Time Course Of Brain Activity Research Articles

Abstract P3-08-01: Cognitive impairment and cortical network dysfunction following chemotherapy

Abstract A common complaint of cancer patients is the experience of cognitive difficulty during and after chemotherapy. However, the mechanisms through which this occurs are still unknown. We hypothesized that chemotherapy-induced cognitive impairment may result from dysfunction in large-scale brain networks, particularly those involved in attentional control. These networks are evident when measuring task-based brain activity during attention-demanding tasks, but can also be studied using resting state functional connectivity magnetic resonance imaging (rs-fcMRI). In rs-fcMRI, connectivity between brain regions is measured using data collected while participants lie awake in the magnet with their eyes open, but performing no task. It reliably distinguishes known sensory, motor, and executive networks based on connectivity patterns. These data complement information about structural (white matter) connectivity obtained using diffusion tensor imaging (DTI). Here we report a case-control study of women with a history of triple negative breast cancer (BrCa) who completed standard adjuvant chemotherapy within two years of study entry. The cases (n = 15) were defined as women who reported cognitive impairment by the Cognitive Failures Questionnaire and controls (n = 13) were women who did not report cognitive impairment. All participants eligible for MRI investigation underwent rs-fcMRI and DTI on a Siemens 3T TIM Trio scanner. DTI parameters measured included Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD), and Axial Diffusivity. The study was conducted in its entirety at Washington University in St. Louis School of Medicine. Institutional review board approval was obtained prior to recruitment. The mean age of cases was 53.1 years and controls 51.6 years; all were diagnosed with invasive ductal or lobular BrCa. For each participant, we extracted the timecourse of brain activity for regions of interest in frontoparietal and cingularopercular control systems, measured indirectly via blood oxygenation level dependent (BOLD) contrast, from the MRI scans, and additional regions of interest distributed across the brain. We excluded scans that showed motion artifact. Pairwise connectivity was calculated using Pearson correlation between all regions of interest; we also used these regions in seed-based analyses. We compared the strength of rs-fcMRI-defined network connections between the two groups and used nonparametric permutation tests to calculate statistical significance. We found significant changes within several regions of the frontoparietal attention network, such that patients reporting greater cognitive difficulty showed weaker neural connectivity. In addition, DTI analyses revealed different patterns of anatomical connectivity between groups, including reduced FA (p<0.03) and increased MD and RD (p<0.02), both of which have been shown to be signatures of brain change in demyelinating disease. Together our results suggest that standard therapeutic levels of chemotherapy for BrCa patients may result in structural and functional connectivity alterations in the brain networks supporting executive attention, which in turn may be a contributing factor in cognitive difficulty. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-08-01.

Time course of brain activation elicited by basic emotions

Whereas facial emotion recognition protocols have shown that each discrete emotion has a specific time course of brain activation, there is no electrophysiological evidence to support these findings for emotional induction by complex pictures. Our objective was to specify the differences between the time courses of brain activation elicited by feelings of happiness and, with unpleasant pictures, by feelings of disgust and sadness. We compared event-related potentials (ERPs) elicited by the watching of high-arousing pictures from the International Affective Picture System, selected to induce specific emotions. In addition to a classical arousal effect on late positive components, we found specific ERP patterns for each emotion in early temporal windows (<200 ms). Disgust was the first emotion to be associated with different brain processing after 140 ms, whereas happiness and sadness differed in ERPs elicited at the frontal and central sites after 160 ms. Our findings highlight the limits of the classical averaging of ERPs elicited by different emotions inside the same valence and suggest that each emotion could elicit a specific temporal pattern of brain activation, similar to those observed with emotional face recognition.

