module 9: biological psych + neurotransmission

neurons/nerve cells - all consist of cell body and its branching fibers

1. dendrite fibers receive info + conduct towards cell body

2. long axon fibers pass the message to other neurons

3. myelin sheath is around the axons, helping to protect and speed up the impulse

   → if the myelin sheath is damaged, the communication to muscles slows , resulting in loss of muscle control (multiple sclerosis)

stimulated by signals from our senses or when triggered by chemical signals from other neurons
- action potential: the impulse that is fired and travels down the axon

ions are exchanged when going from chemical to electrical within neuron
- inside of axon = negatively charged ions, outside of axon = postive charge
- positive outside/negative inside state
→ resting potential

the axons surface is very guarded
but opens when neuron is fired
- positive ions come through cell membrane
→ becomes depolarized, or more positively charged (+30mv)
→ this becomes action potential

the resting pause is called refractory period
- positively charged ions are pumped back outside

the level of stimulation needed to trigger a neural impulse is called the threshold

*increasing the level of stimulation above threshold will not increase neural impulse’s intensity
→ all or none response (either fire or no fire)

how neurons communicate
meeting point between 2 neurons is called the synapses
- the gap is called the synaptic gap

1. action potential reaches the end of axon
2. triggers the release of neurotransmitters
3. neurotransmitter crosses the synaptic gap + binds with receptor site (dendrite) of other neuron
4. excess neurotransmitter is absorbed by original neuron
→ reuptake

how neurotransmitters influence us?

how do drugs and other chemicals alter neurotransmission?

drugs affect brain at synapses
- exciting or inhibiting (calming) neurons’ firing

drugs that are agonist molecules
- similar to neurotransmitter, able to bind to its receptor + mimic effects
- may produce temporary “high”

antagonists
- also bind to receptors but block neurotransmitter’s function

module 10: the nervous + endocrine systems

functions of nervous system’s main divisions + 3 types of neurons
nervous system = body’s speedy electrochemical communication network, consisting of all the nerve cells of peripheral + central nervous sytems

1. central nervous system = brain + spinal cord

2. peripheral nervous system = sensory/motor neurons that connect central nervous system to rest of body
   - nerves are formed by bundles of axons and link the cns with the body’s sensory receptors, muscles, and glands

3 types of neurons that carry info through nervous system:
1. sensory (afferent) neurons
- carry messages from body’s tissues and sensory receptors to the brain and spinal cord for processing
2. motor (efferent) neurons
- carry outgoing info from the brain/spinal cord to the muscles and glads
3. interneurons
- neurons within brain/spinal cord that communicate between the sensory inputs and motor outputs

the peripheral nervous system - 2 components
1. somatic nervous system
- enables voluntary control of skeletal muscles

2. autonomic nervous system
- controls our glands, muscles of internal organs
- involuntary processes (heartrate, breathing, digestion)
→ sympathetic nervous system - arouses, mobilize energy for stressful situations (raise heartbeat, raise blood pressure, slow digestion)
→ parasympathetic nervous system - calms body, conserves energy
(decrease heartbeat, lower blood sugar, faster digestion)

the central nervous system

the spinal cord - connects the peripheral nervous system with the brain
- ascending neural fibers send up sensory info
- descending fibers send back motor control info
- it is in charge of our reflexes, automatic responses to stimuli
ex. finger touches flame, neural activity (excited by heat) travels via sensory neurons to interneurons in spinal cord. the interneurons activate motor neurons, to muscles in arm jerking away before reaches brain

if spinal cord is severed,
- lose all senses of paralyzed lower body
- exhibit reflexes without feeling the tap

the endocrine system
secrete hormones (chemical messengers) that travel through the bloodstream and affect other tissues, including the brain
- take longer than nervous system for messages to travel from gland to tissue
- but endocrine messages outlast nervous system (neural) messages
→ upset feelings may linger beyond awareness

