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PSY100Y5 Lecture Notes - Axon Hillock, Membrane Potential, Mesolimbic Pathway

Course Code
Dax Urbszat

of 4
May 11th
Brain and Behaviour
Components of the Neuron
-dendrites: receive information from other neurons
otree like branches with tiny receptor sites to what the neurotransmitter bind to
send their messages
-cell body: creates transmitter molecules
osummate electrical activity – neuro-impulse (action potential) – release of
energy to terminal buttons
-action hilloch: fires the action potential
-axon: myelin insulates the nerve cell, speeds up conduction of nerve messages
oterminal buttons of the axon release transmitter
otails/highways – sending information down
ofree nerve endings: to help us have feeling
oafferent : sensory neurons
oefferent: motor neurons - send information to the muscles
-glia: structural support for the brain – what we use to create the myelin sheath –
omore myelin: information travels faster
-about 100 billion neurons in brains
-converting electrical energy from our environment to chemical energy through
oaffected by how we think, what you eat, how much sunlight you have etc.
Graded Potentials
-stimulation of the nerve membrane can open ion channels in the membrane
oNA+ ions flowing in will depolarize the membrane (movement from –70mV to
say –60mV)
oK+ ions flowing out of the membrane will hyperpolarize the membrane (-70mV
to say –90mV)
The Action Potential
-graded potentials are generated at the dendrites and are conduced along the membrane
to the axon hillock
-if the summated activity at the axon hillock raises the membrane potential past
threshold, an AP will occur
-during the AP, NA+ ions flow into the cell raising the membrane potential to +40mV,
producing the spike
othe restoration of the membrane potential to –70mN is produces by an opening
of channels to K+
othe AP is conducted along the axon toward the terminals
Details of the Synapse
-cleft: space between the receptor sites of the dendrites and the terminal buttons
-acetylcholine (ach)
omemory and learning – don’t have to build the whole road, just have to repair it
osleep and dreaming – disruptions in the ach process are responsible for
Alzheimer’s and dementia
onecessary to send messages about motor movement
oagonistic: mimic neurotransmitters
oantagonistic: block neurotransmitters
fills up all the receptor sites and blocks it from receiving ach
dying from paralyzation
-epinephrine and norepinephrine
oability to pay attention and stay focussed
odisruptions in the norepinephrine – depression/bipolar disorder
otoo much: manic episodes, not enough: depression
oSSRI/SSNRI: medication for imbalance of norepinephrine
oMAO: enzyme that comes in and deactivates/kills the neurotransmitters (to make
sure we don’t have too many)
oMAO inhibitors: anti-depressant – giving the neurotransmitters a better chance to
bind – a lot of side effects
But MAO deactivates all the neurotransmitters, not just norepinephrine
oepinephrine: released during fight or flight response system – adrenaline
oreward and pleasure neurotransmitter
oaddiction, involuntary motor control
olack of dopamine: Parkinson’s – lack of motor control
otoo much dopamine: schizophrenia
oagonistic: cocaine – mimic dopamine – floods the part of the brain with
dopamine rich receptor sites (reward pathway)
oantagonist: anti-psychotic drugs
oinhibitory neurotransmitters – without it, we are unable to inhibit things
oantagonist: alcohol
oHelps in the creation of new neuro-connections – ie. myelinzation, moving new
terminal buttons to new binding sites, helps solidify new learning potentials
-different neurons have different receptor sites in different areas in the brain
Overview of the Nervous System
-begins with the nervous system peripheral and central
operipheral: somatic and automatic
ocentral: brain and spinal cord
automatic: sympathetic and parasympathetic
-brain and spinal cord in the center
-consider the brain stems as an extension of the brains
-peripheral: on the outside
osomatic and automatic
osomatic: anything to do with the body – conveys information to the central
nervous system and sends messages back
oautomatic: on your own, without control – without conscious thought
heartbeat/lung function, etc
basic life functions
sympathetic and parasympathetic
sympathetic: fight or flight
parasympathetic: calms you down after you have been excited
Automatic Nervous System
-sympathetic: emergency system
othreat or danger
oinflux of bodily changes to fight off the threat or run away as fast as possible
-parasympathetic: vegetative functions (ex. digestion)
okicks in after sympathetic
-the two systems often as in opposition (as in the control of heart rate)
-can act in concert too (like in sexual activity)
Midline View of the Human Brain
-spinal cord: sends the nerve bundles down from the brain stems to all the different
parts of the body – cant repair those connections – unable to send/receive messages
-ARAS: ability to be aware, have arousal – no longer have the ability to maintain
consciousness (not dead, but will not respond ever again)
-corpus callosum: bundles up all the axons together
-medulla: controls heart rate, respiration
-cerebellum: coordinates smooth movements, balance, and posture
-pons: involved in the control of sleep
orelease of hormones that are responsible for dream state/dream paralysis
-pituitary gland: master of glands – tells all the other glands when they should what
they should do
oglands release hormones
ois a puppet of the hypothalamus
-hypothalamus : below the thalamus – responsible for the regulation for the 4 Fs
fighting, fleeing, mating, feeding
-thalamus: station for information in the brain – information is routed through the
thalamus and it sends it to the correct places
Limbic System Functions
-septal area is involve din pleasure and in relief form pain
-amygdala is involved in learning and recognition of fear
olooking for threat in the environment – taking away your ability to think, be
creative, etc – attention is a finite source
-hippocampus is involved in memory
Cerebral Cortex
-provides for flexible control of patterns of movement
-permits subtle discrimination among complex sensory patterns
obeing able to tell a chair from a person
-makes possible symbolic thinking
osymbolic thought is the foundation of human thought and language
obeing able to look at something and knowing it has meaning