Astereognosis: Difference between revisions
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| name = Astereognosis |
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| field = [[Neurology]] |
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'''Astereognosis''' (or tactile agnosia if only one hand is affected) is the inability to identify an object by active touch of the hands without other sensory input, such as visual or sensory information. An individual with astereognosis is unable to identify objects by handling them, despite intact elementary tactile, proprioceptive, and thermal [[sense|sensation]].<ref name="O'Sulivan" /> With the absence of [[Visual perception|vision]] (i.e. eyes closed), an individual with astereognosis is unable to identify what is placed in their hand based on cues such as texture, size, spatial properties, and temperature.<ref name="O'Sulivan" /> As opposed to agnosia, when the object is observed visually, one should be able to successfully identify the object. |
'''Astereognosis''' (or tactile agnosia if only one hand is affected) is the inability to identify an object by active touch of the hands without other sensory input, such as visual or sensory information. An individual with astereognosis is unable to identify objects by handling them, despite intact elementary tactile, proprioceptive, and thermal [[sense|sensation]].<ref name="O'Sulivan" /> With the absence of [[Visual perception|vision]] (i.e. eyes closed), an individual with astereognosis is unable to identify what is placed in their hand based on cues such as texture, size, spatial properties, and temperature.<ref name="O'Sulivan" /> As opposed to agnosia, when the object is observed visually, one should be able to successfully identify the object. |
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Individuals with tactile agnosia may be able to identify the name, purpose, or origin of an object with their left hand but not their right, or vice versa, or both hands. Astereognosis refers specifically to those who lack tactile recognition in both hands. In the affected hand(s) they may be able to identify basic shapes such as pyramids and spheres (with abnormally high difficulty) but still not tactilely recognize common objects by easily recognizable and unique features such as a fork by its prongs (though the individual may report feeling a long, metal rod with multiple, pointy rods stemming off in uniform direction).<ref name="Gerstmann" /> These symptoms suggest that a very specific part of the brain is responsible for making the connections between tactile stimuli and functions/relationships of those stimuli, which, along with the relatively low impact this disorder has on a person's quality of life, helps explain the rarity of reports and research of individuals with tactile agnosia.<ref name="Gerstmann" /> |
Individuals with tactile agnosia may be able to identify the name, purpose, or origin of an object with their left hand but not their right, or vice versa, or both hands. Astereognosis refers specifically to those who lack tactile recognition in both hands. In the affected hand(s) they may be able to identify basic shapes such as pyramids and spheres (with abnormally high difficulty) but still not tactilely recognize common objects by easily recognizable and unique features such as a fork by its prongs (though the individual may report feeling a long, metal rod with multiple, pointy rods stemming off in uniform direction).<ref name="Gerstmann" /> These symptoms suggest that a very specific part of the brain is responsible for making the connections between tactile stimuli and functions/relationships of those stimuli, which, along with the relatively low impact this disorder has on a person's quality of life, helps explain the rarity of reports and research of individuals with tactile agnosia.<ref name="Gerstmann" /> |
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Astereognosis is associated with lesions of the [[parietal lobe]] or [[Dorsal column–medial lemniscus pathway|dorsal column]] or parieto-temporo-occipital lobe (posterior association areas) of either the right or left hemisphere of the [[cerebral cortex]].<ref name="O'Sulivan">{{cite book |last=O'Sullivan |first=S.B. |title=Physical Rehabilitation |url=https://archive.org/details/physicalrehabili00osul |url-access=limited |year=2007 |publisher=F.A. Davis Company |location=Philadelphia |pages=[https://archive.org/details/physicalrehabili00osul/page/n1244 1180]–1181 |edition=5th |author2=Schmitz, T.J.}}</ref><ref name="Gerstmann">{{cite journal|last=Gerstmann |first=J. | year = 2001 | others = Translated by T. Benke |title=Pure Tactile Agnosia | journal = [[Cognitive Neuropsychology (journal)|]] | volume = 18 | issue = 3 |pages=267–274 | doi = 10.1080/02643290042000116 }}</ref> Despite cross-talk between the dorsal and ventral cortices, [[Functional magnetic resonance imaging|fMRI]] results suggest that those with ventral cortex damage are less sensitive to object 3D structure than those with dorsal cortex damage. Unlike the ventral cortex, the dorsal cortex can compute object representations. Thus, those with object recognition impairments are more likely to have acquired damage to the dorsal cortex.<ref>{{cite journal |last1=Freud |first1=E. |last2=Ganel |first2=T. |last3=Shelef |first3=I. |last4=Hammer |first4=M. |last5=Avidan |first5=G. |last6=Behrmann |first6=M. |date=2015 |title=Three-Dimensional Representations of Objects in Dorsal Cortex are Dissociable from Those in Ventral Cortex |journal=Cerebral Cortex |doi=10.1093/cercor/bhv229 |pmid=26483400 |doi-access=free }}</ref> |
