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Biology 70, Fall 2007 Handouts Lectures #2-#3 1 Biology 70, Fall 2007 Handouts Lectures #2-#3 Biology 70 Lectures #2-#3 Biology 70 Part II Sensory Systems lectures 2-3 http://www.biology.ucsc.edu/classes/bio70/ better make it a triple (3 x) 1 2 Blind spot demonstration (close left eye) Blind spot 3 4 temporal right eye nasal light microscope picture of the retinal layers (≈ fig 6.16 Kalat) •••• + 0 5 6 1 Biology 70, Fall 2007 Handouts Lectures #2-#3 retina is “backwards” rods and cones back of eye (choroid) interior of eye (vitreous humor) 7 8 micrograph of rods and cones (≈ fig. 6.8 Kalat) from lecture outline 1. What are the differences between the rod and cone receptors with respect to: a. numerosity d. color vision b. distribution across the retina e. visual resolution c. scotoptic and photopic vision 9 10 cross section of fovea (note cones only and pit) light 11 12 2 Biology 70, Fall 2007 Handouts Lectures #2-#3 visual cell: firing rate vs intensity and recovery from light adaptation Figure 5.4 E & B scotopic [rods] vs photopic [cones] sensitivity (E&B fig. 5.6 ) more light ¹ greater firing rate (given state of adaptation) brighter longer in dark (greater ‘dark adaptation’) ¹ higher sensitivity to light longer time in dark in time longer 13 14 from lecture outline from lecture outline 1. What are the differences between the rod and cone receptors with respect to: 5. Understand how the following psychophysical Ê a. numerosity d. color vision Ê phenomena are related to processes occurring in the Ê b. distribution across the retina e. visual resolution c. scotoptic and photopic vision Ê retina: Ê a. dark adaptation b. Pulfrich pendulum c. Mach band 15 16 dark adaptation sea lion psychophysics (Long Marine Lab) 17 Dave Levinson, UCSC18 3 Biology 70, Fall 2007 Handouts Lectures #2-#3 do the marine animals have cones as well as rods ?? Sprouts (cones) Rio (cones) Burnyce (no cones) Pulfrich Pendulum 19 20 Pulfrich pendulum: latency vs light intensity Pulfrich Pendulum 21 22 this illustrates: contrast this illustrates: contrast 23 24 4 Biology 70, Fall 2007 Handouts Lectures #2-#3 neural network for: lateral inhibition LATERAL INHIBITITION: Kalat figures on pp 168-169 25 26 limulus– horseshoe crab recording from limulus eye 27 28 from lecture #2-#3 outline Mach Bands 5. Understand how the following psychophysical phenomena are related to processes occurring in the retina: ‘darker than dark’ ‘brighter than bright’ Ê a. dark adaptation Ê b. Pulfrich pendulum bright Ê c. Mach band dim actual perceived 29 30 5 Biology 70, Fall 2007 Handouts Lectures #2-#3 from lecture #2-#3 outline from lecture #2-#3 outline 2. Know the following terms associated with the cells of the retina and retinal structure: Ê 4. Lateral inhibition is an important example of coding by neural networks. Be sure to understand the discussion on pp. 167-169 a. rods e. amacrine cells in Kalat and the limulus evidence pictured in the “Lateral b. cones f. ganglion cells Inhibition” figure from Scientific American reproduced in “figures for lectures 2-3”. Also the diagram used in class. c. horizontal cells g. ribbon synapse d. bipolar cells h. optic nerve 31 32 cells of the retina Ribbon Synapses triad dyad 33 34 from lecture #2-#3 outline from lecture #2-3 outline 2. Know the following terms associated with the cells of the retina and 3. What are the synaptic connections among the cells of the retina? retinal structure: What kinds of information are coded by each cell type (very a. rods Ê e. amacrine cells Ê generally)? In vertebrates, do receptors hyperpolarize or depolarize b. cones Ê f. ganglion cells Ê in response to light? (See figures 6.2 and 6.15 in Kalat and figure in “figures for lectures 2-3”. c. horizontal cells Ê g. ribbon synapse Ê d. bipolar cells Ê h. optic nerve Ê 35 36 6 Biology 70, Fall 2007 Handouts Lectures #2-#3 electrical activity in retinal cells: graded vs action potentials What types of patterns selectively activate cells in the visual system? [receptive fields] Are differing aspects of an image processed by different parts of the brain? [concurrent pathways or streams] 37 38 Receptive Field (Kalat figure 6.18) Receptive Field (RF) Map of how light presented to various positions in the visual field excites or inhibits the firing of a neuron (this map or pattern is the cell’s receptive field). The receptive field indicates the “best” stimulus for the cell (i.e. the feature whose presence in a scene is signaled by the firing of the neuron). 