Anterograde memory impairment in Pick's disease.
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Dementia↗
Biomedical subjects
A B Rubens
Publications and source records attributed to A B Rubens.
False recognition and misidentification of faces following right hemisphere damage.
We report two patients who, following massive damage to the right hemisphere, showed a striking tendency for false recognition and misidentification of faces. Neuropsychological investigations revealed that excessive reliance on a feature-based left hemisphere strategy in face processing, combined with an inability to evaluate critically the output generated by the dysfunctional face recognition system, played a major role in the recognition errors and misidentifications. Our findings suggest that the feature based left hemisphere face recognition system is potentially error-prone, presumably because component facial features are likely to be shared among several different individuals, and that reliable recognition and identification of faces is critically dependent upon the efficient processing of configurational facial information by the right hemisphere. We propose further that decision making and monitoring functions relevant to the operations of the face recognition system are primarily lateralized to the right frontal lobe.
Aged↗
Praxis and the right hemisphere.
We report our observations on praxis in a strongly right-handed man following a massive stroke that resulted in virtually complete destruction of the left cerebral hemisphere. Our patient was severely impaired in pantomiming transitive gestures with the left hand and in reproducing novel non-symbolic hand and arm movement sequences. However, overlearned habitual actions like actual object use and intransitive gestures were relatively spared. Performance of axial commands was intact. Gesture recognition and discrimination were also preserved. Based on these findings, we propose that the praxis system of the right hemisphere is strongly biased toward "concrete" or context-dependent execution of familiar, well-established action routines. The right hemisphere is critically dependent on transcallosal contribution from the left hemisphere for control of the left hand in "abstract" or context-independent performance of transitive movements and in learning novel movement sequences. At least in some individuals, the right hemisphere can recognize and discriminate gestures. Possible implications of our findings for the cerebral control of praxis and for recovery from apraxia are discussed.
Aphasia, Broca↗
Anomia for facial expressions: neuropsychological mechanisms and anatomical correlates.
We report a patient with a selective impairment in naming and pointing to emotional facial expressions following a circumscribed lesion of the right temporal lobe. Detailed investigation of this patient's deficit revealed that the neuropsychological mechanism underlying his anomia for facial expressions is best understood as a category-specific bidirectional visual-verbal disconnection between intact visual semantic and verbal semantic representations for facial emotions. Magnetic resonance imaging findings from this case and from another patient previously described with this unique syndrome (Rapcsak, Kaszniak, & Rubens, 1989), together with the results of cortical electrical stimulation studies and microelectrode recordings of cortical neuronal activity in epileptic patients, provide converging evidence that the inferotemporal visual association cortex of the right middle temporal gyrus plays an important functional role in the verbal labeling of emotional facial expressions. The implications of these findings for cognitive and neural models of facial affect processing are discussed.
Aged↗
Memory impairment and executive control in individuals with stroke-induced aphasia.
The purpose of this study was to examine memory abilities of aphasic individuals in relation to site of neurological lesion. Fourteen individuals with stroke-induced aphasia (7 with anterior lesions; 7 with posterior lesions) and 14 demographically matched control subjects were given selected tests of short-term memory (STM) and long-term memory (LTM). Stroke patients were impaired relative to control subjects on tests of verbal memory, with greater impairment of LTM associated with anterior lesions and greater impairment of STM associated with posterior lesions. Verbal memory performance did not correlate highly with language ability, and did not appear to be simply a consequence of language impairment. Executive control deficits were postulated as explanatory of the LTM impairment associated with anterior lesions.
Aged↗
Writing with the right hemisphere.
We studied writing abilities in a strongly right-handed man following a massive stroke that resulted in virtually complete destruction of the language-dominant left hemisphere. Writing was characterized by sensitivity to lexical-semantic variables (i.e., word frequency, imageability, and part of speech), semantic errors in writing to dictation and written naming, total inability to use the nonlexical phonological spelling route, and agrammatism in spontaneous writing. The reliance on a lexical-semantic strategy in spelling, semantic errors, and impaired phonology and syntax were all highly consistent with the general characteristics of right hemisphere language, as revealed by studies of split-brain patients and adults with dominant hemispherectomy. In addition, this pattern of writing closely resembled the syndrome of deep agraphia. These observations provide strong support for the hypothesis that deep agraphia reflects right hemisphere writing.