Astereognosis is associated with lesions of the [[parietal lobe]] or [[Dorsal column–medial lemniscus pathway|dorsal column]] or parieto-temporo-occipital lobe (posterior association areas) of either the right or left hemisphere of the [[cerebral cortex]].<ref name="O'Sulivan">{{cite book |last=O'Sullivan |first=S.B. |title=Physical Rehabilitation |url=https://archive.org/details/physicalrehabili00osul |url-access=limited |year=2007 |publisher=F.A. Davis Company |location=Philadelphia |pages=[https://archive.org/details/physicalrehabili00osul/page/n1244 1180]–1181 |edition=5th |author2=Schmitz, T.J.|isbn=9780803612471 }}</ref><ref name="Gerstmann">{{cite journal|last=Gerstmann |first=J. | year = 2001 | others = Translated by T. Benke |title=Pure Tactile Agnosia | journal = [[Cognitive Neuropsychology (journal)|Cognitive Neuropsychology]] | volume = 18 | issue = 3 |pages=267–274 | doi = 10.1080/02643290042000116 |pmid=20945214 |s2cid=30352886 }}</ref> Despite cross-talk between the dorsal and ventral cortices, [[Functional magnetic resonance imaging|fMRI]] results suggest that those with ventral cortex damage are less sensitive to object 3D structure than those with dorsal cortex damage. Unlike the ventral cortex, the dorsal cortex can compute object representations. Thus, those with object recognition impairments are more likely to have acquired damage to the dorsal cortex.<ref>{{cite journal |last1=Freud |first1=E. |last2=Ganel |first2=T. |last3=Shelef |first3=I. |last4=Hammer |first4=M. |last5=Avidan |first5=G. |last6=Behrmann |first6=M. |date=2015 |title=Three-Dimensional Representations of Objects in Dorsal Cortex are Dissociable from Those in Ventral Cortex |journal=Cerebral Cortex |volume=27 |issue=1 |pages=422–434 |doi=10.1093/cercor/bhv229 |pmid=26483400 |doi-access=free }}</ref> |
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While astereognosis is characterized by the lack of tactile recognition in both hands, it seems to be closely related to tactile agnosia (impairment connected to one hand). Tactile agnosia observations are rare and case-specific. [[Josef Gerstmann]] recounts his experience with patient JH, a 34-year-old infantryman who suffered a lesion to the posterior parietal lobe due to a gunshot. Following the injury, JH was unable to recognize or identify everyday objects by their meaning, origin, purpose and use with his left hand using [[Somatosensory system|tactile sensation]] alone. His [[motility]] performance, elementary sensitivity, and [[speech]] were intact, and he lacked abnormalities in [[Cranial nerves|brain nerves]].<ref name="Gerstmann" /> |
While astereognosis is characterized by the lack of tactile recognition in both hands, it seems to be closely related to tactile agnosia (impairment connected to one hand). Tactile agnosia observations are rare and case-specific. [[Josef Gerstmann]] recounts his experience with patient JH, a 34-year-old infantryman who suffered a lesion to the posterior parietal lobe due to a gunshot. Following the injury, JH was unable to recognize or identify everyday objects by their meaning, origin, purpose and use with his left hand using [[Somatosensory system|tactile sensation]] alone. His [[motility]] performance, elementary sensitivity, and [[speech]] were intact, and he lacked abnormalities in [[Cranial nerves|brain nerves]].<ref name="Gerstmann" /> |
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The majority of all objects JH touched with his left hand went unrecognized, but very simple objects (i.e. globes, pyramids, cube, etc.) were regularly recognized based on form alone. For more complex objects, his behavior and recognition varied daily based on his tactile resources that changed over time and depended on his [[fatigue]]. That is, JH’s ability to recognize depended on his concentration and ability to recognize simple forms and single qualities like size, shape, etc. With further interrogation and greater effort, he was able to correctly identify more specific features of an object (i.e. softness, rounded or cornered, broad or narrow) and could even draw a copy of it, but he was often left unable to identify the object by name, use, or origin. This behavioral deficit occurred even if JH had handled the object in his fully intact right hand.<ref name="Gerstmann" /> |
The majority of all objects JH touched with his left hand went unrecognized, but very simple objects (i.e. globes, pyramids, cube, etc.) were regularly recognized based on form alone. For more complex objects, his behavior and recognition varied daily based on his tactile resources that changed over time and depended on his [[fatigue]]. That is, JH’s ability to recognize depended on his concentration and ability to recognize simple forms and single qualities like size, shape, etc. With further interrogation and greater effort, he was able to correctly identify more specific features of an object (i.e. softness, rounded or cornered, broad or narrow) and could even draw a copy of it, but he was often left unable to identify the object by name, use, or origin. This behavioral deficit occurred even if JH had handled the object in his fully intact right hand.<ref name="Gerstmann" /> |
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Interventions tend to focus on helping these patients and their family and caregivers cope and adapt to the condition, and furthermore, to help patients function independently within their context.<ref>{{ cite book | |
Interventions tend to focus on helping these patients and their family and caregivers cope and adapt to the condition, and furthermore, to help patients function independently within their context.<ref>{{ cite book |last1=Kumar|first1= A. |title= StatPearls| last2 = Wroten | first2 = M.| date = 2019 | chapter = Agnosia |pmid=29630208|access-date=2020-01-21| chapter-url = https://www.ncbi.nlm.nih.gov/books/NBK493156/ }}</ref> |
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==References== |
==References== |
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Latest revision as of 23:18, 22 July 2024
| Astereognosis | |
|---|---|
| Specialty | Neurology |
Astereognosis (or tactile agnosia if only one hand is affected) is the inability to identify an object by active touch of the hands without other sensory input, such as visual or sensory information. An individual with astereognosis is unable to identify objects by handling them, despite intact elementary tactile, proprioceptive, and thermal sensation.[1] With the absence of vision (i.e. eyes closed), an individual with astereognosis is unable to identify what is placed in their hand based on cues such as texture, size, spatial properties, and temperature.[1] As opposed to agnosia, when the object is observed visually, one should be able to successfully identify the object.
