scholarly journals Comparison of stimulus-evoked BOLD responses in human and monkey visual cortex

2018 ◽  
Author(s):  
Gaurav H. Patel ◽  
Alexander L. Cohen ◽  
Justin T. Baker ◽  
Lawrence H. Snyder ◽  
Maurizio Corbetta
Keyword(s):  
Visual Cortex ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Bold Response ◽  
Stimulus Interval ◽  
Bold Responses ◽  
Oxygenation Level ◽  
The Mean ◽  
Single Response ◽  
Monkey Visual Cortex

AbstractWe characterized the blood oxygenation level dependent (BOLD) signal in humans and macaque monkeys by comparing the response in visual cortex to a single checkerboard or two checkerboards, spaced 1.5, 3.0, or 4.5 s apart. We found that the magnitude and shape of the BOLD response to a single checkerboard was similar in the two species. In addition, we found that the BOLD responses summed similarly, and that at an inter-stimulus interval (ISI) of 4.5 sec BOLD summation was nearly linear in both species. When comparing the ratio of the amplitude of the response to the second checkerboard at the 4.5 sec ISI with that of the single checkerboard between subjects in both species, the results from both monkey subjects fell within one standard deviation of the mean human results (human mean (n=12): .95 +/− .31 second/single response amplitude; monkey 1: 1.16; monkey 2: .86). At the shorter ISIs, both species demonstrated increased suppression of the BOLD response to the second checkerboard. These findings indicate that the magnitude of the BOLD response to events separated by 4.5 seconds can be accurately measured in and compared between human and monkey visual cortex.

scholarly journals Feedback to distal dendrites links fMRI signals to neural receptive fields in a spiking network model of the visual cortex

2015 ◽  
Vol 114 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Hanna Heikkinen ◽  
Fariba Sharifian ◽  
Ricardo Vigario ◽  
Simo Vanni
Keyword(s):  
Visual Cortex ◽  
Feedback Loop ◽  
Receptive Fields ◽  
Blood Oxygenation ◽  
High Fidelity ◽  
Bold Signal ◽  
Bold Response ◽  
Spiking Network ◽  
Oxygenation Level ◽  
The Brain

The blood oxygenation level-dependent (BOLD) response has been strongly associated with neuronal activity in the brain. However, some neuronal tuning properties are consistently different from the BOLD response. We studied the spatial extent of neural and hemodynamic responses in the primary visual cortex, where the BOLD responses spread and interact over much longer distances than the small receptive fields of individual neurons would predict. Our model shows that a feedforward-feedback loop between V1 and a higher visual area can account for the observed spread of the BOLD response. In particular, anisotropic landing of inputs to compartmental neurons were necessary to account for the BOLD signal spread, while retaining realistic spiking responses. Our work shows that simple dendrites can separate tuning at the synapses and at the action potential output, thus bridging the BOLD signal to the neural receptive fields with high fidelity.

scholarly journals Dynamic metabolic changes in human visual cortex in regions with positive and negative blood oxygenation level-dependent response

2018 ◽  
Vol 39 (11) ◽  
pp. 2295-2307 ◽  
Author(s):  
Miguel Martínez-Maestro ◽  
Christian Labadie ◽  
Harald E Möller
Keyword(s):  
Visual Cortex ◽  
Tricarboxylic Acid Cycle ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Metabolic Changes ◽  
Resonance Spectroscopy ◽  
Bold Response ◽  
Full Field ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Dynamic metabolic changes were investigated by functional magnetic resonance spectroscopy (fMRS) during sustained stimulation of human primary visual cortex. Two established paradigms, consisting of either a full-field or a small-circle flickering checkerboard, were employed to generate wide-spread areas of positive or negative blood oxygenation level-dependent (BOLD) responses, respectively. Compared to baseline, the glutamate concentration increased by 5.3% ( p = 0.007) during activation and decreased by −3.8% ( p = 0.017) during deactivation. These changes were positively correlated with the amplitude of the BOLD response ( R = 0.60, p = 0.002) and probably reflect changes of tricarboxylic acid cycle activity. During deactivation, the glucose concentration decreased by −7.9% ( p = 0.025) presumably suggesting increased consumption or reduced glucose supply. Other findings included an increased concentration of glutathione (4.2%, p = 0.023) during deactivation and a negative correlation of glutathione and BOLD signal changes ( R = −0.49, p = 0.012) as well as positive correlations of aspartate ( R = 0.44, p = 0.035) and N-acetylaspartylglutamate ( R = 0.42, p = 0.035) baseline concentrations with the BOLD response. It remains to be shown in future work if the observed effects on glutamate and glucose levels deviate from the assumption of a direct link between glucose utilization and regulation of blood flow or support previous suggestions that the hemodynamic response is mainly driven by feedforward release of vasoactive messengers.

