Browsing by Subject "Neuroimaging"

Now showing 1 - 7 of 7

Open Access
Accelerated phase-cycled SSFP imaging with compressed sensing
(Institute of Electrical and Electronics Engineers Inc., 2015) Çukur, T.
Balanced steady-state free precession (SSFP) imaging suffers from irrecoverable signal losses, known as banding artifacts, in regions of large B0 field inhomogeneity. A common solution is to acquire multiple phase-cycled images each with a different frequency sensitivity, such that the location of banding artifacts are shifted in space. These images are then combined to alleviate signal loss across the entire field-of-view. Although high levels of artifact suppression are viable using a large number of images, this is a time costly process that limits clinical utility. Here, we propose to accelerate individual acquisitions such that the overall scan time is equal to that of a single SSFP acquisition. Aliasing artifacts and noise are minimized by using a variable-density random sampling pattern in k-space, and by generating disjoint sampling patterns for separate acquisitions. A sparsity-enforcing method is then used for image reconstruction. Demonstrations on realistic brain phantom images, and in vivo brain and knee images are provided. In all cases, the proposed technique enables robust SSFP imaging in the presence of field inhomogeneities without prolonging scan times. © 2014 IEEE.
Open Access
All-fiber nanosecond laser system generating supercontinuum spectrum for photoacoustic imaging
(IEEE, 2013) Yavas, S.; Kipergil, E. A.; Akçaalan, Önder; Eldeniz, Y. Burak; Arabul, U.; Erkol H.; Unlu, M.B.; Ilday, F. Ömer
Photoacoustic microscopy (PAM) research, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, coronery artery, cardiovascular disease from their effect on the microvasculature, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping, neuroscientific evaluations. Clinically, PAM can be used as a diagnostic and predictive medicine tool; even have a part in disease prevention[1]. © 2013 IEEE.
Open Access
Color vision in humans and computers
(IEEE, 2008) Boyacı, Hüseyin; Akarun L.
Humans and many other species rely on color for object recognition. What are the biological underpinnings of color vision and how can we computationally model human color perception? In this study we briefly summarize recent advences regarding the very early, retinal stages of color vision, as well as recent behavioral models of color perception in three dimensional world within rich context. We also emphasize the recent events on the neuroimaging front that allow the researchers begin to systematically study the cortical processes related to color vision. ©2008 IEEE.
Open Access
Effect of visual stimuli with fearful emotional cue on population receptive field estimates
(2019-07) Yılmaz, Cemre
Previous studies showed that the content of stimulus might affect the results of population receptive field (pRF) estimation method [1, 2, 3]. In addition, emotion might modulate visual processing in humans by increasing BOLD activity [4, 5]. Taken together, the stimulus with emotional cue might affect the pRF parameters. To investigate the effect of emotion on visual processing, we used the population receptive field (pRF) method [6], with simultaneous wedge and ring stimuli rendered with scrambled, neutral or emotional images. Results showed that the pRF estimations were affected by the stimulus content in visual areas hV4 and V3A, as well as lower retinotopic regions: V1, V2 and V3. Moreover, we showed the emotional content of stimulus might lead to the increased pRF sizes as well as a shift in pRF centers toward the eccentric side. We argue that the increased pRF size and the pRF shift might be a result of emotional modulation of visual processing.
Open Access
The Genetics of Endophenotypes of Neurofunction to Understand Schizophrenia (GENUS) consortium: a collaborative cognitive and neuroimaging genetics project
(Elsevier, 2018) Blokland, G. A. M.; Del Re, E. C.; Mesholam-Gately, R. I.; Jovicich, J.; Trampush, J. W.; Keshavan, M. S.; DeLisi, L. E.; Walters, J. T. R.; Turner, J. A.; Malhotra, A. K.; Lencz, T.; Shenton, M. E.; Voineskos, A. N.; Rujescu, D.; Giegling, I.; Kahn, R. S.; Roffman, J. L.; Holt, D. J.; Ehrlich, S.; Kikinis, Z.; Dazzan, P.; Murray, R. M.; Di Forti, M.; Lee, J.; Sim, K.; Lam, M.; Wolthusen, R. P. F.; De Zwarte, S. M. C.; Walton, E.; Cosgrove, D.; Kelly, S.; Maleki, N.; Osiecki, L.; Picchioni, M. M.; Bramon, E.; Russo, M.; David, A. S.; Mondelli, V.; Reinders, A. A. T. S.; Falcone, M. A.; Hartmann, A. M.; Konte, B.; Morris, D. W.; Gill, M.; Corvin, A. P.; Cahn, W.; Ho, N. F.; Liu, J. J.; Keefe, R. S. E.; Gollub, R. L.; Manoach, D. S.; Calhoun, V. D.; Schulz, S. C.; Sponheim, S. R.; Goff, D. C.; Buka, S. L.; Cherkerzian, S.; Thermenos, H. W.; Kubicki, M.; Nestor, P. G.; Dickie, E. W.; Vassos, E.; Ciufolini, S.; Marques, T. R.; Crossley, N. A.; Purcell, S. M.; Smoller, J. W.; Van Haren, N. E. M.; Toulopoulou, Timothea; Donohoe, G.; Goldstein, J. M.; Seidman, L. J.; McCarley, R. W.; Petryshen, T. L.
