•We present a novel method for lesion delineation in individual T1 MRI scans.•We compared our method with manual delineation for a large group of stroke patients.•Our method reliably predicted lesion ...extents and volumes.•Our method identified lesion effects that pose challenges for manual delineation.•Our method can be used for lesion-symptom mapping and clinical volume estimation.
Manual lesion delineation by an expert is the standard for lesion identification in MRI scans, but it is time-consuming and can introduce subjective bias. Alternative methods often require multi-modal MRI data, user interaction, scans from a control population, and/or arbitrary statistical thresholding.
We present an approach for automatically identifying stroke lesions in individual T1-weighted MRI scans using naïve Bayes classification. Probabilistic tissue segmentation and image algebra were used to create feature maps encoding information about missing and abnormal tissue. Leave-one-case-out training and cross-validation was used to obtain out-of-sample predictions for each of 30 cases with left hemisphere stroke lesions.
Our method correctly predicted lesion locations for 30/30 un-trained cases. Post-processing with smoothing (8mm FWHM) and cluster-extent thresholding (100 voxels) was found to improve performance.
Quantitative evaluations of post-processed out-of-sample predictions on 30 cases revealed high spatial overlap (mean Dice similarity coefficient=0.66) and volume agreement (mean percent volume difference=28.91; Pearson's r=0.97) with manual lesion delineations.
Our automated approach agrees with manual tracing. It provides an alternative to automated methods that require multi-modal MRI data, additional control scans, or user interaction to achieve optimal performance. Our fully trained classifier has applications in neuroimaging and clinical contexts.
•Studies examining how physical activity and cognition are related in PWE are rare.•There is a potential positive association between physical activity and cognition in PWE.•Known physical activity ...benefits suggest its promise as a cognitive treatment in PWE.•Large physical activity RCTs in PWE are needed to investigate the effects on cognition.
This study aimed to systematically review the published literature evaluating the association between physical activity and cognitive function in people with epilepsy (PWE).
A comprehensive search of PubMed, Cochrane, Embase, and PsychInfo was performed on June 20, 2022. Studies were excluded if they were not available in the English language, contained animal data only, did not include any original data, were not peer-reviewed, or did not include PWE as a discrete group. PRISMA guidelines were followed. The GRADE scale was used to assess the risk of bias.
Six studies were identified with a total of 123 participants. These included one observational study and five interventional studies, only one of which was a randomized controlled trial. In all studies, there was a positive association between physical activity and cognitive function in PWE. Both interventional studies showed improvement in at least one domain of cognitive functioning, though there was heterogeneity in the outcome measures used.
There is a potential positive association between physical activity and cognitive function in PWE, but available data is limited by heterogeneity, small sample size, and an overall lack of published studies in this area of research. There is a need for more robust studies to be performed in larger samples of PWE.
Vagus nerve stimulation (VNS) was the first device-based therapy for epilepsy, having launched in 1994 in Europe and 1997 in the United States. Since then, significant advances in the understanding ...of the mechanism of action of VNS and the central neurocircuitry that VNS modulates have impacted how the therapy is practically implemented. However, there has been little change to VNS stimulation parameters since the late 1990s. Short bursts of high frequency stimulation have been of increasing interest to other neuromodulation targets e.g., the spine, and these high frequency bursts elicit unique effects in the central nervous system, especially when applied to the vagus nerve. In the current study, we describe a protocol design that is aimed to assess the impact of high frequency bursts of stimulation, called "Microburst VNS", in subjects with refractory focal and generalized epilepsies treated with this novel stimulation pattern in addition to standard anti-seizure medications. This protocol also employed an investigational, fMRI-guided titration protocol that permits personalized dosing of Microburst VNS among the treated population depending on the thalamic blood-oxygen-level-dependent signal. The study was registered on clinicaltrials.gov (NCT03446664). The first subject was enrolled in 2018 and the final results are expected in 2023.