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 Independence of Anticipatory Signals for Spatial Attention From Number of Nontarget Stimuli in the Visual Field

2008 ◽  
Vol 100 (2) ◽  
pp. 829-838 ◽  
Author(s):  
C. Sestieri ◽  
C. M. Sylvester ◽  
A. I. Jack ◽  
G. d'Avossa ◽  
G. L. Shulman ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Spatial Attention ◽  
Visual Stimulation ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Signal Modulation ◽  
Low Contrast ◽  
Upper Visual Field ◽  
Oxygenation Level

Covertly attending to a location modulates the activity of visual areas even in the absence of visual stimulation. These effects are widespread, being found in the cortical representations of both attended and unattended portions of the visual field. It is not clear, however, whether preparatory modulations depend on subjects' expectation regarding the presence of additional nontarget stimuli in the visual field. Here, we asked subjects to endogenously direct attention to a peripheral location in the upper visual field, to identify the orientation of a low-contrast target stimulus, and we manipulated the number and behavioral relevance of other low-contrast nontarget stimuli in the visual field. Anticipatory (i.e., prestimulus) blood oxygenation level–dependent (BOLD) signal increments in visual cortex were strongest at the contralateral attended location, whereas signal decrements were strongest at the unattended mirror-opposite ipsilateral location/region of visual cortex. Importantly, these strong anticipatory decrements were not related to the presence/absence of nontarget low-contrast stimuli and did not correlate with either weaker target-evoked responses or worse performance. Second, the presence of other low-contrast stimuli in the visual field, even when potential targets, did not modify the anticipatory signal modulation either at target or nontarget locations. We conclude that the topography of spatial attention–related anticipatory BOLD signal modulation across visual cortex, specifically decrements at unattended locations, is mainly determined by processes at the cued location and not by the number or behavioral relevance of distant low-contrast nontarget stimuli elsewhere in the visual field.

scholarly journals BOLD-Perfusion Coupling during Monocular and Binocular Stimulation

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Claudine Gauthier ◽  
Richard D. Hoge
Keyword(s):  
Visual Cortex ◽  
Oxidative Metabolism ◽  
Visual Stimulation ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Blood Oxygenation Level ◽  
Monocular Stimulation ◽  
Binocular Stimulation ◽  
Oxygenation Level

Previous studies have suggested that during selective activation of a subset of the zones comprising a columnar system in visual cortex, perfusion increases uniformly in all columns of the system, while increases in oxidative metabolism occur predominantly in the activated columns. This could lead to disproportionately large blood oxygenation level-dependent (BOLD) signal increases for a given flow increase during monocular (relative to binocular) stimulation, due to contributions from columns which undergo large increases in perfusion with little or no change in oxidative metabolism. In the present study, we sought to test this hypothesis by measuring BOLD-perfusion coupling ratios in spatially averaged signals over V1 during monocular and binocular visual stimulation. It was found that, although withholding input to one eye resulted in statistically significant decreases in BOLD and perfusion signals in primary visual cortex, the ratio between BOLD and perfusion increases did not change significantly. These results do not support a gross mismatch between spatial patterns of flow and metabolism response during monocular stimulation.

scholarly journals Altered neurochemical coupling in the occipital cortex in migraine with visual aura

Cephalalgia ◽  
2015 ◽  
Vol 35 (11) ◽  
pp. 1025-1030 ◽  
Author(s):  
Holly Bridge ◽  
Charlotte J Stagg ◽  
Jamie Near ◽  
Chi-ieong Lau ◽  
Aimee Zisner ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Occipital Cortex ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Resonance Spectroscopy ◽  
Bold Signal ◽  
Visual Aura ◽  
Oxygenation Level ◽  
Neurochemical Profile

Background Visual aura is present in about one-third of migraine patients and triggering by bright or flickering lights is frequently reported. Method Using migraine with visual aura patients, we investigated the neurochemical profile of the visual cortex using magnetic resonance spectroscopy. Specifically, glutamate/creatine and GABA/creatine ratios were quantified in the occipital cortex of female migraine patients. Results GABA levels in the occipital cortex of migraine patients were lower than that of controls. Glutamate levels in migraine patients, but not controls, correlated with the blood-oxygenation-level-dependent (BOLD) signal in the primary visual cortex during visual stimulation. Conclusion Migraine with visual aura appears to disrupt the excitation-inhibition coupling in the occipital cortex.

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 Voxel-Wise Linearity Analysis of Increments and Decrements in BOLD Responses in Human Visual Cortex Using a Contrast Adaptation Paradigm

2021 ◽  
Vol 15 ◽  
Author(s):  
Yun Lin ◽  
Xi Zhou ◽  
Yuji Naya ◽  
Justin L. Gardner ◽  
Pei Sun
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Bold Signal ◽  
Transient Responses ◽  
Bold Fmri ◽  
Human Visual Cortex ◽  
Contrast Adaptation ◽  
Bold Responses

The linearity of BOLD responses is a fundamental presumption in most analysis procedures for BOLD fMRI studies. Previous studies have examined the linearity of BOLD signal increments, but less is known about the linearity of BOLD signal decrements. The present study assessed the linearity of both BOLD signal increments and decrements in the human primary visual cortex using a contrast adaptation paradigm. Results showed that both BOLD signal increments and decrements kept linearity to long stimuli (e.g., 3 s, 6 s), yet, deviated from linearity to transient stimuli (e.g., 1 s). Furthermore, a voxel-wise analysis showed that the deviation patterns were different for BOLD signal increments and decrements: while the BOLD signal increments demonstrated a consistent overestimation pattern, the patterns for BOLD signal decrements varied from overestimation to underestimation. Our results suggested that corrections to deviations from linearity of transient responses should consider the different effects of BOLD signal increments and decrements.

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.

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