Sensation and Perception: Exam 4

Olfaction

Chemicals floating in the air, smell

Nociception

Perception of pain

Proprioception

Perception mediated by kinesthetic and internal receptors

Interoception

Perception of internal organs

A-beta Fibers

Myelinated sensory nerve fibers that transmit signals from mechanical stimulation

A-delta Fibers

Myelinated sensory nerve fibers that transmit pain and temperature signals

C Fibers

Unmyelinated sensory nerve fibers that transmit pain and temperature signals

Layers of Skin (In Order)

Epidermis, dermis, subcutaneous tissue

Glaborous Skin

Skin that does not contain hair

Meissner's Corpuscles

Small receptive field, fast adaption, temporal changes in skin deformation

Merkel Cell Neurite Complexes

Small receptive field, slow adaption, sustained pressure with very low frequency

Pacinian Corpuscles

Large receptive field, fast adaption, temporal changes in skin deformation

Ruffini Endings

Large receptive field, slow adaption, sustained downward pressure with lateral skin stretch

Kinesthetic Receptors

Receptors in the muscles, joints and skin that provide information about where your limbs are in space and movements made

Thermoreceptors

Receptors that provide information on changes in skin temperature

Labeled Lines

Each fiber type from the skin codes a particular touch sensation

Dorsal Horn

Where axons from tactile fibers enter the spinal cord

Laminae

Roof of the vertebral arch

Somatopic Organization

Organization of motor and somatosensory areas of the brain arranged like a spatial map of the body

Spinothalamic Pathway

Carries most of the information about skin temperature and pain (slower)

Dorsal Column-medial Leminiscal Pathway (DCML)

Carries tactile and kinesthetic information (faster)

S1

Primary somatosensory cortex

S2

Secondary somatosensory cortex

Sensory Homunculus

Maplike representation of the amount of somatosensory cortex devoted to each part of the body

Sensorimotor System

Motor and somatosensory cortex interact to produce movement

Phantom Limb Pain

Pain in a limb that no longer exists

Body Image

The impression of our bodies in space

Gate Control Mechanism (Substantia-gelatinosa)

Excitation (nociceptors) and inhibition (neurons in substantia-galatinosa and a-beta fibers) Stimulating a-beta fibers can help close the gate

Analgesia

Decreasing pain sensation during conscious experience

Hyperalgesia

Heightened response to normally painful stimulus

Tactile Sensitivity

Sensitivity to mechanical pressure

Two-point Threshold

The minimum distance between two points of stimulation on the skin where they can be distinguished as two different stimuli

Exploratory Procedures

Hand movements made in order to identify and object

Haptic Search

Task to recognize materials presented haptically to the fingers such as roughness or temperature stimuli

Age Related and Individual Differences in Tactile Sensitivity

Individual differences: sighted vs non-sighted individuals (braille) For sighted people, tactile sensitivity declines with age. For blind people, tactile sensitivity remains high into older age

Cribriform Plate

The horizontal plate of the ethmoid bone separating the cranial cavity from the nasal cavity

OSNs

Small neurons located beneath a watery mucous layer in the epithelium. All have cilia. All cilia have olfactory receptors. Olfactory sensory neurons

Olfactory Bulb

The brain center for smell, located above the nasal cavity and below the frontal lobes

Glomeruli

The spherical conglomerates containing the incoming axons of the olfactory sensory neurons

Olfactory Epithelium

Mucous membrane that is home to the olfactory receptors

Cillia

Hair like protrusions on olfactory sensory neuron dendrites

Basal Cells

Precursor cells to OSNs

Odorant

A molecule that is defined by physiochemical characteristics, which are capable of being translated by the nervous system into the perception of smell

Odor

The translation of a chemical stimulus into a smell sensation

Orthonasal vs Retronasal Olfaction

Orthonasal: sniffing and perceiving odors through the nostrils

Retronasal: Breathing in odorants through the mouth

Primary Olfactory Cortex

The neural area where olfactory information is first processed, includes the amygdala, parahippocampal gyrus,and interconnected areas, and alsoentorhinal cortex

Lymbic System

The encompassing group of neural structures that includes the olfactory cortex, the amygdala, the hippocampus, thepiriform cortex, and the entorhinal cortex

