The Eye.

The Eye

Energy v. Chemical senses
Energy Senses Chemical Senses

Transduction Transduction -Transforming stimulus energy (signals i.e. light rays, sound waves etc.) into neural impulses an action potential. Each sense has its own process of transduction Information goes from the senses to the thalamus , then to the various areas in the brain. Example: Converting Light Rays into neural messages Remember Ethan in Sky High. He changes his body to slime. Solid form to liquid form. Transduction is changing from one form of energy to another. he process by which our sensory systems convert stimulus energies into neural messages is called Sound waves into neural messages Light waves into neural messages Transduction is important because it converts physical stimuli into neural messages

Julie’s book bag is twice as heavy as Chandler’s
Julie’s book bag is twice as heavy as Chandler’s. If it takes 2 extra books to make Chandler’s feel heavier, how many books will it take to make Julie’s feel heavier? 1 2 4 5 6

Vision Our most dominating sense.
Visual Capture – tendency to allow visual images to dominate our perception Example: In a movie theater tend to think voices are coming from the screen, rather than the speakers

Phase One: Gathering Light
Gamma rays as short as the diameter of atom to radio waves over a mile long. The narrow band of wavelengths is visible to the human eye Short waves are blue-violet, long waves are red light Blue have a short wavelength and short amplitude, Red have a long wavelength and tall (high) amplitude Light reflecting off an object - The surface of the red apple absorbs all of the colored light rays except red. It reflects red to the eye, so the apple is perceived as red.

The Stimulus Input: Light Energy
Wavelength – distance from one wave to the next Determines hue (color) Eyes receive light energy and transduce or transform it into neural messages that our brain then processes into what we consciously see VISIBLE LIGHT = ELECTROMAGNETIC ENERGY ELECTROMAGNETIC SPECTRUM RANGES FROM SORT GAMA RAYS TO A NARROW BAND OF VISIBLE LIGHT – Some animals are sensitive to differing portions of the spectrum (bees can not see red, but can see ultraviolet rays) WAVELENGTH – DISTANCE FROM ONE WAVE PEEK TO THE NEXT – determine quality DETERMINES HUE – COLOR WE EXPERIENCE SUCH AS BLUE O GREEN INTENSITY – AMT OF ENERGY IN THE LIGHT WAVES (DETERMINES WAVE AMPLITUDE OR HEIGHT

Phase One: Gathering Light
Longest waves red, shortest are blue violet Draw colors on the board HUE Hue - The length of the wave gives us it’s hue (color). ROY G BIV Example: Red = longest wavelength Blue-violet = shortest wavelength

The Physical Property of Waves
Intensity Intensity - the amount of energy in a light wave, determined by amplitude or height Height of a wave gives us it’s intensity (brightness). Example: The higher the height, the brighter the color The lower the height, the duller the color Amplitude = intensity = brightness

Hue and Amplitude

Phase Two: Getting the light in the eye
Iris regulates the amount of light entering the eye, dilates and constricts the pupil Dilation of the pupil allows more light to reach the periphery of the retina where the rods are located Cornea - the round, transparent area that allows light to pass into the eye. 2) Lens – the transparent structure that focuses light onto the retina. Accomodation process by which the lens changes shape to focus images on the retina. 3) Retina - inner membrane of the eye that receives information about light using rods and cones. The functioning of the retina is similar to the spinal cord - both act as a highway for information to travel on. 4) Pupil – adjustable opening at the center of the eye which controls the amount of light entering the eye. Dilates and Constricts. 5) Retina – light sensitive inner surface of eye containing Rods & Cones - many more rods (approximately 120 million) than cones (approx 6.4 million) that begin to process the visual information a) cones - visual receptor cells that are important in daylight vision and color vision. the cones work well in daylight, but not in dim lighting. This is why it is more difficult to see colors in low light. most are located in the center of the retina...called the FOVEA, which is a tiny spot in the center of the retina that contains ONLY cones...visual acuity is best here. SO...when you need to focus on something you attempt to bring the image into the fovea. b) rods - visual receptor cells that are important for night vision and peripheral vision. the rods are better for night vision because they are much more sensitive than cones. in addition, the rods are better for peripheral vision because there are many more on the periphery of the retina. The cones are mostly in and around the fovea but decrease as you go out. to see best at night, look just above or below the object...this keeps the image on the rods. Light rays bent by cornea Pupil opened by iris Light further bent by lens

