Lecture 13 - With Professor Darcy Kelley PDF

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With Professor Darcy Kelley...

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Experiment to see if ants see ultraviolet - see if UV light causes them to scurry, if they don't do anything, they don't see UV light o Discovered that ants are sensitive to UV wavelengths Possible to see what things look like for animals with UV sensibility o Fish in coral reef can see more b/c UV o Centerpiece of flowers more visible than under visible light spectrum o Under UV light, male/female butterflies look completely different Two ways to change what wavelengths of life we're sensitive to o What limits the wavelength of life that we're sensitive to?  We have trichromatic vision (three types of color-sensitive cones) o Retune rhodopsin molecules so they're sensitive to longer or shorter wavelengths o Add a new rhodopsin that's sensitive to those wavelengths o Can group things based on structure of proteins (C-type, R-type, etc.) o Whole bunch of pigments that enable photoreceptors to respond to light; we only have a small fraction of them Ultraviolet: What do animals do with this/under what circumstances might these things emerge? o Arctic reindeer: see deep into UV o Urine was dark under UV, so could see where other animals were peeing o If you want to map receptive field of these reindeer -> what wavelengths of light are they sensitive to? o Electroretinogram - recorded summed activity of all of the light sensitive cells o Flashed different wavelength of light at the animal o What wavelengths were filtered out by cornea and lins? Lens filtered out some, but still have quite a bit of sensitivity down into the UV o Stimulate at different frequencies, map the sensitivities that way Infrared: Vampire bats Receptors for heat pain: TRPV1 o TRPV1 KO mice have impairments in _____ Gracheva et al, 2011 o Cloned TRPV1 channel in vampire bats  Variant TRP channel that's overrepresented in vampire bats and not fruit bats o If you put the TRP channel from vampire bats in a heterologous system (fruit bats), it's sensitive to temperature o Nerve cells sensitive to heat (enclosing channel) are in trigeminal ganglion People have gone in and cloned molecules responsive to heat from various species (python, boa, rat snake, etc.); expressed them in heterologous systems and looked at Ca2+ imaging; temp sensitivity of heat sensor in python has been shifted relative to rat snake (most sensitive to broader range of temps and is most sensitive around 34') o Ca2+ imaging in trigeminal ganglion at three diff temps; python TG neurons are more sensitive an have broader range of temps than rat snake Multimodal cells in rattlesnake superior colliculus (Newman and Hartline) o Shit i wasn't listening Magnetoreception (sense of earth's magnetic field) o Two types of molecules called magnetite; bees have magnetite on their heads (assists in navigation) o Nobody reasonably demonstrated magnetite in the eyes, but recently a series of molecules have been identified that have the characteristic of being able to do this

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Molecules that change their conformation when they're in a magnetic field Idea: cryptochrome exists in eye of many animals (esp. birds); is between the outer segment discs of the phtoreceptors, chryptochrome state can be changed in response to a magnetic field; have animals that can see the earth's magnetic field at some sense; managed to confer on outer segment of photoreceptors sensitivity to a magnetic field o Most salient example: cockroaches  Take cockroaches and put them in a magnetic coil; flip the field and discover that the cockroaches respond by changing their body position; two species of cockroaches (periplaneta and blattella) and they both respond to it  Dead cockroaches remain magnetized significantly longer than live ones Touch foveation: star nosed moles o Mole moves this whole organ as one piece (the rays don't move as though they were fingers) o Uses outer rays to bring object it's interested in to the middle of the array where the big fat rays are (bc it's very highly innervated, has small RFs)  Somatosensory form of attention o Eimer's organs (?) - specialized skin receptor highly innervated, on the nose of the mole, probably going into trigeminal ganglion o Missed some stuff here o What type of experiment would you do to see what cortex the rays were represented in?  Cytochrome oxidase  Rayunculus of star nosed mole; S2 = secondary somatosensory cortex  Middle ray is very highly represented in terms of neural space  Ray is like 50% of somatosensory cortex o Ken Catania went in and mapped receptive fields of all of these neurons; SC is multimodal in this animal, also gets touch Electric fish o Two kinds of electroreceptors: passive and active o Asking how electric fish subtract information as they move thru the world; how do they tell if the change in their electric field is due to their own motion or due to change in the EF, that's called active electromotion o Myrids and the gymbnodids (?) o Electric fish sense the world by painting a pic of the world due to the EF they generate o Generate the EF with a neuromuscular system (electric organ in their tail consists of coupled muscle fibers, which fire together and generate an EF around the animal) o Sense it with electroreceptors that are distributed all over the body and especially the head of the animal o Electroreceptors -> spinal cord -> midbrain o Jamming avoidance response (?) - each fish shifts their frequency so they don't jam each other in terms of being able to perceive the world Echolocation (active sensing) o Constant frequency exists as a series of frequency bands that are called harmonics; main energy is up in CF2, from each sound pulse comes back a series of echoes, echoes depend on size of object encountered and distance of bat doing echolocating o Big area of auditory cortex in echolocating bats devoted to processing returning echoes from outgoing pulses; divided into number of areas (one area compensates for doppler shift)

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Bat has acoustic fovea in its cochlea; is most sensitive only to a specific set of frequencies that are around its main frequency in its outgoing call Bat has circuit that enables it to lower or raise its frequency of the outgoing sound pulse according to object location Doppler shifted constant frequency area... Unsure, look at figure 31-12 Example of magnification principle...