1.1 Interaction of Heredity and Environment

• What has the most impact on human behavior and mental processes?

  • nature OR nurture (outdated)

  • nature AND nurture (current)

• heredity - the passing on of different physical and mental traits from one generation to another

• nature

  • biological makeup and genetic predispositions

    • genetic inheritance

    • physical traits

    • inherited personality traits

    • cognitive development

• nurture

  • environmental factors

    • family life

    • social groups

    • education

    • societal influences

• theory of evolution - evolution happens by natural selection; individual traits that are beneficial to species survive and would be passed on, while undesirable traits would die off

• eugenics - belief in improving genetic quality of human population by selectively breeding for desirable traits and discouraging reproduction with traits considered undesirable

• epigenetics - focuses on how environment and a person’s behavior affect their genes and how they work

  • focuses on how a person’s body read a DNA sequence

  • different genes are being turned on or off due to sustained environmental pressures

  • help explain why identical twins share ~100% of genes, but develop different physical and mental characteristics

• plasticity - brain’s ability to change and adapt as a result of experiences

  • involves strengthening and weakening of neural connections

1.2 Nervous System

• central nervous system (CNS)

  • made up of brain and spinal cord

  • sends out orders to the body

• peripheral nervous system (PNS)

  • consists of different nerves that branch off from brain and spine

  • connects CNS to all body’s organs + muscles

    • somatic nervous system (SNS)

      • aka skeletal nervous system

      • includes 5 senses and skeletal muscle movements, which happen consciously and voluntarily

    • autonomic nervous system (ANS)

      • controls involuntary activities

      • ex) makes sure heart is beating, stomach is digesting, and you are breathing

      • keeps you alive

        • sympathetic division

          • mobilizes your body and gets it ready for action

          • ex) makes heart beat faster, your eyes dilate, increases your breathing, decreases digestion

          • known as fight or flight

        • parasympathetic division

          • relaxes your body

          • ex) slows heart rate, increases digestion, helps focus on saving and storing energy

          • known as rest and digest

          • TIP TO REMEMBER! → PARAchute slows you down before you land

• nervous system uses 2 types of nerves to deliver information

  • afferent/sensory neurons - send signals from sensory receptors to CNS

    • TIP TO REMEMBER! → afferent APPROACHES brain

  • efferent/motor neurons - send signals from CNS to PNS

    • TIP TO REMEMBER! → efferent EXITS brain

1.3 The Neuron & Neuron Firing

• 2 common types of neural cells

  • glial cells

    • provide structure

    • insulation and communication

    • waste transportation

    • form basis of nervous system and are building blocks of all behavior and mental processes

    • most abundant cells in nervous system

    • support neurons through protection + provide them with nutrients

    • do not process information → don’t send any messages/signals for body

  • neurons

    • basic functional unit of nervous system

    • communicate with each other by using electrical impulses and chemical signals to send information throughout nervous system

      • electrical inside neuron

      • chemical outside neuron

  

• reflex arc → nerve pathway that allows body to respond to stimulus without thinking

  • made up of 3 types of neurons

    • sensory neurons

    • motor neurons

    • inter neurons - connect sensory and motor neurons in CNS, including the brain and spinal cord

  • made to protect us // allows body to respond to threat before processing what is going on

  • ex) When you touch something hot, skin receptors detect heat and send signal through the sensory neuron to spinal cord, which then goes to inter neurons (neurons within brain + spinal cord), which communicate internally and connect sensory neurons to motor neurons within CNS; When the signal goes to motor neurons, it goes back to muscles in hand/arm to move, resulting in your hand being pulled away from hot surface (autonomic response).

• neural transmission

  • in order for neurons to send a message, they need to receive enough stimulation that causes an action potential

  • action potential - when neuron fires and sends impulse down the axon

    • for this to happen, you need positively charged and negatively charged ions

  • cell membrane separate the ions + creates environment on either side of barrier that is overall positive or negative → this is what gives neurons potential

  • some ions cross barrier more easily, which is called permeability

  • when neuron is not sending signal, it has more negative ions in the inside than outside, which is known as resting potential

  • to trigger an action potential, neuron must depolarize, which happens when outside stimulus is strong enough to meet threshold that causes depolarization to occur + neuron then fires action potential

  • if stimulus does not meet threshold, there is no firing and neuron will return to resting state

  • “all or nothing” response

  • When action potential occurs, it sends signal down axon to other neurons in nervous system. After that, a neuron goes through the process of repolarization, which brings neuron back to resting potential. During this process, channels will be open to try and rebalance charges by letting more positive ions back outside cell membrane. When this is happening, neuron cannot respond to any other stimulus, which is known as the refractory period.