The Eye Cornea – protects the eye and bends light to provide focus
Iris – ring of muscle tissue that controls the size of the pupil opening Pupil – small adjustable opening in the center of the eye which light enters Dilation of the pupil allows more light to reach the periphery of the retina where the rods are located so you can see in dim light Lens – transparent structure that focuses light onto the retina Accomodation - process by which the lens changes shape (curvature and thickness) to focus near or far images on the retina Retina – light sensitive, inner membrane of the eye containing rods and cones where the process of transduction occurs. Fovea is located here. Retina - inner membrane of the eye that receives information about light using rods and cones. The functioning of the retina is similar to the spinal cord - both act as a highway for information to travel on. Changes in the Curvature and thickness of the lens bring objects into focus cones - visual receptor cells that are important in daylight vision and color vision. Through transduction, impulses are reassembled into a perceived, upright image

Retina Rods - receptor cells Cones – receptor cells
Black, white, gray sensitive Peripheral vision Twilight, Night vision Sensitively to dim light - High Cones – receptor cells Color sensitive – distinguish different wavelengths of light central vision Daylight, well-lit Fine detail Sensitivity to dim light - Low Fovea - center of the retina Sharp, detailed vision needed for reading, driving or any activity where detail is important Contains only CONES the cones work well in daylight, but not in dim lighting. This is why it is more difficult to see colors in low light. Damage to fovea = effect on visual acuity most are located in the center of the retina...called the FOVEA, which is a tiny spot in the center of the retina that contains ONLY cones...visual acuity is best here. SO...when you need to focus on something you attempt to bring the image into the fovea. b) rods - visual receptor cells that are important for night vision and peripheral vision. the rods are better for night vision because they are much more sensitive than cones. in addition, the rods are better for peripheral vision because there are many more on the periphery of the retina. The cones are mostly in and around the fovea but decrease as you go out. to see best at night, look just above or below the object...this keeps the image on the rods.

Rods versus Cones Example: Peripheral vision and color vision
Do activity with colored pencils or markers Example: Peripheral vision and color vision

Optic Nerve Optic Nerve – nerve that carries neural impulses from the eye to the brain Blind Spot – point at which optic nerve leaves the eye Blind spot = no receptor cells Example: Pg. 127 in textbook Black dot and red car If an image falls on the eye's blind spot, you do not detect it because without receptor cells no transduction can occur.

Phase III: Transduction
Overview: cornea, iris, pupil, lens, retina, optic nerve, thalamus, occipital lobe, visual cortex, feature detector cells.

Transduction Rods and Cones convert light energy to neural impulses = transduction (an action potential occurs) Rods and cones synapse with neurons called bipolar cells located in the retina Cones hotline to the brain Direct link between single cone to bipolar preserves fine detail of cones message Bipolar Cells transmit to ganglion cells (another type of neuron) whose axons form the Optic Nerve) 1/2 axons in optic nerve crisscross (called optic chasm) sending impulses to opposite side of brain Can Iris pass the lens to the retina Color is RBGO – red, blue green orange Cones have a hotline to the brain (bipolar cells that relay the cone’s individual message to the visual cortex Bipolar cells are located in the retina Ganglion cells axon’s form the optic nerve

Visual Problems Farsighted – cornea too flat or distance from cornea to retina too short Nearsighted – cornea too curved or distance from cornea to retina too long Astigmatism – irregularly shaped cornea (like a football instead of a baseball

Rank the following from most important to least important --What do you think is the most important part of the eye? Why? Least important? Why Cornea Pupil Iris Lense Retina Rods Cones Fovea Optic Nerve

Light wave amplitude determines its
Intensity of color Color hue we experience Firing of rods in the retina Curvature and thickness of the lens Parallel processing of a scene Table