Massive Modulation of Brain Areas After Mechanical Pain Stimulation: A Time-Resolved fMRI Study

To date, relatively little is known about the spatiotemporal aspects of whole-brain blood oxygenation level-dependent (BOLD) responses to brief nociceptive stimuli. It is known that the majority of brain areas show a stimulus-locked response, whereas only some are characterized by a canonical hemodynamic response function. Here, we investigated the time course of brain activations in response to mechanical pain stimulation applied to participants' hands while they were undergoing functional magnetic resonance imaging (fMRI) scanning. To avoid any assumption about the shape of BOLD response, we used an unsupervised data-driven method to group voxels sharing a time course similar to the BOLD response to the stimulus and found that whole-brain BOLD responses to painful mechanical stimuli elicit massive activation of stimulus-locked brain areas. This pattern of activations can be segregated into 5 clusters, each with a typical temporal profile. In conclusion, we show that an extensive activity of multiple networks is engaged at different time latencies after presentation of a noxious stimulus. These findings aim to motivate research on a controversial topic, such as the temporal profile of BOLD responses, the variability of these response profiles, and the interaction between the stimulus-related BOLD response and ongoing fluctuations in large-scale brain networks.

Individual differences in cognitive reappraisal usage modulate the time course of brain activation during symptom provocation in specific phobia

BackgroundExtinction learning is proposed to be one key mechanism of action underlying exposure-based cognitive-behavioral therapy (CBT) in specific phobia. Beyond that, cognitive reappraisal, one important strategy to regulate negative emotions, is a crucial component of CBT interventions, but has been disregarded in previous studies investigating neural change processes in specific phobia. The aim of this study was to investigate the association of individual differences in habitual/dispositional cognitive reappraisal usage and the time course of brain activation during phobic stimulation in specific phobia.MethodsDental phobic patients and healthy control subjects participated in a functional magnetic resonance imaging (fMRI) study whilst being confronted with phobic, disgust, fear and neutral pictures. Individual differences in cognitive reappraisal usage were assessed via a self-report questionnaire and correlated with activation decreases over the course of time.ResultsPhobic individuals with higher dispositional cognitive reappraisal scores showed a more pronounced activation decline in the right dorsomedial prefrontal cortex (dmPFC) which might be associated with a diminution of explicit cognitive emotion regulation over the course of time. Less decrease of activation in the right ventromedial prefrontal cortex (vmPFC) and the lateral orbitofrontal cortex (lOFC) over time in subjects with higher cognitive reappraisal scores might be related to a stronger automatic regulation of emotions or even emotional relearning. Additionally, phobic subjects compared with healthy controls showed a stronger habituation of the left dmPFC over the course of symptom provocation.ConclusionsThe results of this study show for the first time that individual differences in cognitive reappraisal usage are associated with the time course of brain activation during symptom provocation in specific phobia. Additionally, the present study gives first indications for the importance of considering individual differences in cognitive reappraisal usage in the treatment of specific phobia.

Signatures of conscious processing in the human brain

Event Abstract Back to Event Signatures of conscious processing in the human brain Stanislas Dehaene1* 1 Inserm­CEA Cognitive Neuroimaging Unit, CEA/SAC/DSV/DRM/NeuroSpin, France Understanding how brain activity leads to a conscious experience remains a major experimental challenge. I will describe a series of experiments that probe the signatures of conscious processing. In these experiments, my colleagues and I ask whether a specific type of brain activity can be detected when a person suddenly becomes aware of a piece of information. We create minimal contrasts whereby the very same visual stimulus is sometimes undetected, and sometimes consciously seen. We then use time-resolved methods of electro- and magnetoencephalography to follow the time course of brain activity, and multivariate decoding techniques to extract the activity profiles that encode conscious or unconscious information. The results show that conscious access relates to a global burst of late synchronized activity (a cortical “ignition”), distributed through many cortical areas, and with strong inter-areal communication across distant cortical sites. They fit with the theory of a global neuronal workspace, according to which what we experience as a consciousness is the global availability of information in a large-scale network of pyramidal neurons linked by long-distance axons. This knowledge is now being applied to the monitoring of conscious states in non-communicating patients. By combining event-related and EEG-based measures of cortical activation, local fluctuations and global long-distance synchrony, we can reliably begin to sort out patients in coma, vegetative state or minimal consciousness. References Dehaene, S., & Changeux, J. P. (2011). Experimental and theoretical approaches to conscious processing. Neuron, 70, 200-227. Keywords: Consciousness, Magnetoencephalography, EEG/ERP, masking, vegetative state, Coma, MMN (Mismatch negativity) Conference: Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012. Presentation Type: Oral Presentation (only for invited speakers) Topic: Higher Brain Functions in health and disease: cognition and memory Citation: Dehaene S (2012). Signatures of conscious processing in the human brain. Conference Abstract: Belgian Brain Council. doi: 10.3389/conf.fnhum.2012.210.00132 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 20 Jul 2012; Published Online: 12 Sep 2012. * Correspondence: Dr. Stanislas Dehaene, Inserm­CEA Cognitive Neuroimaging Unit, CEA/SAC/DSV/DRM/NeuroSpin, GIF/YVETTE, F-91191, France, Stanislas.Dehaene@cea.fr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Stanislas Dehaene Google Stanislas Dehaene Google Scholar Stanislas Dehaene PubMed Stanislas Dehaene Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Tracking the Time Course of Action Priming on Object Recognition: Evidence for Fast and Slow Influences of Action on Perception