  • refractory period - time period when cell cannot fire and needs to wait until repolarization occurs and the cell goes back to resting potential

  • once signal makes it way down axon of neuron, it is sent down to axon terminal, where signal is converted + sent to another neuron through a small pocket of space between axon terminal button (of one neuron) and the dendrite (of another neuron), which is called the synapse

  • synapse

    • chemical synapse - use neurotransmitters (chemical messengers that send messages through nervous system)

    • electrical synapse - for messages that need to be sent quickly and immediately

  • when neurotransmitters are sent, they diffuse through synaptic gap to deliver messages

  • synaptic gap - narrow space between 2 neurons, between presynaptic terminal of one neuron, and postsynaptic terminal of another

    • presynaptic terminal - axon terminal of neuron which converts electrical signal to chemical one, and sends neurotransmitters into synaptic gap

    • postsynaptic terminal - where neurotransmitters are accepted in dendrite of receiving neuron

  • once neurotransmitters pass message onto postsynaptic neuron, they unbind with receptors

  • some neurotransmitters are destroyed, and other get reabsorbed

  • reuptake - process of taking excess neurotransmitters left in synaptic gap

    • sending neuron reabsorbs extra neurotransmitters

    • recycling process

  • excitatory neurotransmitter - increase likelihood that neuron will fire action potential through the depolarization process in postsynaptic neuron

  • inhibitory neurotransmitter - decrease likelihood that neuron will fire action potential, leading to hyperpolarization to occur which is when inside of neuron becomes more negative, moving neuron farther away from its threshold needed from action potential

  • neural transmission summary

    1. Action potential sends a signal down axon of neuron to presynaptic terminal.

    2. Channels in axon terminal are opened and neurotransmitters are released into synaptic gap (chemical messages).

    3. The neurotransmitters diffuse through the synaptic gap, and bind to receptor sites in the postsynaptic terminal.

    4. Neurotransmitters unbind with receptors; some are destroyed and others go through the reuptake.

  • multiple sclerosis - occurs when myelin sheath is damaged, disrupting transmission of electrical signals, which lead to symptoms such as muscle weakness, coordination problems, fatigue

  • myasthenia gravis - autoimmune disorder that affects communication between nerves and muscles

    • antibodies block or destroy acetylcholine receptors, preventing muscle contraction and causing muscle weakness and fatigue

• hormones

  • adrenaline - helps with body’s response to high emotional situations and forms memories; involved in fight or flight response

  • leptin - regulates energy balance by inhibiting hunger; signals that body has enough stored fat, reducing appetite

  • ghrelin - signals to brain that we are hungry and helps promote release of growth hormones

  • melatonin - produced by pineal gland and helps regulate sleep-wake cycles (circadian rhythms); promotes sleep and is more prevalent in evening in response to darkness

  • oxytocin - produced in hypothalamus and released by pituitary gland; promotes feelings of affection and emotional bonding

• agonist drugs - increase effectiveness of neurotransmitter

  • mimic neurotransmitters (have similar molecular structure)

  • fit into receptor site and cause same response

• antagonist drugs - decrease effectiveness of neurotransmitter

  • similar in molecular structure to neurotransmitters

  • fits into receptor site, but does not cause action potential

  • blocks receptor site

• psychoactive substances - purposely alter individual’s perception, consciousness, or mood

  • stimulants - excite and promote neural activity; give individual energy, reduce appetite, cause them to be irritable

    • ex) caffeine, nicotine, cocaine

  • depressants - reduce neural activity; cause drowsiness, muscle relaxation, lowered breathing, if abused, possibly death

    • ex) alcohol, sleeping pills

  • hallucinogens - cause individual to sense things not actually there; reduce motivation, can lead individual to panic

