Sensation Information coming into our brain from our sensory receivers Name the 5 senses and their more formal names!

Scientific Names for the Seven Senses (You Should Know These) Seeing: Visual Hearing: Auditory Tasting: Gustatory Smelling: Olfactory Sense of Touch: Tactile Balance: Vestibular Body Sense Kinesthetic

The EYE vision

The Eye Preview Question 5: How does the eye transform light energy into neural messages?

Biology of Vision: Know the Steps Light enters the eye through the cornea: (transparent protector) and passes through the pupil: (small opening/hole). The size of the opening (pupil) is regulated by the iris: the colored portion of your eye that is a muscular tissue which widens or constricts the pupil causing either more or less light to get in.

Biology of Vision: Know the Steps Behind the pupil, the lens, a transparent structure, changes its curvature in a process called accommodation, and focuses the light rays into an image on the light-sensitive back surface called the retina: where image is focused.

Biology of Vision: Know the Steps Image coming through activates photoreceptors in the retina called rods and cones (process information for darkness and color). As rods and cones set off chemical reactions they form a synapse with bipolar cells which transducts light energy into neural impulses.

The action potential travels along the ganglion cells which send information up the optic nerve (bundle of neurons that take information from retina to the brain)

Biology of Vision: Know the Steps The Optic Nerve carries neural information to be processed by the Thalamus (sensory switchboard). Thalamus sends information to the visual cortex which resides in the occipital lobe. The brain then constructs what you are seeing and turns image right side up.

Parts of Retina Fovea: central focal point of the retina, where cones cluster. Cones: photoreceptor located near center of retina (fovea) fine detail and color vision daylight or well-lit conditions Rods: photoreceptor located near peripheral retina detect black, white and gray twilight or low light Bipolar Cells: create visual neural impulses

Most Common Errors In Vision Acuity: the sharpness of vision Nearsightedness: (you can see near) nearby objects seen more clearly lens focuses image of distant objects in front of retina Farsightedness: (you can see far) faraway objects seen more clearly lens focuses near objects behind retina

COLOR vision

Physical Characteristics of Light Wavelength = hue/color Different wavelengths of light result in different colors. Violet Indigo Blue Green Yellow Orange Red 400 nm 700 nm Short wavelengths Long wavelengths

Amplitude = intensity/brightness

COLOR mixing Subtractive Color Mixing Additive Color Mixing mixing pigments (like paint). Result is: - If something appears black, then no color is projected into our eyes Additive Color Mixing mixing different colored lights. Result is: -if something appears white, then all colors are projected to our eyse

Retina Retina: The light-sensitive inner surface of the eye, containing receptor rods and cones in addition to layers of other neurons (bipolar, ganglion cells) that process visual information.

Let’s do a little experiment to “map” our rods & cones Photoreceptors Let’s do a little experiment to “map” our rods & cones E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969

Thomas YOUNG & Hermann HELMOLTZ key name Thomas YOUNG & Hermann HELMOLTZ Trichromatic color theory (RGB) - some cones are especially sensitive to red, some to green, some to blue

Typical cases of Color Blindness support the Trichromatic theory.

Opponent Process Theory There are three opponent channels: red vs Opponent Process Theory There are three opponent channels: red vs. green blue vs. yellow & black vs.white While the trichromatic theory defines the way the retina of the eye allows the visual system to detect color with three types of cones, the opponent process theory accounts for mechanisms that receive and process information from cones.

Opponent Process Theory Gaze at the middle of the flag. When it disappears, stare at the dot and report whether or not you see Britain's flag. What just happened is called a NEGATIVE AFTERIMAGE

another example of OPPONENT PROCESS THEORY: the Castle Illusion

David HUBEL & Torsten WIESEL key name David HUBEL & Torsten WIESEL Discovered that most cells in the visual cortex only respond to particular features. For example, maybe a cell responds only to lines at this \ angle. Wiesel was awarded the 1981 Nobel prize in Medicine and Physiology. His Nobel Lecture was entitled 'The postnatal development of the visual cortex and influence of environment.’ Wiesel recognized that covering one eye of a young animal could cause that eye to lose its connection to the visual cortex.

Feature Detection Nerve cells in the visual cortex respond to specific features, such as edges, angles, and movement. Ross Kinnaird/ Allsport/ Getty Images