The distance from one light wave to the next determines
Intensity Amplitude Hue Absolute threshold Transduction Table

The amount of light entering the eye is regulated by the
Lens Iris Retina Optic Nerve Feature Detectors Table

Objects are brought into focus on the retina by changes in the curvature and thickness of the
Rods and cones Lens Bipolar cells Optic nerve Cornea Table

The receptor cells that convert light energy into neural signals are called
Bipolar cells Ganglion Cells Rods and cones Lens Iris Table

The most light-sensitive receptor cells are the
Bipolar Cells Ganglion Cells Rods Cones Iris Table

Phase IV: In the Brain Thalamus to Occipital lobe to Visual Cortex to…
Feature Detectors –nerves cells in the brain that respond to specific features – edges, lines, angles and movement Example: Turkey Supercell clusters – teams of cells that fire in response to complex patterns Example: Perceiving Faces Example: Feature Detector cells – allow you to see the lines, motion, curves and other features of this turkey. Rods/cones to bipolar to ganglion to optic nerve to thalamus to occipital to feature detector cells Feature detector cells are located in the occipital lobes Two separate brain images process faces and objects (ie Heather Sellers)

Parallel Processing - Vision
Parallel Processing – brain simultaneously process stimulus elements Example: Visual cortex allows you to simultaneously see the color, form, depth, and motion of a rhino charging you Blindsight – localized area of blindness in part of their field of vision caused by damage to visual cortex Example: Can’t perceive your textbook on your desk but you can read the title In sound simultaneously hearing pitch, loudness, melody of a song Blindsight caused by damage to visual cortex Allows you to speedily recognize familiar objects Color motion form of a bird, dog etc.

Color Vision Two Major Theories: Trichromatic Opponent Process
Both are valid in explaining color vision

Trichromatic Theory/ Young-Hemholtz Theory
Trichromatic Theory - Three types of cones: Red Blue Green These three types of cones can make millions of combinations of colors. Explains color blindness Does not explain afterimages Young Helmholtz Theory – retina contains three kinds of color receptors Color blind don’t have red or green cones

Opponent-Process Theory
Opponent Process Theory - The sensory receptors come in pairs. Red/Green Yellow/Blue Black/White If one color is stimulated, the other is inhibited. Opponent process cells are located in the thalamus Example: Afterimages According to the opponent-process theory, cells that are stimulated by exposure to yellow light are inhibited by exposure to blue light. Green light inhibited by red light Color blindness also explains the opponent process theory

Afterimages

Which of the following types of cells are located in the brain's occipital lobe?
Rods Cones Ganglion Cells Bipolar Cells Feature Detector Cells Table

The human ability to speedily recognize familiar objects best illustrates the value of
Accomodation Parallel Processing Subliminal Stimulation Sensory Interaction Difference Threshold Table

Experiencing a green afterimage of a red object is most easily explained by
Opponent process theory Gate control Theory Place Theory The Young Helmholtz Theory Frequency Theory Response Counter

Hearing, Touch, Taste and Smell

Audition – the sense of hearing

Frequency of Sound Waves
Frequency - the number of the waves gives us the pitch if the sound. Example: short wavelength = high pitch; long wavelength = low pitch Amplitude = loudness = brightness Pitch is determined by the frequency of the sound wave = color

Amplitude of Sound Waves
Amplitude - the height of the wave = loudness of the sound Example: High height = loud noise; low height = soft noise

Absolute Threshold Absolute Threshold = zero decibels
10 decibels = 10X increase in sound intensity Example: A 30 decibel sound is _____ times louder than a 10 decibel sound 10X10 = 100 A 40 decibel sound is _____ times louder than a 10 decibel sound 10X10X10 = 1000 A rock concert is ______ times louder than normal Conversation

Parts of the Ear Outer Ear – channels sound waves to the eardrum in the Middle Ear Middle Ear – chamber between the eardrum and cochlea containing three tiny bones that concentrate vibrations of the eardrum on cochlea’s oval window Inner Ear – the innermost part of the ear containing the cochlea, semicircular canals, and vestibular sacs Cochlea – fluid filled tube of inner ear which trigger neural impulses

