9/17/14 1:53 PMIntroduction Kroghs Principle For every principle, there is an appropriate organism that you can use to study it Lorenz and Tinbergen Fathers of classic ethology Called for a need to know what is going on in the animals natural environment, not just in sterile conditions Why is the animal doing what it is doing? Dogs evolved from wolves who live out in the wild used to have to pad down the vegetation where they would be living for the night Studied multiple animals Gray Lag Geese Egg-rolling behavior if you pull the egg away from the goose, it will continue to roll the imaginary egg bag to the nest Example of fixed action patterns Once the stimulus starts the action will go to completion Innate chain of motor sequences 3 Spined Stickleback the reason another male will get attacked is the distinct red belly will only occur if they have the red belly Escape response of Turkeys Immediately move if a shadow is flown above them Robert Provine Studied Humans Yawning releaser Contagious and runs to completion Eyes are very key in the beginning of a yawn Tears Crying is a cue that indicates a state of being Very hard to tell if someone is sad in the absence of tears Supernormal Stimulus Exaggerated verision of a stimulus to which there is an existing response tendency, or any stimulus that elicits a response more strongly than the stimulus for which it evolved Birds can be made to prefer their own eggs to artificial ones Bird wants a HUGE egg, but it is impossible to actually do Code-breaking The idea that if you evolve a response to a few simple stimuli you can be taken advantage of Rove Beetle Imitates the behavior of ants and can live on the ant nest and feed off of them The formica ants have evolved to accept these actions to be a part of their colony House Finch lays egg in another nest so that another bird will take care of the finchs young Brood parasitism Yellow Warbler builds a nest on top of its nest to protect itself from brood parasites Painted Red Starred Bird High contrast plumage when it moves, the insects take flight and the bird goes and eats them Takes advantage of the insects escape response from looming predators Rare Enemy Effect usually the insects would escape but in this case they cannot Human Code-breaking Laughter laughter tracks on sitcoms hack into your predisposition to think things are funny Siegel (1982) Examination of tolerance to heroin and learning Three groups of rats One group received dextrose in the home cage and heroin in the noisy cage One group received dextrose in the noisy cage and heroin in the home cage One not given heroin Heroin overdose was then administered If the dose was received in the same condition as they received it before, only 1/3 died If the dose was received in a different condition than before 2/3 died Conclusion associative learning is a component of tolerance Garcia and Koelling Examined the cues that are associated with different effects and results Two groups of rats Both drank sweetened water in the presence of flashing lights and clicking bells 1 group was shocked and the other was made nauseous In the presence of lights and bells both groups avoided the sweet water Without the lights and bells group that was shocked drank the sweet water Shocked rats associated the shock with lights and bells not the water The nauseated rats associated nausea with the water Taste Aversion

Axons and Neurons Gogli and Cajal Debate Golgi neurons are continuous Cajal separate cells Golgi invented a stain to prove his point, but Cajal ended up using this to prove him wrong Nissl Stain Used extensively by Brodmann Does not look at individual cells but instead looks at the cytoarchitecture cell bodies that are only partly stained Used this to come up with the 6 layers of the neocortex Basics of Neurons Consists of an output axon and an input dendrite SAME DAVE Sensory afferent, motor efferent, dorsal afferents, ventral efferent Action Potentials Ions Sodium (+) outside Potassium (+) inside Chlorine (-) Calcium (+2) Hodgskin and Huskey Studied squid axon very large axon and neuron Actions You know this shit Absolute refractory period 1mm during which you cannot get another action potential because voltage gated sodium channels cannot be reopened until you return to the threshold Relative refractory period Undershoot, more polarized so during this time you need to inject more positive charge to make the neuron go (although not impossible) Synapses Chemical (Otto Loewi) Nuerotransmitters and stuff Electrical Gap junctions and stuff At the synapse, the action potential makes it positive which opens the voltage gated calcium channels and the calcium moves into the axon terminal Post-synaptic potentials Excitory postsynaptic potential a bunch can add up to an action potential Inhibitory postsynaptic potential makes it more negative Summation Temporal summation firing rapidly in succession, even one neuron can cause summation of these events Spatial summation firing in different places at the same exact time just at different locations to add up to give one big positivity

