Representation of Umami Taste in the Human Brain

2003 ◽  
Vol 90 (1) ◽  
pp. 313-319 ◽  
Author(s):  
I.E.T. de Araujo ◽  
M. L. Kringelbach ◽  
E. T. Rolls ◽  
P. Hobden
Keyword(s):  
Orbitofrontal Cortex ◽  
Anterior Part ◽  
Monosodium Glutamate ◽  
Blood Oxygenation ◽  
Anterior Cingulate ◽  
Bold Signal ◽  
Taste System ◽  
Umami Taste ◽  
Oxygenation Level ◽  
Cortical Regions

Umami taste stimuli, of which an exemplar is monosodium glutamate (MSG) and which capture what is described as the taste of protein, were shown using functional MRI (fMRI) to activate similar cortical regions of the human taste system to those activated by a prototypical taste stimulus, glucose. These taste regions included the insular/opercular cortex and the caudolateral orbitofrontal cortex. A part of the rostral anterior cingulate cortex (ACC) was also activated. When the nucleotide 0.005 M inosine 5′-monophosphate (IMP) was added to MSG (0.05 M), the blood oxygenation-level dependent (BOLD) signal in an anterior part of the orbitofrontal cortex showed supralinear additivity; this may reflect the subjective enhancement of umami taste that has been described when IMP is added to MSG. These results extend to humans previous studies in macaques showing that single neurons in these taste cortical areas can be tuned to umami stimuli.

Coherent Spontaneous Activity Identifies a Hippocampal-Parietal Memory Network

2006 ◽  
Vol 96 (6) ◽  
pp. 3517-3531 ◽  
Author(s):  
Justin L. Vincent ◽  
Abraham Z. Snyder ◽  
Michael D. Fox ◽  
Benjamin J. Shannon ◽  
Jessica R. Andrews ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Hippocampal Formation ◽  
Normal Subjects ◽  
Blood Oxygenation Level Dependent ◽  
Retrosplenial Cortex ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Inferior Parietal Lobule ◽  
Oxygenation Level ◽  
Memory Network

Despite traditional theories emphasizing parietal contributions to spatial attention and sensory-motor integration, functional MRI (fMRI) experiments in normal subjects suggest that specific regions within parietal cortex may also participate in episodic memory. Here we examined correlations in spontaneous blood-oxygenation-level-dependent (BOLD) signal fluctuations in a resting state to identify the network associated with the hippocampal formation (HF) and determine whether parietal regions were elements of that network. In the absence of task, stimuli, or explicit mnemonic demands, robust correlations were observed between activity in the HF and several parietal regions (including precuneus, posterior cingulate, retrosplenial cortex, and bilateral inferior parietal lobule). These HF-correlated regions in parietal cortex were spatially distinct from those correlated with the motion-sensitive MT+ complex. Reanalysis of event-related fMRI studies of recognition memory showed that the regions spontaneously correlated with the HF (but not MT+) were also modulated during directed recollection. These regions showed greater activity to successfully recollected items as compared with other trial types. Together, these results associate specific regions of parietal cortex that are sensitive to successful recollection with the HF.

scholarly journals Dynamic Forcing of End-Tidal Carbon Dioxide and Oxygen Applied to Functional Magnetic Resonance Imaging

2007 ◽  
Vol 27 (8) ◽  
pp. 1521-1532 ◽  
Author(s):  
Richard G Wise ◽  
Kyle TS Pattinson ◽  
Daniel P Bulte ◽  
Peter A Chiarelli ◽  
Stephen D Mayhew ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Oxygenation ◽  
Dynamic Responses ◽  
Bold Signal ◽  
Tidal Forcing ◽  
Partial Pressures ◽  
Oxygenation Level ◽  
Mri Environment ◽  
Dynamic Forcing ◽  
End Tidal

