Apperceptive agnosia versus associative agnosia

[edieb]

I am a little confused on the difference between the two broad categories of agnosias in the Lezak book:

It says that apperceptive agnosia is secondary to "higher level perceptual disturbances" and associative agnosia is secondary to "breakdowns in the patients information store"

So I am assuming that dementing processes would produce associative agnosia (??) Can anyone give me examples of specific diseases that would produce the two types of agnosias?

Thanks in advance

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[alienarms]

I am a little confused on the difference between the two broad categories of agnosias in the Lezak book:

It says that apperceptive agnosia is secondary to "higher level perceptual disturbances" and associative agnosia is secondary to "breakdowns in the patients information store"

So I am assuming that dementing processes would produce associative agnosia (??) Can anyone give me examples of specific diseases that would produce the two types of agnosias?

Thanks in advance

If I remember cognitive neuroscience correctly, either type of agnosia could be produced by degenerative disease, such as Alzheimer's, or by mechanical damage to the cortex. ( I think the affected areas would include the cingulate cortex as well as intraparietal sulci, as these are involved in object recognition.) Apperceptive agnosia would be a deficit in perception, i.e., the patient is uable to draw the object correctly or group it with similar objects, whereas associative agnosia is a deficit in recognizing the object, although it is perceived. So in associative agnosia, the object could be drawn, but not named.

 

[edieb]

That's right (I Just figured it out). W/ apperceptive agnosia primary sensory processing is in tact; however, secondary visual processing is deficient and the percept is not perceived correctly. Therefore, the person could not match the percept to an akin object.

With associative agnosia, the percept is processed correctly, but the person does not perceive the meaning of the object. For example, the person may look at a face with a scared expression and only see a face....

If I remember cognitive neuroscience correctly, either type of agnosia could be produced by degenerative disease, such as Alzheimer's, or by mechanical damage to the cortex. ( I think the affected areas would include the cingulate cortex as well as intraparietal sulci, as these are involved in object recognition.) Apperceptive agnosia would be a deficit in perception, i.e., the patient is uable to draw the object correctly or group it with similar objects, whereas associative agnosia is a deficit in recognizing the object, although it is perceived. So in associative agnosia, the object could be drawn, but not named.

 

[alienarms]

That's right (I Just figured it out). W/ apperceptive agnosia primary sensory processing is in tact; however, secondary visual processing is deficient and the percept is not perceived correctly. Therefore, the person could not match the percept to an akin object.

With associative agnosia, the percept is processed correctly, but the person does not perceive the meaning of the object. For example, the person may look at a face with a scared expression and only see a face....

Glad you figured it out...P.S. Agnosia is FASCINATING.

 

[Neuro-Dr]

The gist of it always comes down to the temporal lobe. Since this area is rather conscripted you can get deficits in category specific areas not associated with other types of brain regions. Her is the rule of thumb:

If a person can't name an object seen, can't copy object or match it - apperceptive agnosia, likely area of deficits is occipital temporal association cortex or earlier into the occipital pathway (V3 or later). This liky pathological process is stroke.

If a person can't name an object presented visually, but can copy or match, and can't name object even when handled - associative agnosia. Likely damage is temporal lobe - Damasio found some evidence of anterior pole for human faces, inferior temp for animal naming and posterior for tools. This is likely due to functional versus visual description neuron density, not animals or tolls per say. Some other studies showed mixed findings.

If a person can't name an object seen, can match or copy and can describe the uses of object and name it when handled - optic aphasia. Damage to occipital pathways to language centers in temporal lobe, no damage to pathways to semantic stores. PAthological process can be stroke or other cortical dementia.

 

[mindboggler]

The gist of it always comes down to the temporal lobe. Since this area is rather conscripted you can get deficits in category specific areas not associated with other types of brain regions. Her is the rule of thumb:

If a person can't name an object seen, can't copy object or match it - apperceptive agnosia, likely area of deficits is occipital temporal association cortex or earlier into the occipital pathway (V3 or later). This liky pathological process is stroke.

If a person can't name an object presented visually, but can copy or match, and can't name object even when handled - associative agnosia. Likely damage is temporal lobe - Damasio found some evidence of anterior pole for human faces, inferior temp for animal naming and posterior for tools. This is likely due to functional versus visual description neuron density, not animals or tolls per say. Some other studies showed mixed findings.

If a person can't name an object seen, can match or copy and can describe the uses of object and name it when handled - optic aphasia. Damage to occipital pathways to language centers in temporal lobe, no damage to pathways to semantic stores. PAthological process can be stroke or other cortical dementia.

in the case of associative agnosia u said that a person might not be able to name an object even when let to handle it , is this the same with apperceptive..? can a person suffering from apperceptive agnosia percieve an object by touching it/ handling it..?