Bats Overview of Bat Biology Megachiroptera Large in size (flying foxes) Have large eyes and good eyesight DO NOT echolocate Microchiroptera Smaller in size More numerous in diversity CAN echolocate, do not need to use their eyesight History Spallazani Discovered that bats could not fly when ears were plugged Griffin and Pierce Built a machine to transmit ultrasound to audible sound Put bats under the machine and realized the bats are giving off ultrasound Echolocation Bat calls When engaged in a difficult navigational task or during the final seconds of pursuing insect prey bats dramatically increase their call rate. By greatly increasing their call rate, bats can achieve almost constant auditory illumination of nearby objects Search phase Lowest call rate 5 pulses/second Approach phase Higher call rate Terminal phase Last moments before prey capture 100+ pulses/sec Why ultrasound? Resolution Echoes from high frequency sounds provide much more information By using high frequencies, bats are trading off detection at a distance for higher resolution Distance detection Determined by the delay between the outgoing pulse and the returning echo. Sound travels at 340m/s 17cm/ms Size information Bats can determine the subtended angle of an object from the amplitude of the returning echo but this does not tell you size This ambiguity is resolved by determining object distance from pulse-echo delay The combination of subtended angle and object distance = relative size Velocity determination Relative velocity of moving prey is determined from the Doppler shift of their returning echoes. Doppler shift change in the apparent frequencies of sound due to motion Shift = frequency*(2*relative velocity)/c c=speed of sound Location in space Horizontal plane (Azimuth) Determined by detecting timing differences between the two ears Vertical plane (elevation) Determined by quickly moving their ears up and down while comparing echo loudness for the different ear positions Types of Bat Calls Constant frequency (CF) call Continuous, pure tone that does not vary over time Frequency Modulated (FM) call Changes frequency over time and is said to sweep through a range of different tones CF-FM call Starts out with a pure tone but ends with an abrupt downward FM sweep Mustached Bat Gives off a FM and a CF When it gives off a call and the echo comes back, they are all overlapping Echo is 1000x lower than the initial call FM component is used primarily for timing determining distance Varies in frequency and provides multiple echoes at differing frequencies so it can make a lot of timing comparisons CF component is used primarily for velocity Long constant tones provide a stable frequency reference for both the pulse and the Doppler shifted echo Prey Determination How do bats know they are following a moth? When a moth is flapping its wings, the bat witnesses a dramatic change in the apparent size of the moth during different parts of the wing-beat cycle When the wing is in full profile, a large surface will reflect the echolocation call As the wing moves upward, it becomes nearly invisible, resulting in a 75% reduction in the moths surface area and corresponding reduction in echo intensity In addition to changes in echo intensity, the movement of the wing will cause subtle Doppler shifts to the echo. The wing of the moth is alternately moving toward the bat, away from the bat, and then back toward the bat with each wing-beat cycle. Examples Moth wings up (+) Doppler shift and moderate amplitude echo Moth wings in the plane no Doppler shift, low amplitude echo Moth wings down no Doppler shift, high amplitude echo. The mustache bat uses the CF2 component to detect the wing-beats of insects Inanimate objects do not modulate the CF signal Animate objects cause amplitude and frequency modulations Modulations will be minimal when bat is approaching from the back Acoustic Fovea (60 kHz) A part of the bats auditory system that has incredibly high resolution in sound detection Bat ear anatomy The outer ear focuses sounds into the canal leading to the tympanic membrane (ear drum) which responds to sounds by vibrating These vibrations are transferred by the ossicles of the middle ear to the fluid filled cochlea The basilar membrane vibrates in different places depending on sound frequency High frequencies vibrate the portion closest to the outer ear Low frequencies cause the opposite end to vibrate In mustache bats, the part of the basilar membrane representing CF2 is extra long and the hair cells in the area are contacted by a large number of auditory nerve fibers. These hair cells are bent causing