Many persons with epilepsy (PWE) experience problems with a wide range of cognitive functions, including learning, memory, attention, and executive control. These deficits in cognition result in ...diminished quality of life for PWE and are related to many factors, including the etiology of their epilepsy, recurrent seizures, side effects of antiseizure medications, or a combination of these factors. Various treatments to ameliorate cognitive deficits experienced by PWE have been implemented, although noninvasive and nonpharmacologic strategies may be more appealing options due to their relatively low cost, reduced risk of side effects, and/or reduced potential interactions with antiseizure medications. Physical activity and exercise may improve cognition in PWE but have not been well researched in this respect. To date only 1 study has directly investigated the effects of exercise on cognition in PWE, and it showed improved performance on tests of attention and executive function. The goal of the present article was to examine how increased physical activity and exercise contributes to 3 strategies (reducing seizure frequency, reducing epileptiform discharges, and decreasing symptoms of depression) that have been described as having a positive impact on cognition in PWE, as well as highlight related findings in experimental models of epilepsy. There is a definite need for more randomized controlled trials to establish greater clinical evidence for the use of physical activity and exercise in ameliorating cognitive impairment in PWE. We also need to better understand the factors contributing to reduced physical activity in PWE, as well as ways to overcome such barriers. With the available research in the area of exercise in epilepsy showing positive results, and a supportive research climate encouraging PWE to engage in greater physical activity overall, further investigations into the relationships between physical activity and cognition in epilepsy are warranted.
Reinforcement learning depends upon the integrity of emotional circuitry to establish associations between environmental cues, decisions, and positive or negative outcomes in order to guide behavior ...through experience. The emotional dysregulation characteristic of major depressive disorder (MDD) may alter activity in frontal and limbic structures that are key to learning. Although reward and decision-making have been examined in MDD, the effects of depression on associative learning is less well studied. We investigated whether depressive symptoms would be related to abnormalities in learning-related brain activity as measured by functional magnetic resonance imaging (fMRI). Also, we explored whether melancholic and atypical features were associated with altered brain activity. We conducted MRI scans on a 4T Varian MRI system in 10 individuals with MDD and 10 healthy subjects. We examined event-related brain activation during feedback-based learning task using Analysis of Functional NeuroImages (AFNI) for image processing and statistical analysis. We observed that MDD patients exhibited reduced activation in visual cortex but increased activation in cingulate and insular regions compared to healthy participants. Also, in relation to features of depressive subtypes, we observed that levels of activation in striatal, thalamic, and precuneus regions were negatively correlated with atypical characteristics. These results suggest that the effects of MDD change the neural circuitry underlying associative learning, and these effects may depend upon subtype features of MDD.
Stroke victims tend to prioritize speaking, writing, and walking as the three most important rehabilitation goals. Of note is that two of these goals involve communication. This underscores the ...significance of developing successful approaches to aphasia treatment for the several hundred thousand new aphasia patients each year and over 1 million stroke survivors with chronic aphasia in the U.S. alone. After several years of growth as a research tool, non-invasive brain stimulation (NBS) is gradually entering the arena of clinical aphasiology. In this review, we first examine the current state of knowledge of post-stroke language recovery including the contributions from the dominant and non-dominant hemispheres. Next, we briefly discuss the methods and the physiologic basis of the use of inhibitory and excitatory repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) as research tools in patients who experience post-stroke aphasia. Finally, we provide a critical review of the most influential evidence behind the potential use of these two brain stimulation methods as clinical rehabilitative tools.
