Frequency based mutual information measures between clusters of brain regions in functional magnetic resonance imaging

NeuroImage ◽  
2007 ◽  
Vol 35 (1) ◽  
pp. 83-88 ◽  
Author(s):  
R. Salvador ◽  
A. Martínez ◽  
E. Pomarol-Clotet ◽  
S. Sarró ◽  
J. Suckling ◽  
...  
2021 ◽  
Author(s):  
Yu Wang ◽  
Hongfei Jia ◽  
Yifan Duan ◽  
Hongbing Xiao

Abstract Alzheimer's disease (AD) is a progressive neurodegenerative disease, which changes the structure of brain regions by some hidden causes. In this paper for assisting doctors to make correct judgments, an improved 3DPCANet method is proposed to classify AD by combining the mean (mALFF) of the whole brain. The main idea includes that firstly, the functional magnetic resonance imaging (fMRI) data is pre-processed, and mALFF is calculated to get the corresponding matrix. Then the features of mALFF images are extracted via the improved 3DPCANet network. Finally, AD patients with different stages are classified using support vector machine (SVM). Experiments results based on public data from the Alzheimer’s disease neuroimaging initiative (ADNI) show that the proposed approach has better performance compared with state-of-the-art methods. The accuracies of AD vs. significant memory concern (SMC), SMC vs. late mild cognitive impairment (LMCI), and normal control (NC) vs. SMC reach respectively 92.42%, 91.80%, and 89.50%, which testifies the feasibility and effectiveness of the proposed method.


2020 ◽  
Vol 63 (9) ◽  
pp. 3051-3067
Author(s):  
Amy E. Ramage ◽  
Semra Aytur ◽  
Kirrie J. Ballard

Purpose Brain imaging has provided puzzle pieces in the understanding of language. In neurologically healthy populations, the structure of certain brain regions is associated with particular language functions (e.g., semantics, phonology). In studies on focal brain damage, certain brain regions or connections are considered sufficient or necessary for a given language function. However, few of these account for the effects of lesioned tissue on the “functional” dynamics of the brain for language processing. Here, functional connectivity (FC) among semantic–phonological regions of interest (ROIs) is assessed to fill a gap in our understanding about the neural substrates of impaired language and whether connectivity strength can predict language performance on a clinical tool in individuals with aphasia. Method Clinical assessment of language, using the Western Aphasia Battery–Revised, and resting-state functional magnetic resonance imaging data were obtained for 30 individuals with chronic aphasia secondary to left-hemisphere stroke and 18 age-matched healthy controls. FC between bilateral ROIs was contrasted by group and used to predict Western Aphasia Battery–Revised scores. Results Network coherence was observed in healthy controls and participants with stroke. The left–right premotor cortex connection was stronger in healthy controls, as reported by New et al. (2015) in the same data set. FC of (a) connections between temporal regions, in the left hemisphere and bilaterally, predicted lexical–semantic processing for auditory comprehension and (b) ipsilateral connections between temporal and frontal regions in both hemispheres predicted access to semantic–phonological representations and processing for verbal production. Conclusions Network connectivity of brain regions associated with semantic–phonological processing is predictive of language performance in poststroke aphasia. The most predictive connections involved right-hemisphere ROIs—particularly those for which structural adaptions are known to associate with recovered word retrieval performance. Predictions may be made, based on these findings, about which connections have potential as targets for neuroplastic functional changes with intervention in aphasia. Supplemental Material https://doi.org/10.23641/asha.12735785


Nutrients ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 3010
Author(s):  
Andy Wai Kan Yeung ◽  
Natalie Sui Miu Wong

This systematic review aimed to reveal the differential brain processing of sugars and sweeteners in humans. Functional magnetic resonance imaging studies published up to 2019 were retrieved from two databases and were included into the review if they evaluated the effects of both sugars and sweeteners on the subjects’ brain responses, during tasting and right after ingestion. Twenty studies fulfilled the inclusion criteria. The number of participants per study ranged from 5 to 42, with a total number of study participants at 396. Seven studies recruited both males and females, 7 were all-female and 6 were all-male. There was no consistent pattern showing that sugar or sweeteners elicited larger brain responses. Commonly involved brain regions were insula/operculum, cingulate and striatum, brainstem, hypothalamus and the ventral tegmental area. Future studies, therefore, should recruit a larger sample size, adopt a standardized fasting duration (preferably 12 h overnight, which is the most common practice and brain responses are larger in the state of hunger), and reported results with familywise-error rate (FWE)-corrected statistics. Every study should report the differential brain activation between sugar and non-nutritive sweetener conditions regardless of the complexity of their experiment design. These measures would enable a meta-analysis, pooling data across studies in a meaningful manner.


2006 ◽  
Vol 189 (6) ◽  
pp. 560-561 ◽  
Author(s):  
Therese Van Amelsvoort ◽  
Nicole Schmitz ◽  
Eileen Daly ◽  
Quinton Deeley ◽  
Hugo Critchley ◽  
...  

