10 Vision II Vision II2 Image formation Vision II3 http://www.slideshare.net/drpsdeb/presentations Retina Vision II4 • Photoreceptors • Interneurons – Horizontal cells • Horizontal interconnection – Bipolar cells • Vertical interconnection – Amacrine cells • Both horizontal and vertical interconnection • Ganglion cells – AP generation – Transmission of AP to the brain http://www.slideshare.net/CsillaEgri/presentations Retina Vision II5 • Fovea – Low convergence • Small receptive field • High resolution – Lower sensitivity to light • Periphery of retina – High degree of convergence • Large receptive field • Low resolution – High sensitivity to light http://www.slideshare.net/CsillaEgri/presentations Receptive field Vision II6 http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II7 http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II8 http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II9 http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II10 • Magnocellular system – Large receptive field – Rods and cones – M ganglion cells (10%) – High speed of velocity – Brightness/low contrast sensitivity – Minimal sensitivity to color • Parvocellular system – Small receptive field – Cones and rods – P ganglion cells (80%) – Low speed of velocity – Low sensitivity in low contrast – Good sensitivity to color http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II11 • Magnocellular system – Large receptive field – Rods and cones – M ganglion cells (10%) – High speed of velocity – Brightness/low contrast sensitivity – Minimal sensitivity to color • Parvocellular system – Small receptive field – Cones and rods – P ganglion cells (80%) – Low speed of velocity – Low sensitivity in low contrast – Good sensitivity to color http://www.slideshare.net/drpsdeb/presentations Receptive field Vision II12 • Magnocellular system – Large receptive field – Rods and cones – M ganglion cells (10%) – High speed of velocity – Brightness/low contrast sensitivity – Minimal sensitivity to color • Parvocellular system – Small receptive field – Cones and rods – P ganglion cells (80%) – Low speed of velocity – Low sensitivity in low contrast – Good sensitivity to color http://www.slideshare.net/drpsdeb/presentations Optic nerve and optic tract Vision II13 • Optic nerve – Signal from one eye – Signal from „whole“ visual field • Optic tract – Signal from both eyes – Signal from half of visual field http://www.slideshare.net/CsillaEgri/presentations Optic nerve and optic tract Vision II14 • Optic nerve – Signal from one eye – Signal from „whole“ visual field • Optic tract – Signal from both eyes – Signal from half of visual field http://www.slideshare.net/CsillaEgri/presentations https://www.aafp.org/afp/2013/0901/p319.pdf Visual pathways Vision II15 • Nucleus corporis geniculati lateralis – Thalamus – Majority of projections – Via optic radiation to neocortex • Hypothalamus – Regulation circadian activity • Pretectum – Pupillary reflex • Colliculi superiores – Reflex movement of eyes and head http://www.slideshare.net/drpsdeb/presentations Nucleus corporis geniculati lateralis Vision II16 • Six nuclear layers • Retinotopic organization • Each layer receives input from only one eye • Layers 1-2 – Magnocellular system • M ganglion cells • Large receptive field/brightness sensitivity – Information about localization and movement • Layers 3-6 – Parvocellular system • P ganglion cells • Small receptive field / color sensitivity – Information about form and color http://www.slideshare.net/CsillaEgri/presentations Primary visual cortex Vision II17 Retinotopic organization http://www.slideshare.net/CsillaEgri/presentations http://www.slideshare.net/drpsdeb/presentations http://fourier.eng.hmc.edu/e180/lectures/v1/node2.html Gerald Schneider. 9.14 Brain Structure and Its Origins, Spring 2014. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed). License:Creative Commons BY-NC-SA http://www.slideshare.net/CsillaEgri/presentations Vision II18 Primary visual cortex Vision II19 Retinotopic organization http://www.slideshare.net/CsillaEgri/presentations http://www.slideshare.net/drpsdeb/presentations Primary visual cortex Vision II20 http://www.slideshare.net/drpsdeb/presentations ✓ Retinotopic organization ✓ Columnar organization • Orientation columns ➢ Respond to specific orientation • Blobs ➢ Respond to color • Occular dominance column ➢ Information from left or right eye ✓ Horizontal connections Spatial vision Binocular http://www.slideshare.net/drpsdeb/presentations Vision II21 Spatial vision Binocular http://www.slideshare.net/drpsdeb/presentations Monocular – based on previous experience Vision II22 Motion perception http://www.slideshare.net/drpsdeb/presentations 23 Vision II Vestibuloocular reflex http://d2avczb82rh8fa.cloudfront.net/content/jn/92/1/20/F3.large.jpg?width=800&height=600&carousel=1 24 Vision II Nystagmus Vision II25 • Involuntary rhythmic eye movement • Physiological – Postrotatinal – Optokinetic • Pathologic ✓ Peripheral • Vestibular system pathologies ✓ Central • CNS damage (cerebellum, midbrain…) http://dxline.info/img/new_ail/nystagmus.jpg Saccadic eye movements https://en.wikipedia.org/wiki/Saccade#/media/File:Szakkad.jpg Vision II26 Saccadic eye movements https://s-media-cache-ak0.pinimg.com/564x/51/f7/26/51f7267e7c8a59caa90f904cd4f965eb.jpg https://en.wikipedia.org/wiki/Saccade#/media/File:Szakkad.jpg Reflexive exploration Intentional exploration Assistance in controlling saccades during movement Vision II27 http://www.nature.com/nrn/journal/v5/n3/box/nrn1345_BX1.html Vision II28 Pupillary reflex http://www.ubooks.pub/Books/B0/E27R7642/MAIN/images/1509_Pupillary_Reflex_Pathways.jpg 29 Vision II 78. The basic physiology of visual system – rods and cones function, on/off receptive field, nervus opticus vs. tractus opticus Vision II30 • Rods and cons function • Characterization and comparison • Phototransduction mechanism and adaptation • Brief overview of retina organization (retina process receptor potential – analog, AP is generated in ganglion cells) • Receptive field organization • On/off receptive fields • Magnocellular system (BW) • Parvocellular system (Color) • Nervus opticus vs. tractus opticus • Projections from tractus opticus (Main centers in the brain involved in visual signals processing)