Agraphia↗
Priming effects in a letter-by-letter reader depend upon access to the word form system.
Several types of cognitive and neuropsychological evidence suggest that priming effects on such implicit memory tests as word identification are mediated by a pre-semantic visual word form system that can operate independently of episodic memory. We investigate priming in a letter-by-letter reader, P.T., whose pattern of performance on neuropsychological tests indicates preservation of the word form system. Experiment 1 revealed robust priming on a word identification test following letter-by-letter study of target words, despite P.T.'s great difficulty in identifying non-studied words. Experiment 2 showed that the priming effect was modality specific whereas Experiment 3 indicated that recall of previously studied words was not modality specific, thus indicating that the observed priming could not be attributed to explicit memory strategies. Experiment 4 revealed no priming of illegal nonwords on a letter identification test. The results support the notion that priming on the word identification test depends on access to the word form system.
Attention↗
Disruption of semantic influence on writing following a left prefrontal lesion.
We report a patient with impaired spontaneous writing, written naming, and homophone spelling, consistent with a disruption of semantic influence on writing. However, writing to dictation by both the phonological and lexical spelling systems was intact. In addition, general semantic abilities were spared, as indicated by preserved auditory and reading comprehension. We propose that our patient could not incorporate meaning into writing because of a disruption of both direct and indirect connections between semantics and the orthographic output lexicon. The writing dysfunction was accompanied by a similar impairment of speech output, suggesting that it was part of a more general disturbance of semantic influence on language production following left prefrontal damage.
Anomia↗
From letters to words: procedures for word recognition in letter-by-letter reading.
There are two alternative interpretations of how word recognition is accomplished in letter-by-letter reading. One postulates that it relies on the spelling system operating "in reverse," whereas the other claims that it is mediated by the reading system. Because of the close association between patterns of reading and spelling in previously reported cases of letter-by-letter reading, both hypotheses may be considered equally plausible. We now report a patient with letter-by-letter reading who demonstrated a striking dissociation between reading and spelling. Our observations in this patient argue against the concept of "reading via spelling" and suggest that word recognition in letter-by-letter reading is mediated by the orthographic input lexicon used in normal reading.
Agraphia↗
Mixed transcortical aphasia without anatomic isolation of the speech area.
We report two patients with mixed transcortical aphasia following left frontal lobe infarctions. Although there was no evidence of anatomic isolation of the speech area on computed tomograms or magnetic resonance imaging scans, single-photon emission computed tomography in one case demonstrated diminished blood flow over the left parietal convexity suggestive of "functional isolation" of the posterior perisylvian language zone.
Aged↗
Lexical agraphia in Alzheimer's disease.
We studied spelling in 11 patients with senile dementia of the Alzheimer type (SDAT), and their performance was contrasted with that of normal controls. A consistent and specific pattern of linguistic agraphia was identified in the group with SDAT. Although patients with SDAT spelled regular words and nonwords as well as controls, they performed significantly worse when they spelled irregular words. These findings indicated an impairment of the lexical spelling system, consistent with the diagnosis of lexical agraphia. Our observations suggested a loss of word representations from the orthographic lexicon in SDAT and/or an inability to access these representations. However, phonological spelling (phoneme-grapheme conversion) was largely spared.
Aged↗
Impaired recognition of meaningful sounds in Alzheimer's disease.
We studied recognition of meaningful nonverbal sounds using a sound-picture matching test in 18 patients with senile dementia of the Alzheimer type (SDAT) and 19 age-matched controls. A significant impairment of sound recognition was found in the SDAT group, consistent with auditory sound agnosia. Although sound recognition performance correlated significantly with auditory verbal comprehension scores, a sound recognition defect was also identifiable in the subgroup of patients with SDAT who had normal verbal comprehension. Qualitative analysis of sound recognition errors revealed that nonaphasic patients with SDAT made predominantly acoustic errors, whereas semantic errors were found almost exclusively in aphasic patients. These findings suggest that the auditory sound agnosia of patients with SDAT may be subdivided into perceptual-discriminative and semantic-associative types.
