EEOB Exam 3/Final
Which of these sources are of interest to the bat, and how does the bat distinguish among them?
bat is insensitive to CF2 and CF3 of his outgoing call -listening for CF2 and CF3 of echo and comparing to CF1 of his outgoing call --neurons tuned to CF2 of outgoing call fall in lower rage of sensitivity than those responding to CRF2 of the echo, so the bat can distinguish outgoing from echo -signals from other bats rarely fall into correct timing of the bats echo return and the CF1 of other bats is too soft/low in volume
How might the availability of microhabitats or microclimates affect a species' response to climate change?
microclimates or microhabitats provide refuge from abiotic change -allow behavioral response that buffers the animals from the effects of increasing temperatures --increase survival in extreme temperatures --alter breeding seasons (most have evolved to maximize survival of the young) --change daily activity patterns *animal who might go out and collect insects at a certain time may go later to avoid heat *requires existing neural plasticity
Exam 2- During a jamming avoidance response in electric fish, neurons in the nucleus electrosensorius (nE) encode a Df (difference in frequency) of <0 or >0. In terms of the frequency of its electric field, when would a fishes nE encode a Df of <0 and then what happens to the frequency of the fishes electric field?
*if difference in frequency of 3-4 Hz is detected, fish will change frequency of EOD to maximize deltaF -triggered by detecting phase and amplitude differences at different body locations a degree of freedom of >0 means that prepacemaker neurons will be inhibited -
Exam 2- be able to explain/understand use in a sentence the terms time constant, length constant, membrane resistance, longitudinal resistance, and capacitance particularly as they relate to the speed of AP.
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Exam 2- review the correct answer to question ab why axons of different diameter are used to innervate a squids mantle and the lecture info related... Explain how different speeds of propagation in axons of different diameters help a squid move
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Lecture 11- Bats and biosonar
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Lecture 12b- climate change and coral reef fish
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Longitudinal resistance
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What details about an object can a bat determine using sonar?
--distance to object (time/echo delay; faster=longer) (FM) --size of object (strength of echo + delay) (FM ONLY) --relative velocity (CM) --movement (wing movement results in frequency fluctuations)(CM) --direction to object(vertical and horizontal) --shape of object
Exam 1- explain the meaning of Tinbergens's survival value and evolution questions- what do those questions ask? Be able to answer those questions for either gull chick pecking behavior or graylag goose egg retrieval behavior.
-> apply to any behavior, structure or mechanism Proximate Causes(close in time): 1. Ontogeny- How does the behavior develop during the animal's lifetime? 2. Causation- What are the stimuli that produce the response? Ultimate Causes (why/evolutionary): 3. Evolution- How did the behavior arise in the species? 4. Survival Value- How does the behavior contribute to survival and reproductive success? *egg collecting behavior is a late in life thing, happens after laying eggs.. much different from imprinting, egg retrieval is a reproductive/lifespan thing, caused by egg being outside of nest
Within a song, what is the difference between a syllable and a motif? What is a tutor song, and how does it differ from a birds own songs (BOS)?
-a motif is a stereotyped, unique song that consists of song units which we call 'syllables' -called syllable when separated by a silence of at least 10 msec tutor song is the learned, memorized song the bird hears early in life birds own song is individual
Advantages of topographic map:
-lateral inhibition useful for sharpening -no need to keep track of one parameter --labelled lines -minimize tissue cost
How do neurons in the cochlea of a bat (or any mammal) represent the frequency of a sound?
-represent frequency encoded by POSITION on basilar membrane --high freq detect at base --low freq detected at top -position of neurons on basilar membrane results in a place code
How do neurons in the cochlea of a bat (or any mammal) represent the quantities of time?
-represent quantities of time via onset of sounds encoded when neuron responds
What were the major findings for prey behavior and were there any combined effects of water temperature and CO2 levels?
-significant combined effects of elevated CO2 and high T for reaction distance (RD), ALT, prey escape distance and prey escape speed -high T -> decreased RD but no significant difference for high T/high CO2 -high T increased ALT (reduced responsiveness) -all treatments decreased directionality away from predator- independent effect of CO2 so possible mechanism for increased capture success -high T decreased escape distance -control prey had fastest escape speed
Aspects of song learning that vary among species
-timing or when learning occurs -how many songs (repertoire size) -is there a need for early exposure to tutor or can the bird learn in isolation? -is a template required? -is the tutor song imitated or used as basis for own, unique song?