    • ex) marijuana, peyote, LSD

  • opioids - function as depressant, but very addictive; gives pain relief

    • ex) morphine, heroin, oxycodone

1.4 The Brain

• neuroplasticity - brain’s ability to rewire itself after injury

• 3 major regions of the brain

  • hindbrain

    • spinal cord - connects your brain to rest of your body

      • allows for nerves to send information to brain and vice versa

    • brain stem - located on top of spinal cord

      • if damaged, most likely results in death because it controls autonomic functions

        • medulla - regulates cardiovascular and respiratory system; takes care of autonomic functions

        • pons - bridge between different areas of nervous system; connects medulla with cerebellum and help coordinate movement; helps with sleep and dreams

        • reticular formation - network of nerve cell bodies and fibers within brain stem; regulates arousal, alertness, sleep-wake cycles; helps with motivation

        • cerebellum - coordinates voluntary movements, maintains posture and balance, refines motor skills, plays role in cognitive functions

  • midbrain - helps with visual and auditory information, motor control, integrating sensory and motor pathways

  • forebrain

    • cerebrum - deals with complex thoughts

      • left hemisphere

      • right hemisphere

      • made up of gray matter called cerebral cortex and white matter

      • cerebral cortex - thin outer layer of billions of nerve cells that cover the whole brain

      • corpus callosum - thick band of nerve fibers that connect cerebral hemispheres; allows hemispheres to communicate with each other

      • frontal lobe - deals with higher level thinking

        • prefrontal cortex - deals with foresight, judgement, speech, complex thought

        • motor cortex - deal with voluntary movement

          • left motor cortex controls movement on right side of body, and vice versa

        • broca’s area (left hemi) - crucial for language production, particularly controlling movements of muscles involved in speech

          • if damaged, individual experiences broca’s aphasia → loss in ability to produce language // can still understand, but struggles to speak fluently

      • parietal lobe - receives sensory information and helps processing and organizing information

        • somatosensory cortex - processes touch, pressure, temperature, and body position

          • left sensory cortex controls right side of the body and vice versa

      • temporal lobe - processes auditory and linguistic information, recognizing faces, assisting with memory

        • hippocampus - helps learn and form memories; NOT WHERE MEMORIES ARE STORED!

        • amygdala - where you get your emotional reactions from

        • auditory cortex - processes different sounds that you hear and allows you to recognize things like music/speech

        • wernicke’s area (left hemi) - responsible for creating meaningful speech

          • if damaged, individual experiences wernicke’s aphasia → loss of ability to create meaningful speech

      • occipital lobe - responsible for processing visual information; recognizing objects, understanding spatial relationships, perceiving depth, movement

        • works with parietal and temporal lobe // occipital lobe recognizes object’s color and shape; temporal lobe identifies object; parietal lobe helps understand spatial orientation

          • primary visual cortex - receives visual input from the eyes

    • thalamus - receives sensory information from sensory organs, for everything except the sense of smell; relays info to appropriate areas of cerebral cortex for processing (“relay station”)

      • limbic system - main functions: TIP TO REMEMBER! → The 4 F’s: Fighting, Feeding, Fleeing, F... (reproductive behavior)

        • amygdala

        • hippocampus

        • thalamus

        • cerebellum

        • corpus collosum

        • hypothalamus - keeps body balanced and allows you to have homeostasis; controls thirst, hunger, temperature, sex

          • works with pituitary gland to regulate and control hormones

          • pituitary gland - “master gland” → produces and releases hormones that regulate many bodily functions and controls other endocrine glands throughout body

        • cingulate gyrus

        • basal ganglia

• brain laterization - differing functions of the left and right hemispheres

  • division of labor between two hemispheres

  • everyone uses both hemispheres, and no one is right-brained or left-brained (MYTH)

• hemispheric specialization

  • left hemisphere

    • recognizes words

    • letters

    • interpreting language

  • right hemisphere

    • understands spatial concepts

    • facial recognition

    • discerning direction

• research that have helped us better understand brain

  • phineas gage

    • railroad work who had iron rod shot through his head

    • survived and walked away without any cognitive defects BUT had had severe personality change, because rod had severed limbic system

    • allowed researchers to better understand different brain structures

  • split brain research (researcher gazzaniga)

    • split brain procedure → cuts corpus collosum to help treat those with severe epilepsy

    • when corpus collosum is cut, left and right hemispheres cannot communicate

    • no change with personalities/intelligence

    • researchers test for cortex specialization → allows researchers to understand how different areas of cerebral cortex are specialized for specific functions