Investigations into the blood oxygenation level-dependent (BOLD) functional MRI signal have used respiratory challenges with the aim of probing cerebrovascular physiology. Such challenges have altered the inspired partial pressures of either carbon dioxide or oxygen, typically to a fixed and constant level (fixed inspired challenge (FIC)). The resulting end-tidal gas partial pressures then depend on the subject's metabolism and ventilatory responses. In contrast, dynamic end-tidal forcing (DEF) rapidly and independently sets end-tidal oxygen and carbon dioxide to desired levels by altering the inspired gas partial pressures on a breath-by-breath basis using computer-controlled feedback. This study implements DEF in the MRI environment to map BOLD signal reactivity to CO2. We performed BOLD (T2*) contrast FMRI in four healthy male volunteers, while using DEF to provide a cyclic normocapnichypercapnic challenge, with each cycle lasting 4 mins (PetCO2 mean±s.d., from 40.9 ± 1.8 to 46.4 ± 1.6 mm Hg). This was compared with a traditional fixed-inspired (FiCO2 = 5%) hypercapnic challenge (PetCO2 mean±s.d., from 38.2 ± 2.1 to 45.6 ± 1.4 mm Hg). Dynamic end-tidal forcing achieved the desired target PetCO2 for each subject while maintaining PetCO2 constant. As a result of CO2-induced increases in ventilation, the FIC showed a greater cyclic fluctuation in PetCO2. These were associated with spatially widespread fluctuations in BOLD signal that were eliminated largely by the control of PetCO2 during DEF. The DEF system can provide flexible, convenient, and physiologically well-controlled respiratory challenges in the MRI environment for mapping dynamic responses of the cerebrovasculature.

A NEW MATHEMATICAL APPROACH FOR DETECTION OF ACTIVE AREA IN HUMAN BRAIN fMRI USING NONLINEAR MODEL

2010 ◽  
Vol 22 (05) ◽  
pp. 409-418 ◽  
Author(s):  
Ali Taalimi ◽  
Emad Fatemizadeh
Keyword(s):  
Moving Average ◽  
Simulated Data ◽  
Nonlinear Behavior ◽  
Blood Oxygenation ◽  
Superior Performance ◽  
Model Parameters ◽  
Bold Signal ◽  
Mathematical Approach ◽  
Region Detection ◽  
Oxygenation Level

Functional magnetic resonance imaging (fMRI) is widely-used for detection of the brain's neural activity. The signals and images acquired through this imaging technique demonstrate the human brain's response to pre-scheduled tasks. Several studies on blood oxygenation level-dependent (BOLD) signal responses demonstrate nonlinear behavior in response to a stimulus. In this paper we propose a new mathematical approach for modeling BOLD signal activity, which is able to model nonlinear and time variant behaviors of this physiological system. We employ the Nonlinear Auto Regressive Moving Average (NARMA) model to describe the mathematical relationship between output signals and predesigned tasks. The model parameters can be used to distinguish between rest and active states of a brain region. We applied our proposed method for active region detection on real as well as simulated data sets. The results show superior performance in comparison with existing methods.

Widespread and intense BOLD changes during brief focal electrographic seizures

Neurology ◽  
2006 ◽  
Vol 66 (7) ◽  
pp. 1049-1055 ◽  
Author(s):  
E. Kobayashi ◽  
C. S. Hawco ◽  
C. Grova ◽  
F. Dubeau ◽  
J. Gotman
Keyword(s):  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Angular Gyrus ◽  
Temporal Region ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Focal Seizures ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Electrographic Seizures

