Agnosia and Prosopagnosia Flashcards
What is agnosia?
It is the impairment of visual object recognition in individuals with sufficiently preserved visual fields, acuity, and other elementary visual abilities, where the impairment cannot be attributed to a loss of knowledge about objects.
What brain regions are typically affected in agnosia?
The occipital or inferior temporal cortex.
What important insight do different types of agnosia provide?
They reveal clues about the processes underlying object recognition.
What is apperceptive agnosia?
A condition where low-level binding of features is absent, resulting in the inability to perform basic copying and matching tasks despite knowledge of object size and shape.
What stage of object recognition is damaged in apperceptive agnosia?
Stage 2: Shape representation.
What is associative agnosia?
A condition where individuals can copy and match objects but are unable to name them, due to a failure in accessing knowledge about the objects.
What stage of object recognition is damaged in associative agnosia?
Stage 3: Object representation.
What is prosopagnosia?
A profound loss of the ability to recognize faces, usually caused by a right inferotemporal lesion.
How do prosopagnosic individuals recognize familiar people?
Through other modalities such as voice recognition.
What evidence supports covert recognition in prosopagnosia?
Prosopagnosic patients show larger skin conductance responses (SCRs) to familiar faces compared to unfamiliar ones, indicating unconscious recognition.
What is Capgras delusion?
A condition where patients recognize a face but deny the identity of the individual, believing them to be an imposter.
What is the difference between prosopagnosia and Capgras syndrome?
Prosopagnosia results from ventral stream loss (overt recognition failure), while Capgras syndrome results from dorsal stream loss (covert recognition disruption).
What is the significance of modularity in visual object recognition?
It supports the idea that distinct stages or modules in the brain are responsible for different aspects of recognition, as seen in conditions like agnosia and prosopagnosia.
What are the two key types of agnosia distinguished by Lissaur (1890)?
- Apperceptive Agnosia: Failure in low-level binding of features.
- Associative Agnosia: Failure in accessing knowledge associated with objects
What do cases like John, who has both visual agnosia and prosopagnosia, demonstrate?
The modularity of visual object and face recognition processes and the complexity of their interactions in the brain.
