THE CENTRAL VISUAL SYSTEM
RETINOFUGAL PROJECTIONIt’s the neural pathway that leaves the eye and it include:The Optic Nerve, Optic Chiasm, and Optic ...
RETINOFUGAL PROJECTIONThe visual field is the entire region of the space that could be seen by both  eye looking straight ...
RETINOFUGAL PROJECTION           LGN             Optic radiation                                  R optic tractretina     ...
RETINOFUGAL PROJECTION              Transection              Optic nerve                                     Transection  ...
THE LATERAL GENICULATE NUCLEUSIn the LGN is present the segregation of input by Eye and by Ganglion Cell Type
THE STRIATE CORTEXRetinotopy    Neighboring representation of the object are spatially kept along all the visual    pathwa...
THE STRIATE CORTEX
THE STRIATE CORTEXLamination of the Striate Cortex (I – VI)   Spiny stellate cells: Spine-covered dendrites mainly in laye...
THE STRIATE CORTEXOutputs of the Striate Cortex:    Layers II, III, and IVB: Projects to other cortical areas    Layer V: ...
THE STRIATE CORTEXOcular Dominance ColumnsInformation coming from the left and the right eye (already segregate in LGN) is...
THE STRIATE CORTEXCytochrome Oxidase Blobs    Cytochrome oxidase is a mitochondrial enzyme used for cell metabolism    Blo...
THE STRIATE CORTEXReceptive Fields outside Layer IVC   Orientation Selectivity: Neuron fires action   potentials in respon...
THE STRIATE CORTEXReceptive Fields   Direction Selectivity: Neuron fires action potentials in response to moving bar   of ...
THE STRIATE CORTEXParallel Pathways: Magnocellular; Koniocellular; Parvocellular
THE STRIATE CORTEXCortical Module: dimension of 2x2mm.Necessary and sufficient module for the visual perception
THE EXTRASTRIATE CORTEXDorsal stream (V1, V2, V3, MT, MST, Otherdorsal areas)    Analysis of visual motion and the visual ...
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Ch10

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Ch10

  1. 1. THE CENTRAL VISUAL SYSTEM
  2. 2. RETINOFUGAL PROJECTIONIt’s the neural pathway that leaves the eye and it include:The Optic Nerve, Optic Chiasm, and Optic Tract
  3. 3. RETINOFUGAL PROJECTIONThe visual field is the entire region of the space that could be seen by both eye looking straight ahead. Right and Left Visual Hemifields are defined by the space divided by the midline temporal retina nasal temporal retina retina
  4. 4. RETINOFUGAL PROJECTION LGN Optic radiation R optic tractretina V1 R LGN R optic radiation V1
  5. 5. RETINOFUGAL PROJECTION Transection Optic nerve Transection Optic chiasmTransectionOptic tract
  6. 6. THE LATERAL GENICULATE NUCLEUSIn the LGN is present the segregation of input by Eye and by Ganglion Cell Type
  7. 7. THE STRIATE CORTEXRetinotopy Neighboring representation of the object are spatially kept along all the visual pathway In the cortex there is an overrepresentation of central visual field Perception is based on the brain’s interpretation of this information
  8. 8. THE STRIATE CORTEX
  9. 9. THE STRIATE CORTEXLamination of the Striate Cortex (I – VI) Spiny stellate cells: Spine-covered dendrites mainly in layer IVC, they receive information from LGN Pyramidal cells: Spines; thick apical dendrite; mainly layers III, IVB, V, VI Inhibitory neurons: Lack spines; All cortical layers; Forms local connections Magnocellular LGN neurons: Project to layer IVCα Parvocellular LGN neurons: Project to layer IVCβ Koniocellular LGN axons: Bypasses layer IV to make synapses in layers II and III
  10. 10. THE STRIATE CORTEXOutputs of the Striate Cortex: Layers II, III, and IVB: Projects to other cortical areas Layer V: Projects to the superior colliculus and pons Layer VI: Projects back to the LGN Receptive Fields in Layer IV C Layer IVC: Monocular; center-surround receptive field (like in LGN) Layer IVCα: Insensitive to the wavelength – projection from Magno Layer IVCβ: Center-surround color opponency - projection from Parvo Binocularity Layers superficial to IVC: First binocular receptive fields in the visual pathway
  11. 11. THE STRIATE CORTEXOcular Dominance ColumnsInformation coming from the left and the right eye (already segregate in LGN) is keptseparate in layer IV of the visual cortex Only on layer III mixing of the information from the two eyes
  12. 12. THE STRIATE CORTEXCytochrome Oxidase Blobs Cytochrome oxidase is a mitochondrial enzyme used for cell metabolism Blobs: Cytochrome oxidase staining in cross sections of the striate cortex. Each centered on a ocular dominance stripe in layer IV Color-sensitive, monocular, with no orientation or direction selectivity. They are specialized for the analysis of object color The neuron observed in the space between Blobs (interblob) are binocular, with orientation or direction selectivity.
  13. 13. THE STRIATE CORTEXReceptive Fields outside Layer IVC Orientation Selectivity: Neuron fires action potentials in response to bar of particular orientation
  14. 14. THE STRIATE CORTEXReceptive Fields Direction Selectivity: Neuron fires action potentials in response to moving bar of light
  15. 15. THE STRIATE CORTEXParallel Pathways: Magnocellular; Koniocellular; Parvocellular
  16. 16. THE STRIATE CORTEXCortical Module: dimension of 2x2mm.Necessary and sufficient module for the visual perception
  17. 17. THE EXTRASTRIATE CORTEXDorsal stream (V1, V2, V3, MT, MST, Otherdorsal areas) Analysis of visual motion and the visual control of action In Area MT (temporal lobe) most cells: Direction-selective; Respond more to the motion of objects than their shape Area MST (parietal lobe) for navigation, directing eye movements, motion perceptionVentral stream (V1, V2, V3, V4, IT, Otherventral areas) Perception of the visual world and the recognition of objects, Area V4 orientation and perception of color Area IT is major output of V4. Receptive fields respond to a wide variety of colors and abstract shapes. Important also for memory

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