Background: Combined recording of EEG and fMRI has shown changes in blood oxygenation level dependent (BOLD) signal during focal interictal epileptic spikes. Due to difficult assessment of seizures inside the scanner little is known about BOLD changes during seizures.Objectives: To describe BOLD changes related to brief focal electrographic seizures in a patient with right temporo-parietal gray matter nodular heterotopia.Methods: The patient underwent two EEG-fMRI sessions during which several focal seizures were recorded. EEG was acquired continuously during scanning and seizure timing was used for statistical analysis. Functional maps were thresholded to disclose positive (activation) and negative (deactivation) BOLD changes.Results: Twenty-five focal electrographic seizures were analyzed, consisting of runs of polyspikes lasting 2 to 6 s in the right temporal region. Activation included a large volume, involving the heterotopia and the abnormal temporo-parietal cortex overlying the nodule, with a clear maximum over the angular gyrus. Deactivation was bilateral and maximum in the occipital regions. The hemodynamic response function showed a return to baseline of the BOLD signal 30 s after seizure end.Conclusions: The brief focal seizures resulted in high amplitude and widespread blood oxygenation level dependent (BOLD) responses taking 30 s to return to baseline. This suggests that such brief events could have important behavioral consequences despite absent overt manifestations. A clear focal BOLD peak was found at some distance from the main EEG discharge, raising the possibility that the seizure could have started in a region that did not generate a visible EEG change despite its superficial location.

scholarly journals Haemodynamic Activity Characterization of Resting State Networks by Fractal Analysis and Thalamocorticalmorpho functional Integrity in Chronic Migraine

2020 ◽  
Author(s):  
Camillo Porcaro ◽  
Antonio Di Renzo ◽  
Emanuele Tinelli ◽  
Giorgio Di Lorenzo ◽  
Vincenzo Parisi ◽  
...  
Keyword(s):  
Chronic Migraine ◽  
Resting State ◽  
Diffusion Tensor ◽  
Anterior Part ◽  
Mean Diffusivity ◽  
Blood Oxygenation ◽  
Resting State Networks ◽  
Or Efficiency ◽  
Oxygenation Level ◽  
Haemodynamic Activity

Abstract Background - Chronic migraine (CM)can be associated with aberrant long-range connectivity of MRI-derived resting-state networks (RSNs). Here, we investigated how the fractal dimension (FD) of blood oxygenation level dependent (BOLD) activity maybe used to estimatethe complexity of RSNs, reflecting flexibility and/or efficiency in information processing in CM patients respect to healthy controls (HC).Methods -Resting-state MRI data were collected from 20 untreated CM without history of medication overuse and 20 HC. On both groups, we estimated the Higuchi’sFD. On the same subjects,fractional anisotropy (FA) and mean diffusivity (MD)values of bilateral thalami were retrieved from diffusion tensor imaging andcorrelated with the FD values.Results - CM showed higher FD values within dorsal attention system (DAS) and the anterior part of default-mode network (DMN), and lower FD values within the posterior DMN compared to HC.Although FA and MD were within the range of normality, both correlated with the FD values of DAS.Conclusions - FDof DAS and DMN may reflect disruption of cognitive control of pain in CM.Normal microstructure of the thalamus and its positive connectivity with the cortical networking may be yet another evidence in supporting CM as a never-ending migraine attack.

Optogenetic fMRI Sheds Light on the Neural Basis of the BOLD Signal

2010 ◽  
Vol 104 (4) ◽  
pp. 1838-1840 ◽  
Author(s):  
Helen. S. Palmer
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Neural Basis ◽  
Bold Responses ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used as a measure of neuronal activity, despite an incomplete understanding of the hemodynamic and neural bases for BOLD signals. Recent work by Lee and colleagues investigated whether activating genetically specified neurons elicits BOLD responses. Integrating optogenetic control of specific cells and fMRI showed that stimulating excitatory neurons triggers a positive BOLD signal with conventional kinetics locally and delayed weaker BOLD signals distally.

scholarly journals Grasping the Intentions of Others: The Perceived Intentionality of an Action Influences Activity in the Superior Temporal Sulcus during Social Perception

2004 ◽  
Vol 16 (10) ◽  
pp. 1706-1716 ◽  
Author(s):  
Kevin A. Pelphrey ◽  
James P. Morris ◽  
Gregory McCarthy
Keyword(s):  
Social Perception ◽  
Cognitive Neuroscience ◽  
Time Course ◽  
Brain Activity ◽  
Superior Temporal Sulcus ◽  
Blood Oxygenation ◽  
Passive Viewing ◽  
Oxygenation Level ◽  
Cortical Regions ◽  
The Right