Perception and action are classically thought to be supported by functionally and neuroanatomically distinct mechanisms. However, recent behavioral studies using an action priming paradigm challenged this view and showed that action representations can facilitate object recognition. This study determined whether action representations influence object recognition during early visual processing stages, that is, within the first 150 msec. To this end, the time course of brain activation underlying such action priming effects was examined by recording ERPs. Subjects were sequentially presented with two manipulable objects (e.g., tools), which had to be named. In the congruent condition, both objects afforded similar actions, whereas dissimilar actions were afforded in the incongruent condition. In order to test the influence of the prime modality on action priming, the first object (prime) was presented either as picture or as word. We found an ERP effect of action priming over the central scalp as early as 100 msec after target onset for pictorial, but not for verbal primes. A later action priming effect on the N400 ERP component known to index semantic integration processes was obtained for both picture and word primes. The early effect was generated in a fronto-parietal motor network, whereas the late effect reflected activity in anterior temporal areas. The present results indicate that action priming influences object recognition through both fast and slow pathways: Action priming affects rapid visuomotor processes only when elicited by pictorial prime stimuli. However, it also modulates comparably slow conceptual integration processes independent of the prime modality.

Quantitative pharmacologic MRI in mice

Pharmacologic MRI (phMRI) uses functional MRI techniques to provide a noninvasive in vivo measurement of the hemodynamic effects of drugs. The cerebral blood volume change (ΔCBV) serves as a surrogate for neuronal activity via neurovascular coupling mechanisms. By assessing the location and time course of brain activity in mouse mutant studies, phMRI can provide valuable insights into how different behavioral phenotypes are expressed in deferring brain activity response to drug challenge. In this report, we evaluate the utility of three different intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for phMRI using a gradient-echo technique, with temporal resolution of one min at high magnetic field. The tissue half-life of the USPIOs was studied using a nonlinear detrending model. The three USPIOs are candidates for CBV weighted phMRI experiments, with r(2)/r(1) ratios ≥ 20 and apparent half-lives ≥ 1.5 h at the described doses. An echo-time of about 10 ms or longer results in a functional contrast to noise ratio (fCNR) > 75 after USPIO injection, with negligible decrease between 1.5-2 h. phMRI experiments were conducted at 7 T using cocaine as a psychotropic substance and acetazolamide, a global vasodilator, as a positive control. Cocaine acts as a dopamine-serotonin-norepinephrine reuptake inhibitor, increasing extracellular concentrations of these neurotransmitters, and thus increasing dopaminergic, serotonergic and noradrenergic neurotransmission. phMRI results showed that CBV was reduced in the normal mouse brain after cocaine challenge, with the largest effects in the nucleus accumbens, whereas after acetazolamide, blood volume was increased in both cerebral and extracerebral tissue.

