scholarly journals Time Course of Neural Activity Correlated with Colored-Hearing Synesthesia

2007 ◽  
Vol 18 (2) ◽  
pp. 379-385 ◽  
Author(s):  
G. Beeli ◽  
M. Esslen ◽  
L. Jancke
Keyword(s):  
Neural Activity ◽  
Time Course

Spinal cord neural activity of patients with fibromyalgia and healthy controls during temporal summation of pain: an fMRI study

2021 ◽  
Vol 126 (3) ◽  
pp. 946-956
Author(s):  
Roland Staud ◽  
Jeff Boissoneault ◽  
Song Lai ◽  
Marlin S. Mejia ◽  
Riddhi Ramanlal ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Neural Activity ◽  
Central Sensitization ◽  
Temporal Summation ◽  
Time Course ◽  
Pain Modulation ◽  
Healthy Controls ◽  
Fmri Study ◽  
Second Pain

“Windup” and its behavioral correlate “temporal-summation-of-second pain” (TSSP) represent spinal cord mechanisms of pain augmentation associated with central sensitization and chronic pain. Fibromyalgia (FM) is a chronic pain disorder, where abnormal TSSP has been demonstrated. We used fMRI to study spinal cord and brainstem activation during TSSP. We characterized the time course of spinal cord and brainstem BOLD activity during TSSP which showed abnormal brainstem activity in patients with FM, possibly due to deficient pain modulation.

scholarly journals The Neural Correlates of Cognitive Reappraisal during Emotional Autobiographical Memory Recall

2013 ◽  
Vol 25 (1) ◽  
pp. 87-108 ◽  
Author(s):  
Alisha C. Holland ◽  
Elizabeth A. Kensinger
Keyword(s):  
Neural Activity ◽  
Visual Imagery ◽  
Time Course ◽  
Cognitive Reappraisal ◽  
Neural Correlates ◽  
Memory Recall ◽  
Emotional Intensity ◽  
Autobiographical Memories ◽  
Neural Processes ◽  
Emotion Generation

We used fMRI to investigate the neural processes engaged as individuals down- and up-regulated the emotions associated with negative autobiographical memories (AMs) using cognitive reappraisal strategies. Our analyses examined neural activity during three separate phases, as participants (a) viewed a reappraisal instruction (i.e., Decrease, Increase, Maintain), (b) searched for an AM referenced by a self-generated cue, and (c) elaborated upon the details of the AM being held in mind. Decreasing emotional intensity primarily engaged activity in regions previously implicated in cognitive control (e.g., dorsal and ventral lateral pFC), emotion generation and processing (e.g., amygdala, insula), and visual imagery (e.g., precuneus) as participants searched for and retrieved events. In contrast, increasing emotional intensity engaged similar regions during the instruction phase (i.e., before a memory cue was presented) and again as individuals later elaborated upon the details of the events they had recalled. These findings confirm that reappraisal can modulate neural activity during the recall of personally relevant events, although the time course of this modulation appears to depend on whether individuals are attempting to down- or up-regulate their emotions.

Sensorimotor Locus of the Buildup Activity in Monkey Lateral Intraparietal Area Neurons

2010 ◽  
Vol 103 (5) ◽  
pp. 2664-2674 ◽  
Author(s):  
Joonkoo Park ◽  
Jun Zhang
Keyword(s):  
Neural Activity ◽  
Time Course ◽  
Temporal Dynamics ◽  
Neuronal Firing ◽  
Firing Activity ◽  
Motor Representation ◽  
Lateral Intraparietal Area ◽  
Response Mapping ◽  
Stimulus Response ◽  
Dot Motion

A study in 2002 using a random-dot motion-discrimination paradigm showed that an information accumulation model with a threshold-crossing mechanism can account for activity of the lateral intraparietal area (LIP) neurons. Here, mathematical techniques were applied to the same dataset to quantitatively address the sensory versus motor representation of the neuronal activity during the time course of a trial. A technique based on Signal Detection Theory was applied to provide indices to quantify how neuronal firing activity is responsible for encoding the stimulus or selecting the response at the behavioral level. Additionally, a statistical model based on Poisson regression was used to provide an orthogonal decomposition of the neural activity into stimulus, response, and stimulus-response mapping components. The temporal dynamics of the sensorimotor locus of the LIP activity indicated that there is no stimulus-response mapping-specific neuronal firing activity throughout a trial; the neural activity toward the saccadic onset reflects the development of the motor representation, and the neural activity in the beginning of a trial contains little, if any, information about the sensory representation. Sensorimotor analysis on individual neurons also showed that the neuronal activation, as a population, represent pending saccadic direction and carry little information about the direction of the motion stimulus.