mechanically gated channels to open which leads to depolarization and release of neurotransmitter Doppler shift compensation Lowering their outgoing calls so that echoes will always return at the frequency of their acoustic fovea If a bat sends out a call at 60 kHz and it comes back at 62 kHz, it simply lowers its next call to 58 kHz and the subsequent echoes return at 60 kHz Also helps distinguish the echoes from louder outgoing calls Mustached bats are relatively insensitive to frequencies just below their auditory fovea so they can avoid blasting their own auditory system while trying to listen for faint echoes during flight. This does not work for the FM component of the call because it covers such a wide range of frequencies This is why FM parts of the call and echo never overlap bats receive the FM echo without any interference CNS Pathways and Auditory Cortex General Information from the ear is communicated along the auditory nerve to the cochlear nucleus of the brainstem All auditory information in these pathways passes through the inferior colliculus and the medical geniculate complex before arriving at the cortex Basilar membrane spiral ganglion cochlear nucleus inferior colliculs medical geniculate neocortex Cortical Organization in the Mustached Bat The neocortex is a six-layered sheet of neural tissue found in all mammalian brains Final destination of many pathways carrying sensory information from the eyes, ears, skin Organization reflects the sensory preferences or specializations for a particular species Microchiropteran bats devote much of their neocortex to analyzing auditory information Neocortex of mustached bat A1 The primary auditory cortex High frequencies are represented toward the front of the brain, and low frequencies are located toward the back A1 is a map of the basilar membrane which in turn codes for different sound frequencies along its length Doppler-shifted CF (DSCF) area Located within A1 and functions of process information from the auditory fovea at frequencies around 60 kHz 59-61 kHz represented in a series of concentric rings, with 59 kHz at the center and 61 towards the outer ring in addition to the frequency axis, the amplitude of echoes is represented at different loactions around the circumference of the circle DSCF area has a frequency vs. amplitude axis Ideal for coding the wing-beat modulations of the CF2 echo FM-FM Area (Distance) Located just in front and above the DSCF area FM component is useful for measuring pulse-echo delays, and therefore for determining range information about objects and prey. Neurons Neurons in this region respond poorly to all CF components of the call and echo Also respond poorly to an singular component of the FM call or echo Respond well to FM part of the 1st harmonic is presented in combination with the echo harmonics 2,3,or 4 Organization Computational map of object distance Delay axis running from anterior to posterior Short delays are represented at the front end, long delays at the back CF-CF area (Velocity) Computational map of relative velocity High velocities at the front, negative velocities at the back The lowest harmonic (CF1) is compared to higher harmonics Neurons respond poorly to either component alone, but when CF1 is paired with the delayed and Doppler shifted CF2, neurons in the dorsal area respond CF1-CF3 respond in the ventral area First part of the paired pulse and echo combination needed to activate any neuron is part of the first harmonic of the acll The first harmonic is so quiet, only an emitting bat can detect it Prevents jamming and confusion to the auditory system from other nearby bats Echo Colors If a depression in a surface is the wavelength of a component to the FM pulse, the peaks of the reflected sound waves will cancel each other out Leaves a gap in the frequency from part of the reflected FM echo Vampire BatsInfrared detection to determine where blood vessels are most superficialEars tuned to animal breathingAnticoagulants (Draculin) dont want blood to clot and stop flowingInsect Defenses General Bat calls are 1000x louder than their retuning echos the call is available as a warning to insects long before a bat is close enough to detect an insect Kenneth Roeder Studied moth behavior in response to bat calls Moth Behavior In field tests, neither vision nor air disturbances triggered moth evasion Response to ultrasound When the moth was a good distance away from the ultrasound (sound received at low intensity), the moth often turned and flew directly away from the speaker Directional avoidance of weak ultrasound (negative phonotaxis) When moths were stimulated with higher intensity sound at a shorter distance, they exhibited much more dramatic responses. Radical speed and course changes followed by a dive into the underlying vegetation Evasive maneuvers Ear location and anatomy Ears