Dynamics and nonlinearities of the BOLD response at very short stimulus durations

IntroductionThe aim of this study was the analysis of dynamics of motor cortex metabolite in the norm and in early stage of schizophrenia in period of BOLD response to event related single stimulus.ObjectivesThe patients group consisted of 9 mails of 16–28 years old in initial stage of schizophrenia and in remission. The group of 9 age matched healthy mails was used as a control.MethodsPhillips Achieva 3.0 T scanner was used for the study. Volume of interest in motor cortex was localized on the base of fMRI. 1Н МR spectra were run using synchronization of FID signals acquisition (PRESS, TE = 30 ms TR = 3000 ms) with dynamics of BOLD response at the same paradigm.ResultsThe BOLD signal in both groups demonstrated maximum at the 6th s after target stimulus, however its value was reliably lover in schizophrenia in comparison with the control. The only [NAA] in normal motor cortex was changed after stimulation. The stable values of [NAA], [Cr] and [Cho] were observed in dynamic of resting state as well. [NAA] in normal cortex statistically significantly decreased at the 12th s after stimulus presentation and returned to initial value at the 15th s.ConclusionDifferent behavior of [NAA] in the norm and schizophrenia might be related with a difference in location (or activity) of aspartoacylaze (ASPA). Decreased expression of glutamate transporters in schizophrenia could also reduce consumption of NAA as a source of acetate in synthesis of AcCoA which is used for restoration of ATP.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Variations in BOLD response latency estimated from event-related fMRI at 3T: Comparisons between gradient-echo and Spin-echo

International Journal of Imaging Systems and Technology ◽

10.1002/ima.22054 ◽

2013 ◽

Vol 23 (3) ◽

pp. 215-221 ◽

Cited By ~ 1

Author(s):

Mei-Yu Yeh ◽

Changwei W. Wu ◽

Wan-Chun Kuan ◽

Pei-Shan Wei ◽

Yung-Liang Wan ◽

...

Keyword(s):

Response Latency ◽

Spin Echo ◽

Bold Response ◽

Gradient Echo

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Interactions between Auditory and Visual Semantic Stimulus Classes: Evidence for Common Processing Networks for Speech and Body Actions

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2010.21593 ◽

2011 ◽

Vol 23 (9) ◽

pp. 2291-2308 ◽

Cited By ~ 24

Author(s):

Georg F. Meyer ◽

Mark Greenlee ◽

Sophie Wuerger

Keyword(s):

Human Performance ◽

Inferior Frontal Gyrus ◽

Audiovisual Integration ◽

Visual Signals ◽

Bold Response ◽

Activation Patterns ◽

Semantic Congruency ◽

Low Level ◽

Semantic Categories ◽

Premotor Areas

Incongruencies between auditory and visual signals negatively affect human performance and cause selective activation in neuroimaging studies; therefore, they are increasingly used to probe audiovisual integration mechanisms. An open question is whether the increased BOLD response reflects computational demands in integrating mismatching low-level signals or reflects simultaneous unimodal conceptual representations of the competing signals. To address this question, we explore the effect of semantic congruency within and across three signal categories (speech, body actions, and unfamiliar patterns) for signals with matched low-level statistics. In a localizer experiment, unimodal (auditory and visual) and bimodal stimuli were used to identify ROIs. All three semantic categories cause overlapping activation patterns. We find no evidence for areas that show greater BOLD response to bimodal stimuli than predicted by the sum of the two unimodal responses. Conjunction analysis of the unimodal responses in each category identifies a network including posterior temporal, inferior frontal, and premotor areas. Semantic congruency effects are measured in the main experiment. We find that incongruent combinations of two meaningful stimuli (speech and body actions) but not combinations of meaningful with meaningless stimuli lead to increased BOLD response in the posterior STS (pSTS) bilaterally, the left SMA, the inferior frontal gyrus, the inferior parietal lobule, and the anterior insula. These interactions are not seen in premotor areas. Our findings are consistent with the hypothesis that pSTS and frontal areas form a recognition network that combines sensory categorical representations (in pSTS) with action hypothesis generation in inferior frontal gyrus/premotor areas. We argue that the same neural networks process speech and body actions.

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Negative BOLD Response to Interictal Epileptic Discharges in Focal Epilepsy

Brain Topography ◽

10.1007/s10548-013-0302-1 ◽

2013 ◽

Vol 26 (4) ◽

pp. 627-640 ◽

Cited By ~ 26

Author(s):

Francesca Pittau ◽

Firas Fahoum ◽

Rina Zelmann ◽

François Dubeau ◽

Jean Gotman

Keyword(s):

Focal Epilepsy ◽

Bold Response ◽

Epileptic Discharges ◽

Negative Bold

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Arterial blood stealing as a mechanism of negative BOLD response: From the steady-flow with nonlinear phase separation to a windkessel-based model

Journal of Theoretical Biology ◽

10.1016/j.jtbi.2021.110856 ◽

2021 ◽

pp. 110856

Author(s):

Alejandro Suarez ◽

Pedro A. Valdes-Hernandeza ◽

Arash Moshkforoush ◽

Nikolaos Tsoukias ◽

Jorge Riera

Keyword(s):

