9. Perception and sensorimotor system Flashcards
What are the main structures for seeing in the eye?
Iris, pupil and lens
What are the visual receptors in the retina?
Cone receptors and Rod Receptors
What is the retina-geniculate-striate pathway?
Visual stimulus from the visual field is imputed through both the left and right eyes. Images from the right visual field travel through the nasal hermietinas in the right eye and the temporal hemiretina and vice versa for images from the left visual field.
Then the stimulus activates the Optic nerve and travels down the optic chiasm of each side. The Stimulus then ends up at the primary visual cortex of the opposite side. i.e. From the right visual
How many layers does the Lateral Geniculate Nuclei have?
Six layers.
What do layers 2, 3, and 5 of the LGN receive?
Receive input from the ipsilateral eye
What do layers 1, 4, and 6 of the LGN receive?
Receive input from the contralateral eye
What are the two systems of differential processing of visual stimuli?
Magnocellular system and Parvocellular system
What systems are involved in colour processing?
NO Magnocellular and YES parvocellular
What systems are involved in contrast sensitivity processing?
HIGH Magnocelular and LOW parvocellular
What systems are involved in spatial resolution processing?
LOW magnocelluar and HIGH parvocellular
What systems are involved in temporal resolution processing?
FAST magnocellular and SLOW Parvocellular
What layers of the LGN are involved in the Magnocellular system?
Layers 1 and 2
What layers of the LGM are involved in the Parvocellular system?
Layers 3-6
What is the laminar organisation of the primary visual context? i.e. What are the 6 layers of the neocortex?
- Axon and dendrites: few cell bodies
- Densely packed stellate cells: a few small pyramid cells
- Loosely packed stellate cells: intermediate sized pyramid cells.
- Brands of densely packed stellate cells; not pyramidal cells
- Very large pyramidal cells; a few loosely packed stellate cells
- Pyramidal cells of various sizes; loosely packed stellate cells.
What is white matter?
Myelinated pyramidal cell axons; few cell bodies
What are the main functions of the Primary visual cortex (V1)?
Receives information from the LGN.
Located in the posterior areas of the occipital lobe
Biggest portion is found in the Longitudinal fissure
What is the main function prestriate cortex and Inferotempral cortex (V2)?
Secondary visual context
Receives information from V1
Located around v1 in the occipital lobe, and in the inferotemporal cortex
What is the main function of the posterior parietal cortex?
Receivs information from V2 and from the secondary areas of other sensory systems.
Largest areas located in the posterior parietal cortex
What are the main areas of the cerebral cortex relevant to the visual system?
Posterior parietal cortex
Prestriate cortex
Primary visual (striate) cortex
Inferotempral cortex
What is the Dorsal stream?
From the V1 → dorsal prestriate cortex → Posterior Parietal Cortex
What is the ventral stream?
From the v1 → ventral prestriate cortex → Inferotempral Cortex
What are the two theories of the dorsal and ventral streams?
“where” vs “what” theory – What type of information
VS
“Control of Behaviour” vs “Conscious perception” Theory – How the information is used?
prosopagnosia
Also known as face blindness, is an inability to recognise faces.
What causes prosopagnosia?
Lesions often bilateral to occipito-temporal junctions (fusiform face area) of the fusiform gyrus.