Basic emotions: Differences in time sequence and functional imaging with low resolution brain electrical tomography (LORETA)

AbstractThe aim of the present study is to investigate the relationship between the time course of brain activation during the observation of pictures depicting scenes associated with the four basic emotion of happiness, sadness, fear and disgust. Twenty-nine right-handed volunteers (17 male, 12 female; mean age 24.6 years) took part in the study. To study the time course of the affective processing the low resolution brain electromagnetic tomography (LORETA) has been used. Each emotional condition has shown specific activation patterns in different brain regions, changing over time. Our findings are in good agreement with other brain-imaging studies (PET/fMRI) but with the advantage to investigate the temporal evolution of the emotional process in the millisecond range. The results showed that the time sequence of activations is different and characteristic for each emotion conditions.

High density event-related potential data acquisition in cognitive neuroscience.

Functional magnetic resonance imaging (fMRI) is currently the standard method of evaluating brain function in the field of Cognitive Neuroscience, in part because fMRI data acquisition and analysis techniques are readily available. Because fMRI has excellent spatial resolution but poor temporal resolution, this method can only be used to identify the spatial location of brain activity associated with a given cognitive process (and reveals virtually nothing about the time course of brain activity). By contrast, event-related potential (ERP) recording, a method that is used much less frequently than fMRI, has excellent temporal resolution and thus can track rapid temporal modulations in neural activity. Unfortunately, ERPs are under utilized in Cognitive Neuroscience because data acquisition techniques are not readily available and low density ERP recording has poor spatial resolution. In an effort to foster the increased use of ERPs in Cognitive Neuroscience, the present article details key techniques involved in high density ERP data acquisition. Critically, high density ERPs offer the promise of excellent temporal resolution and good spatial resolution (or excellent spatial resolution if coupled with fMRI), which is necessary to capture the spatial-temporal dynamics of human brain function.

Time course of brain activation elicited by discrete emotions.

Time course of brain activation elicited by discrete emotions.

Time course of regional brain activation associated with onset of auditory/verbal hallucinations

The time course of brain activation prior to onset of auditory/verbal hallucinations was characterised using functional magnetic resonance imaging in six dextral patients with schizophrenia. Composite maps of pre-hallucination periods revealed activation in the left anterior insula and in the right middle temporal gyrus, partially replicating two previous case reports, as well as deactivation in the anterior cingulate and parahippocampal gyri. These findings may reflect brain events that trigger or increase vulnerability to auditory/verbal hallucinations.

Multi‐Site Phasic Neural Activity Mediates the Execution of An Auditory Continuous Performance Task: A PET and Electrophysiological Study

We studied an auditory continuous performance task with positron emission tomography(PET) and EEG-derived current density reconstructions (CDRs) to define the spatial and temporal aspects of auditory attention. The CDRs were employed to segregate responses to targets and non-targets at sites identified by PET. We then studied the time course of brain activity using statistical parametric mapping (SPM) of the CDR data. In contrast to target EEG activity, non-targets did not produce significant peaks after 300 ms. Pre-300 ms biphasic activation of auditory, left posterior frontal, left supplemental,and primary motor cortices and the anterior cingulate (AC) and biphasic suppression of posterior cingulate and occipital cortex were identical for targets and non-targets and may mediate the target non-target decision. SPM analysis of post-300 ms CDRs showed cingulate cortices were the first to be reactivated, remained active through 672 ms, and were accompanied by reactivation and deactivation of the same sites observed in the pre-P300 responses. The cingulate may play an important role in post-decisional activity and control activity at other sites involved in post-decisional cognitive processing.

