The Human Brain and Senses: Memory

Transcription

1 The Human Brain and Senses: Memory Methods of Learning Methods of Learning Learning The acquisition of new knowledge and skills. There are several types of memory, and each is processed in a different part of the brain. Remembering facts visual images events and experiences how to do things smells, tastes, and feelings Mirror Writing Today we will be learning by doing. We will practice learning a new skill Mirror writing A skill becomes easier with practice and repetition.

2 Memory Retention Effective ways of memory retention learning Emotional You remember things that are emotionally important to YOU You remember things that make you feel a strong emotion. Fear Anger Happiness We use multiple senses when learning Sight Smell Tough Sound When you combine multiple senses, you tend to learn better Questioning Leading Questions: Questions that assume something is true. You assume in a logical way, but it may not be true. You are creating a fictional scenario.

3 Memory Strategies Senses (the more you combine, the better your remember) Verbal Hearing the word being said Sight Seeing the word Seeing the object Touch Feeling the object Writing the word

4 Memory Strategies Association When something reminds you of something else. Example When remembering a name, associate it to something. Like Ms. Wedige, sort of reminds you of wedgie. This word is funny, and you remember funny things. Mnemonic (nee MON ic) Using a phrase, word, acronym, or song to help you remember. Principal vs. Principle Principal is your pal like the person principal. In order for this to work, it must be something that you are already familiar with.

5 The Human Brain and Senses: Lenses History of Lenses Greeks thought that eyes send out invisible rays that allow a person to perceive objects. They thought vision takes place in space since objects appear to be outside of a person s body. This was until 1625 when a priest demonstrated it is within the eye. By scraping the sclera off the back of an eye he created a small inverted and reversed image on a screen.

6 How Eyes Operate - Eyes collect light from the environment and focus that light on a light-sensitive structure inside the eye. - In order for any object to be visible, it must either produce light or reflect it. Radiant light - - Sun, candle flame, and a lightbulb all produce Reflected light - - Moon, candle stick, and people reflect Transmitted light - - When light shines THROUGH an object Refraction - - Light travels through transparent media (air, water, glass) in a straight line as long as it is of the same consistency When it changes composition, it bends at the point of contact called Refraction.

7 Every medium has an index of refraction that tells the degree that light will bend

8 Lens A lens is a clear, curved object that has a different index of refraction than its surrounding medium The curvature of the surface of the lens bends light rays differentially.

9 Focus When light passes through it bends so all of the rays of light come together at one point. This point is called the focus point

10 Focal Length A lens refracts light rays coming in parallel to one another and they converge at a point known as the principal focus or focal length for that lens. When the rays come together to focus, they form an image_

11 Real Image Converging (convex) lens is thicker in the middle, and as the light rays pass through, they converge (meet) at one point. Below shows an image of the optical bench applet with beams (many parallel light rays) passing through the convex lens. Diverging (concave) lens is thinner in the middle, the lens curves in. As the light rays pass through, they diverge (spread out), the rays do not meet like the convex lens. Below shows an image of the optical bench applet with beams (many parallel light rays) passing through the concave lens.

12 Inside of the Eye The image that is projected on the screen is smaller than the actual object. This size reduction allows the image to fit inside the eyeball. - After the image focuses on the retina, it travels to the brain where it can be interpreted as an image that is in its correct orientation. -

13 Projected Image If light passing through a convex lens is bent or refracted so that a real image forms on a surface, it is a projected image. These images are always inverted and reversed because the light rays cross. The distance between the lens and the screen on which a projected image is focused is the image focal distance. The only ray that is not refracted is the one that enters the center of the lens absolutely perpendicular to the plane of the lens.

14 Parts of the Retina The eye has two lenses The lens in the eye itself is the most obvious but not as important as the cornea. The lens in the eye make slight adjustments in focus as you look at something far away and then close up. The curved surface of the cornea and the fluid behind it act as the main lens for focusing and image for eyes that function in the air. The cornea bends light more than the lens because the difference between the index of refraction of the cornea and that of the air is greater than the difference between the index of refraction of the lens and that of the fluid that surrounds it in the eye. Ex.) opening eyes under water with no mask, then with a diver s mask.

15 Muscles Muscles Adjustments in focus is called accommodation This is controlled by delicate muscles called ciliary muscles. As we age, the ciliary muscles continue to pull on the lens, but no longer change shape to create a focused image of an object that is close to the eye.

16 Glasses and Contacts Focus can be corrected with glasses or contacts The lenses in glasses and contacts work with the lens in the eye to change the overall focal length of the lens system. Overstimulation of Photoreceptors Capturing Images Using what they knew about how the eye works, scientists were able to capture images using a dark box and light-sensitive paper. The brighter the light, the faster the reaction on the paper.