Background: Schizophrenia has a large genetic component, and the pathways from genes to illness manifestation are beginning to be identified. The Genetics of Endophenotypes of Neurofunction to Understand Schizophrenia (GENUS) Consortium aims to clarify the role of genetic variation in brain abnormalities underlying schizophrenia. This article describes the GENUS Consortium sample collection. Methods: We identified existing samples collected for schizophrenia studies consisting of patients, controls, and/or individuals at familial high-risk (FHR) for schizophrenia. Samples had single nucleotide polymorphism (SNP) array data or genomic DNA, clinical and demographic data, and neuropsychological and/or brain magnetic resonance imaging (MRI) data. Data were subjected to quality control procedures at a central site. Results: Sixteen research groups contributed data from 5199 psychosis patients, 4877 controls, and 725 FHR individuals. All participants have relevant demographic data and all patients have relevant clinical data. The sex ratio is 56.5% male and 43.5% female. Significant differences exist between diagnostic groups for premorbid and current IQ (both p < 1 × 10− 10). Data from a diversity of neuropsychological tests are available for 92% of participants, and 30% have structural MRI scans (half also have diffusion-weighted MRI scans). SNP data are available for 76% of participants. The ancestry composition is 70% European, 20% East Asian, 7% African, and 3% other. Conclusions: The Consortium is investigating the genetic contribution to brain phenotypes in a schizophrenia sample collection of > 10,000 participants. The breadth of data across clinical, genetic, neuropsychological, and MRI modalities provides an important opportunity for elucidating the genetic basis of neural processes underlying schizophrenia.
Open Access
Intelligence, educational attainment, and brain structure in those at familial high‐risk for schizophrenia or bipolar disorder
(Wiley, 2020) de Zwarte, S. M. C.; Brouwer, R.; Agartz, I.; Alda, M.; Alonso-Lana, S.; Bearden, C.; Bertolino, A.; Bonvino, A.; Bramon, E.; Buimer, E.; Cahn, W.; Canales-Rodríguez, E.; Cannon, D. M.; Cannon, T. D.; Caseras, X.; Castro-Fornieles, J.; Chen, Q.; Chung, Y.; De la Serna, E.; del Mar Bonnin, C.; Demro, C.; Di Giorgio, A.; Doucet, G.; Eker, M.; Erk, S.; Fatjó-Vilas, M.; Fears, S.; Foley, S.; Frangou, S.; Fullerton, J.; Glahn, D.; Goghari, V.; Goikolea, J.; Goldman, A.; Gonul, A.; Gruber, O.; Hajek, T.; Hawkins, E.; Heinz, A.; Ongun, C.; Hillegers, M.; Houenou, J.; Pol, H.; Hultman, C.; Ingvar, M.; Johansson, V.; Jönsson, E.; Kane, F.; Kempton, M.; Koenis, M.; Kopecek, M.; Krämer, B.; Lawrie, S.; Lenroot, R.; Marcelis, M.; Mattay, V.; McDonald, C.; Meyer-Lindenberg, A.; Michielse, S.; Mitchell, P.; Moreno, D.; Murray, R.; Mwangi, B.; Nabulsi, L.; Newport, J.; Olman, C.; van Os, J.; Overs, B.; Ozerdem, A.; Pergola, G.; Picchioni, M.; Piguet, C.; Pomarol-Clotet, E.; Radua, J.; Ramsay, I.; Richter, A.; Roberts, G.; Salvador, R.; Saricicek-Aydogan, A.; Sarró, S.; Schofield, P.; Simsek, E.; Simsek, F.; Soares, J.; Sponheim, S.; Sugranyes, G.; Toulopoulou, Timothea; Tronchin, G.; Vieta, E.; Walter, H.; Weinberger, D.; Whalley, H.; Wu, M. -J.; Yalin, N.; Andreassen, O.; Ching, C.; Thomopoulos, S.; van Erp, T.; Jahanshad, N.; Thompson, P.; Kahn, R.; van Haren, N.
