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Non-verbal semantic impairment in stroke aphasia: A comparison with semantic dementia
Brain and Language 95 (2005) 244–246 www.elsevier.com/locate/b&l
Non-verbal semantic impairment in stroke aphasia: A comparison with semantic dementia E. Jefferies *, M.A. Lambon Ralph University of Manchester, UK Accepted 8 July 2005 Available online 6 September 2005
Introduction Semantic dementia (SD) is a neurodegenerative disease, associated with focal atrophy of the anterior temporal lobes bilaterally. SD produces a specific and progressive impairment of semantic memory that affects comprehension in all modalities (Bozeat et al., 2000; Snowden et al., 1989). This suggests anterior temporal cortex is the repository of multimodal semantic knowledge (Rogers et al., 2004). In contrast, comprehension-impaired CVA patients have infarction of very different brain regions: typically temporoparietal or frontotemporal cortex in the left hemisphere only (Berthier, 2001; Chertkow et al., 1997). The anterior temporal lobes, which receive two arterial supplies, are highly unlikely to be damaged bilaterally after stroke. This apparent inconsistency between SD and stroke aphasia raises several important questions: (1) can stroke aphasics show deficits on non-verbal as well as verbal semantic tasks (limited evidence suggests that they can (Chertkow et al., 1997; Hart & Gordon, 1990) and (2) if so, is the nature of the comprehension impairment the same in the two conditions? We present the first (to our knowledge) case-series comparison of SD and comprehension-impaired stroke aphasics to address these issues.
Method From a database of 52 stroke aphasic patients, we identified 10 cases who failed both verbal and non-verbal semantic tasks. Five of these cases were transcortical sensory aphasics. The remainder had less fluent speech and/or poorer repetition. These patients were compared with SD cases (e.g., 10 patients reported by Bozeat et al., 2000) on the same verbal and non-verbal semantics tasks: (1) The Camel and Cactus Test of semantic association (Bozeat et al., 2000) (e.g., does CAMEL go with cactus, flower, tree or grass?). The same items were presented as pictures and words in separate sessions (N = 96). (2) Spoken word to picture matching (Bozeat et al., 2000) (N = 48, nine semantically
*
Corresponding author. Fax: +44 1612752588. E-mail address: beth.jeff[email protected] (E. Jefferies).
0093-934X/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.bandl.2005.07.127
related distracters). (3) Environmental sound–picture matching using the same items (Bozeat et al., 2000). (4) Synonym judgement varying frequency and imageability (N ¼ 96, three choices per trial). (5) Wordpicture verification varying the specificity of the word (e.g., ‘‘Labrador’’ (specific level), ‘‘Dog’’ (basic level) or ‘‘Animal’’ (general level), N = 144). (6) Spoken picture naming with and without phonemic cues. These tests were administered as part of a larger battery that included further tests of semantic memory as well as reading and repetition and attentional/executive tests.