are located at the back end of the thorax, just below the wings Anatomy A small opening leads to a tympanic membrane that vibrates in response to sounds Very simple anatomy only 2 sensory cells (afferent neurons) that make contact with the tympanic membrane A1 cell and A2 cell transduce vibrations of the tympanic membrane into action potentials Axons of the two cells exit at the rear of the air chamber to form the small tympanic nerve Very broad tuning curves for the A1 and A2 cells Must be able to respond to a broad range of bat calls A1 cell responses Sound intensity is coded by two different variables Number of action potentials per unit time increase progressively with increasing sound intensity The latency (time from stimulus to response) decreases with increasing intensity decreases with increasing intensity Continuous sounds results in habituation of the neurons A1 fibers especially sensitive to short pulses of sound that resemble bat calls, and relatively insensitive to ongoing sounds in the environment Determination of Bat location in space (Horizontal) If the bat is to the right of the moth, sound will be most intense in the right ear and the right A1 cell should fire with more action potentials and a shorter latency than the left A1 cell Strategy = turn away from direction of loudest sound Once accomplished, both A1 cells should fire at the same rate moth is facing directly away from bat Advantages to this strategy Moth is on course directly away from bat, maximizing the distance and time the moth has before it will be detected Minimizing the acoustic profile by facing directly away from bat Minimize the amplitude and frequency modulations in returning echoes that are caused by the wing-beats of the moth Moth may blend with the acoustic clutter generated from surrounding objects Determination of Bat in vertical plane (elevation) Because ears are located just below the back wing, echolocation calls from above are reflected away from the ears In contrast, sounds from below will be relatively strong throughout the wing-beat cycle Although bats can detect a moth at a distance of approximately 5m, moths can hear the echolocation calls of a bat at 30 meters This still only allows for about 5 seconds of warning Bats not facing the moth will not be detected until they are much closer. A2 cell responses Stimulation of the moths ear with strong pulses of ultrasound causes volleys of action potentials in the A2 receptors In these conditions A1 receptors are also firing at maximum Causes initiation of extreme evasive maneuvers Increase wing-beat rate and dive into underbrush or taking a seemingly dangerous upward loop Fold their wings and drop safest destination is the underlying vegetation Moths echo signature can merge with the clutter of surrounding objects making them acoustically invisible Jamming defenses A number of tiger moths have a series of corrugations in the basal segment of their back legs, and by contracting underlying muscles they generate tiny ultrasonic pulses These clicks are timed to coincide with the final attack stage of the bats approach, and bats usually break off their attack in response Clicks degrade echolocation ability of bats, making it more difficult to calculate distances In addition, number of click-generating moths are distasteful Clicks serve as a form of aposematic acoustic coloration Mites Asher Treat Discovered that mites choose only a single ear No matter how many more mites arrive or how crowded it gets in that one ear, the mites rarely infest and destroy the other ear on the opposite side Do this to ensure the moth still has a chance for survival against bats. Directional sensitivity is not possible for the infested moth, but they still retain A2 cell functionality can engage in emergency evasive maneuvers. Dolphins Use sonar pulses to find prey and navigate Sound generated from the nose (melon) Melon focuses sound to come out as a cone Fish Seem to have developed similar sort of defenses mechanism to detect dolphin ultrasound pulses

Somatosensory Systems

Humans Rapidly adapting (RA) mechanoreceptorsReceptors that allow us to not have the constant sensation of touch when wearing clothes for exampleMerkel Cell Nuerite ComplexesSlowly adapting mechanoreceptors at the base of the dermal layerHuge number in fingertipsSmall receptive fields good for time sensationMore neurons, higher activity More sensitive less branchingSupplied by the myelinated afferentPacinian corpuscle RA mechanoreceptors Sensitive to slight movementsVery high acuity We can look at tuning curves to see how sensitive they areNervesAfferent input to the sensory nervous systemEfferent input to the motor system

Some diagramDorsal root ganglion synapse on the dorsal root columnGracile and Cuneate make up dorsal column nucleiCuneate nucleus heavily represented in handReceives information from the hand on the same side of the bodyGracile Nucleus represents feet and surrounding areasTrigeminal sensory nucleus represents face and head