Trigeminal Nerve

Odorants can stimulate somatosensory system through polymodal nociceptors

Shape Pattern Theory

contends that different scents—as a function of odorant-shape to OR-shape fit—activate different arrays of olfactory receptors in the olfactory epithelium

Vibration Theory

Smells have vibrational frequency

Stereoisomers

Molecules that are mirror-image rotations of one another yet can smell completely different

Specific Anosmia

The inability to smell one specific compound amid otherwise normal smell perception

Pattern Detection in Olfaction

We can detect the pattern activity across receptors

Intensity matters

Specific time order of OR receptors

Synthetic Olfaction

Scents combining to have one perceptive smell

Analytical Olfaction

When different scents are presented each nostril, smells are perceived one at a time

Olfactory White

Equivalent of white noise

Binaral Rivalry

Competition between two nostrils for odor perception

Staircase Method

Participant is presented with a stimulus and indicates whether it was detected, and based on that response, the next stimulus is either one step up or one step down in intensity

Triangle Test

Participant is given 3 odors to smell, two of the same and one different. Participant must identify the odd odor

Olfactory Identification

Identification of what is being smelled correctly

Olfaction and Neurological Disease

Olfaction is an emerging biomarker for AD and Parkinson's

Receptor Adaption

Receptors stop responding to odorant and detection ceases

Cross Adaption

The reduction in detection of an odorant in response to another odorant

Chemical Senses

The ability to process the environmental stimuli of taste and smell

Odor Hedonics

The liking dimension of odor perception, typically measures with scales pertaining to an odorant's perceived pleasantness, familiarity, and intensity

Learned Taste Aversion

negative reaction to a particular taste that has been associated with nausea or other illness

Orbitofrontal Cortex

Area of the frontal lobe involved in learning and decision-making

Pheromones

A chemical emitted by one member of a species that triggers a physiological or behavioral response in another member of the same species

Vomeronasal Organ (VNO)

A chemical sensing organ at the base of the nasal cavity with a curved tubular shape used to detect large molecules such as pheromones

Mclintock Effect

Women who are in physical proximity over time start to have menstrual cycles that coincide

Chemosignals

Any of various chemicals emitted by humans that are detected by the olfactory system and that may have some effect on the mood, behavior, hormonal status, and/or sexual arousal of other humans

Ipsilateral vs. Contralateral

Same side of the body vs. opposite side

Taste vs. Flavor

Taste refers to the stimulation of the receptors on the tongue and roof of mouth (not retronasal olfaction) while flavor is the combination of true taste and retronasal olfaction

Filiform Papillae

Small structures on the tongue that provide most of the bumpy appearance and have no taste function

Fungiform Papillae

Mushroom-shaped structures distributed most densely on edges of tongue, especially the tip. Average of 6 taste buds per papillae are buried in the surface

Foliate Papillae

Folds of tissue containing taste buds. Located on the rear of the tongue lateral to the circumvallate papillae, where the tongue attaches to the mouth

Circumvallate Papillae

Circular structures that form and inverted V on the rear of the tongue. Moundlike structures surrounded by a trench and much larger than fungiform papillae

Taste Buds

Create neural signals conveyed to brain by taste nerves

Chorda Tympani

Cranial nerve 7 that provides taste to anterior 2/3rds of the tongue

Vagues Nerve

Cranial nerve 10 that receives input from the taste buds and projects to the brain

Types of Tastants

Small charges particles (salty and sour) transduced via ION channels

(sweet or bitter) transduced via g-protein-coupled-receptors

Four Tastes

Sweet, salty, sour, bitter

Chemicals That Give Rise to Specific Tastes

H+ ions - sourness

NaCl - saltiness

Glucose/sucrose/fructose - sweetness

Many different compounds - bitterness

How Each Taste is Processed

Salty - Na+ cations through ion channel

Sweet - Binds to heterodimer which is a g-protein coupled receptor

Sour - H+ through ion channel

Bitter - Binds to g-protein coupled receptors

Umami

Candidate for 5th basic taste (savory)

Fat

Important nutrient that doesn't have a taste but does signal trigeminal nerve for texture

Supertasters

People with heightened sensitivity to all tastes and mouth sensations

Cross-modality Matching

Ability to match the intensities of sensations that come from different sensory modalities

Specific Hunger Theory

The idea that deficiency of a given nutrient produces craving for that nutrient