scholarly journals Agrammatism and Paragrammatism: A Cortical Double Dissociation Revealed by Lesion-Symptom Mapping

2020 ◽  
Vol 1 (2) ◽  
pp. 208-225 ◽  
Author(s):  
William Matchin ◽  
Alexandra Basilakos ◽  
Brielle C. Stark ◽  
Dirk-Bart den Ouden ◽  
Julius Fridriksson ◽  
...  
Keyword(s):  
Speech Rate ◽  
Region Of Interest ◽  
Lesion Volume ◽  
Double Dissociation ◽  
High Resolution Mri ◽  
Left Posterior ◽  
Fundamental Distinction ◽  
Secondary Analyses ◽  
Lesion Symptom Mapping ◽  
Left Hemisphere Stroke

The fundamental distinction of grammatical deficits in aphasia, agrammatism and paragrammatism, was made over a century ago. However, the extent to which the agrammatism/paragrammatism distinction exists independently of differences in speech fluency has not clearly been investigated. Despite much research on agrammatism, the lesion correlates of paragrammatism are essentially unknown. Lesion-symptom mapping was used to investigate the degree to which the lesion correlates of agrammatism and paragrammatism overlap or dissociate. Four expert raters assessed videos of 53 right-handed patients with aphasia following chronic left-hemisphere stroke retelling the Cinderella story. Consensus discussion determined each subject’s classification with respect to grammatical deficits as Agrammatic, Paragrammatic, Both, or No Grammatical Deficit. Each subject’s lesion was manually drawn on a high-resolution MRI and warped to standard space for group analyses. Lesion-symptom mapping analyses were performed in NiiStat including lesion volume as a covariate. Secondary analyses included speech rate (words per minute) as an additional covariate. Region of interest analyses identified a double dissociation between these syndromes: damage to Broca’s area was significantly associated with agrammatism, p = 0.001 (but not paragrammatism, p = 0.930), while damage to the left posterior superior and middle temporal gyri was significantly associated with paragrammatism, p < 0.001 (but not agrammatism, p = 0.873). The same results obtained when regressing out the effect of speech rate, and nonoverlapping lesion distributions between the syndromes were confirmed by uncorrected whole brain analyses. Our results support a fundamental distinction between agrammatism and paragrammatism.

scholarly journals Agrammatism and paragrammatism: a cortical double dissociation revealed by lesion-symptom mapping

2020 ◽  
Author(s):  
William Matchin ◽  
Alexandra Basilakos ◽  
Brielle C. Stark ◽  
Dirk-Bart den Ouden ◽  
Julius Fridriksson ◽  
...  
Keyword(s):  
Speech Rate ◽  
Region Of Interest ◽  
Lesion Volume ◽  
Double Dissociation ◽  
High Resolution Mri ◽  
Left Posterior ◽  
Fundamental Distinction ◽  
Secondary Analyses ◽  
Lesion Symptom Mapping ◽  
Left Hemisphere Stroke

AbstractThe fundamental distinction of grammatical deficits in aphasia, agrammatism and paragrammatism, was made over a century ago. However, the extent to which the agrammatism/paragrammatism distinction exists independently of differences in speech fluency has not clearly been investigated. Despite much research on agrammatism, the lesion correlates of paragrammatism are essentially unknown. Lesion-symptom mapping was used to investigate the degree to which the lesion correlates of agrammatism and paragrammatism overlap or dissociate. Four expert raters assessed videos of 53 right-handed patients with aphasia following chronic left hemisphere stroke retelling the Cinderella story. Consensus discussion determined each subject’s classification with respect to grammatical deficits as Agrammatic, Paragrammatic, Both, or No Grammatical Deficit. Each subject’s lesion was manually drawn on a high-resolution MRI and warped to standard space for group analyses. Lesion-symptom mapping analyses were performed in NiiStat including lesion volume as a covariate. Secondary analyses included speech rate (words per minute) as an additional covariate. Region of interest analyses identified a double dissociation between these syndromes: damage to Broca’s area was significantly associated with agrammatism, p = 0.001 (but not paragrammatism, p = 0.930), while damage to the left posterior superior and middle temporal gyri was significantly associated with paragrammatism, p < 0.001 (but not agrammatism, p = 0.873). The same results obtained when regressing out the effect of speech rate, and non-overlapping lesion distributions between the syndromes were confirmed by uncorrected whole brain analyses. Our results support a fundamental distinction between agrammatism and paragrammatism.