Another diagramCentral SulcusIndentation that is centrally located from the midline to lateral sidePost central gyrusLocation of somatosensory coretxRight behind central sulcusMade up of 4 somatosensory areas3A, 3B, 1, 23B is the same somatosensory area in primates and shrewsreferred to as the primary somatosensory cortexBrainSmall number of cortical areas directly adjacent to each other M1 motor cortexS1 primary somatosensory cortexA1 primary auditory complexV1 primary visual complexLobesFrontal lobe (front)Parietal lobe (top right)Somatosensory areasOccipital Lobe (back right)Temporal love (bottom left)Central Sulcus between frontal and parietal lobesSlyvian fissure between frontal, partial lobes and temporal lobeDorsal Root GangliaCarry information into the CNSNeurological pathwaysSpinothalamic pathway (Pain and temperature, right side)Dorsal root axon lateral spinothalamic tract (up through the spinal chord and through the medulla) thalamus cerebral cortexDorsal-medial Lemniscal pathway (touch, vibration, etc)Dorsal root axon dorsal column dorsal column nuclei medial lemniscus thalamus cerebral cortexBrown Sequard syndrome lose fine touch left side, right side loses pain and temperatureMiceWoolsey and Van Der LoosDiscovered barrel cortex of miceEach circle provides a visible map of whiskersNaked Mole RatsUse their independently mobile teeth for somatosensation30% of somatosensory cortex is devoted the front incisors Signals come through receptors in the base of the teeth Harbor SealsCan use whiskers to detect wake and water disturbances by other swimming animalsEssentially uses water disturbances like a scent trailManatees Roger ReepDiscovered that manatee whiskers jet out and grab plants forcing them into the mouthMolesFeaturestiny eyes, tiny ears, but very sensitive to vibrationshuge powerful forelimbs for digging Red nose packed with mechanoreceptorsSam SobelCan smell help you localize an object?Found that both dogs and humans used the same strategy in following scent trailSerial sampling Sniffing in different locations in timeWhiskingSweep whiskers back and forth as a way to obtain tactile informationCombined with sniff, merging olfactory and tactile informationBlocking off mole nostrilsMole was still able to locate the food, but veered off slightly based on which nostril was openStar-Nosed MoleHas a large star-like projection on its nose used for tactile sensation11 on each sideused to make very fast and accurate sensory decisionsCan smell underwater by inhaling its own bubblesEmiers organsTouch organs on the tips of the tactile projections Free nerve endings in the epidermis merkel cell nuerite complex (dermis) Paciniform corpuscle (responds to muscle stretch and light pressure)Somatosensory Fovea11th part of the starused for detailed touch always comes back to the 11th fovea to touch foodOn the neocortex, the 11th is much larger than the other representationsDuck-billed platypusBeak contains 50,000 push rodsMechanoreceptors that resemble eimers organsAlso contains 50,000 electroreceptorsCrocodilesVery good sense of touch detects water disturbances and orients towards the disturbance Integumentary Sensory Organs (ISO)give a sense of touch more sensitive than our fingertipsForaging Theory Rate = E/(Ts +Th)Ts time searchingTh time handling (how long is takes to eat something and move on to the next food)Star-Nosed Moles eat so fast that they can efficiently eat little food particles that most animals would just pass overEliminates competition for such food sourcesRaccoonsVery sensitive hands Each finger is represented by a single gyrus in the brain super unusual

SnakesRattlesnakes use infrared radiation emitted by warm-blooded targets to strike at their preyThe infrared eyes are the pit organsA pair of deep cavities in the head that open on the side of the head below and in front of the eyesRichly supplied with heat sensitive nerve fibers connected to the brainAnatomyHeat-sensitive membrane only 15-20 microns thick in diameter is stretched across the cavernHas a low thermal mass heats up very quickly and easilyIntercepts IR radiation that passes through the aperture of the pit7,000 nerve terminalshighly vascular needs to provide highly metabolic area with blood supplyhelps cool heated area to bring it back to baselinereflects visible light and absorbs IR radiation preferentially special layer at the back of pit that absorbs IRa change of only 0.003 C is sufficient to raise the firing rate of the trigeminal nerve fibersPeter HartlineBlindfolded snakes and an IR source was presented to the snakeSnake strikes were accurate to about 5 degrees in the horizontal planeIR pathwayPit organ membrane trigeminal nerve trigeminal nucleus Lateral