Results Both the SD and the CVA groups were impaired across a range of verbal and non-verbal semantic tasks. There were no consistent differences between the fluent and non-fluent CVA subgroups on any of these tests. Correlations between all of the semantic tasks were high for the SD patients, regardless of input modality, and the nature of the semantic decision (see Fig. 1). The CVA group also showed correlations across modalities for the same semantic tests. However, they showed no significant correlations between different semantic tests with differing non-semantic task demands. The SD patients were highly sensitive to word frequency in synonym judgement (proportion correct M = .73 [SD = .17] vs. .47 [SD = .20]) whereas the CVA patients were not M = .66 [SD = .10] vs. .66 (SD = .11). SD patients comprehended general terms better than specific terms in word-picture verification. This effect was greater for patients with more severe SD as measured by word-picture matching (d’: mild SD: general = 1.8; basic = 2.8; specific = 2.2; moderate SD: general = 2.2, basic = 1.7, specific = 1.1; severe SD: general = 2.3; basic = 1.4; specific = 0.2). The CVA group were less sensitive to this variable (mild CVA: general = 2.5; basic = 2.4; specific = 2.5; severe CVA: general = 1.0; basic = 1.4; specific = 1.0). Picture naming in the CVA group was improved by a two phoneme cue (by 25% on average in the Boston Naming Test). The SD cases were at floor on this test even with cues. On higher frequency items (N = 30), the SD patients showed some effect of phonemic cueing (accuracy = 38% ! 51%; N = 4 excluding cases scoring <10 or >90%). The CVA cases showed larger effects of cueing on these
Abstract / Brain and Language 95 (2005) 244–246
Semantic dementia 64
Stroke aphasia 64 56
r = .89, p = .003
Picture CCT
Picture CCT
56 48 Picture vs. word association
40 32 24 16
r = .70, p = .02
48 40 32 24 16 8 0
8 0 0
8
0
16 24 32 40 48 56 64
8
Cross-task correlation
Picture CCT
64
Sound-picture matching
r = .76, p = .01
48 44 40 36 32 28 24 20 16 12
r = .70, p = .02
12 16 20 24 28 32 36 40 44 48
12 16 20 24 28 32 36 40 44 48
Word-picture matching
Word-picture matching 64 56
r = .94, p < .0001
56 48
Picture CCT
Sound-picture matching
Word vs. sound-picture match
16 24 32 40 48 56 64 Word CCT
Word CCT 48 44 40 36 32 28 24 20 16 12
245
40 32 24 16
r = .01, p = .98
48 40 32 24 16 8 0
8 0 12 16 20 24 28 32 36 40 44 48
12 16 20 24 28 32 36 40 44 48
Word-picture matching
Word-picture matching Fluent Non-fluent
Fig. 1. Correlations between semantic tasks.
items (39% ! 73%, N = 5). The two groups also made different types of errors (CVA: fewer superordinate responses, e.g., kangaroo ! ‘‘animal’’ and more associative responses, e.g., train ! ‘‘diesel’’; squirrel ! ‘‘nuts’’). The CVA patients were also consistently impaired on Raven’s Coloured Progressive Matrices Test (<50th %). In contrast, SD patients perform well at this test (Bozeat et al., 2000).
these effects in CVA suggests that stroke aphasics may not have deficits of semantic knowledge per se. CVA patients also show less consistency across different semantic tasks, increased sensitivity to phonological cueing in picture naming and responses that are driven by strong (and sometimes inappropriate) semantic associations. The co-occurring executive deficit in CVA is consistent with the view that these patients fail to appropriately constrain activation of semantic representations in line with task demands.
Conclusions References Stroke aphasia can produce deficits on both verbal and non-verbal semantic tasks but the nature of the semantic impairment is different in the two groups. CVA patients are not affected by two variables, frequency, and specificity, that SD patients are highly sensitive to. More general and higher frequency concepts are thought to be more robust to semantic degradation in SD (Rogers et al., 2004). The failure to find
Berthier, M. L. (2001) Unexpected brain-language relationships in aphasia: Evidence from transcortical sensory aphasia associated with frontal lobe lesions. Aphasiology, 15(2), 99–130. Bozeat, S. et al. (2000) Non-verbal semantic impairment in semantic dementia. Neuropsychologia, 38(9), 1207–1215.
246
Abstract / Brain and Language 95 (2005) 244–246
Chertkow, H. et al. (1997) On the status of object concepts in aphasia. Brain and Language, 58(2), 203-232 Hart, J., & Gordon, B. (1990) Delineation of single-word semantic comprehension deficits in aphasia with anatomical correlation. Annals of Neurology, 27, 226–231.
Rogers, T. T. et al. (2004) The structure and deterioration of semantic memory: A neuropsychological and computational investigation. Psychological Review, 111, 205–235. Snowden, J. S. et al. (1989) Semantic dementia: A form of circumscribed cerebral atrophy. Behavioural Neurology, 2, 167–182.
