fMRI language dominance and FDG-PET hypometabolism

Gaillard, William D.; Berl, Madison M.; Duke, Elizabeth S.; Ritzl, Eva K.; Miranda, Stênio C.; Liew, Charlene; Finegersh, Andrey; Martinez, Ashley R.; Dustin, Irene; Sato, S.; Theodore, William H.

doi:10.1212/wnl.0b013e31821527b5

Cited by 19 publications

(17 citation statements)

References 35 publications

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“…Reduced CBF might be a risk factor for a diminished BOLD response, thus increasing the risk of falsely lateralized language dominance on fMRI. In a previous study, hypometabolism was a marker for diseased temporal lobe and language reorganization, but we did not find evidence of impaired BOLD response in hypometabolic cortex (Gaillard et al., 2011). However, we were not able to perform precise regional comparison of positron emission tomography (PET) and fMRI data.…”

contrasting

confidence: 78%

Cerebral blood flow and fMRI BOLD auditory language activation in temporal lobe epilepsy

et al. 2012

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Purpose BOLD fMRI, an important research and clinical tool, depends on relatively greater transient increases in (cerebral blood flow) rCBF than CMRO2 during neural activity. We investigated whether reduced resting rCBF in patients with TLE affects BOLD signal during fMRI language mapping. Methods We used [15O] water PET to measure rCBF, and 3T EPI BOLD fMRI with an auditory description decision task in 33 patients with temporal lobe epilepsy (16 men; age 33.6±10.6 years; epilepsy onset 14.8±10.6 years; mean duration 18.8±13.2 years; 23 left focus, 10 right focus). Anatomical regions drawn on structural MRI, based on the Wake Forest PickAtlas, included Wernicke’s area (WA), inferior frontal gyrus (IFG), middle frontal gyrus (MFG), and hippocampus (HC)]. Laterality indices (LI), and Asymmetry Indices (AI), were calculated on co-registered fMRI and PET. Key findings Twelve patients had mesial temporal sclerosis (7 left), two a tumor or malformation of cortical development (both left), one a right temporal cyst and 18 normal MRI (14 left). Decreasing relative left WA CBF correlated with decreased left IFG voxel activation and decreasing left IFG LI. However, CBF WA AI was not related to left WA voxel activation itself or WA LI. There was a weak positive correlation between absolute CBF and fMRI activation in left IFG, right IFG, and left WA. Patients with normal and abnormal MRI did not differ in fMRI activation or rCBF AI. Significance Reduced WA rCBF is associated with reduced fMRI activation in IFG but not WA itself, suggesting distributed network effects, but not impairment of underlying BOLD response. Hypoperfusion in TLE does not affect fMRI clinical value.

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confidence: 78%

Cerebral blood flow and fMRI BOLD auditory language activation in temporal lobe epilepsy

et al. 2012

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“…Researchers have defined hemispheric dominance by different levels of the LI, such as > 0.1 or < −0.1 (Niskanen et al 2012), ≥0.2 or ≤ −0.2 (Gaillard et al 2011), or > 0.3 or < −0.3 (Liu et al 2009). In the current study, we consider LI values of > 0.3 or < −0.3 to show definitive lateralization.…”

Section: Resultsmentioning

confidence: 99%

“…To correct for multiple comparisons, cluster thresholding was applied to all data based on a Monte Carlo simulation that produced a corrected family-wise P value of < 0.05 at an individual voxel threshold of P = 0.0001. To determine lateralization of connectivity for specific seed regions, a laterality index (LI) was computed based on comparisons of total volume of significantly activated voxels in each hemisphere (Simonyan et al 2009; Gaillard et al 2011; Niskanen et al 2012). The LI formula that we used accounts for connectivity both within and across hemispheres (Liu et al 2009).…”