Individuals with tactile agnosia may be able to identify the name, purpose, or origin of an object with their left hand but not their right, or vice versa, or both hands. Astereognosis refers specifically to those who lack tactile recognition in both hands. In the affected hand(s) they may be able to identify basic shapes such as pyramids and spheres (with abnormally high difficulty) but still not tactilely recognize common objects by easily recognizable and unique features such as a fork by its prongs (though the individual may report feeling a long, metal rod with multiple, pointy rods stemming off in uniform direction).[2] These symptoms suggest that a very specific part of the brain is responsible for making the connections between tactile stimuli and functions/relationships of those stimuli, which, along with the relatively low impact this disorder has on a person's quality of life, helps explain the rarity of reports and research of individuals with tactile agnosia.[2]
Astereognosis is associated with lesions of the parietal lobe or dorsal column or parieto-temporo-occipital lobe (posterior association areas) of either the right or left hemisphere of the cerebral cortex.[1][2] Despite cross-talk between the dorsal and ventral cortices, fMRI results suggest that those with ventral cortex damage are less sensitive to object 3D structure than those with dorsal cortex damage. Unlike the ventral cortex, the dorsal cortex can compute object representations. Thus, those with object recognition impairments are more likely to have acquired damage to the dorsal cortex.[3]
While astereognosis is characterized by the lack of tactile recognition in both hands, it seems to be closely related to tactile agnosia (impairment connected to one hand). Tactile agnosia observations are rare and case-specific. Josef Gerstmann recounts his experience with patient JH, a 34-year-old infantryman who suffered a lesion to the posterior parietal lobe due to a gunshot. Following the injury, JH was unable to recognize or identify everyday objects by their meaning, origin, purpose and use with his left hand using tactile sensation alone. His motility performance, elementary sensitivity, and speech were intact, and he lacked abnormalities in brain nerves.[2]
The majority of all objects JH touched with his left hand went unrecognized, but very simple objects (i.e. globes, pyramids, cube, etc.) were regularly recognized based on form alone. For more complex objects, his behavior and recognition varied daily based on his tactile resources that changed over time and depended on his fatigue. That is, JH’s ability to recognize depended on his concentration and ability to recognize simple forms and single qualities like size, shape, etc. With further interrogation and greater effort, he was able to correctly identify more specific features of an object (i.e. softness, rounded or cornered, broad or narrow) and could even draw a copy of it, but he was often left unable to identify the object by name, use, or origin. This behavioral deficit occurred even if JH had handled the object in his fully intact right hand.[2]
Interventions tend to focus on helping these patients and their family and caregivers cope and adapt to the condition, and furthermore, to help patients function independently within their context.[4]
References
[edit]- ^ a b c O'Sullivan, S.B.; Schmitz, T.J. (2007). Physical Rehabilitation (5th ed.). Philadelphia: F.A. Davis Company. pp. 1180–1181. ISBN 9780803612471.
- ^ a b c d e Gerstmann, J. (2001). "Pure Tactile Agnosia". Cognitive Neuropsychology. 18 (3). Translated by T. Benke: 267–274. doi:10.1080/02643290042000116. PMID 20945214. S2CID 30352886.
- ^ Freud, E.; Ganel, T.; Shelef, I.; Hammer, M.; Avidan, G.; Behrmann, M. (2015). "Three-Dimensional Representations of Objects in Dorsal Cortex are Dissociable from Those in Ventral Cortex". Cerebral Cortex. 27 (1): 422–434. doi:10.1093/cercor/bhv229. PMID 26483400.
- ^ Kumar, A.; Wroten, M. (2019). "Agnosia". StatPearls. PMID 29630208. Retrieved 2020-01-21.