relating nerve cells to behavior
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Transcript relating nerve cells to behavior
#04: CELLS, SYNAPSES & CIRCUITS
behavior analysis
in a natural environment
in the laboratory
cells, synapses & circuits
basic properties of nerve cells
synaptic transmission
neuronal architecture &
behavior
relating nerve cells to behavior
#04: CELLS, SYNAPSES & CIRCUITS
behavior analysis
in a natural environment
in the laboratory
cells, synapses & circuits
basic properties of nerve cells
synaptic transmission
neuronal architecture &
behavior
relating nerve cells to behavior
#04: CELLS, SYNAPSES & CIRCUITS
behavior analysis
in a natural environment
in the laboratory
cells, synapses & circuits
basic properties of nerve cells
synaptic transmission
neuronal architecture &
behavior
relating nerve cells to behavior
NEURONAL ARCHITECTURE OF BEHAVIOR
behavior circuits of interacting neurons, 3 types:
SENSORY INPUT
CENTRAL PROCESSING
MOTOR OUTPUT
BEHAVIOR
NEURONAL ARCHITECTURE OF BEHAVIOR
behavior circuits of interacting neurons, 3 types:
sensory neurons... signal input
specialized receptor cells
convert features of environment neural
signals
interneurons... central processing
motor neurons... motor output (behavior)
drive muscle activity @ neuromuscular junction
NEURONAL ARCHITECTURE OF BEHAVIOR
electrical
recordings:
electrode type
position ~ cells
extracellular
V,
intracellular
mV,
advantages &
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
extracellular electrode
motor neurons
“unit” activity (>1)
~ current flow in
extracellular space
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
intracellular electrode
single motor
neuron
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
extracellular electrode
records
propagation
of action potentials
along axons
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
intracellular electrode
muscle fiber
EJPs signals...
motor neuron
others
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
extracellular electrode
electromyogram
(EMG)
whole muscle
activity
p.24, fig.1.10
NEURONAL ARCHITECTURE OF BEHAVIOR
behavior circuits... simple ones (in mammals)
e.g., human knee jerk reflex...
tap knee below patella
stretches receptors in
quads (muscle spindles)
activates sensory neurons (Ia)
synapse motor neurons ()
contraction of quads
p.25, fig.1.11
NEURONAL ARCHITECTURE OF BEHAVIOR
behavior circuits... simple ones (in mammals)
e.g., human knee jerk reflex...
simple ?
sensory-motor ?
monosynaptic ?
no, other neurons involved
p.25, fig.1.11
NEURONAL ARCHITECTURE OF BEHAVIOR
circuit complexity
e.g., primate visual cortex
boxes = assemblies of
103 s of neurons
106 s of synapses
2 main pathways
V1 PG... object location
V1 TE... visual form
p.25, fig.1.11
NEURONAL ARCHITECTURE OF BEHAVIOR
circuit complexity
e.g., primate visual cortex
Q: how to study cellular
properties of neurons
among such complexity ?
A: chose:
accessible behavior
in model organism providing special advantages
p.25, fig.1.11
NEURONAL ARCHITECTURE OF BEHAVIOR
advantages & disadvantages
interesting... it is ALL interesting (not only ~
humans)
maintenance, availability & access to sufficient #s
model system... biology & tools available
behavior
anatomy / physiology
cell biology
pharmacology
NEURONAL ARCHITECTURE OF BEHAVIOR
advantages & disadvantages
e.g., C. elegans (nematode)
+ cheap, maintenance, sample sizes, simple
behavior, simple anatomy, small simple & wellcharacterized nervous system, development & cell
biology, genetic & pharmacological tools good
– boring behavior, few properties of neuronal
assemblies or structures, small neurons
(electrophysiology difficult but accessible)
NEURONAL ARCHITECTURE OF BEHAVIOR
advantages & disadvantages
e.g., H. sapiens (humans)
+ interesting behavior, need to knowing how we
function (medical), sequenced genome, ~ easy
research funding arguments
– prohibitively complex in every respect, moral
issues for invasive & experimental study,
expensive, inconvenient & uncooperative subjects
#04: CELLS, SYNAPSES & CIRCUITS
behavior analysis
in a natural environment
in the laboratory
cells, synapses & circuits
basic properties of nerve cells
synaptic transmission
neuronal architecture &
behavior
relating nerve cells to behavior
RELATING NERVE CELLS TO BEHAVIOR
investigating how
neurons behavior
e.g., crayfish response
to tail tactile stimulus
p.27, fig.1.12
record lateral giant interneuron (LGI)
correlation (A): always stimulus behavior ?...
RELATING NERVE CELLS TO BEHAVIOR
investigating how
neurons behavior
e.g., crayfish response
to tail tactile stimulus
p.27, fig.1.12
record lateral giant interneuron (LGI)
correlation (A): always stimulus behavior ?...
sufficient (B): trigger LGI alone response ?...
RELATING NERVE CELLS TO BEHAVIOR
investigating how
neurons behavior
e.g., crayfish response
to tail tactile stimulus
p.27, fig.1.12
record lateral giant interneuron (LGI)
correlation (A): always stimulus behavior ?...
sufficient (B): trigger LGI alone response ?...