Section: Methodsmentioning

confidence: 99%

Functional connectivity and laterality of the motor and sensory components in the volitional swallowing network

et al. 2012

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Functional neuroimaging has shown that multiple brain regions are active during volitional swallowing. Little is known, however, about which regions integrate motor execution and sensory feedback in the swallowing system. Although unilateral brain lesions in either hemisphere can produce swallowing deficits, some functional neuroimaging studies indicate that the left hemisphere has greater activation in certain sensory and motor-related swallowing regions. In this study, correlation coefficients were computed for five seed regions during volitional saliva swallowing to determine the functional relationships of these regions with the rest of the brain: the anterior and posterior insula, inferior frontal gyrus (BA44), primary sensory cortex (S1), and primary motor cortex (M1). A laterality index (LI) was derived that accounts for relative differences in total, positive connected voxels for the left/right hemisphere seeds. Clusters of significantly connected voxels were greater from the anterior and posterior insula than from the other three seed regions. Interactions of the insula with other brain regions were greater on the left than on the right during volitional swallowing. Group means showed laterality in the anterior insula (LI = 0.25) and the posterior insula (LI = 0.33). BA44 showed a lesser degree of difference in left versus right hemisphere interactions (LI = 0.12) while S1 did not show lateralization (LI = 0.02) and M1 showed some predominance of interactions in the right hemisphere (LI = −0.19). The greater connectivity from the left hemisphere insula to brain regions within and across hemispheres suggests that the insula is a primary integrative region for volitional swallowing in humans.

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“…The changed cortical response during the tasks may indicate that alternative networks are involved to compensate for the compromised brain network, so as to achieve adequate task performance [Gaillard et al, 2011]. In the current study, Broca’s area and the left inferior parietal cortex, which are structurally connected through the frontal-parietal AF pathway, showed an increase both in structural and task-modulated functional connectivity.…”

Section: Discussionmentioning

confidence: 51%

“…Activity during language tasks decreases in the conventional language-related cortices in the left hemisphere, while additional areas are activated in both hemispheres [Adcock et al, 2003; Billingsley et al, 2001; Brázdil et al, 2005; Janszky et al, 2006; Powell et al, 2007; Thivard et al, 2005; Voets et al, 2006]. Although multiple factors could contribute to the change in cortical activity during language tasks, it has been suggested that patients with left TLE may have difficulty in recruiting the normal neural networks [Thivard et al, 2005] and the alternative network may be involved [Gaillard et al, 2011]. Considering that the frontal–temporal AF pathway connecting the anterior and posterior language-related cortices is a vulnerable pathway in left TLE, the change in structural connectivity through this pathway in the left hemisphere may underlie the change in cortical activity during language tasks in the these cortical regions.…”

Section: Introductionmentioning

confidence: 99%

Altered anterior‐posterior connectivity through the arcuate fasciculus in temporal lobe epilepsy

Takaya

Liu

Greve

et al. 2016

Human Brain Mapping

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How the interactions between cortices through a specific white matter pathway change during cognitive processing in patients with epilepsy remains unclear. Here, we used surface-based structural connectivity analysis to examine the change in structural connectivity with Broca’s area/the right Broca’s homologue in the lateral temporal and inferior parietal cortices through the arcuate fasciculus (AF) in 17 patients with left temporal lobe epilepsy (TLE) compared with 17 healthy controls. Then, we investigated its functional relevance to the changes in task-related responses and task-modulated functional connectivity with Broca’s area/the right Broca’s homologue during a semantic classification task of a single word. The structural connectivity through the AF pathway and task-modulated functional connectivity with Broca’s area decreased in the left midtemporal cortex. Furthermore, task-related response decreased in the left mid temporal cortex that overlapped with the region showing a decrease in the structural connectivity. In contrast, the region showing an increase in the structural connectivity through the AF overlapped with the regions showing an increase in task-modulated functional connectivity in the left inferior parietal cortex. These structural and functional changes in the overlapping regions were correlated. The results suggest that the change in the structural connectivity through the left frontal–temporal AF pathway underlies the altered functional networks between the frontal and temporal cortices during the language-related processing in patients with left TLE. The left frontal–parietal AF pathway might be employed to connect anterior and posterior brain regions during language processing and compensate for the compromised left frontal–temporal AF pathway.

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fMRI language dominance and FDG-PET hypometabolism

Abstract: Background: Atypical language dominance is common in patients with temporal lobe epilepsy. We

Cited by 19 publications

References 35 publications

Cerebral blood flow and fMRI BOLD auditory language activation in temporal lobe epilepsy

Cerebral blood flow and fMRI BOLD auditory language activation in temporal lobe epilepsy

Functional connectivity and laterality of the motor and sensory components in the volitional swallowing network

Altered anterior‐posterior connectivity through the arcuate fasciculus in temporal lobe epilepsy

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