Chapter 2 Flashcards
neural processing
interaction of signals of many neurons
what kind of signals do neurons create?
electrical signals
neurons
millions of nerve cells that communicate for perception to occur
structure/parts of neurons
dendrite
cell body
axons
sensory receptors
dendrites
area that receives electrical signals via chemicals (neurotransmitters)
cell body
aka soma
important to operate the neuron
contains all organelles
axon
nerve fiber containing fluid that creates electrical signals
aka vertebrae
parts of axon
white matter (lipids that make up axons)
ionic fluids (fluids that can produce electrical signals)
+ myelin sheath (surrounds axon to speed up action potential)
sensory receptors
specialized neurons that respond to specific kinds of energy
small electrode
device that records inside the axon to see electrical signal
resting potential
no electrical signal in neuron
-70 mV inside axon
action potential
aka nerve impulse
electrical signal in neuron
+40 mV inside axon
lasts about 1 ms
properties of action potentials
propagated response
nerve impulse
rate
refractory period
spontaneous activity
propagated response
electrical signal travels down the axon to terminal buttons without decreasing in size
intensity of nerve impulse remains at +40 mV
nerve impulse
electrical firing
rate
strength of nerve impulse
how fast or slow
refractory period
time in which nerve impulses do not occur
heads toward resting potential
prevents process from going back
spontaneous activity
electrical firing that occurs without stimulation from a stimulus
can happen randomly
could be used as baseline comparison for likelihood of an increase or decrease of action potentials
chemical basis of action potentials
axons contain ions in and out of membrane
*Na+ creates action potential; K+ balances
what charged ions are concentrated inside the axon during a resting potential?
more (-) charged ions inside during resting potential
what happens to potassium and sodium ions during an action potential?
during action potential, Na+ gets inside axon and K+ gets out
sodium-potassium (Na+/K+) pump
Na+/K+ pump helps return axon to resting potential after action potential
synapse
tiny space between neurons
neurotransmitters
chemicals released into synapse
determines electrical signals
released by terminal buttons and sent to dendrites to either excite or inhibit signals to that neuron
polarization
resting potential (-70 mV)
on the side of negatively charged ions
depolarization
excitatory response
triggers action potentials
more positive ions inside axon
rising phase of action potentials
hyperpolarization
inhibitory response
prevents action potentials
more negative ions inside axon
falling phase of action potentials
importance of inhibition
allow info to also be processed or detected in the environment just like excitatory responses
not all perception relies on excitatory info only
sensory coding
focuses on how neurons represent various characteristics in the environment in the brain
3 types: specificity, sparse, population
specificity coding
specialized neuron that responds or fires to one concept or stimulus
grandmother cell (by Lettvin in 1960s; anything connected to grandmother would fire a particular neuron for your grandmother in the brain)
why is the grandmother cell theory not accepted anymore?
more than 1 neuron is required for communication
sparse coding
pattern of firing with a small group of neurons to represent stimulus
only some neurons will fire but not the majority of neurons in the brain
population coding
pattern of firing with large number of neurons
Franz Joseph Gall and Johann Spurzheim (1700s)
proposed phrenology
phrenology
mapping of the brain through bumps and contours on the person’s skull (skull represented abilities and traits in the brain)
later debunked because of inconsistencies, but led the idea that the brain had different areas of function
modularity
idea that specific areas of the cortex are specialized to respond to specific types of stimuli
modules
brain areas containing neurons that specialize in processing certain info
early examples came from humans with brain damage
broca’s area
damage to the left frontal lobe would cause problems with speech production
wernicke’s area
damage to the left temporal lobe would cause problems with speech comprehension
neuropsychology
study of how brain damage affects behavior
field that provided evidence for modularity
brain imaging
advanced methods to examine modularity
examples: MRI, fMRI
MRI
magnetic resonance imaging
only see brain structure
fMRI
functional magnetic resonance imaging
can see movement (neural activity) in the brain through blood flow because neurons require oxygen from the blood
hemoglobin
red blood cell
carries oxygen in the blood
contains iron (ferrous molecules) that can be used for magnetic info
what happens to hemoglobin when more brain activity occurs?
more brain activity = more hemoglobin in blood
distributed representation
stimulus fires across different parts of the brain rather than in one single brain area
example: processing (representing) pain (the stimulus) is spread
