KHA303 Lecture Notes - Lecture 1: Prefrontal Cortex, Occipital Lobe, Resting Potential
3 Jul 2018
School
Department
Course
Professor
Cognitive Neuroscience week 1
The Evolution of Cognitive Neuroscience:
- Phrenology:
oFranz Joseph Gall & Spurzheim
oPseudoscience
oLocalization of function, central cognitive neuroscience
oNot widely accepted at the time
oA bump in the brain if the area is in use
oDebunked in 1824: Marie Jean Pierre Flourens
Aggregate field theory: all sensations, all perceptions, and all
volition occupy the same seat in these organs
Cerebral organs
- Localisation holds sway:
oSeizures started in particular part of the body and followed stereotyped
pattern
oTopographic organisation of the brain
oBroca:
Patient who lost ability to speak following damage to left
inferior frontal lobe
oWernicke:
Lost language comprehension following damage to temporo-
parietal junction
- Cyoarchitechtonics:
oBromann’s areas
oExamined cellular organisation to identity 52 distinct brain areas
- Neuron Doctrine:
oOpposing ideas:
Continuous mass
Unitary neurons
- Psychology:
oLate 19th and 20th century
oAssociationism: experience determines the course of mental
development
Ebbinhaus
Brain is blank slate that learns through experience
oBehaviouralism: observed behaviours relate to objective observable
stimulus conditions within the environment
Not within the mind
Responses are caused by stimuli
Thorndike, Watson, Skinner
Very important for learning
Prevented learning about cognitive psychology because they
are not observable
oNeuroscience:
Penfield mapped sensory and motor cortices using electrical
stimulation
Hebb: cells that fire together, wire together
find more resources at oneclass.com
find more resources at oneclass.com
Long term potentiation
Milner: anatomical and physiological evidence of multiple
memory systems
oCognitive science:
Miller
Behaviorist early in his career, but changed
5-9 memory
oChomsky: language is universal and innate component
oInterpretation of stimuli that ultimately shaped behaviour
oCognitive neuroscience:
Miller termed it
Inter-disciplinary
Cognition: mental processes and activities important for
perceiving, remembering, thinking and understanding
Neuroscience: the study of how the nervous system is
organized and functions
Structure and function of the nervous system:
- Structure of neurons:
oInformation received at dendrites
oNucleus held in the cell body:
DNA organized in chromosomes
Ribosomes
Mitochondria
ER
Golgi apparatus
oAxon:
Single process
Information leaves the cells to axon terminals
oAxon terminals
Synapse onto the next cell
oMyelin sheaf
Single fatty cell that wraps around the axon
Insulate axon and speeds neuro-transmission
Jumps from node to node rather than running the whole length
of the axon
oNode of Ranvier
oCell membrane
- Neuronal signaling:
oMembrane potential: difference in voltage between inside and outside
oDetermined by concentration of potassium sodium and chloride ions
and charged protein molecules
oCell membrane contained of double layer of fatty molecules
Lipid membrane stops the flow of water soluble substances
Eg. Fat repels water
oResting potential is -70mv
Differential concentration
find more resources at oneclass.com
find more resources at oneclass.com
Maintained by ion pumps
More Na outside cell
More CL outside cell
More K and negative protein ions inside cell
oIon channels:
Proteins in the membranes
Pore that allows certain ions to flow down the concentration
gradient
Goes to area of less concentration to balance out
One channel for each type of ion
Passive process
oIon pumps:
Actively transport ions across the membrane against
concentration gradient
Active process that requires energy: ATP made from
mitochondria needed here
Powers pumps
oPassive electrical signaling:
Electronic conduction: postsynaptic potentials produced at
dendrites are passively conducted in cytoplasm
Does not involve ion channels
Graded: larger input = larger passive current
Decremental: becomes smaller as travels further
Graded potentials are summed at axon hillock
Spike-triggering zone
oActive electrical signaling:
When membrane potential at axon hillock moves closer to 0mV
the membrane is depolarized
-55mV is threshold
action potential will be generated
all or nothing response unlike postsynaptic
ovoltage-gated ion channels:
when the membrane potential becomes mrore positive, NA
channels open
Na rushes in, down concentration (high to low) and electrical
gradients (positive to negative)
This depolarized cell even more, causinvg more Na to open
Then K channels open and flow out of the cell and the
membrane potential is repolarized
K channels stay open longer, hyperpolarized
Refractory period:
Absolute refractory period: no action potentials can be
generated
Relative refractory period: can generate only if larger
threshold met
Propagating the action potential:
Regenerate along axon
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Phrenology: franz joseph gall & spurzheim, pseudoscience, localization of function, central cognitive neuroscience, not widely accepted at the time, a bump in the brain if the area is in use, debunked in 1824: marie jean pierre flourens. Aggregate field theory: all sensations, all perceptions, and all volition occupy the same seat in these organs. Localisation holds sway: seizures started in particular part of the body and followed stereotyped pattern, topographic organisation of the brain, broca: Patient who lost ability to speak following damage to left inferior frontal lobe: wernicke: Lost language comprehension following damage to temporo- Cyoarchitechtonics: parietal junction: bromann"s areas, examined cellular organisation to identity 52 distinct brain areas. Psychology: late 19th and 20th century, associationism: experience determines the course of mental development. Brain is blank slate that learns through experience: behaviouralism: observed behaviours relate to objective observable stimulus conditions within the environment. Prevented learning about cognitive psychology because they are not observable: neuroscience:
