Ventral and Dorsal Stream (M2) Flashcards
What is the spatial location system that is where things are relative to the head? 1. What area of the brain is this? 2
- head-centered coordinate system
2. dorsal stream
What is the location of the lesion in a pure alexia? 1. What does it disconnect? 2
- left hemisphere lesion, often left occipital and/or adjacent splenium
- disconnect occipital cortex from posterior language areas (esp. left angular gyrus)
For a person with appreceptive agnosia, what are the things that she could NOT recognize or do?
- identify grating orientation
- recognize letters and numerals visually
- recognize line drawings of common objects, including ones she had drawn herself
What stream is responsible for mental rotation of letters?
dorsal stream
What is spared in pure alexia?
- ability to write
- ability to understand spoken language
- ability to read letter-by-letter
- ability to recognize and interpret pictures
Are object agnosia patients able to draw an object from memory? 1. Copy an object? 2
- no
2. yes
What is the inability to recognize faces called?
prosopagnosia
What stream is responsible for passive letter viewing?
ventral stream
What is the roles of V4 in visual perception?
- some color perception
- object perception (non-sophisticated)
- gateway to higher ventral stream locations
What type of functions does the ventral stream contain?
Static:
- pattern recognition
- scrutiny of fine detail
What is the condition that is due to deafferentation of the ventral system? 1. What are they unable to do? 2. What is usually the cause of this? 3
- appreceptive agnosia
- to form a coherent percept of a stimulus
- anoxia from carbon monoxide poisoning
What is the spatial location system that is where the world is relative to the eye? 1. What area of the brain is this? 2
- oculocentric coordinate system
2. superior colliculus
What are the major ways that motion is important to aspects of visual perception?
- figure/ground segregation (camo)
- perception of 3D space
- perception of 3D scene (induced motion)
- perception of self-motion (train)
- perception of change (time-lapse photo)
What are the areas of the brain that respond better when viewing “nonsense object” than “noise”?
- lateral occipital cortex
- V4
- inferotemporal cortex
What is the inability to read words in the presence of intact letter recognition and intact writing?
pure alexia
What is the spatial location system that is where things are relative to each other? 1. What area of the brain is this? 2
- allocentric coordinate system
2. ventral stream