17 The screen in a camera is like the retina in the eye. Both have a lens that allows light to enter a dark container and then focuses the image on the back. If you replace light sensitive paper with light sensitive living tissue, you have an eye. The screen in a camera is like the retina in the eye.

18 The Human Brain and Senses: The Retina The Retina The structures of the eye are dedicated to focusing an image on the retina. The retina is the curved screen on the back of the eye where light energy changes to electric impulses. These electric impulses travel to the brain to be processed. Nerves When light reaches the retina, it passes through two layers of nerve cells called neurons. After passing the neurons, the light hits a dense layer of photoreceptors. Photoreceptors are the specialized light-sensitive neurons that that convert light energy to electric impulses.

19 Photoreceptors There are two types of photoreceptors. Cones Triangular in shape. Respond to bright light Distinguish color and detect fine details in objects. Three types of cones- each respond to a different color (red, green, and blue) Rods Long and skinny. Sensitive to dim light and not sensitive to bright light. Rods cannot detect color.

20 Parts of the Retina Macula- Cone cells are concentrated here Optic disk- the spot where the optic nerve attaches to the back of the eye. Has no photoreceptors at all. Therefore, it is the blind spot in the vision of each eye. Several large blood vessels radiate from the optic disk. Blood Vessels in the Eye Blood vessels- nourish the living tissue in the retina Block light from reaching the photoreceptors beneath them, creating additional blind spots. Fovea- A small depression in the center of the macula that contains only cone cells. The fovea is the area of the retina that has the most sensitivity to color and detail. This contains only cone cells. The fovea is where an image is focused TO when you look directly at the object.

21 Field of Vision What you can see with both eyes open is your field of vision. Typically, this is 180 degrees from side to side. Up and down, your field of vision is about 120 degrees. You cannot see as much up and down because of the eyebrow ridge and cheekbones--- they reduce the vertical field of vision. Color vision is seen in a visual field of up to 120 o for bright colors, and down to 90 o for pale colors Fine detail such as that required for reading, can be seen is a narrow field of vision of about 10 o

22 Blind Spots Blind spots occur where blood vessels and the optic disk block light from reaching the photoreceptors. Blind spots are not easily detected because both eyes work together and compensate for blind spots. In addition to the eyes working together, the brain fills in missing details, making blind spots harder to detect.

23 Peripheral Vision Vision to the sides and top/bottom of our visual field. Provides us mostly with contrast and motion information.

24 Overstimulation of Photoreceptors Rods: Saturation: when the rods get too much light, they lapse into inactivity. Cones respond to intense light. If overstimulated, the cells in the macula and fovea can be destroyed. This can happen if you look directly at the sun or by looking at arc welding.

25 The Human Brain and Senses: TheEye The Eye Vision interacts between outside light, the eye structures, and your brain. We are not really looking at the object, but instead we are looking at the reflection from the light of the object. Step 1 Light hits your cornea which focuses the image. Together with the Aqueous Humor they create the exterior lens. Cornea- The curved outer surface of your eye. Aqueous Humor- Watery fluid behind the cornea Step 2 Light enters the eye through the pupil of the iris. Pupil A small opening that adjusts with the amount of light. Iris The wall that covers your lens but is open for your lens. A pupil will adjust to a variety of lights. The less light there is, the bigger your pupil. The more light there is, the smaller your pupil. Step 3 Once the light passes through the pupil, it becomes more focused at the lens. Lens A focuser that lies just behind the pupil.

26 Step 4 Light then passes through the vitreous humor and projects onto the retina. Vitreous Humor The jelly that fills the bulk of the eye. Retina A delicate tissue filling the back half of the eye which light is reflected upon. Step 5 The retina transforms light into electrical signals which travels to the brain through the optic nerve. Optic Nerve a tough white cordlike structure connecting the back of the eye to the brain. A cow eye, and a human eye have a lot of similarities but few differences. Human vs. Cow Eyes Human Eyes Cow Eyes Pupils are round. No tapetum in a human eye. Tapetum a second lining that helps you see better in the dark. Pupils are oval. A blue-green tapetum is present in a cow eye helping it see better at night. This usually reflects light better making their eyes more shiny when light is flashed on them, like a cat eye.