Exam 1- what is the difference between a mechanically-gated channel and a voltage-gated channel in terms of where each is located in a neuron, which direction Na+ or K+ move if a channel is open, and what happens to membrane potential when Na+ vs K+ channels open. -also note that all ion channels are specific for a given ion, ie only Na+ moves through a Na+ channel
-voltage gated channels open and close in response to changes in membrane potential -mostly located on dendrites and cell body of neuron, but concentrated around the axon hillock, nodes of ranvier *sodium-potassium pump pumps 3 sodium ions out for every 2 potassium ions brought in -mechanically gated channels open in response to physical deformation of the receptor (sensory receptors of touch and pressure) *ions move down their concentration gradient, toward areas of less concentration
Based on this study and those previously discussed, what are the different strategies used by the brain for managing different computational problems? when do we find "neural over representation"?
1. task-specific areas 2. neural over-representation found in the DSCF region 3. use of topographic maps (minimizes need to create new map at every level) 4. Parallel processing (process FM and CF of same sound separately but parallel then combine at top)cochlea 5. combination-sensitive neurons
Lecture 10- song learning in brirds
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How do neurons in the cochlea of a bat (or any mammal) represent the amplitude?
-represent amplitude encoded by rate of firing # AP/sec reflects loudness
Lecture 12a- neurobiology of climate change
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What is the structure of the cochlea, and how does it sense sound?
Cochlea is a complex coiled structure consisting of a long membrane, the basilar membrane -basilar membrane is tuned so that high tones vibrate the region near the base and low tones vibrate the region near the apex neurons in cochlea encoded by pattern of neural activity
What are the three hypothesized outcomes for individuals or populations subject to increased temperatures? What environmental changes should be considered in addition to increased temperatures?
Impairment -decreased performance of fitness -no solution for the animal, increased temperature results in something behavior cannot overcome.. think about polar bears Accommodation/Adaptation -shift in performance of fitness -animal has physiological or behavioral ability to adjust, or accommodate the change --change in respiration, evaporative cooling -as temperature rises, animal can tolerate without loss of fitness Stasis -no shift in performance or fitness bc there is really no shift in ambience or temperature where the animal lives -behavioral adjustment
IID
Interaural intensity differences -vertical direction -owl generally uses f>3kHz to determine
How can the frequency resolution of the cochlear signal by sharpened by later neural processing?
Lateral inhibition- used to sharpen or increase resolution of signals -at higher levels, makes it easier to detect small changes in frequency due to Doppler shift -for determining distance, both M and LB bats use FM sweep so output of many neurons is pooled -frequency in second order neurons is even smaller than afferent neurons --send inhibitory signals to second order neurons
There are three principle processes and their underlying neural circuits that make up the "song system" What are the three processes and what is the experimental evidence that supports the role of various brain nuclei in the song system ??
Motor Pathway is the part of the "song system" that controls sound production and respiration -complex sounds produced in syrinx --can produce 2 sounds at once *motor pathway must be intact for song production Role of HVC and RA -bilateral HVC lesion results in loss of song --stimulation stops and restarts song -unilateral RA lesions do not affect pattern of syllables, but notes disrupted --stimulation changes syllables but song structure maintained The forebrain auditory area provides input to the "song system" -nuclei receiving input from field L respond best to conspecific song AFP critical for song learning -lesions in adults do not disrupt song production -lesions in young birds inhibits learning *AF pathway needed only during learning -juvenile AF neurons auditory but unselective -adult AF become increasingly selective between Area X and LMAN in adults
What are the sources of the sounds a mustached bat will likely receive in the neighborhood of 61 kHz?
Mustached bats hear 61 kHz sounds in the outgoing pulses, returning echoes and call of other mustached bats -signals from other bats will rarely fall into correct timing of the bats echo return and the CF1 of other bats is too soft -bat uses CF1 of outgoing call as a private reference point
Exam 1- understand/be able to explain the difference between the Nernst equation and the Goldman equation... what value is calculated using one vs the other?
