Wednesday February 1 y Ch 13 Olfaction Olfaction Emotion and Memory Odors are associated with explicit memories and emotional associations Odors are not better than other senses at evoking memories in general but are really good at evoking emotional memories People list more emotions associated w olfactory memories than with any other sensory modality cue Emotions have greater intensity Feel more transported to the original time Memories are not necessarily more accurate though amygdala axons from OB synapse directly in amygdala emotional processing including emotional memories activated by smell of a perfume that elicits a personal memory but not by site of that perfume or by scent of different perfume aromatherapy certain odors can elicit beneficial emotional bx phscial effects ONLY if aroma has previously been associated with corresponding emotional experience smell is largely synthetic don t perceive all molecules separately perceive as a whole unless lots of odor training and then can develop analytic ability 1 Wednesday February 1 y Adaptation peripheral mechanism receptor recycling molecule binds to receptor receptor internalized into cell comes uncoupled from molecule emerges on membrane minutes later central mechanism thalamus cross adaptation reduction in detection of an odorant following exposure to another odor probably because 2 odors share common receptors not always reciprocal sensitization sometimes opposite 1 odorant can enhance sensitivity to another cross positive neg descriptions influence evaluations of a smell Perceived Pleasantness familiarity tend to like most familiar odors subjects report that pleasant odors are familiar even if they arent pleasant odors like it to a point then becomes unpleasant unpleasant odors okay in small concentrations drops off fast infants don t display preferences or discriminate between pleasant unpleasant intensity learned 2 infants exposed to volatile things in utero breastfeeding showed preference for Wednesday February 1 y these smells differences between cultures suggest learning and not hard wired responses no smell is universally horrid trigeminal aspect of perception is likely innate trigeminal nerve CN5 stimulation accounts for the feel of odors through polymodal nociceptors touch pain temp learned taste aversion actually linked to the smell chemical compound produced by one animal that elicits a specific behavioral or physiological effect in another animal of the same species within a species different from odorants that stimulate olfactory receptors tiger rubs tree w glands from cheek cat rubs you wi eyebrows and rump female tells male she is fertile and receptive male tells female to initiate sexual bx chem released from stinger of bee when stings tells other bees to join in Pheromones purposes 1 territory 2 mating 3 defense 3 Wednesday February 1 y 2 olfactory systems 1 Main olfactory bulb what we have 2 Accessory olfactory bulb AOB Humans don t have this Added on in back of MOB No connection anatomical or physiological w MOB Activated by vomeronasal organ VNO Amphibians most reptiles many mammals some primates not birds or humans info from VNO goes to amygdala and hypothalamus not to cortex Fewer types of receptors compared to regular olfactory receptors Each receptor responds to only 1 pheromone Receptors are very sensitive 1 in 1 hundred billion No adaptation olfactory receptors show massive adaptation Responds to pheromones Synchronization of women s menstrual cycles when they live together Real or statistical artifact not entirely proven split opinions on female rat testing in humans McClintock Effect AND androstadienone 4 Made in adrenal glands gonads as part of step for making testosterone Wednesday February 1 y estrogens Increases alertness positive mood in women Decreases positive mood in men Hypothalamus activation in women homosexual men not hetero men EST estratetraene activates hypothalamus in men not women Major histocompatibility complex MHC Large gene family chromosome 6 in humans Genes make the molecules that enable immune system to recognize invaders More diverse MHC of parents stronger immune system of offspring Women prefer odor of men w dissimilar MHCs to own Preference reversed if taking oral contraceptives Preference seen in male mice fish too Humans have no functional VNO or AOB so if there is pheromonal communication b t humans it is unclear how it is occurring perhaps thru main olfactory system 5 Wednesday February 1 y 6 Chapter 2 Vision I Light Eye Anatomy Optics Introduction to the Retina Wednesday February 1 y Light nature s way of transferring energy through space Electromagnetic radiation Waves wavelength light when it moves around the world hue color based on wavelength changes Made up of particles photon light when it is absorbed number intensity brightness sensitive to only limited portion of the spectrum 380 760 nm visual spectrum UV and infared rays on both sides of spectrum radiance energy from source intensity of a light beam illuminance energy from source to object amount of light falling onto patch of unit surface area when light hits surface it can be reflected lighter absorbed darker transmitted refracted bent into eye ball refraction necessary to focus light rays 7 Wednesday February 1 y Eyes functions to 1 control light entry focus light on receptors 2 3 transduction photons to electrical light is bent every time it hits a new part of the eyeball CORNEA Transparent tissue covering the front of the eye highly curved and higher refractive index than air most powerful refractive surface in the eye contributes 2 3 eye s focusing power Continuous with sclera protective coating around back 5 6 of eye Light is transmitted refracted No blood vessels gets nutrients and oxygen from aqueous humor liquid behind it 8 transparent sensory nerve endings to detect touch and to force eye to close produce tears if the cornea is scratched to preserve transparency Wednesday February 1 y external layers regenerate quickly within 24 hours Afferent branch is trigeminal V efferent is facial VII AQUEOUS HUMOR Fluid derived from blood Just behind cornea continuously made replenished Supplies oxygen nutrients to cornea and lens Removes waste from cornea lens Helps maintain shape of eye intraocular pressure too much production or too little drainage in glaucoma focus helps refract light but power is fixed so cannot be used to bring close objects into CRYSTALLINE LENS LENS Transparent tissue no
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