27 The Human Brain and Senses: Brain Perception If a tree fell in a forest would it make a sound? What we perceive is limited by the range of physical stimuli that our sensory organs can gather and transform into information that travels to the brain. How we see things is determined by what we gather through our senses and then push into our brain. The accuracy of our perception is not a function of our knowledge of the world, but is a function of our experience. For example when we see a curved surface combined with shadows and light, if the lighter part of the curve is on the top, we assume it to bulge out. Depth Perception We perceive depth because of the following factors: Two eyes or binocular vision. Separation of the eyes is about 7cm. This allows the line of sight to an object to be slightly different for each eye. The brain takes the images that come in from both eyes and process the two slightly different images to calculate depth. Both eyes converge on the same point. As an object gets closer, our eyes begin to cross as they focus on the object. The brain takes information about the angle of each eye to calculate how far away the object is.

28 Motion Perception The brain receives a sequence of individual images and blends them together (i.e. movies and television). Movies are nothing more than a series of still pictures being shown with slight movement one after the other. Like a flip book. Catching a Flick is used for going to the movies because in the in the early 1900 s, movies could not move the still shots quick enough making it flicker. Persistence of Vision - The brain s ability to hold onto and continue to see an image for a split second after it is no longer present. In order for this to be realistic though, the image can only move so far during each frame. Depth, Motion, and Color are all taken in the eyes differently but then combined together in the mind making us see. Perspective Illusion Ambiguous Figures Illusory Figures Recognition Our Amazing Brains Lines that begin to converge (grow closer) tend to look like it is further away. Any objects placed in that area of the drawing seem far away. Our brain compensates for this distance. An image that can be perceived in two ways. The brain tends to see organization, even when there is none present. Several unconnected elements appear to form a figure. Two processes are involved in recognizing something. 1. We perceive the physical properties of the object itself. Our brain reacts to contrast well, so we tend to notice an object s edges and lines. 2. Our brain calls attention to things that are smaller than their surroundings, things that are symmetrical, and things that are vertically or horizontally oriented. One of the most complex abilities our brain has is recognizing faces.

29 Our brain processes information about the features and patterns of a particular face so that we can recognize a person, even when we see them from another angle. We gain this ability as newborns. Misconceptions Ambiguous Figures Unstable Figures Figure-Ground Illusions Illusory Figure Visual Aftereffects Impossible Figure Shape, Size and Length Distortion Perceptual Set Word Perceptions Orientation Illusion From the Eyes to the Brain Even the most sophisticated computers cannot recognize faces. Perceiving something that does not correspond to what is real. These illusions fool us and convince us of things that are not real. Two or more different figures in one figure. Different parts of a figure appear to be closer to the viewer. Difficult to distinguish figures from their background. Seeing something that is not there. Opposite color images after staring and looking away. Logical, but impossible to manufacture in three dimensions. Shape, size, or length distortion is due to field interference. If you notice the person is just in the distant background. Perceptions influenced by expectations. If we are thinking about letters, we see A B C. If we are thinking about numbers we see Words in a nonphonetic languages are subject to some form of distortion. Try to only tell the color, not the word. Totally different images are seen when viewing one picture from a different angle or distance. Close up on GW, and you will see pictures of other people. Different angle on the trees, and you will see no faces. Once the optical system projects an image on the retina, a series of electrochemical interactions begins. The photoreceptors (cones and rods) transform the image (light energy) into electric messages. These messages are transmitted through neurons (nerve cells).

30 The neurons converge at the optic disk where the optic nerve (a thick bundle of nerves) is connected to the eye. Both optic nerves extend into the skull and join at a point called the optic chiasm. The optical nerves continue to the back of the brain. Processing of the images begin in the lateral geniculate nucleus (LGN) The images end up in the back of the brain at the visual cortex. Images from both eyes are processed together to form a complete image.

31 Parts of the Brain Cerebrum: The large wrinkled portion that makes up most of the brain. Has two halves or hemispheres Left and Right These two halves look symmetrical and communicate with each other. Organized into four major lobes Frontal: behind the forehead. Temporal: Along the side in from the ear. Occipital: In the back. Parietal: On the top Cerebellum: underneath the cerebrum, this smaller part of the brain is found in the center of the brain. Brain stem: An extension of the spinal cord. It is found in front of the cerebellum and below the cerebrum.

32 Looking into the Brain Looking at a living brain without opening the skull is done through a scan. Types of scans: Computerized axial tomography (CAT) produced with a computerized x-ray device. Magnetic resonance imaging (MRI)- As a person is slid into a tunnel-shaped scanner, a magnetic field surrounds them. Radio waves are beamed to the area. Electroencephalography (EEG)- measures electric activity in the brain by attaching electrodes to a patient s head. Positron emission tomography (PET) Low-dose radioactive isotope is detected by injecting a substance into the patient. This substance is detected in the brain by the scanner.