FINAL EXAM PSYC310 Olfaction and Taste Olfaction Lecture 1 Olfaction sense of smell Odor converting a chemical stimulus into a smell sensation o Bakeries and a new car smell nuance Odorant a molecule with a particular structure leading to transduction and eventual perception of smell o Able to float in air volatile o Smell o Repellent to water hydrophobic Primary purpose of nose o Filter o Warm o Humidify Olfactory Sensory Neurons OSNs o Relatively slow 400 ms o OSNs are replaced every 28 days o OSN olfactory bulb o Axons pass through cribriform plate Damage can lead to anosmia Olfactory bulb where olfactory info is first processed o One in each hemisphere ipsilateral o Glomerulus receives input from several different olfactory receptors experience produces re wiring Primary Olfactory Cortex o Glomerulus mitrial and tufted cells olfactory tract o Olfactory tract primary olfactory cortex pririform cortex o Interacts with the entorhinal cortex interfaces with cortex and gets sensory input into the hippocampus memory o Parahippocampal gyrus o Amygdala emotion Orbitofrontal Cortex responsible for the conscious experience of olfactory o Also integrates info regarding how food tastes Olfaction Memory Emotion o An odorant can lead to the retrieval of associated information o Cain and Johnson 1978 wintergreen for American and British participants o The combination of all sensory cues smell touch sound lead to best memory recall Smell is no better than other sensory cues o Herz et al 2004 reported increased activation in amygdala for emotionally relevant stimulus perfume Process of Transduction Step 1 a stimulus emits odorants Step 2 when an odorant is breathed in enters nasal cavity some reach the olfactory epithelium o Olfactory epithelium contains olfactory sensory neurons OSNs o OSNs have cilia that contain receptor sites o Odorants have a particular shape Step 3 if the receptor site on the cilia is compatible with an odorant the odorant binds to the receptor o Leads to the opening of a cation ion channel o If enough depolarization occurs action potentials results o Shape pattern theory the degree to which an odorant fits with a receptor site will influence the number of APs Step 4 the message from the OSN is sent to the glomeruli in the olfactory bulb o Ipsilateral o Olfactory nerve Step 5 after the odorant binds the receptor retreats into the cell o This makes binding impossible o Receptor site may retreat for 1 minute or longer Lecture 2 Classification of Odors Odor Detection o Hans Henning 1916 smell prism means to depict principle odors Simple but many people have difficulties classifying odors using only 6 categories flowery fruity putrid resinous spicy burnt Henning also had super smellers in his experiment Different to semantically label a specific smell o Research after Henning Researchers tried to group odors according to qualitative similarities begin with verbal labels ex sweet flowery Questions regarding the ability to put a semantic label to a smell o Ethyl mercaptan detected in concentrations of 1 part per 50 billion parts of air Detected at a concentration 10 million times less than carbon tetrachloride Put in natural gas to make it smell because it has no odor o The detection of an odor depends upon the substance o Olfactometer a device that controls the type concentration and duration of odorant Some can measure the number of inhalations sniffs o Odor detection is better In the morning vs nighttime In young adults vs elderly In females vs males if an odor is there In non smokers vs smokers Exposure o Wysocki Dorries and Beauchamp 1989 Individual insensitive to androstenone Exposed for 3 weeks with one nose plugged Nostril that was plugged during training portion was still able to detect odor Odor identification o Two different thresholds 1 detect whether is in environment 2 what odor is o Scratch and sniff identification females better than males at identifying odor best o Tip of the nose phenomenon a scent may be familiar but we cannot recall performance 20 s to late 40 s specific attributions ex name o Disease Parkinson s associated with difficult identification of smells diminished Sense of smell first thing to go in Alzheimer s patients lose semantic ability to physically sniff labels used as diagnostic tool Adaptation o Odor adaptation exposure to an odor decreases sensitivity to that odor o Receptors no longer available once odorant has binded to it because it has o Sensitivity will steadily decrease with time falls to about 30 of initial level o Odorant binds to an olfactory receptor receptor is pulled into cell body Receptor recycling o Takes roughly 15 20 minutes for an odorant to stop producing an olfactory retreated response Higher concentration means less adaptation o Top down effects on adaptation Dalton 1996 Participants felt that they could still detect hazardous odorant in environment after about 20 minutes Detection for both healthful and hazardous condition was same although reporting was different Odor Hedonics perceived pleasantness of an odor o Tend to like smells we have smelled before o Can vary culturally Taste Lecture 1 the mouth Taste gustation substances dissolved in saliva penetrate the taste buds and surfaces of Flavor smell temperature texture consistency taste and retronasal olfactory sensation of whatever you are eating Tasteable has to be soluble o Roughly 25 oz saliva produced daily o Saliva closely resembles salt water Categorizing different tastes o Aristotle sweet sour salty bitter pungent harsh astringent viscous and fatty added but removed o Early 19th century sweet sour salty bitter o Japanese scientist Ikeda 1909 argued that umami savory should be added Identifying number of taste qualities o Erickson and Covey 1980 Had participants judge whether a solution had 1 or 2 primary taste qualities Also presented 1 tone or a chord Results 1 taste component sometimes judged as 2 Multicomponent solutions sometimes judges as 1 Also difficulties in identifying whether a mixture contained a specific component Mixtures take on their own unique properties Papillae and Taste Buds o Small bumps papillae Filliform papillae anterior portion of tongue center no taste buds Fungiform papillae anterior portion of tongue center but closer to tip each papillae contains roughly 6 taste buds Foliate papillae folds of tissue containing taste buds located at the rear on the sides of tongue Circumvallate papillae located at back of tongue and relatively