scholarly journals Characterising factors underlying praxis deficits in chronic left hemisphere stroke patients

2020 ◽  
Author(s):  
Elisabeth Rounis ◽  
Ajay Halai ◽  
Gloria Pizzamiglio ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Left Hemisphere ◽  
Cognitive Disorders ◽  
Principal Component ◽  
Lesion Volume ◽  
Semantic Retrieval ◽  
Stroke Patients ◽  
Limb Apraxia ◽  
Lesion Symptom Mapping ◽  
Neuropsychological Tasks ◽  
Left Hemisphere Stroke

AbstractLimb apraxia, a disorder of skilled action not consequent on primary motor or sensory deficits, has traditionally been defined according to errors patients make on neuropsychological tasks. Previous models of the disorder have failed to provide a unified account of patients’ deficits, due to heterogeneity in the patients and tasks used. In this study we implemented principal component analysis (PCA) to elucidate core factors of the disorder in a cohort of 41 unselected left hemisphere chronic stroke patients who were tested on a comprehensive and validated apraxia screen. Three principal components were identified: posture selection, semantic control and multi-demand sequencing. These were submitted to a lesion symptom mapping (VBCM) analysis in a subset of 24 patients, controlled for lesion volume, age and time post-stroke. Although the first component revealed no significant structural correlates, the second and third components were related to regions in the ‘ventro-dorsal’ and ‘ventral’ and ‘dorsal’ pathways, respectively. These results challenge the previously reported distinction between ideomotor and ideational deficits and highlight a significant role of common cognitive functions in the disorder, which include action selection, semantic retrieval, sequencing and response inhibition. Further research using this technique would help elucidate the cognitive processes underlying limb apraxia and their relationship with other cognitive disorders.

scholarly journals Syntax-Sensitive Regions of the Posterior Inferior Frontal Gyrus and the Posterior Temporal Lobe Are Differentially Recruited by Production and Perception

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
William Matchin ◽  
Emily Wood
Keyword(s):  
Temporal Lobe ◽  
Inferior Frontal Gyrus ◽  
Regions Of Interest ◽  
Syntactic Processing ◽  
Activation Patterns ◽  
Fmri Study ◽  
Left Posterior ◽  
Lesion Symptom Mapping

Abstract Matchin and Hickok (2020) proposed that the left posterior inferior frontal gyrus (PIFG) and the left posterior temporal lobe (PTL) both play a role in syntactic processing, broadly construed, attributing distinct functions to these regions with respect to production and perception. Consistent with this hypothesis, functional dissociations between these regions have been demonstrated with respect to lesion–symptom mapping in aphasia. However, neuroimaging studies of syntactic comprehension typically show similar activations in these regions. In order to identify whether these regions show distinct activation patterns with respect to syntactic perception and production, we performed an fMRI study contrasting the subvocal articulation and perception of structured jabberwocky phrases (syntactic), sequences of real words (lexical), and sequences of pseudowords (phonological). We defined two sets of language-selective regions of interest (ROIs) in individual subjects for the PIFG and the PTL using the contrasts [syntactic &gt; lexical] and [syntactic &gt; phonological]. We found robust significant interactions of comprehension and production between these 2 regions at the syntactic level, for both sets of language-selective ROIs. This suggests a core difference in the function of these regions with respect to production and perception, consistent with the lesion literature.

scholarly journals Volume Estimation of Pulmonary Lesion Using Chest CT Sequence

2018 ◽  
Vol 7 (3.1) ◽  
pp. 186
Author(s):  
Ramyasri Nayak ◽  
Nandish S ◽  
Prakashini Koteshwara
Keyword(s):  
3D Visualization ◽  
Pulmonary Nodules ◽  
Region Of Interest ◽  
Volume Estimation ◽  
Pulmonary Lesion ◽  
Lesion Volume ◽  
Solid Portion ◽  
Appropriate Treatment ◽  
Magnetic Resonance Imaging Mri ◽  
3D Software

