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75 Cards in this Set
- Front
- Back
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Asymmatries in Game Theory Models |
1. ability to defend a resource (resource holding potential) 2. value of the resource 3. arbitrary asymmetries |
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1. Asymmetry in ability to defend resources (RHP) |
- individuals are rarely equal opponents - some individuals have > RHP --- larger body size, better weaponry, superior tactics - size most consistent predictor of RHP - selection favours "conditional strategy": strategy is dependent upon opponent Hawk if > RHP than opponent Dove if < RHP than opponent |
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Asymmetry in RHP example (spiders) |
- females engage in territorial battles over productive web site - assess size based on deflections of web before fighting - employ conditional strategy --- if intruder larger than resident, resident behaves as a dove --- if intruder smaller than resident, resident behaves as hawk |
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Asymmetry in RHP example (sheep with horns) |
males engage in ritualized contests - assess size of opponent's horns to select strategy - males with smaller horns defer to those with larger horns No contest if size asymmetry pronounced Assessors that show conditional strategies readily invade populations of hawks and doves |
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Sequential Assessment Model |
- treats aggressive interactions as sequene of behavioural bouts - each bout allows assessment of opponent - sequence involves escalating act types until assessment made |
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Sequential Assessment Model Predicts |
1. more evenly matched opponents will engage in more escalated contests 2. where numerous aggressive behavioural acts are possible, these should appear in the same order in all contests |
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WInner and Loser Effects |
Winner effect: where winning a fight increases the probability of future wins Loser effect: where losing a fight decreases the probability of future wins |
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Asymmetry in Resource value |
- resource seldom has same value to two individuals --- vlue of food depends on hunger - individual that values resource most more likely to play hawk - prediction borne out by empirical data |
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Asymmetry in resource value: Marsh hawks |
- defend food-based territories - aggression toward intruders depends on resident's level of satiation: --- if hungry, behave as hawk --- if satiated, behave as dove - value of territory as resource changes with satiation |
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Asymmetry in resource value: bowl and doily spiders |
- strategy adopted by males depends on value assigned to female --- virgin females have an average of 40 eggs for fertilizaiton --- after 5 min copulation: 10 eggs unfertilized --- after 7 min copulation: 4 eggs unfertilized value of female known to copulating male - males acts as hawk to intruders for 1st 5 min of copulation - after 5 min "resident" male acts as dove |
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3. Arbitrary asymmetries (uncorrelated asymmetries) |
asymmetries that aren't connected to RHP or resource value - rules or "social conventions" for settling disputes among conspecifics - adaptive: reduce risk of injury (coin flipping, drawing straws) "prior ownership" is the most common arbitrary asymmetry |
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Prior ownership as arbitrary asymmetry |
- individual that had resource first usually wins - Bourgeois strategy: individuals whose political, economic and social opinions are based on property values (materialists) - resident always plays hawk - intruder always plays dove |
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False bourgeois strategy |
- davies suggested that males followed a bourgeois strategy in relation to "sunspot" territory ---- if owner plays hawk, intruder plays dove - strategy not used when sunspot territories limiting - residents have actually asymmetry of warmth (RHP) |
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Bourgeois strategy example |
Mating: male perceived as owner of female if allowed prior association - rule respected even if intruding male dominant Feeding: - if no prior ownership of item dominant wins - if prior access given to subordinate, dominant doesn't challenge |
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Value of refined game theory models |
- enhance understanding of behavior - organize empirical findings - generate testable hypotheses |
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To express adaptive behavior, animals must (3) |
1. detect stimuli in the environment that warrant a response 2. Process and integrate environmental information 3. Carry out behavior that best suits environmental conditions |
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Physiological basis of behavior Living organisms --> Respond to external stimulation |
product of neurons - specialized cells that receive and transmit signals - signal via propagation of action potentials ---- electrochemical signals - travel along neurons ---- electrically charged ions (Na+ and K+) Organized into nervous systems - allows integration and processing - allows specialization |
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In neurons at rest |
inside of membrane is negatively charged relative to outside - resting membrane potential (-70mV) - established via action of Na+/K+ pump (3Na+ out for every 2 K+ in) |
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Excitatory Event (depolarization of membrane) |
at threshold of excitation (-55mV) - Na+ channels open and Na+ enters cell (inside becomes positive) - at peak, K+ channels open - K+ rushes out of cell temporarily hyerpolarizing membrane (refraction) (+40mV) - resting membrane potential restored by Na+/K+ pump |
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Sensory receptors |
- transduce environmental energy into electrical impulses |
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Specialized thermoreceptors |
Thermoreeptors: respond to changes in temp Mechanoreceptors: respond to physical deformation (touch, pressure, hearing, proprioception, equilibrium) Photoreceptors: respond to light (vision) Chemoreceptors: respond to molecular structure (gustation, olfaction) Electroreceptors: respond to weak electric fields (sharks) Magnetoreceptors: respond to magnetic fields (birds, turtles) |
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Why multiple receptor cells |
- insurance against damage - protection from refraction - increased sensitivity and acuity - greater field of response - allows specialization of cells within (rods, cones of retina) - definition of neighbouring fields |
