sensation and perception final exam

vestibular system

deals with balance and spatial orientation; 3 semicircular canals, 2 otolith organs

spatial orientations

consists of linear motion, angular motion (rotation), tilt

vestibulo-ocular reflex

VOR, stabilizes visual input by counter rotating the eyes to compensate for head movement

vestibular labyrinth

non-hearing part of inner ear

problems with vestibular system

spatial disorientation, dizziness, vertigo, labyrinthitis, imbalance, blurred vision, illusory self motion

dizziness

non specific spatial disorientation

vertigo

sensation of rotating or spinning

labyrinthitis

inflammation of labyrith (vestibular organs and cochlea)

semicircular canals

sense angular acceleration (rotation)

otolith organs

utricle and saccule, sense linear acceleration and gravity (tilt)

semicircular canal roll

rotation on x-axis, maybe

semicircular canal pitch

rotation of y-axis, yes

semicircular canal yaw

rotation of z-axis, no

otolith organs translation

positive x-axis, positive y-axis, positive z-axis

mammalian vestibular system

do not respond to constant velocity, only respond to changes in velocity, gravity and acceleration share equivalent connection

semicircular canal shape

3/4 of a donut, toroid shape, filled with perilymph, 2nd smaller toroid filled with endolymph, canal swells at ampulla

ampulla

where swollen canals join vestibule

hair cells

mechanoreceptors, head motion causes a change in hair cell voltage and alters NT release,

push pull symmetry

hair cells in opposite ears respond in complementary way to each other, left ear depolarize while right ear hyper polarize

utricle

30,000 hair cells

saccule

contains 16000 hair cells

otoconin

hair cells encased in gelatinous structure that contains calcium carbonate

evolution of vestibular system

earliest vertebrate had 1 semicircular canal, soon added horizontal and anterior canals, more complex underwater movement and head/eye coordination

somatosensation

sensory signals from body (skin, joints, tissue, muscle), cutaneous sense (touch, temperature, pain)

kinesthesis

perception of position and movement of limbs in space (exclude vestibular)

proprioception

perception mediated by kinesthetic and vestibular receptors, more of a cognitive function

tactile receptors function

mechanoreceptors that respond to mechanical stimulation, pressure, vibration, movement

tactile receptors anatomy

embedded in outer layer (epidermis) and underlying layer (dermis) of skin

meissner corpuscles

fast adaptation, small receptive field, FA1

merkel cell neurite complexes

slow adaptation, small receptive field, SA1

pacinian corpuscles

fast adaptation, large receptive field, FA2

Ruffini endings

slow adaptation, large receptive field, SA2

kinesthetic receptors

mechanoreceptors in muscles, tendons, joints; play role in proprioception and what kinds of movements

muscle spindle

receptor located in muscle that senses muscle tension, in joints that react when joint is bent to extreme angle

Ian Waterman

cutaneous nerves connecting his kinesthetic receptors to brain destroyed by viral infection, lacks kinesthetic senses, dependent on vision for limb position, partial loss of proprioception is more common

thermoreceptor

signal changes in skin temperature, warmth fibers and cold fibers (can react to very hot temps), constantly regulating internal temp, respond when you make contact with object warmer/colder than skin

pain

sense dangerous objects, subjective experience made up of painful stimulus and emotional response, S1 and S2, can be modulated by gating (shot blocker device)

Miss C

insensitivity to pain, didn’t sneeze, cough, gag, or blink, died at 29 from preventable infections

nociceptors

sensory receptors that transmit info about noxious stimulation that could damage the skin

A-delta fibers

nociceptors, intermediate sized, myelinated sensory nerve fibers, transmit pain and temp signals, quick sharp pain