Many of the imaging modalities like X-ray, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), fMRI have emerged to capture high quality images of anatomical structures of the human body. Radiologist can also have a better visualization if the regions of interest in the images are extracted and visualized 3D. To extract region of interest, sometimes preprocessing steps are performed on the input data. Pulmonary lesion is a small round or oval-shaped growth in the lung. It consists of solid and non-solid portion. The estimation of solid and non-solid portion of the pulmonary nodules will help the clinicians in the diagnosis and to suggest the appropriate treatment methodology. Lesion volume estimation gives a brief idea about the area occupied by the lesion tissues, which in turn can help the radiologist to plan treatment accordingly. In proposed work, lesion is segmented using K-means algorithm and then volume of the lesion is estimated. The slices which have segmented lesion with solid and non-solid regions is used for 3D visualization. The results obtained using the proposed methodology is validated with the Slicer 3D software. Error in the estimated volume of the solid and non-solid portion of the lesion was found to be in the range of 1.11% - 3.30% and 0.1% to 4.55% respectively. Results from the proposed methodology, lesion extraction with solid and non-solid, 3D visualization of the same and volume estimation respectively are validated by taking feedback from the radiologists and segmented lesion slices are used to estimate the volume and 3D visualization in Slicer 3D software for validation.  

scholarly journals Lesion localization of speech comprehension deficits in chronic aphasia

Neurology ◽  
2017 ◽  
Vol 88 (10) ◽  
pp. 970-975 ◽  
Author(s):  
Sara B. Pillay ◽  
Jeffrey R. Binder ◽  
Colin Humphries ◽  
William L. Gross ◽  
Diane S. Book
Keyword(s):  
Language Impairment ◽  
Sentence Comprehension ◽  
Spoken Language ◽  
Control Measures ◽  
Verbal Description ◽  
Middle Temporal Gyrus ◽  
Speech Comprehension ◽  
Posterior Portion ◽  
Lesion Symptom Mapping ◽  
Left Hemisphere Stroke

Objective:Voxel-based lesion-symptom mapping (VLSM) was used to localize impairments specific to multiword (phrase and sentence) spoken language comprehension.Methods:Participants were 51 right-handed patients with chronic left hemisphere stroke. They performed an auditory description naming (ADN) task requiring comprehension of a verbal description, an auditory sentence comprehension (ASC) task, and a picture naming (PN) task. Lesions were mapped using high-resolution MRI. VLSM analyses identified the lesion correlates of ADN and ASC impairment, first with no control measures, then adding PN impairment as a covariate to control for cognitive and language processes not specific to spoken language.Results:ADN and ASC deficits were associated with lesions in a distributed frontal-temporal parietal language network. When PN impairment was included as a covariate, both ADN and ASC deficits were specifically correlated with damage localized to the mid-to-posterior portion of the middle temporal gyrus (MTG).Conclusions:Damage to the mid-to-posterior MTG is associated with an inability to integrate multiword utterances during comprehension of spoken language. Impairment of this integration process likely underlies the speech comprehension deficits characteristic of Wernicke aphasia.

scholarly journals Critical brain regions for action recognition: lesion symptom mapping in left hemisphere stroke

Brain ◽  
2010 ◽  
Vol 133 (11) ◽  
pp. 3269-3280 ◽  
Author(s):  
Solène Kalénine ◽  
Laurel J. Buxbaum ◽  
Harry Branch Coslett
Keyword(s):  
Left Hemisphere ◽  
Action Recognition ◽  
Brain Regions ◽  
Lesion Symptom Mapping ◽  
Left Hemisphere Stroke

scholarly journals The role of conflict, feedback, and action comprehension in monitoring of action errors: Evidence for internal and external routes

2019 ◽  
Author(s):  
Cortney M. Howard ◽  
Louisa L. Smith ◽  
H. Branch Coslett ◽  
Laurel J. Buxbaum
Keyword(s):  
Error Correction ◽  
Production Planning ◽  
Left Hemisphere ◽  
Brain Regions ◽  
Support Vector ◽  
Complex Action ◽  
Gesture Comprehension ◽  
Lesion Symptom Mapping ◽  
Left Hemisphere Stroke

