Distinct mechanisms and timing of language recovery after stroke

Figures & data

Figure 1. The “language network”: Areas of the brain frequently activated across very different language tasks. (A) Areas activated in association with silent word generation in normal controls (Prabhakaran et al., 2007); (B) areas of activation associated with word retrieval (naming and oral reading minus saying, “1, 2, 3”; Parker Jones et al., 2012); (C) areas of activation associated with syntax repetition (Segaert et al., 2012); and (D) areas of activation associated with reading (blue) and spelling (green; Rapp & Lipka, 2011). [To view this figure in colour, please see the online version of this journal.]

Table 1. Participant 1 performance on the Johns Hopkins lexical battery

	Percentage correct
Tasks	Day 1	Day 2	Day 5	Month 2	Year 1
Auditory comprehension
Syntactically complex questions	60	70.0	80	100	100
Syntactically simple questions	92.0 (normal)	92.0	100	100	100
Auditory comprehension: Words	91.0 (normal)	89.1	100	100	100
Written comprehension: Words	100	100.0	100	100	100
Oral naming	0	47.1	89.2	100	100
Tactile naming	6	35.3	100	N/A	100
Lexical decision	100	N/A	100	96.6	100
Oral reading	96.6	N/A	96.6	96.6	1.7

Table 2. Western Aphasia Battery and additional tasks

	Participant
	Participant 5	Participant 4		Participant 2		Participant 3
Test	Day 3	Day 3	Week 2	Day 3	Month 2	Day 3	Month 2
Western Aphasia Battery
Aphasia quotient (AQ)	5030	7740	9000	9800	9990	9240	10,000
Spontaneous speech score (% of total points)
(a) Information content	50	100	100	100	100	100	100
(b) Fluency	20	40	60	90	100	100	100
Auditory verbal comprehension (% total points)
(a) Yes/no questions	85	90	100	100	100	95	100
(b) Auditory word recognition	63	100	100	98	100	98	100
(c) Sequential commands	43	100	100	100	100	94	100
Repetition (% of total points)	89	100	100	100	100	100	100
Naming and word finding (% of total points)
(a) Object naming	33	50	80	100	100	95	100
(b) Word fluency (animal naming) % of 20	0	10	100	100	100	90	100
(c) Sentence completion	7	100	100	100	100	100	100
(d) Responsive speech	4	80	90	100	100	100	100
Additional tasks
Trail Making
(a) Part A (time, s)	250	75		40	30
(b) Part B (time, s)	unable to do	>120		72	54
Word Fluency (F-A-S): Total words	N/A	N/A	N/A	500	1700	N/A	N/A
Silent spelling task score	80	100	100	100	100	100	100
Oral reading task: Lexical reading score	100	100	100	100	100	100	100
Reading comprehension Task score	100	100	100	100	100	100	100
Naming score	75	80	100	100	100	100	100

Figure 2. (A) Participant 1's DWI (left) and PWI (right) before intervention to restore blood flow shows hypoperfusion of left frontal and inferior temporal cortex, and acute infarcts in subcortical watershed areas. TTP = time-to-peak. (B) DWI and PWI post intervention shows reperfusion of left frontal and inferior temporal cortex (and unchanged acute subcortical infarcts). (C) Language testing shows improvement in oral picture naming and oral naming of objects from tactile input after reperfusion of left frontal and inferior temporal cortex. [To view this figure in colour, please see the online version of this journal.]

Figure 3. Temporal correlation between mean arterial pressure and oral picture naming accuracy for Participant 1. The two solid lines at the top of Figure 3 represent times when Participant 1 was receiving intervention to increase blood pressure.

Figure 4. DWI (Panel A) and apparent diffusion coefficient (ADC; Panel B) sequences show a subcentimetre area of diffusion restriction in the left thalamus for Participant 2. Functional magnetic resonance imaging (fMRI) data registered in Montreal Neurological Institute (MNI) space shows areas of activation associated with silent word generation at Day 3 (Panel C) and 8 weeks (Panel D). fMRI activation maps are false discovery rate (FDR) corrected for multiple comparisons and are displayed with a threshold of p < .05. A difference statistical map (Panel E) shows activation that is greater at 8 weeks than 3 weeks in yellow, and activation that is greater at 3 weeks than 8 weeks in blue. This last map shows change in statistical maps as a function of time. [To view this figure in colour, please see the online version of this journal.]

Figure 5. Lateralization index for word generation in eight regions of interest (ROIs) at 3 days compared to 8 weeks in Participant 2. ROIs are: superior frontal gyrus (SFG), medial frontal gyrus (MFG), inferior frontal gyrus (IFG), superior temporal gyrus (STG), middle temporal gyrus (MTG), inferior temporal gyrus (ITG), supramarginal gyrus (SMG), and angular gyrus (AG).