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Afferent Fibers / Sensory Interneurons |
convey signals from receptors to CNS - receive input from receptor cells - make interconnections with other sensory interneurons - responsible for preliminary processing ---- each interneuron fires or doesn't ---- decision to fire determined via summation of all inputs to cell |
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Signals received may be |
Exctiatory: - depolarize membrane toward threshold of excitation - increase probability of firing Inhibitory - hyperpolarize membrane away from threshold of excitation - decrease probability of firing |
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Summation of Signal: spatial summation |
net effect of all excitatory and inhibitory inputs over entire surface of cell |
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Summation of signals: temporal summation |
net effect of all inputs over time - increase rate of firing of excitatory pre-synaptic cells increasing probability of post synaptic cell firing |
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Central Decoders |
- higher level of integration of inputs from multiple afferent pathways - interconnections among adjacent cells forming nuclei - formulate a "decision" based upon temporal and spatial summation of all excitatory and inhibitory inputs - give rise to efferent pathways |
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Efferent Fibers/ motor interneurons |
convey signals from CNS to effectors - receive input from CNS - make interconnections with other motor interneurons facilitating coordinated action of opposed effectors - send projections to motor neurons |
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Motor Neurons |
- innervate muscualture - trigger muscle contraction via propagation of action potential |
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Cockroach evasive behaviour |
giant fibers: wide and long therefore fast - side that receives stimulus goes first, causing it to turn away from stimulus then both are firing and cockroach moves away |
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Accelerating nerual transmission inverts vs. vertebrates |
inverts: giant fibers vertebrates: myelination and saltatory conduction (jump transmission - fast) |
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4 methods of studying neurobiology of behavior |
1. neural recording 2. neural stimulation 3. ablation 4. diagnostic imaging |
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1. Neural recording
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implant microelectrodes in neurons - record activity in resonse to certain stimuli example: electroantennogram |
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2. Neural Stimulation |
- implant microelectrodes - stimulate neurons - quantify behavioural response |
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3. Ablation |
- destroy neruons or nuclei (accidenal or deliberate) - quantify effect on behavior
example) seed storage and memory in chickadees |
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Example: Neruobiology of behaviour Bats hunting Noctuid moths |
early 18th century: thought bats could see really well in the dark - Blinded bats: no collisions/hunting unimpeded - Tubes in ears: --- filled: disrupted navigation --- open: navigation unaffected READ NOTES ON BAT AND MOTHS |
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Echolocation |
- emission of pulses of high-frequency sound (ultrasound) - reflect off obstacles and prey - received and interpreted by bats as weak echos |
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Echolocation in small brown bats |
- emit 4-5 pulses/sec - frequency up to 100 kHz - sound pressure level up to 120 dB - call rate increases when echo detected and when closing on prey |
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Echolocation with obstacles: - nothing played - 20-100kHz - 1-15 kHz |
- bats orient and hunt effectively in a room full of obstacles - 20-100kHz: bats crash into obstacles and rest of ground with broadcast of ultrasound - 1-15 kHz: bats orient and hunt effectively in room full of obstacles |
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intensity of bat echolocation |
over 120 dB - as lound as nearby jet engine - 2000x louder than echoes of prey |
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Why don't bats deafen themselves? - mechanisms maintaining sensitivity |
1. muscle in middle ear - contracts before emission of each pulse - dampens vibrations of ossicles of middle ear - achieves attenuation of sound to 1% of original - relaxes 2-8 msec after pulse 2. inhibitory interneurons - block auditory transmission to brain during signal emission - attenuate sound to 0.01% of original 3. "echo-detector" cells in brain - respond maximally to 2nd of two sound pulses |
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Why don't bats deafen each other |
1. high frequency sound attenuates dramatically with distance - spacing among bats reduces likelihood of receiving a deafening pulse 2. bats within a foraging flock adopt different foraging frequencies - filter centrally for frequencies resulting from those emitted |
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Bats: flying or echolocation first |
fly first, echolocation second |
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Neurophysiology of predator evasion in Noctuid moths |
- moth's "ears" on posterior of thorax - each ear endowed with only 2 receptor cells (A1 and A2) |
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A1Cells |
A1: - fire in response to low intensity sound - rate of firign increases with intensity of sound - fire more in response to pulses of sound |
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A2: |
A2: - fire only in response to very loud sounds |
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A1 and A2 |
- responsive only to high frequencies - not differentially sensitive to different frequencies |
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General Bat detection in moths
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- highly sensitive A1 fibers beign firing when bat is 30m away (long before bat detects moth - 3m) - A1 rate of firing proportional to intensity and therefore distance (tell moth how faraway bat is) |
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How does moth tell whether bat is at front or rear |
equal and higher rate of firing: bat to rear equal and lower rate of firing: bat in front |
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Bat detection on the horizontal plane |
- differential onset and rate of firing of left versus right A1 cell - if bat on left: left cell fires sooner and at a higher rate - if bat on right: right fires sooner and at higher rate |