An explication of the neural substrates for social perception is an important component in the emerging field of social cognitive neuroscience and is relevant to the field of cognitive neuroscience as a whole. Prior studies from our laboratory have demonstrated that passive viewing of biological motion (Pelphrey, Mitchell, et al., 2003; Puce et al., 1998) activates the posterior superior temporal sulcus (STS) region. Furthermore, recent evidence has shown that the perceived context of observed gaze shifts (Pelphrey, Singerman, et al., 2003; Pelphrey et al., 2004) modulates STS activity. Here, using event-related functional magnetic resonance imaging at 4 T, we investigated brain activity in response to passive viewing of goal- and non-goal- directed reaching-to-grasp movements. Participants viewed an animated character making reaching-to-grasp movements either toward (correct) or away (incorrect) from a blinking dial. Both conditions evoked significant posterior STS activity that was strongly right lateralized. By examining the time course of the blood oxygenation level-dependent response from areas of activation, we observed a functional dissociation. Incorrect trials evoked significantly greater activity in the STS than did correct trials, while an area posterior and inferior to the STS (likely corresponding to the MT/V5 complex) responded equally to correct and incorrect movements. Parietal cortical regions, including the superior parietal lobule and the anterior intraparietal sulcus, also responded equally to correct and incorrect movements, but showed evidence for differential responding based on the hand and arm (left or right) of the animated character used to make the reaching-to-grasp movement. The results of this study further suggest that a region of the right posterior STS is involved in analyzing the intentions of other people's actions and that activity in this region is sensitive to the context of observed biological motions.

scholarly journals Simultaneous Blood Oxygenation Level-Dependent and Cerebral Blood Flow Functional Magnetic Resonance Imaging during Forepaw Stimulation in the Rat

1999 ◽  
Vol 19 (8) ◽  
pp. 871-879 ◽  
Author(s):  
Afonso C. Silva ◽  
Sang-Pil Lee ◽  
Guang Yang ◽  
Costantino Iadecola ◽  
Seong-Gi Kim
Keyword(s):  
Correlation Coefficient ◽  
Cerebral Blood Volume ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Single Shot ◽  
Bold Signal ◽  
Doppler Flowmetry ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Signal Changes

The blood oxygenation level-dependent (BOLD) contrast mechanism can be modeled as a complex interplay between CBF, cerebral blood volume (CBV), and CMRO2. Positive BOLD signal changes are presumably caused by CBF changes in excess of increases in CMRO2. Because this uncoupling between CBF and CMRO2 may not always be present, the magnitude of BOLD changes may not be a good index of CBF changes. In this study, the relation between BOLD and CBF was investigated further. Continuous arterial spin labeling was combined with a single-shot, multislice echo-planar imaging to enable simultaneous measurements of BOLD and CBF changes in a well-established model of functional brain activation, the electrical forepaw stimulation of a-chloralose-anesthetized rats. The paradigm consisted of two 18- to 30-second stimulation periods separated by a 1-minute resting interval. Stimulation parameters were optimized by laser Doppler flowmetry. For the same cross-correlation threshold, the BOLD and CBF active maps were centered within the size of one pixel (470 µm). However, the BOLD map was significantly larger than the CBF map. Measurements taken from 15 rats at 9.4 T using a 10-millisecond echo-time showed 3.7 ± 1.7% BOLD and 125.67 ± 81.7% CBF increases in the contralateral somatosensory cortex during the first stimulation, and 2.6 ± 1.2% BOLD and 79.3 ± 43.6% CBF increases during the second stimulation. The correlation coefficient between BOLD and CBF changes was 0.89. The overall temporal correlation coefficient between BOLD and CBF time-courses was 0.97. These results show that under the experimental conditions of the current study, the BOLD signal changes follow the changes in CBF.