BACKGROUND There is an ongoing need for facilitating language recovery in chronic post-stroke aphasia. The primary aim of this study (NCT01512264) was to examine if noninvasive intermittent theta ...burst stimulation (iTBS) applied to the injured left-hemispheric cortex promotes language improvements and fMRI changes in post-stroke aphasia. MATERIAL AND METHODS Participants were randomized to 3 weeks of sham (Tx0) or 1-3 weeks of iTBS (Tx123). We assessed participants who completed the first 2 functional MRI (fMRI) sessions (T1, T2) where they performed 2 overt language fMRI tasks, and examined longitudinal response after 3 months (T3). Language performance and fMRI activation changes, and relationships between these changes were assessed. RESULTS From T1 to T2, both groups showed improvements on the Boston Naming Test (BNT). From T1 to T3, Tx123 improved on the Aphasia Quotient, post-scan word recognition on the verbal paired associates task (VPAT), and perceived communicative ability. Each group exhibited significant activation changes between T1 and T2 for both tasks. Only the Tx123 group exhibited fMRI activation changes between T2 to T3 on the verb-generation task and between T1 and T3 on VPAT. Delayed aphasia symptom improvement for Tx123 was associated with increased left ventral visual stream activation from T1 to T3 (rho=0.74, P=0.0058), and with decreased bilateral supplementary motor area activation related to VPAT encoding from T2 to T3 (rho=-0.80, P=0.0016). CONCLUSIONS Observed iTBS-induced language improvements and associations between delayed fMRI changes and aphasia improvements support the therapeutic and neurorehabilitative potential of iTBS in post-stroke aphasia recovery.
Objective
This study was undertaken to determine whether undiagnosed illness duration (time between functional seizures FS onset and diagnosis) is linked to differences in neural response and ...functional connectivity during processing of stressful experiences.
Methods
Forty‐nine participants with traumatic brain injury preceding the onset of FS confirmed by video‐electroencephalography were recruited prospectively. Participants completed psychiatric symptom assessments before undergoing functional magnetic resonance imaging (fMRI) with an acute psychosocial stress task. Linear mixed effects (LME) analyses identified significant interactions between the factors of group (early vs. delayed diagnosis) and time lag to diagnosis on neural responses to stressful math performance and auditory feedback (corrected α = .05). Functional connectivity analysis utilized clusters from initial LME analyses as seed regions to determine significant interactions between these factors on network functional connectivity.
Results
Demographic and psychiatric symptom measures were similar between early (n = 25) and delayed (n = 24) groups. Responses to stressful math performance within the left anterior insula and functional connectivity between the anterior insula seed region and a precentral gyrus cluster were significantly negatively correlated with time lag to diagnosis for the early but not the delayed FS diagnosis group. There was no correlation between fMRI findings and psychiatric symptoms.
Significance
This study indicates that aberrant left anterior insula activation and its functional connectivity to the precentral gyrus underlie differences in processing of stressful experiences in patients with delayed FS diagnosis. Follow‐up comparisons suggest changes are associated with undiagnosed illness duration rather than psychiatric comorbidities and indicate a potential mechanistic association between neuropathophysiology, response to stressful experiences, and functional neuroanatomy in FS.
A model for visual memory encoding Nenert, Rodolphe; Allendorfer, Jane B; Szaflarski, Jerzy P
PloS one,
10/2014, Letnik:
9, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Memory encoding engages multiple concurrent and sequential processes. While the individual processes involved in successful encoding have been examined in many studies, a sequence of events and the ...importance of modules associated with memory encoding has not been established. For this reason, we sought to perform a comprehensive examination of the network for memory encoding using data driven methods and to determine the directionality of the information flow in order to build a viable model of visual memory encoding. Forty healthy controls ages 19-59 performed a visual scene encoding task. FMRI data were preprocessed using SPM8 and then processed using independent component analysis (ICA) with the reliability of the identified components confirmed using ICASSO as implemented in GIFT. The directionality of the information flow was examined using Granger causality analyses (GCA). All participants performed the fMRI task well above the chance level (>90% correct on both active and control conditions) and the post-fMRI testing recall revealed correct memory encoding at 86.33 ± 5.83%. ICA identified involvement of components of five different networks in the process of memory encoding, and the GCA allowed for the directionality of the information flow to be assessed, from visual cortex via ventral stream to the attention network and then to the default mode network (DMN). Two additional networks involved in this process were the cerebellar and the auditory-insular network. This study provides evidence that successful visual memory encoding is dependent on multiple modules that are part of other networks that are only indirectly related to the main process. This model may help to identify the node(s) of the network that are affected by a specific disease processes and explain the presence of memory encoding difficulties in patients in whom focal or global network dysfunction exists.
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