Aged↗
Anomia for facial expressions: evidence for a category specific visual-verbal disconnection syndrome.
We describe a patient with a selective impairment in naming and pointing to emotional facial expressions following damage to the right temporal lobe. His language functions were otherwise intact, and he performed well on a variety of perceptual and associative emotional facial tasks. We propose that his inability to match facial expressions with their names was induced by a disconnection between visual semantic and verbal semantic representations for facial emotions.
Aged↗
Apraxia in Alzheimer's disease.
We studied apraxia in 28 patients with senile dementia of the Alzheimer type (SDAT). Although SDAT patients were impaired compared with age-matched controls on tests of ideomotor and ideational apraxia, not all types of movements were affected to the same degree. Limb transitive movements were especially vulnerable, while limb intransitive, buccofacial, and axial movements were relatively spared. When pantomiming limb transitive movements, SDAT patients made frequent body part as object and spatial errors. There was no significant difference between performance on verbal command and imitation, but there was considerable improvement with the use of actual objects. Disorders of skilled movement in SDAT were qualitatively similar to the apraxic syndromes following left parietal damage. Apraxia in SDAT suggests posterior left hemisphere cortical involvement and may be apparent even in patients with good language functions.
Aged↗
Lexical agraphia from focal lesion of the left precentral gyrus.
Lexical agraphia reflects a dysfunction of the lexical spelling system and is characterized by better spelling of nonwords and regular words than irregular words. All previously reported cases with documented focal lesions had involvement of temporo-parieto-occipital regions. We now report a case of lexical agraphia following a discrete lesion of the left precentral gyrus. Our case complements previous neuroanatomical accounts of agraphia and provides further support for the independence of neuronal systems that mediate spelling from those involved in spoken language and reading.
Aged↗
The validity of computed tomographic scan findings for the localization of cerebral functions. The relationship between computed tomography and hemiparesis.
We studied recovery from hemiparesis in 52 patients who participated in the Hennepin County (Minnesota) Recovery From Aphasia Study. Our intent was to determine the anatomic correlates of recovery from hemiparesis and then to contrast computed tomography (CT)-hemiparesis relationships with CT-aphasia relationships in this same population. Hemiparesis was assessed at one month after onset and again at six months after onset. Computed tomographic scans were obtained five months after onset and analyzed quantitatively for lesion location. The presence or absence of arm paresis was strongly predicted by CT scan findings in the supratentorial corticospinal pathway. However, three of 25 nonparetic patients had lesions in the corticospinal pathway, and one of 22 severely paretic patients lacked an appropriate lesion. This study demonstrated that a small but inherent lack of specificity and sensitivity existed in the predictive power of CT localization of lesions potentially affecting the motor system, suggesting that some caution is necessary in interpreting the lesion-deficit relationships in less well-localized functions, eg, language. Besides considering the lack of precision in localizing with CT, the existence of individual differences both in anatomy and localization of function must be taken into account.
Adult↗
Longitudinal dichotic listening patterns for aphasic patients. II. Relationship with lesion variables.
Dichotic listening scores and information on lesion size and location were obtained for aphasic patients. All patients had a reduction in dichotic scores at 1 month postonset of symptoms, but some patients returned to normal levels of performance by 6 months postonset. Lesion location was the main determinant of patterns of performance. Right ear scores from the dichotic digit test closely reflected the presence or absence of lesions involving Heschl's gyrus. What appeared to be an effect of lesion volume was confounded by the relationship between increasing lesion volume and a greater likelihood of damage to Heschl's gyrus.
Adult↗
Longitudinal dichotic listening patterns for aphasic patients. III. Relationship to language and memory variables.
Longitudinal dichotic scores were obtained for aphasic patients for whom extensive language and memory data were also available. Severity of language impairments was related to ear advantage, but this occurred because larger lesions yielded more severe language impairments and were more likely to involve Heschl's gyrus. Extent of language recovery was not related to changes in ear dominance. Relationships that occurred generally supported a functional-anatomical interpretation which stressed the importance of the integrity of the posterior superior temporal lobe to performance both on dichotic tests and on specific language or memory tests.
Adult↗