Nernst- used to determine electrochemical equilibrium for a given ion Ex= (RT/zF)ln ([Xout]/[Xin]) Goldman- used to calculate membrane potential (Vm) using info for all ions
Exam 2- review phase ambiguity as it relates to detecting the horizontal position of a sound in barn owls including which neurons encode for ITD, and how and where phase ambiguity is resolved. also be sure you know the correct answer to part 5 of this question regarding why phase ambiguity is not a problem for an owl trying to locate a sound in nature.
Phase ambiguity most problematic when wavelength is shorter than distance between ears (~5 cr) -ambiguity begins to bee resolved in the core of the midbrain auditory area --organized by frequency along dorsoventral axis -finally resolved in external nucleus
What is the "quality factor" of a filter or a neuron? How does the quality factor of neurons across the range of frequencies a bat hears relate to the types of signals that the bats used?
Q= quality factor= Narrowness of tuning or selectivity HIGH Q = very narrow, more selective LOW Q = less selective, will respond to best one but still respond to broad range high Q neurons analyze frequencies near the bats CF2 (echo CF2) of ~61 kHz Neural filters can have good resolution for frequency or time, but NOT both!! mustached bat-high Q at CF2 -poor time resolution little brown bat- low Q -poor frequency resolution
Why do the authors suggest that interpreting their findings related to predator behavior is more complex than for prey behavior ?
Responses of predators requires considering prey's ability to escape and motivation of the predator -prey responses were diminished so they would be easier to capture -no effect of increasing T on attack speed or distance -metabolic rate of fish is a function of T, this likely results in increased motivation to capture prey
What are the stages of song learning, and what happens during each stage? How do the timelines for learning vary among species?
Sensory phase- recognition and memorization of tutor song; end of phase varies with experience Sensorimotor phase- subsong: babbling; variable, non-sensical vocalizations Plastic song- song begins to resemble tutor song; practicing and listening Crystallized phase- plastic song ultimately becomes an adult song or the birds own song (BOS) *selective learning is genetically guided... innate template focuses bird's attention on its particular song or sound
Exam 1- what does tau represent, why is related to membrane capacitance and can you approximate a value of tau (hint: it will be some number of msec) for each of the curves labeled A,B,C,F in figure?
Ta(T)- Time constant describes time required for the voltage change to reach its maximum (63% final value) --takes longer to reach final V as distance increases T=RC
Time Constant
Tau (T), time required for the voltage change to reach its maximum (63% final value) -how fast foes voltage change? decr T -> incr change in Vm at B -> incr speed so need to minimize T to maximize speed of action potential
Why does O'Donnel argue that the nervous system is a key target for the effects of climate change on animals?
The nervous system allows animals to detect and respond to their environment -sensory receptors provide info ab environment (function based on proteins which are impacted by things like temperature change) -cognition via interneurons could be affected by experience/memory (often involved formation of new synapses, trimming of old, non-used synapses) -motor neurons produce behavioral response (driven by interneurons involved in interpretation of the stimulus) --essentially, having the right set of sensory info is essential for survival
A common feature of many regions of the brain is topographic mapping. For instance, it is common to find frequencies arranged from low to high along some dimension in the brain, which is a particular type of topographic mapping referred to as topographic mapping. How are topographic maps created, and what might be their purpose?
Topographic maps are created in the brain, can be based on: -organization of sensory epithelium -synthesis of information by integration of receptor input *bat maintains separation of CF and FM up to certain point then combine them to make a new tonotopic map
Exam 2- What's the difference between a syllable and a chirp in a cricket song? Scientists played trill and burst patterns to determine what pattern of sounds a female cricket will track... what's the difference between those two patterns and which did the female track?
a number of syllable arrangements make up a chirp (short, pure toned sound composed of one of more syllables) -song composed of a continuous series of chirps and intervals *syllables important for response, but duration of each syllable is less important Trill: repeating syllables with no breaks Bursts: long bursts with breaks in between females best track a syllable rate between 20 and 40 syllables/sec -trills are tracked IF the syllable rate is appropriate
How does echolocation work? In other words, what sounds do bats listen to when hunting?