First‐degree relatives of patients diagnosed with schizophrenia (SZ‐FDRs) show similar patterns of brain abnormalities and cognitive alterations to patients, albeit with smaller effect sizes. First‐degree relatives of patients diagnosed with bipolar disorder (BD‐FDRs) show divergent patterns; on average, intracranial volume is larger compared to controls, and findings on cognitive alterations in BD‐FDRs are inconsistent. Here, we performed a meta‐analysis of global and regional brain measures (cortical and subcortical), current IQ, and educational attainment in 5,795 individuals (1,103 SZ‐FDRs, 867 BD‐FDRs, 2,190 controls, 942 schizophrenia patients, 693 bipolar patients) from 36 schizophrenia and/or bipolar disorder family cohorts, with standardized methods. Compared to controls, SZ‐FDRs showed a pattern of widespread thinner cortex, while BD‐FDRs had widespread larger cortical surface area. IQ was lower in SZ‐FDRs (d = −0.42, p = 3 × 10−5), with weak evidence of IQ reductions among BD‐FDRs (d = −0.23, p = .045). Both relative groups had similar educational attainment compared to controls. When adjusting for IQ or educational attainment, the group‐effects on brain measures changed, albeit modestly. Changes were in the expected direction, with less pronounced brain abnormalities in SZ‐FDRs and more pronounced effects in BD‐FDRs. To conclude, SZ‐FDRs and BD‐FDRs show a differential pattern of structural brain abnormalities. In contrast, both had lower IQ scores and similar school achievements compared to controls. Given that brain differences between SZ‐FDRs and BD‐FDRs remain after adjusting for IQ or educational attainment, we suggest that differential brain developmental processes underlying predisposition for schizophrenia or bipolar disorder are likely independent of general cognitive impairment.
Open Access
The effect of SARS-CoV-2 virus on resting-state functional connectivity during adolescence: Investigating brain correlates of psychotic-like experiences and SARS-CoV-2 related inflammation response
(Elsevier B.V., 2023-12) Yilmaz Kafali, H.; Dasgin, Hacer; Sahin Cevik, Didenur; Sozan, S. S.; Oguz, Kader K.; Mutlu, M.; Ozkaya Parlakay, A.; Toulopoulou, Timothea
We first aimed to investigate resting-state functional connectivity (rs-FC) differences between adolescents exposed to SARS-CoV-2 and healthy controls. Secondly, the moderator effect of PLEs on group differences in rs-FC was examined. Thirdly, brain correlates of inflammation response during acute SARS-CoV-2 infection were investigated. Eighty-two participants aged between 14 and 24 years (SARS-CoV-2 (n = 35), controls (n = 47)) were examined using rs-fMRI. Seed-based rs-FC analysis was performed. The positive subscale of Community Assessment of Psychotic Experiences-42 (CAPE-Pos) was used to measure PLEs. The SARS-CoV-2 group had a lesser rs-FC within sensorimotor network (SMN), central executive network (CEN) and language network (LN), but an increased rs-FC within visual network (VN) compared to controls. No significant differences were detected between the groups regarding CAPE-Pos-score. However, including CAPE-Pos as a covariate, we found increased rs-FC within CEN and SN in SARS-CoV-2 compared to controls. Among the SARS-CoV-2 group, neutrophil/lymphocyte and thrombocyte*neutrophil/lymphocyte ratio was correlated with decreased/increased FC within DMN and SN, and increased FC within CEN. Our results showed rs-FC alterations within the SMN, CEN, LN, and VN among adolescents exposed to SARS-CoV-2. Moreover, changes in rs-FC associated with PLEs existed in these adolescents despite the absence of clinical changes. Furthermore, inflammation response was correlated with alterations in FC within the triple network system.