Neurogenic hyperalgesia: psychophysical studies of underlying mechanisms

1991 ◽  
Vol 66 (1) ◽  
pp. 190-211 ◽  
Author(s):  
R. H. LaMotte ◽  
C. N. Shain ◽  
D. A. Simone ◽  
E. F. Tsai
Keyword(s):  
Injection Site ◽  
Neural Activity ◽  
Time Course ◽  
Normal Skin ◽  
Nerve Fibers ◽  
Intradermal Injection ◽  
Mechanical Hyperalgesia ◽  
Underlying Mechanisms ◽  
Psychophysical Studies ◽  
Stimulation Of

1. Psychophysical studies were made, in humans, of the sensory characteristics and underlying mechanisms of the hyperalgesia (often termed “secondary hyperalgesia”) that occurs in uninjured skin surrounding a local cutaneous injury. The hyperalgesia was characterized by lowered pain thresholds and enhanced magnitude of pain to normally painful stimuli. The “injury” was produced by a single intradermal injection of 10 microliters of 100 micrograms of capsaicin, the algesic substance in hot chili peppers. 2. On injection of capsaicin into the volar forearm, the subjects experienced intense burning pain, accompanied immediately by the formation of three areas of hyperalgesia surrounding the injection site. The largest mean area (55 cm2) was hyperalgesic to a normally painful punctate stimulation of the skin. Nested within this was an area of tenderness to gentle stroking (38 cm2) and a much smaller area of hyperalgesia to heat (2 cm2). An area of analgesia to pinprick, approximately 4 mm in diameter and centered on the injection site, developed within minutes and typically disappeared within 24 h. The hyperalgesia to heat and to stroking disappeared within 1-2 h, whereas the hyperalgesia to punctate stimuli, although gradually decreasing in area, lasted from 13 to 24 h. 3. The radial spread of the mechanical hyperalgesia (to punctate and stroking stimuli) away from the injury was dependent on neural activity and not produced, for example, by algesic substances transported away from the injury. The injection of capsaicin into a small area of anesthetized skin did not produce hyperalgesia in the surrounding, unanesthetized skin. Also, the hyperalgesia in normal skin readily crossed a tight arm band that blocked the circulation of blood and lymph. 4. The spread of mechanical hyperalgesia away from the injury was peripherally mediated via cutaneous nerve fibers because it was blocked by a thin mediolateral strip of cutaneous anesthesia placed 1 cm away from the capsaicin injection site. Hyperalgesia developed normally on the capsaicin side of the strip but not on the other side. 5. Heat stimulation of the skin that produced pain that was equivalent in magnitude and time course to that produced by an injection of capsaicin (10 micrograms) resulted in much smaller areas of mechanical hyperalgesia. It was postulated that there exist special chemosensitive primary afferent nerve fibers that are more effective in producing mechanical hyperalgesia than are the known thermo- and mechanosensitive nociceptive nerve fibers. 6. Once developed, the mechanical hyperalgesia became only partially dependent on peripheral neural activity originating at the site of injury.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Changes in neural activity around the time of saccades: Separate contributions of visual and non-visual signals on MEG alpha and theta band activity

2021 ◽  
Author(s):  
David Acunzo ◽  
David Melcher
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Time Course ◽  
Brain Regions ◽  
Visual Input ◽  
Visual Signals ◽  
Perceptual Task ◽  
Alpha Power ◽  
Similar Time ◽  
Retinal Stimulation

Visual processing mainly occurs during fixation, periods separated by saccadic eye movements, necessitating a close coordination between sensory and motor systems. It has been suggested that the intention to make a saccade can modulate neural activity, including predictive changes, suppression of peri-saccadic retinal input and trans-saccadic integration. Consistent with this idea, modulations of neural activity around the time of saccades have been reported in non-human species, showing non-visually mediated, extraretinal responses in specific brain regions. In humans, however, peri-saccadic whole-brain activity has mainly been studied in the context of a perceptual task, making it difficult to disentangle activity related to the task, visual transients from retinal stimulation and non-visual (saccade-related) responses. We measured magnetoencephalography (MEG) theta (3–7 Hz) and alpha (8–12 Hz) activity during voluntary horizontal saccade execution between two fixation points. To distinguish between visually and non-visually mediated activity, participants engaged in three tasks: voluntary saccades in near-darkness, fixation with visual input shifted to simulate the saccade, and volitional saccades in total darkness. Using correlational analyses, we found that patterns of neural activity are consistent with contributions of two separate mechanisms, one related to saccades (non-visual/extraretinal) and the other linked to the processing of visual input at the beginning of the new fixation (visual/retinal). Changes in occipital alpha power and instantaneous frequency showed a similar time course in near-dark and simulated saccade conditions, suggesting an effect of visually evoked responses. In contrast, alterations in parietal-occipital theta power and phase clustering were consistent with a non-visually-driven (extraretinal) mechanism, with similar multivariate patterns for near-dark and full-darkness conditions. Some effects, such as theta phase reset and alterations in alpha power, showed separable contributions of both the saccade and visual transient, with differing time courses. This combination of visual and non-visual mechanisms may support sensorimotor integration during active vision.