bats compare sounds they emit with reflections (echoes) of those sounds -use that to locate/identify -sonar provides bats with variety of info about distant object Bats are better at hearing certain harmonics
What is bird song and why is it important?
bird song is a complex vocalization typically produced by males, territorial and breeding purposes -long distance signal -different from a bird call because its learned, and all birds can produce a call but only songbirds produce song -studied as a potential model for human language
Why study bird song? What are the features of song learning that make it an appropriate model for understanding human speech and language?
both bird song and human language -are learned systems of vocal communication -are structurally complex -have a sensitive phase for learning -are genetically-guided behaviors -there is also evidence that vocal production is lateralized within the brain in birds (as in humans) also, can change over time and show regional variation
First place you find a topographic map?
cochlea
In studying the function of the DSCF area, Suga and his colleagues found that bats in which this region of the auditory cortex had been destroyed could still perform Doppler shift compensation, but they did so half as quickly and with less precision. How did the investigators interpret these results?
determined that the DSCF area is responsible for the PRECISION of the DC compensations -but Not for performing the actual compensation
Based on what is known about variations in the behavior of a species relative to its geographic range, what evolutionary changes in the nervous system might be expected to occur?
existing geographic variation provides insight into possible neurobiological consequences... -black-capped chickadees living in regions with harsh winters rely on cached food, lack of food can stimulate hippocampal development and function --larger hippocampus found in more northern (extreme cold) populations.. its more important to learn and remember where they put food -lizards living on white sands have smaller cortices than conspecifics living on dark sand. Navigation less complex in lighter environment --portion of cortex where navigation info is processed is generally smaller in animals who live on white sands, implies fewer neurons used for navigation
Exam 1- recognize that 10-50 Hz is NOT a frequency of sound that stimulates moth auditory neurons... 10-50 kHz IS --ie understand that bats produce ultrasonic (very high freq) sounds
got it lol -> moths hear ultrasonic bat cries but their sensory (auditory) neurons do NOT encode frequency -exhibit variable sensitivity due to mechanics of tympanic cavity and tympanum
What do the authors suggest as the neural mechanism underling the loss in directionality in prey fish exposed to increased temperature and/or increased CO2?
high T known alter responses in circuit of mauthner cells which control rapid escape response -directionality of the escape response was random in prey subject to increased T or CO2
Recent changes in global climate have resulted in alterations in the environment of marine organisms. The effects of two alterations were examined by Allan et al. - what two environmental changes did they study ?
increased temperature and rising atmospheric CO2 levels- which cause decreased pH in oceans
Describe the effects of increasing axon diameter or myelination on each of the terms
increasing diameter (D) decreases time constant and increases length constant -> T decreases slightly as D increases because R decreases more than C increases -> length constant increases as D increases bc length constant= Rm/Tl **invertebrates use large axons when rapid responses are needed and when coordinated responses are needed **myelin increases conduction velocity bc of its effects on time constant and length constant
Exam 1- there are four ways by which responses of moth auditory neurons can encode differences in sound intensity... What are they? for each of the four ways, how would an oscilloscope tracing of the neural responses differ for loud vs quiet sounds
information encoded by A fibers -detect differences in sound intensity or pressure -encoded in four ways: 1. Number of nerve impulses -peak voltage increases 2. Rate of firing -more responses/sec 3. Latency to firing -decr time to first response 4. A1 vs A2 -A1 more sensitive than A2 by ~20 db *moths use time and intensity differences to determine horizontal direction an approaching bat
ITD
intramural time differences -horizontal direction (azimuth) -different locations may have same ITD
Length Constant
is a measure of how far along an axon an electrical impulse can propagate. Without myelin the insulator, the length constant will decrease. -how far ahead will action potential from A have an effect at B? incr length constant ->incr distance -> incr speed so need to maximize length constant to maximize action potential
At the time this study was published, there were numerous reports of physiological and behavioral responses of marine fish to climate change. How did the aim and experimental design of this study differ from all but one earlier investigation into the effects of the consequences of climate change on fish behavior?