Transduction Overview – Pinna, Auditory Canal, Eardrum, Hammer, Anvil, Stirrup, Oval Window, Cochlea, Auditory Nerve, Thalamus,Temporal Lobe, Auditory Cortex Outer Ear - Pressure waves to … Pinna, Auditory Canal, Middle Ear –Ear Drum – tight membrane that vibrates with sound waves. Transmits sound to the bones of the middle ear. Produces Mechanical waves from… hammer, anvil, stirrup (ossicles) to cochlea’s oval window Inner Ear – oval windows produces Fluid waves in… Cochlea – coiled fluid filled tube where transduction occurs vibrations cause basilar membrane’s hair cells (Cillia) to turn vibrations into neural impulses 4. Auditory Nerve – sends neural messages to thalamus. Thalamus to Temporal lobes to Auditory cortex Vibrating air to moving piston to fluid waves to electrical impulses to the brain Basilar membrane is located in the cochlea The mechanical vibrations triggered by sound waves are transduced into neural impulses by hair cells Hair cells line the surface of the basilar membrane Rods and cones are to vision as hair cells are to audition Cochlea – fluid filled tube in which sound waves trigger neural impulses eardrum, hammer, anvil, stirrup, cochlea It is all about the vibrations!!!

The structure of the ear
Movement of hair cells along the basilar membrane initiates transduction of neural messages to the auditory cortex Hair cells have extreme sensitivity and extreme speed Mechanical vibrations triggered by sound waves are transduced into neural impulses by _____________? _____________ do the same job for vision as __________ do for audition

Neural impulse to the brain

Perceiving Loudness # of activated hair cells allows us to perceive loudness If hair cells lose sensitivity to soft sounds can still respond to loud sounds Compression – amplify soft sounds and not loud Hearing aids produce compressed sound Movement of hair cells along the basilar membrane initiates transduction of neural messages to the auditory cortex Hard of hearing people like sound compressed because they remain sensative to loud sounds – what hearing aids do Damage to hair cells = most hearing loss If we can’t talk over a loud noise it is harmful, especially over long periods of time---over 100 decibles

Place Theory and Frequency Theory
Pitch Theories Place Theory and Frequency Theory

Place Theory or Herman von Helmholtz Theory
Place Theory - Brain determines pitch by recognizing the place on the membrane that is generating the neural impulse Best explains how we sense high pitches Example: High frequencies produce large vibrations at beginning of cochlear membrane

Frequency Theory Frequency Theory - Brain knows pitch by the frequency of the neural impulse Frequency (speed) of sound wave matches the speed of the neural impulse. Theory limitations: Can’t explain high pitch sounds (neural impulses can only travel at 1000 impulses per sec.) Best explains how we hear low pitches Example: Frequency of sound wave = 100 waves per second, then 100 impulses per sec. travel to the auditory nerve The rate at which impulses travel up the auditory nerve matches the frequency of the tone being heard

Volley Principle Volley Principle-Neural cells alternate firing in rapid succession Can achieve a combined frequency of above 1000 waves/sec Current Research suggests that both frequency and place theory explain how we hear pitch

Think Pair Share A musician is walking home alone late one night and is startled when a dog in a yard to his left barks unexpectedly Trace the path that the sound waves travel as they enter the ear and proceed to receptor cells for hearing and then to the brain Using the two theories of pitch perception explain how the brain might process the pitch of the dog’s bark.

Locating Sound Sound waves strike one ear sooner and more intensely in the direction of the sound Locating sound – activity with person sitting in a chair facing the class. Clap at varing locations around the head. Left, right, front, back top (should have more difficulty locating sound in the 360 degree plane equidistant between the ears – overhead, back, front Cock head to hear location of sound Sound waves strike one ear sooner than the other, helps us to locate the direction of the sound When sound is directly overhead it reaches both ears simultaneously Time lag between left and right auditory stimulation is important for accuratley locating sound

Compare the Eye to the Ear
Frequency Amplitude Transduction Receptor cells Path to brain Theories