Time Course of Brain Activity during Change Blindness and Change Awareness: Performance is Predicted by Neural Events before Change Onset

2006 ◽  
Vol 18 (12) ◽  
pp. 2108-2129 ◽  
Author(s):  
Gilles Pourtois ◽  
Michael De Pretto ◽  
Claude-Alain Hauert ◽  
Patrik Vuilleumier
Keyword(s):  
Change Detection ◽  
Neural Activity ◽  
Time Course ◽  
Brain Activity ◽  
Change Blindness ◽  
Event Related Potentials ◽  
Distinct Pattern ◽  
Event Related Potential ◽  
Related Potentials ◽  
Visual Changes

People often remain “blind” to visual changes occurring during a brief interruption of the display. The processing stages responsible for such failure remain unresolved. We used event-related potentials to determine the time course of brain activity during conscious change detection versus change blindness. Participants saw two successive visual displays, each with two faces, and reported whether one of the faces changed between the first and second displays. Relative to blindness, change detection was associated with a distinct pattern of neural activity at several successive processing stages, including an enhanced occipital P1 response and a sustained frontal activity (CNV-like potential) after the first display, before the change itself. The amplitude of the N170 and P3 responses after the second visual display were also modulated by awareness of the face change. Furthermore, a unique topography of event-related potential activity was observed during correct change and correct no-change reports, but not during blindness, with a recurrent time course in the stimulus sequence and simultaneous sources in the parietal and temporo-occipital cortex. These results indicate that awareness of visual changes may depend on the attentional state subserved by coordinated neural activity in a distributed network, before the onset of the change itself.

scholarly journals Multivoxel Pattern Analysis for fMRI Data: A Review

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Abdelhak Mahmoudi ◽  
Sylvain Takerkart ◽  
Fakhita Regragui ◽  
Driss Boussaoud ◽  
Andrea Brovelli
Keyword(s):  
Neural Activity ◽  
Time Course ◽  
Pattern Analysis ◽  
Reference Model ◽  
Performance Estimation ◽  
Support Vector ◽  
Brain Areas ◽  
Experimental Conditions ◽  
Multivoxel Pattern Analysis ◽  
Brain Functions

Functional magnetic resonance imaging (fMRI) exploits blood-oxygen-level-dependent (BOLD) contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM) approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA) represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs). In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC) curves.

scholarly journals Distinct Characteristics of Odor-evoked Calcium and Electrophysiological Signals in Mitral/Tufted Cells in the Mouse Olfactory Bulb

2021 ◽  
Author(s):  
Han Xu ◽  
Chi Geng ◽  
Xinzhong Hua ◽  
Penglai Liu ◽  
Jinshan Xu ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Neural Activity ◽  
Single Unit ◽  
Time Course ◽  
Response Characteristics ◽  
Neuronal Populations ◽  
New Information ◽  
Electrophysiological Signals ◽  
Electrophysiological Measurements ◽  
Tufted Cells

AbstractFiber photometry is a recently-developed method that indirectly measures neural activity by monitoring Ca2+ signals in genetically-identified neuronal populations. Although fiber photometry is widely used in neuroscience research, the relationship between the recorded Ca2+ signals and direct electrophysiological measurements of neural activity remains elusive. Here, we simultaneously recorded odor-evoked Ca2+ and electrophysiological signals [single-unit spikes and local field potentials (LFPs)] from mitral/tufted cells in the olfactory bulb of awake, head-fixed mice. Odors evoked responses in all types of signal but the response characteristics (e.g., type of response and time course) differed. The Ca2+ signal was correlated most closely with power in the β-band of the LFP. The Ca2+ signal performed slightly better at odor classification than high-γ oscillations, worse than single-unit spikes, and similarly to β oscillations. These results provide new information to help researchers select an appropriate method for monitoring neural activity under specific conditions.

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