SummaryWe studied the functional neuroanatomy of social behaviour in velo-cardio-facial syndrome (VCFS) using a facial emotional processing task and functional magnetic resonance imaging in adults with this syndrome and controls matched for age and IQ. The VCFS group had less activation in the right insula and frontal brain regions and more activation in occipital regions. Genetically determined abnormalities in pathways including those involved in emotional processing may underlie deficits in social cognition in people with VCFS.


2020 ◽  
Vol 9 (3) ◽  
pp. 151-162
Author(s):  
Doris Grössinger ◽  
Silvia Erika Kober ◽  
Stefan M. Spann ◽  
Rudolf Stollberger ◽  
Guilherme Wood

Abstract. Neurofeedback allows participants to voluntarily control their own brain activity. Consequently, neurofeedback is a potential intervention tool in diverse clinical domains. Different brain signals can be fed back to the neurofeedback users, such as the hemodynamic response of the brain using functional magnetic resonance imaging (fMRI) and near-infrared spectroscopy (NIRS) or electrophysiological brain signals as measured with electroencephalography (EEG). Each of these neuroscientific methods has its advantages and disadvantages. For instance, using fMRI all brain regions can be targeted, while in EEG and NIRS signals from deeper regions cannot be precisely differentiated. Hence, fMRI-based neurofeedback allows treatment of mental and physical diseases, which are associated with activation patterns in deeper brain regions. Until now, only the blood oxygen level dependent signal (BOLD) has been used as feedback signal in fMRI-based neurofeedback studies. However, we have started to develop a neurofeedback pipeline using a different fMRI signal, namely arterial spin labeling (ASL), which will be introduced in this article. ASL neurofeedback enables a direct modulation of the cerebral blood flow and, consequently, might improve rehabilitation of disorders caused by perfusion imbalance in the future.


Neurosurgery ◽  
2004 ◽  
Vol 55 (3) ◽  
pp. 569-581 ◽  
Author(s):  
John L. Ulmer ◽  
Lotfi Hacein-Bey ◽  
Vincent P. Mathews ◽  
Wade M. Mueller ◽  
Edgar A. DeYoe ◽  
...  

Abstract OBJECTIVE: To illustrate how lesion-induced neurovascular uncoupling at functional magnetic resonance imaging (fMRI) can mimic hemispheric dominance opposite the side of a lesion preoperatively. METHODS: We retrospectively reviewed preoperative fMRI mapping data from 50 patients with focal brain abnormalities to establish patterns of hemispheric dominance of language, speech, visual, or motor system functions. Abnormalities included gliomas (31 patients), arteriovenous malformations (AVMs) (11 patients), other congenital lesions (4 patients), encephalomalacia (3 patients), and tumefactive encephalitis (1 patient). A laterality ratio of fMRI hemispheric dominance was compared with actual hemispheric dominance as verified by electrocortical stimulation, Wada testing, postoperative and posttreatment deficits, and/or lesion-induced deficits. fMRI activation maps were generated with cross-correlation (P < 0.001) or t test (P < 0.001) analysis. RESULTS: In 50 patients, a total of 85 functional areas were within 5 mm of the edge of a potentially resectable lesion. In 23 of these areas (27%), reduced fMRI signal in perilesional eloquent cortex in conjunction with preserved or increased signal in homologous contralateral brain areas revealed functional dominance opposite the side of the lesion. This suggested possible lesion-induced transhemispheric cortical reorganization to homologous brain regions (homotopic reorganization). In seven patients, however, the fMRI data were inconsistent with other methods of functional localization. In two patients with left inferior frontal gyrus gliomas and in one patient with focal tumefactive meningoencephalitis, fMRI incorrectly suggested strong right hemispheric speech dominance. In two patients with lateral precentral gyrus region gliomas and one patient with a left central sulcus AVM, the fMRI pattern incorrectly suggested primary corticobulbar motor dominance contralateral to the side of the lesion. In a patient with a right superior frontal gyrus AVM, fMRI revealed pronounced left dominant supplementary motor area activity in response to a bilateral complex motor task, but right superior frontal gyrus perilesional hemorrhage and edema subsequently caused left upper-extremity plegia. Pathophysiological factors that might have caused neurovascular uncoupling and facilitated pseudo-dominance at fMRI in these patients included direct tumor infiltration, neovascularity, cerebrovascular inflammation, and AVM-induced hemodynamic effects. Sixteen patients had proven (1 patient), probable (2 patients), or possible (13 patients) but unproven lesion-induced homotopic cortical reorganization. CONCLUSION: Lesion-induced neurovascular uncoupling causing reduced fMRI signal in perilesional eloquent cortex, in conjunction with normal or increased activity in homologous brain regions, may simulate hemispheric dominance and lesion-induced homotopic cortical reorganization.


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