Documents about Optic Nerve

  • 2 Pages

    Class Notes - 10-10-07

    Allegheny, PSYCH 105

    Excerpt: ... stics of the environment o Also sensitive to different types of drugs. Results in iris changing its shape Example: Heroin causes constriction of the Iris Hallucinogens increase activation of the parasympathetic nervous system very dilated, wide open pupils. o Iris controls the color and the size of the pupil opening. Lens transparent and is behind the pupil o Changes in the shape of the lens bring objects into or out of focus Nearsightedness or farsightedness in addition to the shape of the eyeball being different Light from distant objects focus in front of the retina farsightedness. Light from distant objects come into focus behind the retina nearsightedness We all have a blind spot o Optic nerve distinct anatonomical nerve NO RODS AND CONES RIGHT WHERE THE OPTIC NERVE Your cortex fills in the blind spot with information from the opposite eye 2 eyes allows us to see in 3-D (fine depth perception) Blindness in one eye causes compromised depth perception (still have depth perception , bu ...

  • 5 Pages

    lecture_notes_12_(ta)

    UC Davis, NPB 101

    Excerpt: ... the retina, the ganglion cells, which send their axons out of the eye to form the optic nerve (Figure 6-22). Half of the fibers in each optic nerve cross at a junction called the optic chiasm, and then project to the visual thalamus. This crossover insures that the left half of the visual field will be represented in the right thalamus and vice versa (Figure 6-31). The thalamic neurons project to the primary visual cortex, where information from the two eyes is first integrated (Figure 6-32). The primary visual cortex sends its projections to multiple secondary visual cortical areas. Processing in these areas is responsible for our perception of the visual world. The spatial relationships among the photoreceptors in the retina are preserved at each step of the pathway. In this manner a retinotopic map of the contralateral visual field is maintained at each stage of the pathway. (see end of Notes Supplement) Auditory Afferent signals from the hair cells are relayed to the output neurons of the inner ear wh ...

  • 2 Pages

    bio lab notes

    MCPHS, BIO 152

    Excerpt: ... Notes for bio lab quiz Nervous system -most complex system in the mammalian body both in structure and in function. -function: control and coordinate body functions and allow the organism to operate an an integrated whole. -functional unit = neuron -3 kinds of neurons: sensory, interneuron, and motor -nervous system can be divided into the CNS (brain & spinal cord) and PNS (all nerve tissue outside CNS) Brain -3 main areas: cerebellum, cerebrum, and the brain stem -Cerebrum: intelligence, memory, sensory perception *has folds (gyri) *composed of 2 hemispheres separated by the longitudinal fissure (the transwerve fissure separates the cerebrum from the cerebellum) -Cerebellum: motor activities, equilibrium -Brain Stem: breathing, circulation, reflexes -olfactory lobes: smell - optic nerve s: vision -pituitary gland: secretes variety of hormones -pons: passageway for nerves running from the medulla to higher centers of the brain -corpus callosum: connects the 2 cerebral hemispheres -thalamus: regulator of sensory ...

  • 21 Pages

    Lec18 02_25_08 Brain and vision

    UCF, BSC 1005

    Excerpt: ... hasis in language Musical/ Artistic ability Romance Left brain Right brain Right half cortex Connection corpus callosum Seeing with our brain the primary visual cortex Visual system partial cross-wiring Image reversed by lens Retinal fields split Left and right halves Send info to right and left visual cortex Images on right go to left visual cortex. Vice versa Visual fields Optic nerve s Cross at optic chiasma End in lateral geniculate nucleus (LGN) Optic nerve s end at LGN LGN nerves to occipital lobe 30+ regions different aspects of vision Human visual processes Increasing the focused field Depth perception Some defects in the visual system The roles of the brain in seeing Blind sight Defect in pathway to visual lobe Pathway to brain stem intact Role of corpus callosum Integration of right and left images Visual neglect Defect in parietal lobe Capgras delusion Connecting images to emotions B ...

  • 8 Pages

    Lec2-basic physiology of the senses

    Trinity College Dublin, PSYCH 2006

    Excerpt: ... is not useful for colour and taste. Qualitative is used for this, with qualitative there is a recpeot type for each type of stimulus. TRANSDUCTION- a process by which sensory receptors produce neural impulses when they receive physical or chemical stimulation. ABSOLUTE THRESHOLD- the minimum intensity of stimulation that must occur before one can experience a sensation. DIFFERENCE THRESHOLD- the minimum amount of change required in order to detect a difference between intensities of stimuli. The stimuli, receptors and pathways for each sense SENSE Hearing Vision STIMULUS Sound waves Light waves RECEPTORS Pressure-sensitive hair cells in the cochlea of inner ear Light-sensitive rods and cones in retina of eye Sensitive ends of touch neurons in skin Sensitive ends of pain neurons in skin and other tissues Taste cells in taste buds on the tongue PATHWAY TO THE BRAIN Auditory nerve (8th cranial nerve) Optic nerve (2nd cranial nerve) Touch Pressure on the skin TRIGEMINAL nerve (5th cranial nerve) for ...

