Touch, Taste, & Smell Kimberley A. Clow kclow2@uwo.ca

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