Modeling Adult Visual Function Dr. James A. Bednar jbednar@inf.ed.ac.uk http://homepages.inf.ed.ac.uk/jbednar CNV Spring 2012: Modeling adult function 1
Surround modulation (Series et al. 2003) Apparent contrast Detection facilitated Contour pops out reduces Many types of contextual interactions are known CNV Spring 2012: Modeling adult function 2
Surround modulation Effects depend strongly on contrast (Hirsch & Gilbert 1991), (Weliky et al. 1995) and on (Schwabe et al. 2006) distance Distance- related effects match both lateral and feedback connections CNV Spring 2012: Modeling adult function 3
Proposed model circuit From Schwabe et al. (2006): High-threshold inhibitory interneurons (Schwabe et al. 2006) Long-range excitatory lateral connections Long-range excitatory feedback connections CNV Spring 2012: Modeling adult function 4
LISSOM/GCAL SM model • LISSOM/GCAL circuit for V1 L2/3I surround modulation • Separate inhibitory interneurons V1 L2/3E • Long-range excitatory lateral connections • Separate simple and V1 L4 complex cell layers • Feedback connections in progress (Philipp Rudiger) (Antolik 2010; Antolik & Bednar 2012) CNV Spring 2012: Modeling adult function 5
SM model size tuning (Antolik 2010) Single-unit response to larger patterns typically increases, then decreases as inhibition is recruited CNV Spring 2012: Modeling adult function 6
Diversity in size tuning (Antolik 2010) Model matches both typical and unusual size tuning responses CNV Spring 2012: Modeling adult function 7
Diversity in OCTC tuning (Antolik 2010) Model matches both typical and unusual orientation-contrast tuning types CNV Spring 2012: Modeling adult function 8
The Tilt Aftereffect (TAE) • Bias in orientation perception after prolonged exposure • Allows model structure to be related to adult function • Classic explanation: “fatigue” – activated neurons get tired, shifting the population average away CNV Spring 2012: Modeling adult function 9
Measuring perceived orientation Average: o OR preference = −3.0 Activation Neuron 2: o OR preference = 0.0 Activation = 1.0 Neuron 3: o OR preference = −16.8 Activation = 0.6 Neuron 1: o OR preference = +22.5 Activation = 0.24 • Assumption: perception based on population average • Vector average good for cyclic quantities • Decode perception before and after adaptation CNV Spring 2012: Modeling adult function 10
TAE in Humans and LISSOM o 4 Aftereffect Magnitude • Direct effect for o 2 small angles o 0 • Indirect effect for larger angles o −2 • Null effect at o −4 training angle o o o o o o o −90 −60 −30 0 30 60 90 Angle on Retina • Human, model match closely Mitchell & Muir 1976 HLISSOM CNV Spring 2012: Modeling adult function 11
TAE Adaptation in LISSOM • Null at zero : More inhibition, but no net Adaptation + change in perception − 0 ◦ • Direct effect: More inhibition for angles < 10 ◦ + Direct – Perception shifts − from 10 to 14 ◦ 10 ◦ • Indirect effect: Less inhibition for angles < 60 ◦ + Indirect − – Perception shifts 60 ◦ from 60 to 58 ◦ • Due to synapses, not Input Histogram V1 Activity pattern difference tired neurons! CNV Spring 2012: Modeling adult function 12
McCollough effect test pattern Before adaptation, this pattern should appear monochrome CNV Spring 2012: Modeling adult function 13
Adaptation pattern Stare alternately at the two patterns for 3 minutes, moving your gaze to avoid developing strong afterimages CNV Spring 2012: Modeling adult function 14
McCollough effect (McCollough 1965) After adaptation: • Vertical bars should be slightly magenta • Horizontal bars should be slightly green • The effect should reverse if you tilt your head 90 ◦ , and disappear if you tilt 45 ◦ . CNV Spring 2012: Modeling adult function 15
McCollough effect: data • Effect measured in humans at each angle between (Ellis 1977) adaptation and test • Strength falls off smoothly with angle (Landisman & Ts’o 2002) • V1 is earliest possible substrate – first area showing OR selectivity; has 2.3 × 5.3mm macaque V1 color map CNV Spring 2012: Modeling adult function 16
LISSOM Color V1 Model • Input: RGB V1 images • Decomposed into LGN Red, Green Luminosity channels Green/Red (no blue in central (Bednar et al. 2005) Red/Green fovea, Calkins 2001 ) ON OFF Retina • Processed by color opponent Red Green Channel Channel retinal ganglia Color Image CNV Spring 2012: Modeling adult function 17
