Lesion Localization in Apractic Agraphia

Alexander, Michael P.; Fischer, Richard S.; Friedman, Rhonda B.

doi:10.1001/archneur.1992.00530270060019

Cited by 97 publications

(52 citation statements)

References 17 publications

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“…It is often associated with other features of Gerstmann's syndrome, and results from lesions classically aecting the inferior parietal lobule, possibly the cortex surrounding the IPS [20,23,38]. Patient ATH did not present this semantic type of anarithmetia, and indeed showed none of the other de®cits that, in addition to acalculia, constitute Gerstmann's syndrome: she had no left-right confusion and no ®nger agnosia, and her agraphia was of the aphasic type, while the agraphia associated with Gerstmann's syndrome is generally of the apraxic type, due to the more dorsal site of parietal lesions [2,28]. Thus, the study of ATH's lesion may provide useful``negative evidence'' for delineating the critical site of lesions responsible for semantic anarithmetia.…”

Section: Discussionmentioning

confidence: 93%

“…The list comprised 38 pairs of single-word numerals and 48 pairs of multiword numerals. 2 Multiword pairs included 10 syntactically simple pairs, and 38 syntactically complex pairs. In simple pairs, the comparison could be performed 1 Some of the syntactic error were detectable only through the absence of the`et' word (e.g., 31 4`dix, vingt, trente...et puis un...trente-un' [ten, twenty, thirty, and then oneF F F thirty-one] instead of the correct`trente et un' [thirty and one].…”

Section: Comparison Of Verbal Numeralsmentioning

confidence: 99%

“…In this latter example, after some trial and error, she managed to select the appropriate words, but could not embed them in an adequate syntactic frame. 2 In 20 out of the 38 single-word pairs, the two number words belonged to the same lexical class (two ones, two teens, or two tens) and the comparison was expected to be easier. In the remaining 18 pairs, the two number words belonged to dierent lexical class and had potentially deceitful stack relationship (e.g., in the pair 14 30, 30 is larger although 3 is smaller than 4) correctly on the basis of a word-by-word strategy, without considering the complete syntactic structure of the numeral.…”

Section: Comparison Of Verbal Numeralsmentioning

confidence: 99%

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Language and calculation within the parietal lobe: a combined cognitive, anatomical and fMRI study

Cohen¹,

Dehaene

Chochon³

et al. 2000

Neuropsychologia

217

128

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We report the case of a patient (ATH) who suered from aphasia, deep dyslexia, and acalculia, following a lesion in her left perisylvian area. She showed a severe impairment in all tasks involving numbers in a verbal format, such as reading aloud, writing to dictation, or responding verbally to questions of numerical knowledge. In contrast, her ability to manipulate nonverbal representations of numbers, i.e., Arabic numerals and quantities, was comparatively well preserved, as evidenced for instance in number comparison or number bisection tasks. This dissociated impairment of verbal and non-verbal numerical abilities entailed a dierential impairment of the four arithmetic operations. ATH performed much better with subtraction and addition, that can be solved on the basis of quantity manipulation, than with multiplication and division problems, that are commonly solved by retrieving stored verbal sequences. The brain lesion aected the classical language areas, but spared a subset of the left inferior parietal lobule that was active during calculation tasks, as demonstrated with functional MRI. Finally, the relative preservation of subtraction versus multiplication may be related to the fact that subtraction activated the intact right parietal lobe, while multiplication activated predominantly left-sided areas. 7

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Section: Discussionmentioning

confidence: 93%

Section: Comparison Of Verbal Numeralsmentioning

confidence: 99%

Section: Comparison Of Verbal Numeralsmentioning

confidence: 99%

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Language and calculation within the parietal lobe: a combined cognitive, anatomical and fMRI study

Cohen¹,

Dehaene

Chochon³

et al. 2000

Neuropsychologia

217

128

View full text Add to dashboard Cite

show abstract

“…For example, handwriting can be impaired selectively by brain damage while other manual motor control tasks are relatively well preserved (1). Indeed, recent evidence suggests that even the writing of cursive vs. print and uppercase vs. lowercase (2) can dissociate after brain damage.…”

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confidence: 99%

The neural development and organization of letter recognition: Evidence from functional neuroimaging, computational modeling, and behavioral studies

Polk

Farah

1998

Proc. Natl. Acad. Sci. U.S.A.

155

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Although much of the brain's functional organization is genetically predetermined, it appears that some noninnate functions can come to depend on dedicated and segregated neural tissue. In this paper, we describe a series of experiments that have investigated the neural development and organization of one such noninnate function: letter recognition. Functional neuroimaging demonstrates that letter and digit recognition depend on different neural substrates in some literate adults. How could the processing of two stimulus categories that are distinguished solely by cultural conventions become segregated in the brain? One possibility is that correlation-based learning in the brain leads to a spatial organization in cortex that ref lects the temporal and spatial clustering of letters with letters in the environment. Simulations confirm that environmental co-occurrence does indeed lead to spatial localization in a neural network that uses correlation-based learning. Furthermore, behavioral studies confirm one critical prediction of this co-occurrence hypothesis, namely, that subjects exposed to a visual environment in which letters and digits occur together rather than separately (postal workers who process letters and digits together in Canadian postal codes) do indeed show less behavioral evidence for segregated letter and digit processing.Localization of function is a basic feature of brain organization, revealed by the selectivity of impairments after brain damage and by techniques for recording regional brain activity. A wide variety of behavioral functions are now thought to be localized in the brain, ranging from sensorimotor functions such as motor control and sensation in the various modalities to high level cognitive functions such as explicit learning.What leads such functions to become localized in the brain? For the previous cases, the answer is presumably genetics. Sensorimotor functions, explicit learning, and many other examples of localized functions are old on an evolutionary scale, are shared with other species, provide a clear adaptive advantage, and develop automatically with no systematic training. It is thus possible that the brain has evolved to dedicate tissue to these functions. Consistent with this hypothesis, there is no evidence for the localization of functions like ballet dancing or chess playing: These functions are not old on an evolutionary scale, are not shared with other species, do not provide a clear adaptive advantage, and do not develop automatically without systematic training.There are, however, a few cognitive functions that may violate this simple generalization. For example, handwriting can be impaired selectively by brain damage while other manual motor control tasks are relatively well preserved (1). Indeed, recent evidence suggests that even the writing of cursive vs. print and uppercase vs. lowercase (2) can dissociate after brain damage. The fact that these functions can be impaired selectively suggests that their neural substrates are localized and spatially...

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“…5 A writing disorder in which orthographic movements are diminished despite normal sensorimotor function of the hand and with preserved oral spelling and typing have been discussed as "apractic agraphia," which might result from a loss of representation for movements of writing due to interruption of associative fibers from the angular gyrus to the superior parietal lobule within the dominant (left) hemisphere. 6 The reading sample in video 1 is considered to be an easy text given the patient's age, but she has significant difficulties reading it. In particular, she appears to be dysfluent and hesitant, omits the initial letters of words, has omissions, transpositions, and substitutions of function words, and at one point she actually stops reading halfway across the page, ignoring the right half of the sentence.…”

Section: Sectionmentioning

confidence: 99%