      • when patients are shown word on their right side of visual field, patient was able to say the word

      • when words were shown on left side of visual field, patient would say they did not see anything

      • however, they could draw the word with their left hand and then were able to identify it, because right visual field could identify and see what they drew

  • lesion studies - doctors/researchers will destroy parts of brain to gain insight into different functions of brain

  • autopsies - examination of deceased body to find out cause of death

  • EEG - uses electrodes that are placed on individual’s scalp

    • allows researchers to record electrical signals from neurons firing

    • helps with sleep and seizure research

  • fMRI - similar to MRI, but show metabolic functions, which help with better understanding brain activity

    • shows more detailed image

1.5 Sleep

• consciousness - our awareness of ourselves and our environment

  • wakefulness - awake; aware of surroundings and can think, feel, and react to events

  • sleep - lower level of awareness; not fully aware of surroundings, but brains are still active and can process some information like sounds and sensations

• cognitive neuroscience - studying how brain activity is linked with cognition

• circadian rhythm - body’s internal clock; about a 24-hour cycle

  • changes blood pressure, internal temperature, hormones, regulates sleep-wake cycle

  • adjusts with age and different life experiences

  • can become disrupted due to working night-shift or travelling across time zones → jet lag

• using an EEG helps us visualize brain waves to help understand which stage were are in

  • allows us to measure frequency of waves i.e. number of waves per second and amplitude i.e. size of the wave

• alpha waves - relatively slow brain waves of a relaxed awake state

1. NREM Stage 1

   • lasts about 5-10 mins

   • body starts to relax and mind starts to slow

   • alpha waves

2. NREM Stage 2

   • lasts about 10-20 mins

   • individual will experience k-complexes and sleep spindles, which are bursts of neural activity

   • theta waves

3. NREM Stage 3

   • lasts around 30 mins

   • growth hormones are produced and individual may experience sleepwalking or sleep talking

   • delta waves

4. REM (rapid eye movement)

   • external muscles = paralyzed

   • internal muscles = active

   • beta waves

   • lasts about 10 mins

   • may experiences dreams/nightmares

   • considered paradoxical sleep since brain waves are similar to wakefulness, but body is at its most relaxed state

   • as sleep cycle progresses, periods of REM sleep become more longer and frequent

• REM deprivation - occurs when individual keeps getting up in the middle of the night due to hunger, crying baby, etc.

• REM rebound - occurs as a result of REM deprivation, which means that the next time they sleep, they will enter REM sleep more quickly and spend more time in REM to make up for the lost sleep

• hypnagogic sensations - occur during NREM stage 1; when individual experiences sensations you imagine are real, and happen when you are in light sleep

  • ex) feeling like you’re falling

• theories that seek to explain purpose of dreams/sleep

  • activation-synthesis theory - takes perspective that dreams are the brain’s way of making sense of random neural activity during sleep

  • consolidation theory - takes perspective that dreams help process and strengthen our memories and experiences

  • restoration theory - takes perspective that we sleep because we get tired from daily activities and we sleep to restore energy and resources

• Why do we sleep?

  • to protect an individual; different animals sleep for different lengths of time and at different times of fay depending on when they are active and when other threats may be out

  • helps memory consolidation, allowing body to strengthen neural pathways, allowing for better recall in future

  • supports growth, with pituitary gland releasing growth hormones, which helps with muscle development, and conserves energy and save it for when we need it during the day

  • can help individual become more creative; reference their dreams as what sparked curiosity

• sleep disorders

  • insomnia - individual will have trouble falling asleep or staying asleep

    • may be caused due to stress, pain medication, or irregular sleep schedule

  • sleep apnea - individual has trouble falling asleep or staying asleep because they are struggling with breathing

    • prevents them from entering REM, because they keep waking up

  • REM sleep behavior disorder - person acts out dreams during REM sleep

    • typically, we are paralyzed in REM

    • in RBD, paralysis is absent or possibly incomplete

    • risk for self-injury

  • somnambulism (sleep walking) - person gets up and walks around while still sleeping

    • most commonly occurs during stage 3 sleep (deep sleep)

    • more common in children

  • night terrors - individual experiences intense fear while sleeping

    • causes sleep deprivation and disrupted sleep schedule

  • narcolepsy - individuals struggle to sleep at night and will uncontrollably fall asleep during day