Please enable JavaScript.
Coggle requires JavaScript to display documents.
Information Processing: The Communicative Neurons (Neural Representation…
Information Processing:
The Communicative Neurons
Brain
one part of nervous system
include
sensory system
motor system
considerable information processing happens outside brain
Neuron
most important component of nervous system
definition
a cell that receives and transmits signals through electrochemical activity
100 billion neurons in brain
each has processing capability like a small computer
process information through interaction
Neuron (details)
various shapes and sizes
depending on location and function
prototype
soma
main body
dendrites
short branches attached to soma
axon
a long tube extending from soma
fixed path neurons communicate with one another
extends toward the dendrites of other neurons
more myelination, faster transmission
arborizations
axon branches to arborizations
terminal boutons
arborization ends in terminal boutons
almost make contact with the dendrite of another neuron
synapse
gap separating terminal bouton (axon) and dendrite
excitatory: decrease potential difference (negetive -> positive)
inhibitory: increase difference (negative -> more negative)
neurotransmitters
neurons communicate by releasing chemicals from axon terminal
act on membrane of receptor dendrite to change its polarization (electric potential)
axon hillock
where axon joins soma
polarization
inside membrane 70 mV more negative than outside
negative ions inside
positive sodium ions outside
enough net excitatory input
potential difference in soma drop sharply
if reduction in potential is large enough - reach a threshold
depolarization occur at axon hillock
caused by rush of positive sodium ions into the inside of neuron
inside of neuron momentarily becomes more positive than outside = action potential (or spike)
propagate down axon
reaches axon end
1 more item...
billions of these activities occurring simultaneously throughout the brain
Neural Representation of Information
important quantities
membrane potential
rate of firing
number of action potentials or nerve impulses,
an axon transmits per second
greater rate, greater effect on cells
contrast with computer
computer: 0/1
neural cell: continuous
action level
corresponds to
firing rate
degree of depolarization
interacts by driving up(excitation) /down(inhibition)
action level of other neusons
individual neurons respond to specific feature of a stimulus
e.g.some neurons active when
a line in the visual field at a particular angle
a single neuron cannot represent complexity of cognition
human cognition achieved through large patterns of neural activity (ASCII table) across many regions
redundancy
if certain cells are damaged, can still determine what pattern is encoding
experiment:
meaningful story involves activity in many regions of the brain
neural activation pattern is transitory
cannot encode our permanent knowledge
permanent knowledge
memories are encoded by changes in synaptic connections among neurons
brain can reproduce specific patterns
effectiveness of synapses can change by experience (learning), with increased release of neurotransmitters,
increased sensitivity of dendritic receptors