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Ophthalmology
Anatomy of Visual Pathway and Neurophysiology of Vision
Built from Khurana — Neuro-Ophthalmology
What’s inside
8 sections · 82 slides
Overview
- What this topic covers
Anatomy of the Visual Pathway
The relay chain from retina to occipital cortex
- The visual pathway - the whole chain at a glance
- The visual pathway from eye to occipital cortex
- Optic chiasma - the great crossroads
- Chiasma position over the pituitary
- Positions of the optic chiasma over the sella
- Relations of the optic chiasma
- Vascular and sellar relations of the chiasma
- Optic tracts and the lateral geniculate body (LGB)
- Optic radiations - the fan into the occipital lobe
- Course of the optic radiations
- Visual cortex - the final screen
- Striate and para-striate visual areas 17, 18, 19
- Six-layered microscopic structure of the cortex
Arrangement of Nerve Fibres
The seating plan at every station - the key to field defects
- Fibre arrangement in the retina
- Nerve-fibre pattern of the retina
- Fibre arrangement in the optic nerve
- Fibre lamination at the optic disc
- Fibre quadrants in the optic nerve
- Macular fibres central near the chiasma
- Fibre crossing in the optic chiasma
- Fibre crossing at the chiasma
- Fibre arrangement in the optic tract
- Fibre arrangement in the optic tract
- Fibre arrangement in the lateral geniculate body (LGB)
- Position of fibres in the lateral geniculate body
- Six-laminae relay in the lateral geniculate body
- Fibres in the optic radiations and visual cortex
- Fibre arrangement in the optic radiations
- Fibre relay in the visual cortex
Neurophysiology: the Retina
Turning light into signal and pre-processing it before it leaves the eye
- Genesis of the visual impulse in photoreceptors
- The dark current in a photoreceptor
- Phototransduction cascade
- Cone versus rod receptor potential
- Passing the signal on inside the retina
- Horizontal cells and lateral inhibition
- Lateral inhibition by horizontal cells
- Bipolar cells and their centre-surround field
- Centre-surround antagonism of bipolar cells
- Amacrine cells - timing and motion analysis
- Amacrine-cell reciprocal inhibition at the dyad
- Ganglion cells - the eye's output
- AM versus FM signalling in the retina
- Sustained X and transient Y cell responses
Transmission Along the Pathway
Optic nerve, chiasma, tract and the two channels of the LGB
- Optic nerve, chiasma and optic tract
- Lateral geniculate body - relay and gate
- Two channels through the LGB - magno vs parvo
- Electrophysiology of the LGB and the optic radiations
- Magnocellular and parvocellular channels
Analysis in the Visual Cortex
From dots to lines, columns, colour blobs and the specialized areas
- Retinotopy and the layout of the visual cortex
- Six-layered lamination of the visual cortex
- Connections of the primary visual cortex
- Receptive fields of the striate cortex
- Simple cells - orientation detectors
- Receptive fields of simple cortical cells
- Complex and hypercomplex cells
- Complex-cell responses to an oriented moving slit
- Columnar organization - orientation columns
- Orientation columns across the cortex
- Ocular dominance columns and colour blobs
- Ocular dominance columns
- Serial versus parallel analysis of the image
- Hubel-Wiesel hierarchical model
- Role of the extra-striate (association) cortex
- Psychophysiological aspect of vision
- Psychophysiological connections of the visual pathway
The 'Three-Part-System'
How the brain splits and then reunites the image
- Three-part-system hypothesis of visual perception
- The three-part system of visual perception
Summary and Review
- Vision by the numbers
- Key take-home messages
- A patient with a pituitary tumour develops bitemporal hemianopia. Why, and which fibres are involved first?
- References (1/2)
- References (2/2)
- Neuro-Ophthalmology