Vision 2 - Vision 2 Module 1 Visual Pathways Visual input...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Vision 2: Module 1: Visual Pathways: Visual input from our right visual field travels along the optic nerve to the left hemisphere and visual input from the left visual field travels along the optic nerve to the right hemisphere A visual field receives information from both eyes and so, each hemisphere receives information from both eyes The axons from the inner regions of each retina (the region closest to the nose) have to cross over to the opposite hemisphere The point at which the optic nerves from the inside half of each eye crosses over to the opposite hemisphere is called the optic chiasm After the optic chiasm, the information from each visual field arrives in the opposite hemisphere at which point the optic nerve fibres split and travel along two pathways Most of the retinal or ganglion cells travel along the main pathway and synapse in the lateral geniculate nucleus , which is part of the thalamus that receives visual information After being processed here, the visual signals are sent to areas in the occipital lobe that make up the primary visual cortex A smaller portion of the axons from the retinas takes a detour to an area in the midbrain called the superior colliculus, after which the information is sent upwards to the thalamus and on to the occipital lobe or downward to the structures in the brain stem This smaller pathway seems to deal with coordinating visual input with information coming in from other senses, as well as localizing objects in space through head and eye movements and helping to guide those movements Within the main pathway there are two subdivisions of specialization that are able to process their specific information in parallel The magnocellular pathway is specialized to process movement information The parvocellular pathway deals specifically with colour and form information Main pathway: Lateral geniculate nucleus: The first stop for visual information that is sent from ganglion cells LGN cells also have receptive fields, made from a combination of many ganglion cells Information from many smaller bits is getting combined into one overall neural signal LGN is made up of 6 layers Information from each eye projects to different layers of the LGN Each layer also receives input from a specific subpathway Movement information that is processed along the magnocellular runs to 2 of the layers Information specific to the parvocellular pathway goes to the other 4 layers
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
From the LGN, the visual information is sent to the occipital lobe for further processing See vision 2 pathway There are over 20 cortical areas that process visual information but most research has been done on visual processing has concentrated on area V1 of the occipital lobe, known as the primary visual cortex The visual processing areas in the occipital lobe outside of the striate cortex are known as the extrastriate cortex Just as the receptive field of the LGN is made up of many ganglion cells, the receptive field of a single V1 cell is a combination of the receptive fields of many LGN cells
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2009 for the course PSYCHOLOGY 1XX3 taught by Professor Kim during the Spring '09 term at McMaster University.

Page1 / 7

Vision 2 - Vision 2 Module 1 Visual Pathways Visual input...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online