  • 2 Pages

    class notes 3-27

    Philadelphia, PSYCH 101

    Excerpt: ... Iris controls the size of the pupil (smaller too much light, bigger not enough) Periphery are where the receptors are to dim illumination Retina is a many clear layered membrane, which contains the important receptors for vision (photo receptors) The image on the retina upside down and a mirror image, the connection to the brain straightens it out. Also known as the laws of optical projection The receptors in the retina are in the back, for protection The cones are in the center of the retina and the rods are located in the in the periphery Cones: 6 million, center=fovea, used for bring illumination, pickup clear details, responsible for full color Rods: 120 million, out edges=periphery, used for dim illumination, totally colorblind, dark adaptation Rods are the most sensitive in dim light Visual purple is what the rods need to work in dim illumination From the receptors, the nerve fibers leave the eyeball through the meshwork going to the brain. Visual information processing The optic nerve fiber going into ...

  • 16 Pages

    Lec4DevtVision

    UCSD, PSYC 106

    Excerpt: ... directs axons from the posterior retina to the anterior portion of the tectum. Fig. 5-7, p. 127 Sperry = Cut optic nerve & invert eye = optic nerve axons grow back to original targets. Evid. for chemical guide Fig. 5-6, p. 127 Apoptosis of motor neurons in ventral spinal cord of human fetus VIDEO 1: Secret Life of the Brain baby cataracts Visual system neurons: use it or lose it Axons that fail to make synapses die Fig. 5-8, p. 129 VIDEO 2: Secret Life of the Brain stroke recovery of penumbra? Fig. 5-14, p. 139 Plasticity After Brain Damage Phantom limb refers to the continuation of sensation of an amputated body part Can lead to the feeling of sensations in the amputated limb when other body parts are stimulated Cortex reorganizes after amputation: Original somatosensory cortical axons degenerate leaving vacant synaptic sites into which others axons sprout. Example: amputated hand ctx neurons degenerate, face neurons move (sprout) in Fig. 5-16, p. 141 VIDEO 3: Phan ...

  • 3 Pages

    lecture 5

    UC Davis, PSC 001

    Excerpt: ... people see black. ii. The Trichromatic theory states that you can see all three wavelengths. iii. Color deficiency is when one or more groups of cones are not functioning correctly. iv. The Opponent Process theory states that some colors are opponents of others. Some colors make your cones work really hard, and neurons get tired, so the second you stop looking at that object you see the opposite color. 1. This is how after images work. b. The Optic nerve projects images to the thalamus. i. 90% of the information gets projected to the thalamus, which determines what is important and what is not. 1. the information goes into the occipital love of the cortex. PSC 1-3 Lecture 5 Page 2 of 3 a. The dorsal stream informs us where something is. It flows into the parietal lobe. i. When this is damaged people cannot recognize where something is. b. The ventral stream flows into the temporal cortex and tells us what something is. i. Prosopagnosia is the inability to recognize faces that someone used to recognize be ...

  • 15 Pages

    vision

    UNC, BIOL 252

    Excerpt: ... or) The Eye Items to note: 1. Cornea 2. Iris / Pupil 3. Lens 4. Ciliary Body 5. Optic disc 6. Optic nerve Vision Part 1: Focusing Light To reach retina, light passes through the: Cornea Aqueous humor Lens Vitreous humor Cornea and lens focus light onto the retina Air/water interface at cornea bends light (refraction) Lens dynamically adjusts its shape to fine-tune focus (accommodation) Vision Part 1: Focusing Light Accommodation by lens For objects far away, ciliary muscles relaxed, lens flat For objects up close, ciliary muscles contracted, lens round Vision Part 1: Focusing Light Problems with light focusing Eyeball too long Eyeball too short or Cornea too round or Cornea too flat nearsighted farsighted Vision Part 1: Focusing Light LASIK Laser Assisted In Situ Keratomileusis Precise method of reshaping cornea to correct refractive issues Flap cut into cornea (by knife or, more recently, laser) Laser zaps away tiny amounts of co ...

  • 7 Pages

    +Vision

    University of Michigan, BIOMEDE 418

    Excerpt: ... BME 418, Quantitative Cell Biology Lecture #23: Signal Transduction - Vision, a special case Alan J. Hunt Eye: We won't dwell on the optics. It will suffice to be aware that the lens forms an image on the retina. Note fovia and blind spot where optic nerve attaches. Features of the visual system: - functions well over 5 orders of magnitude (photographic film only 1-2) - time resolution: "flicker-fusion" frequency = 20 Hz - distance from lens to retina is ~ constant, the focal length (f) must be varied to form images of objects at different distances (1/p + 1/q = 1/f) BME 418, Quantitative Cell Biology Alan J. Hunt Retina: - - - - photoreceptive cells = rods, cones these form synapses with various cells that carry electrical response passively to ganglionic cells, which then send a actively propagated action potential down the optic nerve Pigmented epithelium absorbs light, helps isolate photoreceptors (increase resolution). In cat this reflects light to increase sensitivity (two passes through recep ...