LISSOM OR + Color map (Bednar et al. 2005) • Orientation map similar to animal maps • Color-selective cells occur in blobs • Preferences of neurons in each blob? CNV Spring 2012: Modeling adult function 18
Calculating McCollough Effect • Perceived color estimated as a vector average of all units • Vector direction: + for red-selective units, - for green-selective units • Weighted by activation level and amount of color selectivity Result is a number from extreme red (positive) to extreme green (negative), with approximately 0 being monochrome. CNV Spring 2012: Modeling adult function 19
Model McCollough Effect 6 4 strength of the ME (in the model) 2 0 −2 −4 −6 −45 −30 −15 0 15 30 45 60 75 90 105 120 135 orientation of the test pattern CNV Spring 2012: Modeling adult function 20
Compared with human 1.2 simulated ME human data 1 0.8 strength of the ME 0.6 0.4 0.2 0 −0.2 −45 −30 −15 0 15 30 45 orientation of the test pattern CNV Spring 2012: Modeling adult function 21
Summary • LISSOM/GCAL can be compatible with actual circuit • Reproduces surprising features of surround modulation • Afteffects arise from Hebbian adaptation of lateral connections • The same self-organizing processes can drive both development and adaptation: both structure and function • Novel prediction: Indirect effect due to weight normalization • Project: exactly how does inverted Mexican Hat work? CNV Spring 2012: Modeling adult function 22
McCollough Effect Is the effect still present? CNV Spring 2012: Modeling adult function 23
References Antolik, J. (2010). Unified Developmental Model of Maps, Complex Cells and Surround Modulation in the Primary Visual Cortex . Doctoral Dissertation, School of Informatics, The University of Edinburgh, Edinburgh, UK. Antolik, J., & Bednar, J. A. (2012). A unified developmental model of maps, com- plex cells and surround modulation in the primary visual cortex. In prepa- ration. Bednar, J. A., De Paula, J. B., & Miikkulainen, R. (2005). Self-organization of color opponent receptive fields and laterally connected orientation maps. Neurocomputing , 65–66 , 69–76. Calkins, D. J. (2001). Seeing with S cones. Progress in Retinal and Eye Research , 20 (3), 255–287. CNV Spring 2012: Modeling adult function 23
Ellis, S. R. (1977). Orientation selectivity of the McCollough effect: Analysis by equivalent contrast transformation. Perception and Psychophysics , 22 (6), 539–544. Hirsch, J. A., & Gilbert, C. D. (1991). Synaptic physiology of horizontal connections in the cat’s visual cortex. The Journal of Neuroscience , 11 , 1800–1809. Landisman, C. E., & Ts’o, D. Y. (2002). Color processing in macaque striate cortex: Relationships to ocular dominance, cytochrome oxidase, and orientation. Journal of Neurophysiology , 87 (6), 3126–3137. Law, J. S. (2009). Modeling the Development of Organization for Orientation Pref- erence in Primary Visual Cortex . Doctoral Dissertation, School of Infor- matics, The University of Edinburgh, Edinburgh, UK. Law, J. S., & Bednar, J. A. (2006). Surround modulation by long-range lateral CNV Spring 2012: Modeling adult function 23
connections in an orientation map model of primary visual cortex devel- opment and function. In Society for Neuroscience Abstracts . Society for Neuroscience, www.sfn.org. Program No. 546.4. McCollough, C. (1965). Color adaptation of edge-detectors in the human visual system. Science , 149 (3688), 1115–1116. Mitchell, D. E., & Muir, D. W. (1976). Does the tilt aftereffect occur in the oblique meridian?. Vision Research , 16 , 609–613. Schwabe, L., Obermayer, K., Angelucci, A., & Bressloff, P . C. (2006). The role of feedback in shaping the extra-classical receptive field of cortical neurons: A recurrent network model. The Journal of Neuroscience , 26 (36), 9117– 9129. CNV Spring 2012: Modeling adult function 23
Series, P ., Lorenceau, J., & Fregnac, Y. (2003). The “silent” surround of V1 recep- tive fields: Theory and experiments. Journal of Physiology (Paris) , 97 (4– 6), 453–474. Weliky, M., Kandler, K., Fitzpatrick, D., & Katz, L. C. (1995). Patterns of excitation and inhibition evoked by horizontal connections in visual cortex share a common relationship to orientation columns. Neuron , 15 , 541–552. CNV Spring 2012: Modeling adult function 23
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