39 40 movie of receptive field concentric receptive field of retinal ganglion cells on-center off-surround off-center on-surround 41 42 7 Biology 70, Fall 2007 Handouts Lectures #2-#3 Concentric Receptive Fields how receptors may be connected for on-center off-surround RF (found for ganglion cells) on-center off-surround 43 44 explanation of Hermann Grid illusion 45 46 explanation of Hermann grid Craik-Obrien Illusion 47 48 8 Biology 70, Fall 2007 Handouts Lectures #2-#3 nothing-for-nothing something-for-something 49 50 something-for-nothing (Craik-Obrien) nothing-for-something 51 52 Craik-Obrien Illusion: explanation from lecture outline: lectures #2-#3 7. Understand the following functional concepts: a. receptive field g. simple cell something-for-something Ê b. retinotopic map h. complex cell c. feature detector i. "grandmother" cell ↑ ↑ Ê d. concentric on-center≈ receptive field j. spatial frequency detector s s Ê g g e. concentric off-center receptive field k. what vs where pathways something-for-nothing ↓ ↓ f. orientationally tuned neuron Ê (same outside and center bright nesses) ↑ ↑ 9. What does the Craik-Obrien illusion imply about information processing by s s the visual system? nothing-for-something Ê ↑ ↑ nada g g sharp change in spatial brightness: PERCEIVED 53 54 gradual change in spatial brightness: NOT PERCEIVED 9 Biology 70, Fall 2007 Handouts Lectures #2-#3 central visual pathways 55 56 V1, V2, IT, MT, MST MST retinotopic map 57 58 concurrent pathways magnocellular vs parvocellular [in “low level” streams] Concurrent Processing temporal (ventral) vs parietal (dorsal) [in ‘streams’ “higher level” processing] 59 60 10 Biology 70, Fall 2007 Handouts Lectures #2-#3 what (temporal, ventral) vs where (parietal, dorsal) pathways Figure 6.19 Kalat– Concurrent processing streams MST 61 62 n’er do well good guys 63 64 from lecture outlines: lectures #2-#3 6. Know the following terms related to the gross anatomy of the central visual system and their general function in visual information processing. a. optic nerve f. inferior temporal cortex Ê b. optic chiasm Ê g. medial temporal cortex (MT, V5) and medial Ê Ê superior cortex (MST) c. lateral geniculate Ê nucleus (LGN) d. superior colliculus h. ventral (temporal cortex) vs. Ê Ê dorsal (parietal cortex) streams e. visual cortex (V1, V2, V4) i. fusiform area Ê 9. In the "simple" picture what are the types of information selectively processed by the parvocellular and magnocellular pathways (pp. 162-164, Table 6.2 Ê and Figure 6.21 of Kalat)? 65 66 11 Biology 70, Fall 2007 Handouts Lectures #2-#3 the what pathway: form perception In the initial stages of visual processing the visual system analyzes an image by detecting individual features in the image (ie by the ‘feature demons). These may be thought of as ‘letters’ of the image alphabet. Later, the elementary features are assembled into objects (‘words of “Classical” Feature Detection the image’ and complex images (by the cognitive demons). There are two competing theories on the nature of the individual features: CLASSICAL FEATURE DETECTION and SPATIAL FREQUENCY THEORY 67 68 simple cell 69 complex cell 70 “face cells” in monkey inferotemporal cortex 71 72 12 Biology 70, Fall 2007 Handouts Lectures #2-#3 Sinusoidal Gratings Spatial Frequency “Features” low spatial frequency high spatial frequency 73 high contrast low contrast 74 Demonstration of Adding Sinusoids 75 76 Anstis Demo: low frequency sinusoid (f) Anstis Demo: high frequency sinusoid ( ⅓ 3f) vertical blur yields ‘sinusoidal grating’ vertical blur yields ‘sinusoidal grating’ f ⅓ 3f 77 78 13 Biology 70, Fall 2007 Handouts Lectures #2-#3 Anstis Demo: combination (f+ 1/3 3f) Anstis Demo: combination (f+ 1/3 3f + 1/5 5f …….) ⅓ 3f + f 79 80 Anstis Demo: combination (f+ 1/2 2f + …..) Adding sinusoids (2D-Fourier synthesis) 1 frequency component (out of 32,000) 81 82 2 frequency components 4 frequency components 83 84 14 Biology 70, Fall 2007 Handouts Lectures #2-#3 16 frequency components 32 frequency components (0.1%) 85 86 64 frequency components (0.2%) 5% of total spatial frequencies 87 88 receptive fields of V1 cells which act as spatial frequency detectors 100% of total spatial frequencies 89 90 15 Biology 70, Fall 2007 Handouts Lectures #2-#3 “face cells” in monkey inferotemporal cortex 91 92 from lecture outline: lectures #2-#3 7. Understand the following functional concepts: a. receptive field Ê g. simple cell Ê face specific area b. retinotopic map Ê h. complex cell Ê (fusiform face area) c. feature detector ≈ Ê Ê i. "grandmother" cell Ê d. concentric on-center receptive fieldÊ j. spatial frequency detector Ê place specific area e. concentric off-center receptive fieldÊ k. what vs where pathways Ê (parahippocampal f. orientationally tuned neuron Ê place area) right left 8. What does the Craik-Obrien illusion imply about information processing by hemisphere hemisphere the visual system? Ê from Prof. Nancy Kanwisher, MIT, 2001 fMRI studies 93 94 from lecture outlines: lectures #2-#3 from lecture outline: lectures #2-#3 Ê 10. Compare the "classical feature" and "spatial frequency" models of 6.
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