Phase Separation ◽

Steady Flow ◽

Bold Response ◽

Nonlinear Phase ◽

Arterial Blood ◽

Negative Bold

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Development of Memory Structures for Homographs Using Pathfinder Network Representations

The Spanish Journal of Psychology ◽

10.1017/s1138741600005175 ◽

2003 ◽

Vol 6 (1) ◽

pp. 12-27 ◽

Cited By ~ 3

Author(s):

Francisco Nievas ◽

Fernando Justicia

Keyword(s):

Semantic Priming ◽

Cohort Effect ◽

Stimulus Onset ◽

Developmental Differences ◽

Memory Structure ◽

Short Stimulus Onset Asynchrony ◽

Semantic Priming Effect ◽

Short Stimulus ◽

Pathfinder Network ◽

Memory Structures

Some studies with children have shown that there is no semantic priming at short stimulus onset asynchrony (SOA) in lexical decision and naming tasks for homographs. The predictions of spreading activation theories might explain this missing effect. There may be differences in children's and adults' memory structures. We have explored this hypothesis. The development of memory structure representations for homographs was measured by a Pathfinder algorithm. In Experiment 1, the three dependent variables were: the number of links in the network, closeness measures (C), and distances between nodes. Results revealed developmental differences in network structure representations in adults and children. In Experiment 2, results revealed that these differences were not due to the cohort effect. In Experiment 3, the relationship between associative strength, as measured by associative norms, and distances, as measured by Pathfinder algorithm, was explored. The results of these three experiments and empirical research from semantic priming experiments show that these differences in memory structure representations could be one of the sources of the missing semantic priming effect in children.

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Depth-resolved ultra-high field fMRI reveals feedback contributions to surface motion perception

10.1101/653626 ◽

2019 ◽

Author(s):

Ingo Marquardt ◽

Peter De Weerd ◽

Marian Schneider ◽

Omer Faruk Gulban ◽

Dimo Ivanov ◽

...

Keyword(s):

Visual Cortex ◽

Motion Perception ◽

High Field ◽

Depth Distribution ◽

Middle Layer ◽

Bold Response ◽

Ultra High Field ◽

Surface Motion ◽

Visual Hemifield ◽

Early Visual Cortex

AbstractHuman visual surface perception has neural correlates in early visual cortex, but the extent to which feedback contributes to this activity is not well known. Feedback projections preferentially enter superficial and deep anatomical layers, while avoiding the middle layer, which provides a hypothesis for the cortical depth distribution of fMRI activity related to feedback in early visual cortex. Here, we presented human participants uniform surfaces on a dark, textured background. The grey surface in the left hemifield was either perceived as static or moving based on a manipulation in the right hemifield. Physically, the surface was identical in the left visual hemifield, so any difference in percept likely was related to feedback. Using ultra-high field fMRI, we report the first evidence for a depth distribution of activation in line with feedback during the (illusory) perception of surface motion. Our results fit with a signal re-entering in superficial depths of V1, followed by a feedforward sweep of the re-entered information through V2 and V3, as suggested by activity centred in the middle-depth levels of the latter areas. This positive modulation of the BOLD signal due to illusory surface motion was on top of a strong negative BOLD response in the cortical representation of the surface stimuli, which depended on the presence of texture in the background. Hence, the magnitude and sign of the BOLD response to the surface strongly depended on background properties, and was additionally modulated by the presence or absence of illusory motion perception in a manner compatible with feedback. In summary, the present study demonstrates the potential of depth resolved fMRI in tackling biomechanical questions on perception that so far were only within reach of invasive animal experimentation.

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Exploring Cortical Attentional System by Using fMRI during a Continuous Perfomance Test

Computational Intelligence and Neuroscience ◽

10.1155/2010/329213 ◽

2010 ◽

Vol 2010 ◽

pp. 1-6 ◽

Cited By ~ 31

Author(s):

M. G. Tana ◽

E. Montin ◽

S. Cerutti ◽

A. M. Bianchi

Keyword(s):

Performance Test ◽

Continuous Performance Test ◽

Blood Oxygen Level Dependent ◽

Brain Regions ◽

Brain Network ◽

Anterior Cingulate ◽

Visual Object ◽

Bold Response ◽

Object Processing ◽

The Right

Functional magnetic resonance imaging (fMRI) was performed in eight healthy subjects to identify the localization, magnitude, and volume extent of activation in brain regions that are involved in blood oxygen level-dependent (BOLD) response during the performance of Conners' Continuous Performance Test (CPT). An extensive brain network was activated during the task including frontal, temporal, and occipital cortical areas and left cerebellum. The more activated cluster in terms of volume extent and magnitude was located in the right anterior cingulate cortex (ACC). Analyzing the dynamic trend of the activation in the identified areas during the entire duration of the sustained attention test, we found a progressive decreasing of BOLD response probably due to a habituation effect without any deterioration of the performances. The observed brain network is consistent with existing models of visual object processing and attentional control and may serve as a basis for fMRI studies in clinical populations with neuropsychological deficits in Conners' CPT performance.

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