Non-verbal semantic impairment in stroke aphasia: A comparison with semantic dementia E. Jefferies *, M.A. Lambon Ralph University of Manchester, UK Accepted 8 July 2005 Available online 6 September 2005
Introduction Semantic dementia (SD) is a neurodegenerative disease, associated with focal atrophy of the anterior temporal lobes bilaterally. SD produces a specific and progressive impairment of semantic memory that affects comprehension in all modalities (Bozeat et al., 2000; Snowden et al., 1989). This suggests anterior temporal cortex is the repository of multimodal semantic knowledge (Rogers et al., 2004). In contrast, comprehension-impaired CVA patients have infarction of very different brain regions: typically temporoparietal or frontotemporal cortex in the left hemisphere only (Berthier, 2001; Chertkow et al., 1997). The anterior temporal lobes, which receive two arterial supplies, are highly unlikely to be damaged bilaterally after stroke. This apparent inconsistency between SD and stroke aphasia raises several important questions: (1) can stroke aphasics show deficits on non-verbal as well as verbal semantic tasks (limited evidence suggests that they can (Chertkow et al., 1997; Hart & Gordon, 1990) and (2) if so, is the nature of the comprehension impairment the same in the two conditions? We present the first (to our knowledge) case-series comparison of SD and comprehension-impaired stroke aphasics to address these issues.
Method From a database of 52 stroke aphasic patients, we identified 10 cases who failed both verbal and non-verbal semantic tasks. Five of these cases were transcortical sensory aphasics. The remainder had less fluent speech and/or poorer repetition. These patients were compared with SD cases (e.g., 10 patients reported by Bozeat et al., 2000) on the same verbal and non-verbal semantics tasks: (1) The Camel and Cactus Test of semantic association (Bozeat et al., 2000) (e.g., does CAMEL go with cactus, flower, tree or grass?). The same items were presented as pictures and words in separate sessions (N = 96). (2) Spoken word to picture matching (Bozeat et al., 2000) (N = 48, nine semantically
*
Corresponding author. Fax: +44 1612752588. E-mail address: beth.jeff[email protected] (E. Jefferies).
0093-934X/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.bandl.2005.07.127
related distracters). (3) Environmental sound–picture matching using the same items (Bozeat et al., 2000). (4) Synonym judgement varying frequency and imageability (N ¼ 96, three choices per trial). (5) Wordpicture verification varying the specificity of the word (e.g., ‘‘Labrador’’ (specific level), ‘‘Dog’’ (basic level) or ‘‘Animal’’ (general level), N = 144). (6) Spoken picture naming with and without phonemic cues. These tests were administered as part of a larger battery that included further tests of semantic memory as well as reading and repetition and attentional/executive tests.
