touch, taste, & smell kimberley a. clow kclow2@uwo.ca
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Touch, Taste, & SmellTouch, Taste, & Smell
Kimberley A. ClowKimberley A. Clow
kclow2@kclow2@uwouwo.ca.ca
http://instruct.uwo.ca/psychology/215a-570http://instruct.uwo.ca/psychology/215a-570
OutlineOutline
TouchTouch– BiologyBiology– PainPain– HapticsHaptics
TasteTaste– BiologyBiology– Individual DifferencesIndividual Differences
SmellSmell– BiologyBiology– Interesting EffectsInteresting Effects
TouchTouch
Our skin is our largest Our skin is our largest sensory systemsensory system
Touch allows us to Touch allows us to explore and manipulate explore and manipulate the worldthe world– tactile explorationtactile exploration– assessment of texturesassessment of textures – feedback from object feedback from object
manipulationmanipulation Touch is more Touch is more
“trustworthy” than “trustworthy” than other sensesother senses
Importance of TouchImportance of Touch
ReceptorsReceptors
Two PathwaysTwo Pathways
Medial-Lemniscal PathwayMedial-Lemniscal Pathway – carries basic touch carries basic touch
informationinformation
– through white matter of spinal through white matter of spinal cord to medullacord to medulla
– crossover to the contralateral crossover to the contralateral side of the bodyside of the body
– through the medial lemniscus through the medial lemniscus to the ventral posterior to the ventral posterior nucleus of the thalamus nucleus of the thalamus
Spinothalamic PathwaySpinothalamic Pathway – carries pain and carries pain and
temperature informationtemperature information
– crossover to contralateral crossover to contralateral side at spinal cordside at spinal cord
– ascends thru the ascends thru the spinothalamic tract to the spinothalamic tract to the ventral posterior nuclei of ventral posterior nuclei of the thalamusthe thalamus
CortexCortex
Mot
or C
orte
x
Som
atos
enso
ry C
orte
x
Posterior Parietal Cortex involved in touch
Mapping the BrainMapping the Brain
Star-Nosed MoleStar-Nosed Mole
Effects of ExperienceEffects of Experience
Monkey
Human
PainPain
Survival FunctionSurvival Function Free Nerve EndingsFree Nerve Endings
– pressurepressure
– heat & coldheat & cold
– chemical damage chemical damage » lactic acid, stingslactic acid, stings
Two PathwaysTwo Pathways Pain PerceptionPain Perception
– BiologicalBiological
– PsychologicalPsychological
– CulturalCultural
Gate Control TheoryGate Control Theory
AcupunctureAcupuncture
Limbic System
Somatosensory Cortex
Touch AcuityTouch Acuity
Haptic ExplorationHaptic Exploration
Applied HapticsApplied Haptics
Taste & SmellTaste & Smell
Taste = GustationTaste = Gustation Smell = OlfactionSmell = Olfaction
– Both are chemical Both are chemical sensationssensations
– InterdependentInterdependent
TasteTaste
Taste ReceptorsTaste Receptors
bittersoursaltysweet
Oversimplification
Central PathwayCentral Pathway
CortexCortex
Individual DifferencesIndividual Differences
Identifying SupertastersIdentifying Supertasters
Identifying TastesIdentifying Tastes
Taste & SmellTaste & Smell
Durian FruitDurian Fruit– Smells horribleSmells horrible
– Tastes deliciousTastes delicious
Can’t tell the difference Can’t tell the difference between grated apple between grated apple and grated onion without and grated onion without smellsmell
Durian Fruit
SmellSmell
ReceptorsReceptors
Central PathwayCentral Pathway
CortexCortex
IdentificationIdentification
Recognition
Detection
PheromonesPheromones
DefinitionDefinition– Chemical signals Chemical signals
found in natural found in natural body scentsbody scents
Truffle pigsTruffle pigs Human reactionsHuman reactions
– McClintock EffectMcClintock Effect
AnosmiaAnosmia
““I always thought I would sacrifice smell to I always thought I would sacrifice smell to taste if I had to choose between the two, but taste if I had to choose between the two, but I suddenly realized how much I had missed. I suddenly realized how much I had missed. We take it for granted and are unaware that We take it for granted and are unaware that everything smells: people the air, my house, everything smells: people the air, my house, my skin”my skin”
--anosmic patient --anosmic patient
(Birnberg,1988, in Ackerman, 1990)(Birnberg,1988, in Ackerman, 1990)
Smell & MemorySmell & Memory
Smell evokes memoriesSmell evokes memories Damage to memory regions in temporal Damage to memory regions in temporal
lobe does not affect ability to detect smelllobe does not affect ability to detect smell– Deficits in odour identification!Deficits in odour identification!
Strong aversions develop when smell is Strong aversions develop when smell is associated with negative experiencesassociated with negative experiences
Smell better cue for memory than touch or Smell better cue for memory than touch or auditionaudition
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