1 / 12

Exam in 12 days

Exam in 12 days. in class assortment of question types including written answers. Read this article!. How does the visual system represent visual information?. Brainstorm this: what are the different ways the visual system might encode a feature?.

wyatt
Télécharger la présentation

Exam in 12 days

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Exam in 12 days • in class • assortment of question types including written answers

  2. Read this article!

  3. How does the visual system represent visual information? • Brainstorm this: what are the different ways the visual system might encode a feature?

  4. How does the visual system represent visual information? • Brainstorm this: what are the different ways the visual system might encode a feature? • “labeled lines” • many different subnetworks of neurons - activity in a network indicates presence/nature of a feature • spike timing • absolute rate or # of spikes per second might indicate presence/nature of a feature • “multiplexed” • Hybrid of these two

  5. Visual Pathways • Themes to notice: • Contralateral nature of visual system • Information is organized: • According to spatial location • According to features and kinds of information

  6. Visual Pathways • Image is focused on the retina • Fovea is the centre of visual field • highest acuity • Peripheral retina receives periphery of visual field • lower acuity • sensitive under low light

  7. Visual Pathways • Retina has distinct layers

  8. Visual Pathways • Retina has distinct layers • Photoreceptors • Rods and cones respond to different wavelengths

  9. Visual Pathways • Retina has distinct layers • Amacrine and bipolar cells perform “early” processing • converging / diverging input from receptors • lateral inhibition leads to centre/surround receptive fields - first step in shaping “tuning properties” of higher-level neurons

  10. Visual Pathways • Retina has distinct layers • signals converge onto ganglion cells which send action potentials to the Lateral Geniculate Nucleus (LGN) • two kinds of ganglion cells: Magnocellular and Parvocellular • visual information is already being shunted through functionally distinct pathways as it is sent by ganglion cells

  11. Visual Pathways • visual hemifields project contralaterally • exception: bilateral representation of fovea! • Optic nerve splits at optic chiasm • about 90 % of fibers project to cortex via LGN • about 10 % project through supperior colliculus and pulvinar • but that’s still a lot of fibers! Note: this will be important when we talk about visuospatial attention

  12. Visual Pathways • Lateral Geniculate Nucleus maintains segregation: • of M and P cells • of left and right eyes P cells project to layers 3 - 6 M cells project to layers 1 and 2

More Related