adrenal glands - located on top of the kidneys
in moment of danger, ANS (involuntary) orders adrenal glands to release epinephrine and norepinephrine
- increasing heartrate, blood pressure, surge of energy
→ fight or flight
- when the emergency passes, the hormones and feelings linger a while

pituitary gland - located in core of the brain
- controlled by the hypothalamus
- releases growth hromones to stimulate physical development
- releases oxytocin, associated with birthing, social trust

hypothalamus keeps body in homeostasis, regulating hormones
ex. stressful events trigger hypothalamus to tell pituitary to release a hormone that causes adrenal glands to flood body with cortisol, a stress hormone
(brain → pituitary → other glands → hormones → body and brain)

module 11: studying brain, older brain structures

body’s right side wired to the brain’s left side, vice versa

scientists can lesion (tissue destruction) without harming the surrounding tissue

electroencephalogram (eeg) - reading brain waves, measured by electrodes placed on the scalp

ct (computed tomography) scan - examines brain by taking xray photographs that reveal brain damage

pet (positron emission tomography) - shows brain activity that detects where radioactive glucose goes while brain performs a given task (see gamma rays released)

MRI (magnetic resonance imaging) - uses magnetic fields + radio waves to produce computer generated images of soft tissue, showing brain anatomy

fMRI (funcional MRI) - shows blood flow in the brain to show which areas are the most active. shows brain function and structure

what is the brainstem, what are the functions of brainstem, thalamus, cerebellum?

brainstem
- brains oldest and innermost region
- beginning where the spinal cord swells as it enters skull
- responsible for automatic survival functions
medulla
- the part that swells on spinal cord
- controls breathing, heartrate
pons
- right above the medulla, bridge between brain + spinal cord
- helps coordinate movement
- produces chemicals the body needs for sleep

thalamus
- egg shaped structure on top of brainstem
- sensory control center
- receives info from all senses except smell, sending it to higher brain regions that deal with seeing hearing tasting touching
- directs replies to medulla + cerebellum

reticular formation
- extends from spinal cord through thalamus
- some sensory from spinal flows up thalamus to reticular formation
- filters incoming stimuli + relays important info to other brain areas (arousal)

cerebellum
- located at rear of brainstem
- enables nonverbal learning + memory
- processing sensory input, coordinating movement output (w/ pons), balance

limbic system

neural system (includes hippocampus, amygdala, hypothalamus)
- associated with emotions like fear, aggression, food + sex drives

hippocampus
- processes conscious memories (spatial)
- if hippocampus is lost to injury, lose ability to form new memories of facts/events, cause amnesia

amygdala
- aggression + fear
- lima bean shaped

hypothalamus
- just below thalamus
- maintain homeostasis in body
→ influence hunger, regulate thirst, body temp

module 12: the cerebral cortex

the forebrain
cerebral cortex - layer of neural cells that cover cerebral hemispheres
→ learn + store complex info, read, make projections

*wrinkles of brain help reduce area
tissue folded, forming sulci (valley) and gyri (peaks)

glial cells - provide nutrients to neurons, helping with neurotransmission
- also play role in learning + thinking

BOTH hemispheres have 4 lobes (they are connected by the corpus callosum)

frontal lobes - front of brain, moving over top
- command center for decision making, personality, reasoning
- willpower + motivation
- the motor cortex is located here, controlling voluntary movements
- broca’s area is near the motor, linked with speech production
→ damage disrupts speaking
- wernicke’s area is linked to language comprehension
→ damage disrupts understanding

parietal lobes - at top and to the rear
- process touch, pressure, temperature, pain
- somatosensory cortex - processes body touch/movement sensations
→ more sensitive the body region, the larger the somatosensory devoted to it

occipital lobes - back of head
- processes, interprets, coordinates visual signals
- visual association cortex - helps recognize lines, angles, shadows, movement

