Perception - PSYB55 Week 4 PDF

PERCEPTION From Sensation to Perception - Information (light, sound e.t.c) > Sensation (raw data by sensory receptors - eyes, ears, nose, skin, tongue) > Perception (sensations are processed in the brain) - Light energy to neural signal (transductional) - Example: Tree > light...

PERCEPTION From Sensation to Perception - Information (light, sound e.t.c) > Sensation (raw data by sensory receptors - eyes, ears, nose, skin, tongue) > Perception (sensations are processed in the brain) - Light energy to neural signal (transductional) - Example: Tree > light waves > occipital lobes of the brain receives sensory information from the eye and process it as a ‘tree’ Anatomy of the eye - Layers of photosensory neurons reside in the back of the eye - Retina 1. Light enters eye a. Information is consolidated (not too much information at once) 2. Refracted by the lens to the back of the eye a. Light is passing by translucent cells b. Ganglion and bipolar cells 3. Photosesors capture information a. Millions of receptors b. Most continue going through (blind spot) 4. Info is sent to retina a. Made of rods and cones b. Capture colour, movement e.t.c. * Blind spot = certain spots of the eye that don’t have any photoreceptors - Left and right eye usually fills in most of the gaps for each other Retinal Implant Device - Device that mimics what a retina does (for detached retinas and retina disorders) The Primary Projection Pathways of the visual system - Eye left and right eye capture both the left and right visual field - Information leaves the eye and enter the crossing called the optic chiasm - Peripheral visual is crossed at the optic chiasm - Right visual field processed by left side of brain - Left visual field processed by right side of brain Blind Spots Caused by Brain Injury - Retinotopic mapping on primary visual cortex - First part of the occipital lobe to receive visual information - Middle part of retina = fovea - Injury to the retinotopic map results in a scotoma corresponding to that location  - Cortical blindness - Blindness is due to brain issue - You can see to a degree (blindsight) Hemianspias caused by visual system damage 1. Right-side circumferential blindness due retrobulbar neuritis 2. Total blindness of the right eye due to lesion 3. Right nasal hemianopia due to partial lesion 4. Bitemporal hemianopia due to a complete lesion of the optic chiasm 5. Left temporal and right nasal hemianopia due to a lesion of the right optic tract 6. Left temporal and right nasal hemianopia 7. Left temporal and right nasal hemianopia due to a lesion of the right visual cortex Congenital blindness (eye dysfunction) and possible brain reorganization - When they learned braille, they used their occipital lobe - Their occipital lobes were remapped - Different parts of the hands on different parts of the occipital lobe - Remapping doesn’t work if you’ve ever seen something in your life Discovering the color processing centre (V4) - Vision vs Eyes Closed - Occipital lobe is activated when eyes are open - Colour vs Grey - V4 is important for the perception and analysis of colour - Area is sensitive to colour constancy - Selective attention to a hemifield - Can map which visual field is being processed Cerebral Achromatopsia - cannot see colour due to brain Prosopagnosia - inability to distinguish between faces Discovering the motion processing centre (V5) - Flickering with pixel movement - static image - Illusory movement - control Inducing cerebral akinetopsia using TMS - Disrupts you ability to perceived motion Specificity of V5 neurons - Direction of movement - Speed of movement - Faster movement = more signals Akinetopsia - damaging V5 on both sides