Figure 6. Panel A: DWI and PWI at Day 1 for Participant 3. Panel B: Activation associated with picture naming for Participant 3 at Day 3. Panel C: Activation associated with picture naming at 8 weeks. Functional magnetic resonance imaging (fMRI) activation maps are false discovery rate (FDR) corrected for multiple comparisons and are displayed with a threshold of p < .05. Panel D: A difference statistical map shows activation that is greater at 8 weeks than 3 weeks in yellow, and activation that is greater at 3 weeks than 8 weeks in blue. [To view this figure in colour, please see the online version of this journal.]

Figure 7. Lateralization index for picture naming in eight regions of interest (ROIs) at 3 days compared to 8 weeks in Participant 3. ROIs are: superior frontal gyrus (SFG), medial frontal gyrus (MFG), inferior frontal gyrus (IFG), superior temporal gyrus (STG), middle temporal gyrus (MTG), inferior temporal gyrus (ITG), supramarginal gyrus (SMG), and angular gyrus (AG).

Figure 8. Probabilistic fibre tract lesion disruption analysis. The bar graph illustrates the percentage of disruption to each white matter tract for Participant 2 (top panel) and Participant 3 (lower panel). CST_L, cortico spinal cord (left); PrCG_L = precentral gyrus (left).

Figure 9. Global analysis of cortical function disruption in Participant 3. The degree of white matter tract disruption in each cortical region is determined from the intersection of the lesion region of interest (ROI) and a probabilistic fibre tract atlas. The results are presented as a percentage of total white matter tract disruption, normalized to the region of highest level of disruption, in Participant 3. [To view this figure in colour, please see the online version of this journal.]

Figure 10. Panel A: DWI (top) and PWI (bottom) at Day 1 for Participant 4. Panel B: DWI (top) and PWI (bottom) at Day 1 for Participant 5. Panel C: Functional magnetic resonance imaging (fMRI) activation associated with the orthographic task (retrieval of spelling) for Participant 4. Panel D: fMRI activation associated with the orthographic task (retrieval of spelling) for Participant 5. Panel E: Activation for Participant 4 minus activation for Participant 5, associated with the orthographic task. fMRI activation maps are false discovery rate (FDR) corrected for multiple comparisons and are displayed with a threshold of p < .05. Volumes with greater than 2 mm movement were censored out. [To view this figure in colour, please see the online version of this journal.]

Table 3. Number of voxels with activation in nine regions of interest in each hemisphere

	Participant 4		Participant 5
Region of interest	Spelling	Reading	Spelling	Reading
LSFG	6165	0	169	31
RSFG	8743	0	35	673
LMFG	3300	0	0	268
RMFG	7068	0	0	249
LIFG	5853	0	0	262
RIFG	2092	0	0	762
LSTG	507	0	50	947
RSTG	4990	0	0	102
LMTG	6940	0	0	26
RMTG	6206	0	160	29
LITG	492	0	0	0
RITG	552	0	0	0
LSMG	648	0	0	0
RSMG	906	0	0	298
LAG	1301	0	0	0
RAG	894	0	0	0
LFG	400	0	0	45
RFG	727	0	0	179

Note: During orthographic task (retrieval of spelling) and reading at p < .05. L = left; R = right; SFG = superior frontal gyrus; MFG = medial frontal gyrus; IFG = inferior frontal gyrus; STG = superior temporal gyrus; MTG = middle temporal gyrus; ITG = inferior temporal gyrus; SMG = supramarginal gyrus; AG = angular gyrus; FG = fusiform gyrus.

Figure 11. Activation associated with reading for Participant 5. Functional magnetic resonance imaging (fMRI) data are adjusted for multiple corrections and are presented with threshold of p < .05. [To view this figure in colour, please see the online version of this journal.]

Prabhakaran, V., Raman, S. P., Grunwald, M. R., Mahadevia, A., Hussain, N., Lu, H.,…Hillis, A. E. (2007). Neural substrates of word generation during stroke recovery: The influence of cortical hypoperfusion. Behavioural Neurology, 18, 45–52. doi: 10.1155/2007/430402

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Parker Jones, O., Green, D. W., Grogan, A., Pliatsikas, C., Filippopolitis, K., Ali, N.,…Price, C. J. (2012). Where, when and why brain activation differs for bilinguals and monolinguals during picture naming and reading aloud. Cerebral Cortex, 22, 892–902. doi: 10.1093/cercor/bhr161

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Segaert, K., Menenti, L., Weber, K., Petersson, K. M., & Hagoort, P. (2012). Shared syntax in language production and language comprehension--an FMRI study. Cerebral Cortex, 22, 1662–1670. doi: 10.1093/cercor/bhr249

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Rapp, B., & Lipka, K. (2011). The literate brain: The relationship between spelling and reading. Journal of Cognitive Neuroscience, 23, 1180–1197. doi: 10.1162/jocn.2010.21507

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