temporal lobes - just above ears
- processes auditory info + auditory memory
- right temporal processes melody in music
- left temporal, wernickes area, allows language comprehension
- lower part of temporal responsible for some visual processing
→ if damaged, can cause agnosia, objects become unrecognizable
- aphasia impacts speech

brain plasticity

neurogenesis = forming new neurons (limited in brain)
brain plasticity = allows tissue in brain to reorganize to deal w/ damage

phineas gage
rod went through left cheek, skull, damaging fontal lobes
- his personality was changed to be more irritable
- frontal lobe affects personality

module 13: brain hemisphere organization + biology of consciousness

epliepsy calused by abnormal brain activity bouncing between two hemispheres
- cut the corpus callosum (neural fibers that connect the hemispheres, carrying messages between them)

• seizures disappeared, personality unaffected

• unruly independence of left hand

• our speaking ability lies in left hemisphere

• right can see but lacks ability to speak about what it perceives

consciousness - awareness of ourselves + environment

cognitive neuroscience - study of brain acitivty linked with mental processes
→ woman who showed no signs of conscious awareness revealed brain activity in an area that controls arm and leg movement when asked to imagine playing tennis
→ even in a motionless body, the brain is still active

dual processing : brain operates on two distinct tracks simultaneously
- fast automatic unconscious system
- slower, conscious processing system

module 14: behavior genetics

individuals differ based on interplay of biology + upbringing
behavior genetics - study of relative power + limits of genetic and environmental influences on behavior
→ study differences

molecular genetics - subfield of bio that studies the structure and function of genes

heritability = percentage of variability in a population due to genetics
→ NOT percentage of a trait

epigenetics = study of environmental influences on gene expression that occur without a dna change
→ triggered by environment

module 15: evolutionary psych

mutations = random error in gene replication that leads to a change

woman nurses one infant at a time, male can spread genes through other females
- men attracted to women whose ages (in past) would be associated with peak fertility
- women attracted to men who seem mature, bold

Sleep + Dreams

internal biological clock called circadian rhythm with 16 hrs awake and 8 hrs asleep
- rods in eyes detect lower light levels, retina communicates with hypothalamus (homeostasis)
- then signals gland do secrete melatonin

stage 1: brain produces low amp alpha waves as body goes into awake but relaxed, goes into dreaming state (easy to wake)

stage 2: brain waves slow down, sleep spindles may occur (may sleep talk/respond to outside stumulus)

stage 3: slow delta waves occur, hormones released, immune system refreshed (very hard to wake)

REM sleep: back to waking beta waves, eyes move rapidly, pulse + breathing irregular, muscle groups immobilized, adrenal/sex hormones rise, nightmares happen

if need for sleep overwhelms system, we experience shift in brain activity known as microsleep, where we zone out

sleep disorders:
insomnia - difficulty falling asleep → stress, drug, alcohol use
sleep apnea - breathing stops while sleeping, causing gasp for breath
narcolepsy - falling into REM sleep during waking hours
nightmares/night terrors - nightmares are disturbing dreams during REM sleep, night terrors in stage 3 wake up screaming

theories of dreaming
information processing:
- dreams help us rehearse behavior to survive when facing danger

activation synthesis:
- dreams are random events caused by firing of neurons in brain
- brain creates narrative but no meaning

REM rebound:
- if REM deprived, makes up by falling quickly into REM
- intense dreams

drugs
tolerance: increasing large doses are needed to achieve the same effect because of neuroadaption
withdrawal: symptoms that occur with discontinuing use

depressant increases GABA (calming)
- alcohol
- opioids (agonist for dopamine, relieve pain)
→ heroin, morphine

stimulants increases activity with norepinephrine, dopamine
- nicotine (agonist for acetylcholine)
- cocaine (agonist for dopamine)

hallucinogens alter emotions perception thought
- cannabis (agonist for dopamine)
→ attack hippocampus, loss of learning/memory
- LSD (agonist for serotonin)
→ causes delusion, hallucinations