves from hippocampus to cortex

Amygdala

• Emotion center

Misc.

Medulla

• Controls autonomic (nervous system) functions

• Carries signals from the brain to the rest of the body for essential life functions

  • breathing, circulation, swallowing, and digestion

• Includes Reticular Activating system (reticular formation)

  • Filters out unnecessary information

  • Regulates behavioral arousal and consciousness in brain stem

• At base of brain, where it meets the spinal cord

Left vs Right Brain

Left Brain

• Logical, analytical, verbal, factual information

Right Brain

• Creative, intuitive, artistic, emotional, imaginative information

Corpus Callosum

• Connect left and right spheres of brain so they can communicate

Sensation

5 senses

• Sight

• Smell (olfactory)

• Touch (tactile)

• Hearing (auditory)

• Taste (gustatory)

Sensation: sensory receptors detect info and nervous system transits that information

Gustav Fechner + Ernst Weber

Absolute Threshold - minimum stimulus energy needed to detect a particular stimulus, detectable at least half of the time

• Examples: when someone is about to touch you, turning up music very slowly

• The minimum intensity of light we can see

• The lowest volume of a sound we can hear

• The smallest concentration of particles we can smell.

Just-noticeable difference - the amount something must be changed in order for a difference to be noticeable, detectable at least half the time

• Examples: changing font size, voice volume level

Transduction: Sensory systems convert outside energy into a form the brain can use

• Vision - light energy

• Hearing - sound waves

• Taste and smell - chemical stimulus

All senses…

• Receive sensory stimulation

• Transform that stimulation into neural impulses

• Deliver the neural information to the brain