The mechanisms and brain regions underlying error monitoring in complex action are poorly understood, yet errors and impaired error correction in these tasks are hallmarks of apraxia, a common disorder associated with left hemisphere stroke. Accounts of monitoring of language posit an internal route by which production planning or competition between candidate representations provide predictive signals that monitoring is required to prevent error, and an external route in which output is monitored using the comprehension system. Abnormal reliance on the external route has been associated with damage to brain regions critical for sensory-motor transformation and a pattern of gradual error ‘clean-up’ called conduite d’approche (CD). Action pantomime data from 67 participants with left hemisphere stroke were consistent with versions of internal route theories positing that competition signals monitoring requirements. Support Vector Regression Lesion Symptom Mapping (SVR-LSM) showed that lesions in the inferior parietal, posterior temporal, and arcuate fasciculus/superior longitudinal fasciculus predicted action conduite d’approche, overlapping the regions previously observed in the language domain. A second experiment with 12 patients who produced substantial action CD assessed whether factors impacting the internal route (action production ability, competition) versus external route (vision of produced actions, action comprehension) influenced correction attempts. In these ‘high CD’ patients, vision of produced actions and integrity of gesture comprehension interacted to determine successful error correction, supporting external route theories. Viewed together, these and other data suggest that skilled actions are monitored both by an internal route in which conflict aids in detection and correction of errors during production planning, and an external route that detects mismatches between produced actions and stored knowledge of action appearance. The parallels between language and action monitoring mechanisms and neuroanatomical networks pave the way for further exploration of common and distinct processes across these domains.

scholarly journals A Double Dissociation in Sensitivity to Verb and Noun Semantics Across Cortical Networks

2019 ◽  
Vol 29 (11) ◽  
pp. 4803-4817 ◽  
Author(s):  
Giulia V Elli ◽  
Connor Lane ◽  
Marina Bedny
Keyword(s):  
Pattern Analysis ◽  
Light Emission ◽  
Inferior Frontal Gyrus ◽  
Middle Temporal Gyrus ◽  
Cortical Networks ◽  
Multivoxel Pattern Analysis ◽  
Grammatical Class ◽  
Double Dissociation ◽  
Neural Organization ◽  
Left Posterior

AbstractWhat is the neural organization of the mental lexicon? Previous research suggests that partially distinct cortical networks are active during verb and noun processing, but what information do these networks represent? We used multivoxel pattern analysis (MVPA) to investigate whether these networks are sensitive to lexicosemantic distinctions among verbs and among nouns and, if so, whether they are more sensitive to distinctions among words in their preferred grammatical class. Participants heard 4 types of verbs (light emission, sound emission, hand-related actions, mouth-related actions) and 4 types of nouns (birds, mammals, manmade places, natural places). As previously shown, the left posterior middle temporal gyrus (LMTG+), and inferior frontal gyrus (LIFG) responded more to verbs, whereas the inferior parietal lobule (LIP), precuneus (LPC), and inferior temporal (LIT) cortex responded more to nouns. MVPA revealed a double-dissociation in lexicosemantic sensitivity: classification was more accurate among verbs than nouns in the LMTG+, and among nouns than verbs in the LIP, LPC, and LIT. However, classification was similar for verbs and nouns in the LIFG, and above chance for the nonpreferred category in all regions. These results suggest that the lexicosemantic information about verbs and nouns is represented in partially nonoverlapping networks.

scholarly journals A double dissociation in sensitivity to verb and noun semantics across cortical networks

2018 ◽  
Author(s):  
Giulia V. Elli ◽  
Connor Lane ◽  
Marina Bedny
Keyword(s):  
Pattern Analysis ◽  
Light Emission ◽  
Inferior Frontal Gyrus ◽  
Brain Regions ◽  
Middle Temporal Gyrus ◽  
Cortical Networks ◽  
Multivoxel Pattern Analysis ◽  
Double Dissociation ◽  
Neural Organization ◽  
Left Posterior

AbstractWhat is the neural organization of the mental lexicon? Previous research suggests that partially distinct cortical networks are active during verb and noun processing. Are these networks preferentially involved in representing the meanings of verbs as opposed to nouns? We used multivoxel pattern analysis (MVPA) to investigate whether brain regions that are more active during verb than noun processing are also more sensitive to distinctions among their preferred lexical class. Participants heard four types of verbs (light emission, sound emission, hand-related actions, mouth-related actions) and four types of nouns (birds, mammals, manmade places, natural places). As previously shown, the left posterior middle temporal gyrus (LMTG) and inferior frontal gyrus (LIFG) responded more to verbs, whereas areas in the inferior parietal lobule (LIP), precuneus (LPC), and inferior temporal (LIT) cortex responded more to nouns. MVPA revealed a double-dissociation in semantic sensitivity: classification was more accurate among verbs than nouns in the LMTG, and among nouns than verbs in the LIP, LPC, and LIT. However, classification was similar for verbs and nouns in the LIFG, and above chance for the non-preferred category in all regions. These results suggest that the meanings of verbs and nouns are represented in partially non-overlapping networks.

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