Quantitative Analysis of Attention and Detection Signals During Visual Search

2003 ◽  
Vol 90 (5) ◽  
pp. 3384-3397 ◽  
Author(s):  
Gordon L. Shulman ◽  
Mark P. McAvoy ◽  
Melanie C. Cowan ◽  
Serguei V. Astafiev ◽  
Aaron P. Tansy ◽  
...  
Keyword(s):  
Large Fraction ◽  
Additive Model ◽  
Decision Criterion ◽  
Blood Oxygenation ◽  
Anterior Cingulate ◽  
Frontal Eye Field ◽  
Temporoparietal Junction ◽  
Flow Models ◽  
Dependent Signal ◽  
Cortical Regions

Prior work has distinguished regions in the intraparietal sulcus (IPs) and frontal eye field (FEF) involved in the voluntary control of attention, from more ventral regions in the temporoparietal junction (TPJ) involved in target detection. The present results show that when subjects search for and detect a visual target stimulus among nontargets, these regions show sensory-, search-, and detection-related signals that both confirm and refine these functional distinctions. The different signals were isolated by an additive model that accounted for a large fraction of BOLD (blood oxygenation level-dependent) signal modulation over the brain. Both IPs and FEF were activated during search through nontargets, consistent with a role in maintaining attention-related signals during search. However, unlike FEF, IPs also showed stimulus-related activations, and may combine signals related to sensory and task-dependent components of salience. Although IPs-FEF showed search-related activations, the TPJ was deactivated during search. TPJ activations were confined to detection-related signals. These results provide a much stronger dissociation between the TPJ and IPs-FEF than previous work, while indicating functional differences between frontal and parietal regions that are often coactivated in studies of attention. Finally, continuous flow models of information processing predict that during search, signals from missed targets should be fed from sensory to associative regions rather than being gated by the decision criterion. Correspondingly, missed targets significantly activated parietal (e.g., right TPJ) and frontal (e.g., anterior insula, anterior cingulate) regions, although with a smaller magnitude than detected targets. Surprisingly, many cortical regions showed equivalent signals from detected targets and the completion of target-absent trials, reflecting a widespread signal unrelated to motor execution.

Remitted major depression is related to increased functional coupling between ventral striatum and cortical regions in resting state fMRI

2011 ◽  
Vol 26 (S2) ◽  
pp. 948-948 ◽  
Author(s):  
G. Pail ◽  
C. Scharinger ◽  
K. Kalcher ◽  
W. Huf ◽  
R. Boubela ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Orbitofrontal Cortex ◽  
Resting State ◽  
Ventral Striatum ◽  
Resting State Fmri ◽  
Anterior Cingulate ◽  
Functional Coupling ◽  
Healthy Controls ◽  
Full Remission ◽  
Cortical Regions

IntroductionDysfunction in the basal ganglia has been related to impaired reward processing and anhedonia, a core symptom of Major Depressive Disorder (MDD). In particular, the ventral striatum including the nucleus accumbens is increasingly implicated in the pathophysiology of MDD, but evidence for a specific role during episodes of full remission is lacking so far.ObjectivesTo investigate functional connectivity patterns of resting-state activity in patients in the remitted phase of MDD (rMDD).AimsTo determine whether rMDD is related to disruptions of functional coupling between the ventral striatum and cortical regions.MethodsForty-three remitted depressed patients and thirty-five healthy controls were recruited at Medical University of Vienna, Vienna, Austria, and performed a six minute resting-state fMRI scan. Seed time series were extracted from the preprocessed data using individual masks for ventral striatum and correlated with all nodes in a surface based analysis using FreeSurfer, AFNI and SUMA. The resulting correlation coefficients were then Fishertransformed, group results were determined by comparing group mean smoothed z-scores with a two-sample ttest.ResultsIncreased resting-state functional connectivity was revealed between ventral striatum (seed region) and anterior cingulate cortex as well as orbitofrontal cortex in the rMDD group compared to healthy controls.ConclusionsOur preliminary data is in accordance with the idea that increased functional coupling between the ventral striatum and two major emotion processing regions, the anterior cingulate cortex and the orbitofrontal cortex, may represent a neural mechanism contributing to the maintenance of full remission of MDD.

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