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Bat detection on vertical plane |
- if bat approaching from above, A1 cells will show cyclic change in firing rate as wings beat up and down - if bat approaching from below, no cyclic change in firing rate |
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Antidetection strategy |
- orient so that right and left A1 have equal and higher rate of firing - hunting bats rarely fly in straight line - by flying away from bat, moth decreases probability that it will be detected (bat must be within 3m to receive echo, because back presents smaller target for reflection) |
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Anti-detection strategy not effective if bat is within 3m or anti-capture strategy |
- no orient turn away - engage in erratic flight patterns (loops, dives aerobatics) - ultimately crash to ground, shrub or tree ---- makes moth difficult to capture ---- masks moth's echo signature ---- imposes risk of injury on bat |
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Physiology basis of evasion |
- when bat within 3m, sound pressure level of ultrasound high (A2 receptors fire) - A2 fibers synapse with interneurons that send inhibitory input to motor neurons innervating wing musculature - cause shutdown and uncoordinated action of wings (evasive flight) |
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Stimulus filtering |
- animal's nervous system is "tuned" to respond just to those aspects of the environment that are biologically relevant - selective response to certain stimuli from the range of stimuli to which an animal is expose |
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Receptive field |
- each ganglion cell receives input from multiple bipolar cells, which in turn receive input from multiple neighbouring receptor cells (receptive field) |
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How they studied frog vision and prey capture |
- separated single axons from optic nerve and attached microelectrodes to axons of ganglion cells - stimulated retina with beam of light - recorded action potentials produced |
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hartline's frog ganglia |
1. on cells - delayed but prolonged burst of AP when receptors stimulated 2. on-off cells - immediate but brief burst of AP when light turned on or off 3. off cells - immediate and prolonged sequence of AP when light turned off |
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Hartlines interpretation |
- ganglion cells provide information about distribution of light and dark spots on retina --- produces bitmapped image of object in visual field |
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Further work on frog vision |
- implanted microelectrodes in ganglion cells and brain - stimulated frogs with a variety of natural objects (potential prey and predators) - distinguished 5 types of ganglion cells |
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Lettvin et. al Interpretation |
-visual representation not hartline's bitmapped picture of light and dark spots - selective portion of visual stimuli to which frog is exposed: certain networks of cells organized to respond maximally to movement |
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Moving objects |
shouldn't be ignored - potential prey - potential predators |
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Non-moving objects |
safely ignored - of no real value - present no real threat |
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Function of ganglion cells |
- predator detector, prey detector, general arousal, uncertain - information filtered and partially analyzed at level of retina, allowing rapid response |
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Frog brain activity contrasts informatively with toads |
- feed on low, slow moving prey (slugs and eathworm) - predict stimulus parameters promoting maximal response and neural organization to differ from frogs |
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Sensory responses in common toads |
1. moving horizontally elongated stripe - worm stimulus - toads orient toward - represent prey 2. moving vertically elongated stripe - antiworm stimulus - toads "froze" in place - represent predator |
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Sensory Processing in toads |
unlike frogs - no filtering at retina - distinction (integration) not apparent until neurons of optic tectum - without peripheral stimulus filtering, response slower ---- suits needs of toads in terms of prey capture |
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Integration of optic tectum : neural recording |
- T5(2) cells receive info from multiple ganglion cells - have "visual fields" constituting horizontal lines - respond maximally to "worm" configuration |
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Integration of optic tectum: Neural stimulation of t5(2) cells |
- orientation responses as occur with natural prey |
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Integration of optic tectum: Ablation (unilateral of T5(2) cells) |
- no orientation to worm stimulus in opposite visual field to unilateral ablation - toad not "blind" just nonresponsiive to "worm" configuration therefore T5(2) cells are "prey detectors" |
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Examples of t5(2) cells in people |
blind people smile in response to other people smiling because eyes that don't connect to brain may still connect to motor reflex |
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4. Diagnostic Imaging |
techniques resolving the structure and activity of intact nervous systems
- electroencephalogram (EEG) - positron emission tomography (PET) - functional magnetic resonance imaging (fMRI) - molecular diagnostics |
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Electroencephalogram and example |
- representation of electrical activity in different areas of the brain - coarse level of resolution - used EEG on mallard ducks - reported unihemispheric slow wave sleep, particularly when ducks on the edge of flock (asleep on one hemisphere) |
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Positron Emission Tomography |
- like CAT scan, provides information about morphology, but adds activity - addresses correlation between neural structure, activity and behaviour - found hippocampus in cabbies enlarged, consistent with refined spatial memory in chickadees |
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Functional magnetic resonance imaging |
- resolves how acivity of brain regions correlates with expression of behavior - offers insight into previously inaccessible phenomena - found 4 areas of the brain show heightened activity when subjects shown photos of individuals they love - also used to demonstrate human male/female differences in "listening" |