it was the first to examine predator-prey interactions in the presence of independent and combined effects of increasing CO2 and/or temperature
Larval prey and adult predator fish were housed in control conditions or one of three experimental conditions. Why were larval fish used as prey species? What were the three experimental conditions? Which aspect of the experimental conditions was not included in the water in which predator-prey interactions were tested?
larval fish were used as prey because they are at a critical period in their lives where avoiding predation is most important, new to reef control-control control CO2-high temp high CO2- control temp high CO2-high temp Quantified: capture success, attack rate, predation rate, attack distance, and speed fro PREDATOR reaction distance (RD), ALT, directionally, escape distance and speed for PREY
Exam 1- Passive properties of neuronal membrane
membrane resistance (Rm) and Capacitance (C, ability to store electric charge) -no further opening or closing of ion channels -propagation graded and decremental *electronic spread is the passive spread of a change in Vm --influenced by: longitudinal resistance (Rl) membrane resistance (Rm); in parallel with C Capacitance (C) which makes the change in Vm at each option gradual rather than sudden
What is a Mauthner Cell?
neurons which integrate response to predator with escape behavior -contralateral.. mouthier cells on R side of brain control L side of body -this gets disrupted
What kinds of birds learn to sing, and which species are commonly used in studies of bird song learning?
only songbirds -crows and hawks make CALLS -sparrows, zebra finches and canaries make SONGS
CF-CF region
require simultaneous input at two different frequencies -region in auditory cortex containing neurons that respond to specific combination of CF1 in the outgoing call and CF2 or CF3 in the echo to determine VELOCITY of the target
FM-FM region
respond to particular echo delay to determine how far away -require input from two frequency sweeps
Exam 1- You will not be asked to do any calculations but review the electrical model of the membrane (circuit problems) so that you understand what happens to membrane voltage when the permeability to a given ion increases.
rules for circuits: -current must be same -voltage changes around circuit must sum to 0 -voltage gained across the batteries equals voltage lost across resistors
What is aerobic scope?
similar to dynamic range! marine fish are heterotherms; their body temperature is determined by their environment -so increased temperatures will increase body temperatures, increasing metabolic rate --glucose consumed at higher rates to make ATP --oxygen consumption increases with increasing temperatures, increasing energetic needs --difference between resting and maximum metabolic rate (aerobic scope) is smaller with increasing temperatures ---cheetahs have a large aerobic scope, can go from chilling to sprinting very fast
Exam 1- review the similarities and differences between graded and action potentials
similarity: membrane potential (voltage) change when a neuron responds resulting in a graded or action potential -Vm changes -time required for Vm to change Graded potential -change in Vm away from rest in either positive or negative direction, due to opening of non-leak ligand gated ion channels -variable-strength signals that can be transmitted over short distances -may lose strength during transmission -two graded potentials can be added together Action potentials -large depolarizations that can be transmitted over long distances -generated by voltage gated channels -does not lose strength during transmission -two action potentials CANNOt be added together
Exam 2- what is a space-specific neuron and what combination of inputs do they response to, and where in a barn owl brain are they?
space-specific neurons in the midbrain allow an old to localize sound -uses space specific neurons in external nucleus of midbrain auditory area to map precise regions, receptive fields, in auditory space -respond to combination of ITD and IID info.. --greater accuracy achieved by combining output of many neurons -accuracy of determining direction of a sound is based on firing rate of space-specific neurons *IID and ITD info is combined in the midbrain auditory are (inferior colliculus)_
Membrane Resistance
the resistance to current flowing across the membrane -need to decrease resistance to minimize T
What is doppler-shift compensation, and what advantages does it offer? Why does the bat not compensate for negative doppler shifts (lower figure on page 63)?
Advantage is for precision because it keeps the the return echo in the same frequency rage of the normal echolocation call and its neurons are best tuned for this frequency so the bats can quickly ascertain certain properties such as distance and velocity of the target Bat does not compensate for negative doppler shifts because if its negative, that means the prey is getting farther away so the bat will ignore it rather than compensating
O'Donnel discusses three types of mechanistic responses to directional abiotic change, i.e. increased environmental temperature... what are the three categories of these responses?