RELATING NERVE CELLS TO BEHAVIOR
investigating how neurons behavior
e.g., crayfish response to tail tactile stimulus
record lateral giant interneuron (LGI)
correlation (A): always stimulus behavior ?...
sufficient (B): trigger LGI alone response ?...
necessary (C): shut off LGI no response ?...
RELATING NERVE CELLS TO BEHAVIOR
investigating how synapses behavior
e.g., Drosophila escape response
(mutants, pharmacological agents)
inject current across brain
RELATING NERVE CELLS TO BEHAVIOR
investigating how synapses behavior
e.g., Drosophila escape response
(mutants, pharmacological agents)
inject current across brain
measure speed of transmission
in down-stream motor neurons
chemical synapses: slow
RELATING NERVE CELLS TO BEHAVIOR
investigating how synapses behavior
e.g., Drosophila escape response
(mutants, pharmacological agents)
inject current across brain
measure speed of transmission
in down-stream motor neurons
chemical synapses: slow
electrical synapses: fast
(middle leg) escape behavior
RELATING NERVE CELLS TO BEHAVIOR
investigating how restricted
neural networks behavior
e.g., lobster ingestion
food esophagus
3 chamber stomach:
cardiac sac
gastric mill
pylorus
RELATING NERVE CELLS TO BEHAVIOR
investigating how restricted
neural networks behavior
e.g., lobster ingestion
food esophagus
3 chamber stomach:
cardiac sac
pylorus (A) rhythmic
gastric mill (C)
}
p.28, fig.1.13
RELATING NERVE CELLS TO BEHAVIOR
investigating how restricted
neural networks behavior
e.g., lobster ingestion
stomatogastric ganglia
(STG) rhythm
all 30 neurons known
circuits mapped (B,D)
functions in isolated
preparations (A,C)
p.28, fig.1.13
RELATING NERVE CELLS TO BEHAVIOR
neural control behavior in complex organism
e.g., selective attention in monkeys (stimulus
choice)
unit recordings in cortex
cellular response
to peripheral light (A)
p.30, fig.1.14
RELATING NERVE CELLS TO BEHAVIOR
neural control behavior in complex organism
e.g., selective attention in monkeys (stimulus
choice)
unit recordings in cortex
cellular response
to peripheral light (A)
response > if animal
pays attention (B)
p.30, fig.1.14
RELATING NERVE CELLS TO BEHAVIOR
neural control behavior in complex organism
e.g., selective attention in monkeys (stimulus
choice)
unit recordings in cortex
cellular response
to peripheral light (A)
response > if animal
pays attention (B)
response >> if animal
p.30, fig.1.14
RELATING NERVE CELLS TO BEHAVIOR
neural control behavior in complex organism
e.g., selective attention in monkeys (stimulus
choice)
visual system response due to
~ stimulus
other neural systems ~ attention (& ~ activity
?)
gain some understanding of mechanism, even at
this simple level of analysis
#04: CELLS, SYNAPSES & CIRCUITS
behavior analysis
in a natural environment
in the laboratory
cells, synapses & circuits
basic properties of nerve cells
synaptic transmission
neuronal architecture &
behavior
relating nerve cells to behavior
SUMMARY: INTRODUCTION & TERMS
behavior... examples discussed:
field studies ethology
ethograms
FAP, SS, IRM, releasers, interlocking
releasers
laboratory studies associative learning
classical / Pavlovian conditioning,
US, CS, UR, CR
operant/instrumental conditioning
SUMMARY: INTRODUCTION & TERMS
nervous system
neurons
channels, resting potentials, action potentials
synapses
chemical, electrical, EPSPs, IPSPs
plasticity, synaptic depression & potentiation,
presynaptic inhibition & facilitation
circuits
sensory neurons, interneurons, motor neurons
recording neural activity
SUMMARY: INTRODUCTION & TERMS
relating nerve cells to behavior
neurons behavior
crayfish tail flip response
synapses behavior
Drosophila escape response
restricted circuits behavior
lobster digestion
whole organism behavior
monkey selective attention
SUMMARY: WE HAVE NOT DISCUSSED…
nervous system development and plasticity…
neurogenesis, apoptosis and necrosis
growth
cell adhesion and axon pathfinding
formation, maintenance and plasticity of synapses
organogenesis
general brain and nervous system anatomy…
humans
other vertebrates
invertebrates
SUMMARY: WE HAVE NOT DISCUSSED…
brains are not merely composed of neurons… glia…
oligodendrocytes* and astrocytes (CNS)
Schwann cells (PNS)*
form myelin sheath (vertebrates)
neuron cell structure… general categories…
microfilaments, neurofilaments and microtubules
axon transport
structure and functional details at synapses
ion channel anatomy
SUMMARY: WE HAVE NOT DISCUSSED…
details about signals transmission…
action potentials
frequency coding
signal propagation
myelin function
“types” of signalling
silent, beating, bursting
effects of sustained neural stimulation
changing neuron properties
SUMMARY: WE HAVE NOT DISCUSSED…
measuring currents and channels…
electrophysiology…
criteria for ion channel activities
conductance, selectivity, gating, pharmacology
activation, inactivation
whole cell voltage clamp
patch (voltage) clamp
ion channel molecular biology and manipulation
maintenance of ion concentration gradients
SUMMARY: WE HAVE NOT DISCUSSED…
intercellular communication…
gap junctions and neurosecretion
neurotransmitter release
transmitters and hormones
receptors and transduction mechanisms
neuromoduation