  • 7 Pages

    Lecture 23 Vision

    University of Michigan, BIOMEDE 418

    Excerpt: ... BME 418, Quantitative Cell Biology Lecture #23: Signal Transduction - Vision, a special case Alan J. Hunt Eye: We won't dwell on the optics. It will suffice to be aware that the lens forms an image on the retina. Note fovia and blind spot where optic nerve attaches. Features of the visual system: - functions well over 5 orders of magnitude (photographic film only 1-2) - time resolution: "flicker-fusion" frequency = 20 Hz - distance from lens to retina is ~ constant, the focal length (f) must be varied to form images of objects at different distances (1/p + 1/q = 1/f) BME 418, Quantitative Cell Biology Alan J. Hunt Retina: - - - - photoreceptive cells = rods, cones these form synapses with various cells that carry electrical response passively to ganglionic cells, which then send a actively propagated action potential down the optic nerve Pigmented epithelium absorbs light, helps isolate photoreceptors (increase resolution). In cat this reflects light to increase sensitivity (two passes through recep ...

  • 7 Pages

    sample_midterm_3_2006

    UC Davis, NPB 100

    Excerpt: ... (3 pts) The subject has complete blindness. Left Optic Nerve Optic Chiasm Right V1 Left Optic Tract Left Thalamus 8b. (3 pts) The subject can only perceive the left visual field. Left Optic Nerve Optic Chiasm Right V1 Left Optic Tract Left Thalamus 8c (3 pts) The subject can only perceive objects presented to the right eye. Left Optic Nerve Optic Chiasm Right V1 Left Optic Tract Left Thalamus Question 9 (total points 3) 9a. (1 pt) What is the most common excitatory neurotransmitter in the human brain? 9b. (1 pt) What is the most common inhibitory neurotransmitter in the human brain? 9c. (1 pt) What is one neurotransmitter that has a modulatory effect in the human brain? GO ON TO NEXT PAGE! 6 YOUR NAME_ Social Security #_ Question 10. (Total points 8) 10a. (4 pts) Why is transmission at an electrical synapse much faster than transmission at a chemical synapse? 10b. (4 pts) Why do many IPSPs have close to zero amplitude? END OF MIDTERM #3 ...

  • 17 Pages

    W08Lec9VisionOutline[1]

    UCSD, PSYC 2

    Excerpt: ... Sensation & Perception I (Vision) Lecture 9 2/25/08 Eye what you should know Receptors: Receptors in visual system = Rods: Cones: How do we process external information, such as light? Transduction: Transduction occurs in all sensory systems (sensory info must be converted to a neural signal) Main visual pathway Light hits retina Rods or cones (receptors) induce neural signal (via ion exchange) Signal passed on to ganglion cells (GC) in retina GC axons form optic nerve which exits retina Thalamus (LGN) Most go to primary visual cortex (occipital lobe) Transduction of light in rods/cones retinal ganglion cells cone receptors rod receptors light back of eyeball to blind spot and optic nerve Visual Information travels to cortex Right visual field (RVF) Left visual field (LVF) Retinotopic map: areas close together in visual field (& on retina) are represented closely on visual cortex zeus.rutgers.edu/~ikovacs/ SandP/prepI_4_2.html Sensation & Perception Ma ...

  • 2 Pages

    quiz #2

    Indian Hills CC, ? ?

    Excerpt: ... 1. Sensation is the process by which we detect physical energy from the environment and encode it as neural signals. 2. Perception is the process by which the brain. organizes and interprets sensory information. 4. The absolute threshold is the minimum stimulation needed to detect a stimulus 50 percent of the time. 9. Sensory adaptation refers to the decreased sensitivity that occurs with continued exposure to an unchanging stimulus. 10. In the study of sensation, transduction refers to the process by which receptor cells in the eye, ear, skin, and nose convert environmental stimuli into neural impulses. 17. The retina is the light-sensitive, multilayered inner surface of the eye that contains the rods and cones, as well as neurons that form the beginning of the optic nerve . 18. The rods and cones are visual receptors that transduce light into neural impulses. The rods are concentrated in the periphery of the retina, the cones in the fovea. The rods have poor sensitivity, detect black and white, and function ...

  • 5 Pages

    discussion questions 1

    University of Texas, BIO 365R

    Excerpt: ... ell higher up What is meant by "lateral inhibition"? What purpose do you think it might serve? Mechanism by which neurons determine origin of a stimulus. Neurons that are stimulated suppress stimulation of nearby neurons What is meant by the term topographic projection? Give an example. Here are some terms which you should be able to define about the eye either from lecture, the notes, or look up on the web: myopia, hyperopia, presbyopia, optic nerve , bella donna, zonula fibers, lens, ciliary muscle, pupil, iris, astigmatism, bipolar cell, ganglion cell, horizontal cell, rod, cone 10. Describe how the lens is manipulated to change accomodation from that for a near object to one for a far object. Does this require the activation of muscles or their relaxation? Would you suggest this achieved by an increase or decrease in the impulse frequency of motor neurons? Which motor neurons are involved here? Describe the opposing action of the sympathetic and parasympathetic nervous systems on the diameter of the pup ...