ND - Agnosia, Neglect, Dyslexia and Synaesthesia - Week 3 Flashcards
Consider the three pathways in the visual cortex from the retina. List them and state whether they remain segregated and until what structure.
Magnocellular
Parvocellular
Koniocellular
They remain well segregated until they reach the striate cortex
How many visual areas are they beyond the striate cortex in a macaque brain?
Over 30
What is V1?
Striate cortex
Where is the action pathway? What happens with damage to this area?
It is dorsal (where pathway)
Damage leads to impaired goal-directed action
Where is the perception pathway? What happens with damage to this area?
It is ventral (what pathway)
Damage leads to agnosia
Define agnosia.
Inability to perceive
You can see but do not understand what an object is
Consider a lesion in the dorsal stream. What mistakes would the patient mostly make (2)?
Spatial errors and some orientation errors
What are parallel channels?
They are channels that carry visual signals from the retina into the thalamus and then into the cortex
Describe top-down feedback.
Modulation of afferent signals by processes such as attention
Describe what is meant by the two visual streams and the lobe of the brain it is located, including its anotomical position and primary function.
Dorsal parietal - where or action stream
Ventral temporal - what or perception stream
Describe what is meant by functional localisation. Are things processed independently or not?
different attributes of each object being processed in different cortical areas with different modalities.
They are processed independently.
List functions of the posterior parietal cortex.
Helps to bind different attributes of an object together
Gates inputs into the ventral stream
Important for reading (linked to dyslexia)
What does the posterior parietal cortex play a central role in?
Directing attention to spatial locations
What can predict later reading failure?
Pre-reading phonological skills
What do dyslexic children have difficulty with (2)?
Discriminating syllables and rapid acoustic stimuli