Altered Seasonality -changes in temperature not reliably linked to changes in photoperiod -many seasonal activities of animals are tied to photoperiod, not temperature, because photoperiod is more reliable.. ie sun goes up and down/daily sunlight Altered Water Chemistry -increased atmospheric CO2 decreases pH of water -CO2 very soluble in water, dissociated and releases H+, acidifying the water Altered Water Levels -as glaciers melt, water levels rise and freshwater floods into oceans -results in loss of wetlands and important marshy areas
CF/FM bats can detect prey in "clutter," whereas FM bats have difficulty doing this. What is the basis for this difference?
CF/FM -CF portion enables it to detect target motion by the Doppler shift of the echo -can discriminate between motion and "background" motion -as CF/FM bats are flying, they can detect an insect moving on a branch but an FM bat cannot distinguish between a leaf or an insect FM -difficult to detect an insect on a leaf or tree limb -can not easily detect a small moving target among other targets
What are the differences in the sounds produced by CF, FM and CF/FM Bats? Which bat is the subject of many of the authors (Suga) studies, and what sounds does the bat produce?
CF= constant frequency (consistent frequency over time, horizontal line) *single frequency or tone FM=frequency modulated (decreasing frequency over time, negative sloped line) *brown bats CF-FM= constant frequency-frequency modulated (constant then decreases) *mustached bats Studied mustached bat -high Q at CF2; somewhat lower Q at CF1 and CF3 -poor time resolution
What were the major findings for predator behavior and were there any combined effects of water temperature and CO2 levels?
Capture Success highest in high T- control CO2 -elevating CO2 in high T reduced capture success -elevating CO2 in normal T capture success > normal CO2 and T -attack rates tended to be higher in high T- control CO2 than all others!! -high T increased predation rate but no interactions with CO2 -predator attack distance and speed unaffected by either CO2 or T
What factors have been suggested as being important regulators of song learning?
Changes in neuronal populations -IMAN decreases with age -AF neurons unselective for BOS at 30 dB but selective at 60 db for BOS and tutor -AF neurons selective for BOS in adults -neuronal spine decline associated with learning Social interactions Steroid Hormones Sleep
What is doppler shift, and under what circumstances is a returning echo doppler shifted?
Doppler Shift = change in frequency due to movement of source (and/or target) -calls of CF-FM bats have a resting frequency and a reference frequency --will adjust resting to compensate for Doppler Shift *objects moving toward you come back at a higher frequency
What does DSCF stand for, what is the DSCF area and how is it organized?
Doppler Shift Constant Frequency -a cortical region that facilitates doppler shift compensation -cluster of neurons that determine frequency differences near CF2 -tuned to the amplitude of a signal -tonotopic map (topographic map of frequency) -require particular combination of FREQUENCY and AMPLITUDE for best response -large number of neurons makes quickness possible
How and when does song learning occur in birds, and what factors constrain or limit learning i.e. what conditions are important for a bird to learn a particular song?
Early in life! -requires early exposure to tutor song and practice Song learning constrained by: -age or experience -acoustic selectivity -social/auditory interactions during sensitive and sensorimotor phase
How can responses to climate change be used to examine evolution in neural systems? What is the field of neurobiology and what are some examples of adaptations that might be studied?
Evolutionary responses to climate change can occur quickly and responses occur at multiple levels, impacting neural development and cognitive function -Neuroecology: studies how nervous systems evolve or change in response to abiotic changes --loss of visual abilities when living underground, electroreception in dark aquatic environments
What are combination sensitive neurons, and how are they used by bats to localize flying prey? Where do velocity-sensitive neurons first appear in the auditory pathway, and how is their projection to the auditory cortex organized? Why are velocities from 0-4 m/s emphasized?
FM-FM and CF-CF neurons are combination sensitive -both respond poorly to single tones and single elements -fire in response to a specific combination of inputs.. CF-CF neurons require simultaneous input at two different frequencies FM-FM neurons require input from two frequency sweeps with delay between them output from the medial geniculate body, provide distance and velocity map info and sent to auditory cortex, including the DSCF area -velocities from 0-4 m/s emphasized because it is the bats best chance at catching prey --these speeds arise during activities crucial to the animal, such as when a bat is about to land on its roost or capture an insect