Frequency hue pitch Amplitude Transduction Receptor cells Path to brain Theories

Frequency hue pitch Amplitude Brightness loudness Transduction Receptor cells Path to brain Theories

Frequency hue pitch Amplitude Brightness loudness Transduction Retina Cochlea Receptor cells Path to brain Theories

Frequency hue pitch Amplitude Brightness loudness Transduction Retina Cochlea Receptor cells Rods and cones Hair cells Path to brain Theories

Frequency hue pitch Amplitude Brightness loudness Transduction Retina Cochlea Receptor cells Rods and cones Hair cells Path to brain Cornea, Iris, Pupil, Lens , Retina, Rods and Cones, bipolar cells, ganglion cells, optic nerve, thalamus, occipital lobe, visual cortex, feature detector cells, cerebral cortex/supercluster cells Pinna, auditory canal, eardrum, ossicles (hammer, anvil stirrup), cochlea, basilar membrane hair cells, auditory nerve, thalamus, temporal lobe, auditory cortex Theories

Compare the eye to the ear
Frequency hue pitch Amplitude Brightness loudness Transduction Retina Cochlea Receptor cells Rods and cones Hair cells Path to brain Cornea, Iris, Pupil, Lens , Retina, Rods and Cones, bipolar cells, ganglion cells, optic nerve, thalamus, occipital lobe, visual cortex, feature detector cells, cerebral cortex/supercluster cells Pinna, auditory canal, eardrum, hammer, anvil stirrup, cochlea, basilar membrane hair cells, auditory nerve, thalamus, temporal lobe, auditory cortex Theories Opponent-Process Trichromatic Pitch Volley principal

Deafness Conduction Deafness - Nerve (sensorineural) Deafness
Damage to the mechanical system that conducts vibrations in the middle ear (hammer, anvil, stirrup)….or eardrum You can replace the bones of the inner ear through surgery Example: Punctured Eardrum with a Q-tip, Old age The hair cells on the basilar membrane in the cochlea get damaged. Loud noises can cause this type of deafness. NO WAY to replace the hairs. Cochlea implant - converts sound waves to into electrical signals. Example: Old age, prolonged exposure to loud noises

The loudness of a sound is determined by what?
The frequency of a sound wave The amplitude of a sound wave The pitch of a sound wave The decibel level of a sound wave The vestibular level of a sound wave 0 of 0

Which theory best explains how we perceive low-pitched sounds?
Place theory Opponent process theory Frequency Theory Gate Control Theory Young-Hemholtz Theory 0 of 14

Cones and rods are to vision as ________ are to audition.
Eardrums Cochleas Oval windows Hair cells Semicircular canals Table

Touch Receptors located in our skin. Types of touch Pressure* Warmth
Cold Pain Sensation of hot – Activity with paper clip and touch no simple relationship between what we feel at a given spot and the type of specialized nerve endings found there Pressure receptors have been identified Other skin sensations are variations of the basic - pressure, warmth, cold, pain Tickle – stroking adjacent pressure spots Itching – repeated gentle stroking of a pain spot Wetness – touching adjacent cold and pressure spots Hot – stimulating nearby cold and warm spots Top down processing = rubber hand illusion

Touch Tickle – stoking adjacent pressure spots
Itching – repeated gentle stroking of a pain spot Wetness – touching adjacent cold and pressure spots Hot – stimulating nearby cold and warm spots

Touch - Bottoms up AND Top Down Processing
Rubber hand illusion

Kinesthetic Sense Kinesthetic Sense - Tells us where our individual body parts are. Receptors located in our joints, tendons, bones and ears Example: Playing volleyball you know where your limbs are located to hit, pass, set or run to the ball Proprioseption – loss of Kinesthetic sense. Can only move body when they can see their body parts – receptor cells have been identified in joints, tendons, bones, and ear. Detecting whether you are vertical or horizontal Activity - close eyes and touch mouth, nose chin. It is your kinesthetic sense that enables you to do this. stand with right heal in front of left toes and close your eyes…what happens? you wobble. Proprioception – loss of kinesthetic sense. Can only move their bodies when they can see them. In the dark, they become limp and collapse Without the kinesthetic sense you could not touch the button to make copies of your buttocks.