Results Both the SD and the CVA groups were impaired across a range of verbal and non-verbal semantic tasks. There were no consistent differences between the fluent and non-fluent CVA subgroups on any of these tests. Correlations between all of the semantic tasks were high for the SD patients, regardless of input modality, and the nature of the semantic decision (see Fig. 1). The CVA group also showed correlations across modalities for the same semantic tests. However, they showed no significant correlations between different semantic tests with differing non-semantic task demands. The SD patients were highly sensitive to word frequency in synonym judgement (proportion correct M = .73 [SD = .17] vs. .47 [SD = .20]) whereas the CVA patients were not M = .66 [SD = .10] vs. .66 (SD = .11). SD patients comprehended general terms better than specific terms in word-picture verification. This effect was greater for patients with more severe SD as measured by word-picture matching (d’: mild SD: general = 1.8; basic = 2.8; specific = 2.2; moderate SD: general = 2.2, basic = 1.7, specific = 1.1; severe SD: general = 2.3; basic = 1.4; specific = 0.2). The CVA group were less sensitive to this variable (mild CVA: general = 2.5; basic = 2.4; specific = 2.5; severe CVA: general = 1.0; basic = 1.4; specific = 1.0). Picture naming in the CVA group was improved by a two phoneme cue (by 25% on average in the Boston Naming Test). The SD cases were at floor on this test even with cues. On higher frequency items (N = 30), the SD patients showed some effect of phonemic cueing (accuracy = 38% ! 51%; N = 4 excluding cases scoring <10 or >90%). The CVA cases showed larger effects of cueing on these
Abstract / Brain and Language 95 (2005) 244–246
Semantic dementia 64
Stroke aphasia 64 56
r = .89, p = .003
Picture CCT
Picture CCT
56 48 Picture vs. word association
40 32 24 16
r = .70, p = .02
48 40 32 24 16 8 0
8 0 0
8
0
16 24 32 40 48 56 64
8
Cross-task correlation
Picture CCT
64
Sound-picture matching
r = .76, p = .01
48 44 40 36 32 28 24 20 16 12
r = .70, p = .02
12 16 20 24 28 32 36 40 44 48
12 16 20 24 28 32 36 40 44 48
Word-picture matching
Word-picture matching 64 56
r = .94, p < .0001
56 48
Picture CCT
Sound-picture matching
Word vs. sound-picture match
16 24 32 40 48 56 64 Word CCT
Word CCT 48 44 40 36 32 28 24 20 16 12
245
40 32 24 16
r = .01, p = .98
48 40 32 24 16 8 0
8 0 12 16 20 24 28 32 36 40 44 48
12 16 20 24 28 32 36 40 44 48
Word-picture matching
Word-picture matching Fluent Non-fluent
Fig. 1. Correlations between semantic tasks.
items (39% ! 73%, N = 5). The two groups also made different types of errors (CVA: fewer superordinate responses, e.g., kangaroo ! ‘‘animal’’ and more associative responses, e.g., train ! ‘‘diesel’’; squirrel ! ‘‘nuts’’). The CVA patients were also consistently impaired on Raven’s Coloured Progressive Matrices Test (<50th %). In contrast, SD patients perform well at this test (Bozeat et al., 2000).
these effects in CVA suggests that stroke aphasics may not have deficits of semantic knowledge per se. CVA patients also show less consistency across different semantic tasks, increased sensitivity to phonological cueing in picture naming and responses that are driven by strong (and sometimes inappropriate) semantic associations. The co-occurring executive deficit in CVA is consistent with the view that these patients fail to appropriately constrain activation of semantic representations in line with task demands.
Conclusions References Stroke aphasia can produce deficits on both verbal and non-verbal semantic tasks but the nature of the semantic impairment is different in the two groups. CVA patients are not affected by two variables, frequency, and specificity, that SD patients are highly sensitive to. More general and higher frequency concepts are thought to be more robust to semantic degradation in SD (Rogers et al., 2004). The failure to find
Berthier, M. L. (2001) Unexpected brain-language relationships in aphasia: Evidence from transcortical sensory aphasia associated with frontal lobe lesions. Aphasiology, 15(2), 99–130. Bozeat, S. et al. (2000) Non-verbal semantic impairment in semantic dementia. Neuropsychologia, 38(9), 1207–1215.
246
Abstract / Brain and Language 95 (2005) 244–246
Chertkow, H. et al. (1997) On the status of object concepts in aphasia. Brain and Language, 58(2), 203-232 Hart, J., & Gordon, B. (1990) Delineation of single-word semantic comprehension deficits in aphasia with anatomical correlation. Annals of Neurology, 27, 226–231.
Rogers, T. T. et al. (2004) The structure and deterioration of semantic memory: A neuropsychological and computational investigation. Psychological Review, 111, 205–235. Snowden, J. S. et al. (1989) Semantic dementia: A form of circumscribed cerebral atrophy. Behavioural Neurology, 2, 167–182.