C-fibers

nociceptors, narrow, unmyelinated sensory nerve fibers that transmit pain and temp signal, throbbing sensation

spinothalamic pathway

information about skin temp and pain, slower, separate from other input until cortex

dorsal column medial lemniscal

DCML, signals from skin, tendons, muscles, joints, separate from other input until cortex

touch sensations represented somatotopically in cortex

primary somatosensory cortex (S1, top of central sulcus), secondary somatosensory cortex (S2, bottom of central sulcus); analogous to retinotopic mapping in vision

homunculus

maplike representation of regions of body in brain

phantom limb

sensation percieved from physically amputated limb, parts of brain listening to missing limbs not aware of altered connection, so they attribute activity to stimulation from issing limb

cognitive aspects of pain

anterior cingulate (perceived unplesantness), prefrontal cortex (pain sensitization), same area active during social rejection

gate control theory

pain receptors must be activated and neural gate in spinal cord must allow signals through to brain, gate neurons can be activated by extreme pressure and cold, transmitted by small diameter nerve fibers

endogenous opiates

chemicals released in body to block release or uptake of NT transmitting pain stimulation to brain, may be responsible for placebo effects

exogeneous substances

morphine, heroin, codeine

tactile sensitivity and acuity

two point threshold: minimum distance at which 2 stimuli are just perceptiable as separate, sensitivity to pressure, spatial acuity varies across body (fingertips, face, toes highest acuity)

haptic perception

knowledge of world from sensory receptors in skin, muscles, tendons, joings, involve active exploration ex. align childproof pill bottle arrows in the dark

lateral motion

texture

pressure

hardness

static contact

temperature

unsupported holding

weight

enclosure

global shape, volume

contour following

global shape, exact shape

‘what’ system of touch

geometric properties of objects are most important for visual recognition, materials properties of objects are crucial for haptic recognition, 2D picture are easily recognized visually, poor haptically

perceving patterns with touch

braille processed in V1

olfaction

sense of smell, most ancient modality

gustation

sense of taste

olfaction in mammals

receptor gene family is largest mammalian genome, humans can detect millions of airborne odorants

odor

translation of a chemical stimulus into a smell sensation

odorant

capable of being translated by nervous system into perception of smell

odorant qualities

volatile (readily evaporates), small, hydrophobic

methane and carbon monoxide

small and volatile, but we can’t smell them, no evolutionary pressure to detect because they occur in such low []

mercaptan

detectable quality of methane added to signal a gas leak

nose main purpose

filter, warm, humidify air

nasal cycle

primary airflow through nose alternates between nostrils

turbinates

folds in nose, direct air toward lungs, swelling makes nasal cycle, swap dominant nostril

olfactory cleft

narrow space at back of nose where air flows, main olfactory epithelium is located, mucus secretion, neurons

olfactory epithelium function

secretory mucus membrane in human nose primary function is to detect odorants inhaled from air

cribrioform plate

bony structure with many tiny holes, at eyebrow level, separates nose from brain, why you need sterile water in netipot

anosmia

total inability to smell, most often resulting from sinus infection or head trauma, more common with age, can be predictor of natural death coming

side effects of anosmia

loss of flavor perception, loss of smell, symptom of covid

olfactory epithelium anatomy

supporting cells, basal cells, olfactory sensory neurons (OSNs)

supporting cells

metabolic and physical support for OSNs

basal cells

precursor (stem) cells that become OSNs

olfactory sensory neurons

OSNs, main cell type in olfactory epithelium, located beneath mucus layer

cilia

hairlike protrusions on dendrties of OSNs, contain receptor sites for odorants, 1st structure involved in olfactory signal transduction

olfactory receptor

OR, region on cilia where odorants bind, 7 or 8 odorants needed for action potential

glomerulus

father info from OSNs, located in olfactory bulb, sends to mitral cell

olfactory nerves

most anterior cranial nerves, axons of OSN, bundle togerher after passing through cribiform plate to form nerve

feel of scent

polymodial nociceptors, mediated by trigeminal nerve (5th cranial nerve)

polymodial nociceptors

touch, pain, and temperature ex. eating hot pepper

amygdala-hippocampal complex

helps recognize smell of your location

entorhinal cortex

temporal lobe, associations with odor, sensory input from hippocampus,

primary olfactory cortex

O1, 1st place to process olfactory info, frontal lobe

secondary olfactory cortex

O2, orbitofrontal cortex, affective value (good or bad smell)

amygdala

vigilance and attention

parahippocampal gyrus

memory region

limbic system

olfactory cortex, amygdala, piriform cortex, entorhinal cortex, involved in emotion and memory, scents have strong emotions and memories