Descending Trigeminal Tract (LTTD) Reticulus Caloris Optic TectumLTTD nucleus appears to be peculiar to snakes that have specialized IR capabilitiesReticularis caloris serves as a relay station between the LTTD and the tectumOptic TectumVisual and IR information is organized in an orderly way, where connections are made in such a way that a map is formed on the tectal surfaceFront area receives input from the back areas of the pit membrane and from the retina Back area of the tectum receives inputs from the front areas pit and retina Visual and infrared maps in the python tectum correspond fairly well to each otherTectal Nueronsor neuronscan be excited by either visual stimuli or IR stimuliwould be useful in the detection process, signaling events in a particular region of space regardless of whether the events are perceived by way of visual or infrared modalities and neuronsvisual and IR stimuli together were required for stimulus mouse detectorsIR Depressed Visual CellResponds only to visual stimuliCaudal LuringWaving of the tail to attract preyStrikesPit vipers strike and release prey to avoid being attackedSometimes have issues finding prey after a strikeThings that happen in a strikeVenom deliveryTaste the preyUse the specific taste to track the specific prey snake struckIf snake tastes blood, it signals for the snake to track the mouseLay down scentHelps in prey trackingVenomContains hemorrhagic componentsGyrotoxin Causes rodents to move in circlesDecreases mobility and increases scent trailMojave Green Rattlesnake Mojave toxinCalcium channel blocker causing failure of the neuromuscular junctionCrotoxinCauses vesicles to become fusogenic vesicles fuse to different places on the motor neuronForked ToungeKurt Shcwenk researched the fork tongueForked tongue is extremely useful for trail followingProvides 2-point sampling and can tell if snake is on the right pathVomeronasal Organ detects the concentration of odorants in the airNorthern Pacific Rattlensake vs. American Ground SquirrelRattlesnakes make young ground squirrels a large part of the diet mothers need to protect their young.Adult ground squirrels are highly resistant to rattlesnake venomWave tail to make them look bigger and also throw dirt in the snakes eyesTail flagging also heats up the tail, making them look bigger to pit vipersBuprestid BeetleFemales have to lay eggs on burnt woodHave IR receptors underneath the wingsRespond to heat via swelling of the cuticle Mechanoreceptor in cuticle expands in response to heat and pinches the nerve fiber action potential

NeurotoxinsJoe SlowinskiBro who got bit and died on September 11Got bit by a krait, thought it was a dinodonMiniature end-plate potentials (MEPP)1 vesicle is released depolarization of muscle occurs in multiples of quanta 150 fused vesicles = 1 action potential-Bungarotoxinstudied by a dude name ChangFound that with injection of -Bungarotoxin,The motor neuron itself remained perfectly functionalThe muscle itself remained perfectly functionalThe size of MEPP slowly decreased over time-Bungarotoxin decreases and eliminates muscle tension in response to nerve stimulationno response to washWhen curare was injected, muscle also lost tension, but returned with a washIf Curare was added first, then -Bungarotoxin, then wash, muscle function returnedShowed that -Bungarotoxin is binding very tightly to ACH, Curare doesnt bind as tightly, but it is tight enough to compete with -Bungarotoxin for ACHHelped to isolate ACH channel in electric eelsAllowed investigators to determine that myasthenia gravis patients have a below normal number of ACH receptors at the nueromuscular junctionNeostigmineWill interact with ACHaseGreat if you are envenomated with -Bungarotoxin

ResearchersSpallanzani Bat EcholocationBats cannot fly when ears are pluggedGriffin and Pierce Bat EcholocationBuilt ultrasound machine and discovered bats were giving off ultrasoundRoeder Moth Auditory SystemMoth behavior in response to bat callsSuga Bat EcholocationCajal Neuron DoctrineNeurons are separate cellsGolgi Neuron DoctrineNeurons are continuous Brodmann cytoarchitecture Used Nissl StainLorenz and Tinbergen Egg-Rolling BehaviorFathers of classic ethology Studied fixed action patterns in Gray Lag Geese, 3-spined sticklebacks, and TurkeysAsher Treat Moth Auditory System (mites)Simmons Bat EcholocationHartline Snake InfraredBlindfolded snakes, accurate to 5Provine YawningSiegel ToleranceTolerance of rats to heroin and learningGarcia and Koelling aversive learningRats responding to shocks and naseuaHodgskin and Huskey Action PotentialsSquid axonsLoewi chemical synapsesWoolsey and Van Der Loos barrel cortex in miceRoger Reep ManateesSam Sobel olfaction and localization of objectsSchwenk forked tongue of snakeSlowinski SnakesChang -bungarotoxinJarvis Naked mole ratsNeurobio EXAM I9/17/14 1:53 PM

9/17/14 1:53 PM