Vestibular Sense Vestibular Sense - Enables you to sense your body position and balance Located in our semicircular canals in our ears. Example: Spinning around in a chair, you lose your vestibular sense Demo of spinning around in a chair ? Elephant balancing on two legs Riding the corkscrew at Cedar Point – fluid in semicircular canals make us feel dizzy Fluid in the semicircular canals have fluid which moves when head rotates or tilts – movement stimulates hair-like receptors that send messages to the cerebellum enabling you to sense your body position

Pain Biological Influences Psychological influences
Nociceptors – sensory receptors that detect hurtful temperatures, pressure or chemicals Located in skin, joints & tendons, organs Gate-control theory* Endorphins - gene Phantom limb sensations Tinnitus Psychological influences Distraction Memory of Pain – peak pain, end pain Socio Cultural Influences More pain when others experience pain Mirror neurons that empathize with others pain When you burn your finger, noiceptors transmit pain signals to your central nervous system Phantom limb sensations – misinterpretation of central nervous system activity in absence of normal sensory activity Tinnitus – phantom sounds with loss of hearing

Gate Control Theory Gate Control Theory – spinal cord contains a “gate” that blocks pain signals or allows them to pass through to the brain Example: Opened by small nerve fibers = pain sent Closed by large nerve fibers = pain not sent No one theory explains pain Gate control – theory suggests that large fiber activity in spinal chord can prevent pain messages from reaching the brain

The pain circuit If burn your finger noiceptors transmit pain triggering signals to your central nervous system In response to a painful stimulus nociceptors initiate neural impulses leading to the sensation of pain

Taste aka Gustatory Sense
Sweet, sour, salty and bitter Umami Taste buds Chemical sense Taste is Adaptive Declines with age Smoking, alcohol

Taste Bumps on our tongue are called papillae.
Taste buds are located on the papillae 200+ each containing a pore. Pore – taste receptor cells that sense food molecules

Smell Olfaction Chemical sense
Olfactory receptors - odor molecules fit into receptors like a lock and key located in the olfactory bulb Olfactory bulb – transmits smell from the nose to the brain Olfactory nerve – sends neural messages from the olfactory bulb directly to the olfactory cortex in the brain bypassing the thalamus Olfactory cortex – receives information from the olfactory bulb Conscious awareness of odors Identification of odors Hotline between olfactory cortex and limbic system (memory and emotion) Sense of smell is known as olfaction Is chemical sense not energy sense – sent laden molecules Smell when molecules of a substance carried in the air reach receptor cells at the top of the nasal cavity – some odors trigger a combo of receptors Connection between olfactory cortex and Limbic system = smells involved with vivid memories

Smell (olfaction)

Smell and age Smell declines with age, women have a stronger sense of smell than men

Sensory Interaction Sensory interaction – some senses influence others
Examples: Jello in the shape of a brain looks so unappetizing, it tastes terrible too McGurk Effect – seeing mouth movements for ga, but hearing ha, we may perceive da (saying one syllable, while hearing another, you perceive a third) Eyes closed and nose plugged unable to taste the difference between onion and pear McGurk Effect See something that looks unappetizing, it tastes terrrible

The semicircular canals are most directly relevant to
Hearing Kinesthetic Sense Pain Vestibular Sense Accomodation Table

Alex tickles his brother by stroking adjacent ________ spots on his skin.
Pressure Warmth Cold Pain Kinethesis Table

Taste and smell are both what kind of senses?
Vestibular Kinesthetic Energy Chemical Perceptual Table

Which theory suggests that large-fiber activity in the spinal cord can prevent pain signals from reaching the brain? Signal Detection Theory Gate Control Theory Young-Helmholtz Theory Place Theory Opponent Process Theory Table

Think Pair Share Dog scenario again - A musician is walking home alone late one night and is startled when a dog in a yard to his left barks unexpectedly. Using the two theories of pitch perception explain how the brain might process the pitch of the dog’s bark. Explain how the musician would know that the bark originated to his left without even seeing the dog.

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