Chapter 6: perception Flashcards
Ventral pathway
The signal transfers from the primary visual cortex (V1) to the secondary areas V2 and V3, to V4 and then to the inferotemporal cortex. Important for the ‘what’.
Dorsal pathday
The signal transfers form V1 to V2 and V3, to V5 (motion perception area) and then to the parietal cortex. Important for the ‘where’ and ‘how’.
Visual field deficits
Results from damage between the retina and V1, which can cause a loss of part of the visual field. Brain damage in the left hemisphere leads to loss of vision in the right visual field and damage in the right hemisphere leads to loss of vision in the left visual field.
Homonymous hemianopia
When visual field loss occurs in the same visual field in both eyes.
Quadrantanopia
Blindness for a specific quadrant of the visual field.
Blindsight (due to cortical blindness)
Damage that completely destroyed the V1 which resulted in blindness for the full visual field. Someone with cortical blindness does perceive what is there but is not conscious about this. The patients show eye movement to a stimulus and perform above chance level on discrimination tasks, but to them they are just guessing.
Visual anosognosia
People are cortically blind but not aware of their conditions, they are fully convinced that they can see.
Achromatopsia
Loss of color vision due to damage in the V4 in the ventral pathway. People percieve the world in shades of gray.
Cerebral dyschromatopsia
Damage to the V4 that leads to a limited ability to distinguish between colors.
Akinetopsia
Inability to perceive motion. Caused by damage to the V5.
Visual agnosia
Inability to recognise objects based on visual perception. These patients do have an intact visual field, but the information is not sufficiently integrated.
Visual neglect
Caused by a lesion in the parietal lobe that leads to a deficit in attention to half of the visual field. They can see, but don’t consciously perceive the information.
Cortical deafness
Being unable to perceive sound even though there is no damage to the cochlea or middle ear that can explain this.
Auditory agnosia
Impairments in receiving / recognising auditory information. This can be for various types of auditory information or specifically for verbal information, environmental sounds or music.
Tactile agnosia
Patients can recognise an object only with the ipsilateral hand. This is not a disorder in sensory perception, but a disconnection in areas for tactile perception and multimodel integration / semantic memory.