Multi‐Site Phasic Neural Activity Mediates the Execution of An Auditory Continuous Performance Task: A PET and Electrophysiological Study

We studied an auditory continuous performance task with positron emission tomography (PET) and EEG-derived current density reconstructions (CDRs) to define the spatial and temporal aspects of auditory attention. The CDRs were employed to segregate responses to targets and non-targets at sites identified by PET. We then studied the time course of brain activity using statistical parametric mapping (SPM) of the CDR data. In contrast to target EEG activity, non-targets did not produce significant peaks after 300 ms. Pre-300 ms biphasic activation of auditory, left posterior frontal, left supplemental, and primary motor cortices and the anterior cingulate (AC) and biphasic suppression of posterior cingulate and occipital cortex were identical for targets and non-targets and may mediate the target non-target decision. SPM analysis of post-300 ms CDRs showed cingulate cortices were the first to be reactivated, remained active through 672 ms, and were accompanied by reactivation and deactivation of the same sites observed in the pre-P300 responses. The cingulate may play an important role in post-decisional activity and control activity at other sites involved in post-decisional cognitive processing.

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

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.

Cortical activation during word reading and picture naming in dyslexic and non-reading-impaired children

Objective In a recent study on picture naming and word reading in dyslexics and control children we found a combination of normal picture retrieval times and severe reading impairments in dyslexics. Therefore, we hypothesize that brain response patterns differ between patients and controls during word reading, but are similar in picture naming as a non-letter mediated task. Methods Time course of brain activation was investigated by magnetoencephalography during word reading and picture naming in 9 dyslexic children and 13 age-matched controls (aged 9–10 years). Results We found 5 consecutive activations spreading from occipito-parietal to temporo-frontal sites. Group differences occurred only during reading: a delayed response in temporal superior and angular gyri at 235–285 ms and absence of activation in anterior temporal and inferior frontal regions at 430–530 ms for dyslexics. Conclusions Problems in phonological processing are reflected in delay of early activity and absence of late activity in language related brain regions. From the lack of group differences during picture naming, we conclude the presence of two pathways: a phonological/orthographic one for word reading, which is disturbed in dyslexics, and a visual one for picture naming, which can be unaffected in dyslexics. Significance Evidence is provided for different pathways for the processing of letter-mediated and visual-eidetic information. This knowledge may be important for dyslexics in the context of coping with everyday demands and for training of relevant skills.

Time-locked brain activity associated with emotion: A pilot MEG study

Objective: To examine the time course of brain activation in response to emotionally evocative pictures.Methods and procedures: Regions of the brain involved in the processing of affective stimuli in response to picture sets rated unpleasant, pleasant and affectively neutral, as well as the order of activation of each region, were investigated using magnetoencephalography in 10 normal adult volunteers.Results: Spatiotemporal maps were found consisting of two basic components. The first involving activation in the occipital and basal aspects of the temporal cortex- lasted, on average, 270 ms post-stimulus. The second component involving activation in the mesial temporal lobes (MTL) extended from 270 to 850 ms post-stimulus. After (serial) activating the mesial temporal lobe structures or simultaneous (parallel) to it, activation is also observed in the frontal structures.Conclusions: The temporal organization in the brain of an emotional stimulus requires the serial and alternating engagement of frontal and posterior cortices. It is suggested that lesions to the brain may disrupt this temporal course, altering the emotional response commonly observed in patients with brain injury.

Counting in everyday life: Discrimination and enumeration

Enumerating the number of items in a set accurately and quickly is a basic mathematical skill. This ability is especially crucial in the more real-life situations, where relevant items have to be discriminated from irrelevant distracters. Although much work has been done on the brain mechanisms and neural correlates of the enumeration and/or discrimination process, no agreement has been reached yet. We used event-related potentials (ERPs) to show the time course of brain activity elicited by a task that involved both enumeration and discrimination at the same time. We found that even though the two processes run to some extent in parallel, discrimination seems to take place mainly in an earlier time window (from 100 ms after the stimulus onset) than enumeration (beyond 200 ms after the stimulus onset). Moreover, electrophysiological evidence based on the N2 and P3 components make it reasonable to argue for the existence of a dichotomy between subitizing (for sets of less than four items) and counting (for sets of four and more items). Source estimation suggests that subitizing and counting, though being distinct brain processes, do recruit similar brain areas.

Integration of fMRI and simultaneous EEG: towards a comprehensive understanding of localization and time-course of brain activity in target detection

fMRI and EEG are complimentary methods for the analysis of brain activity since each method has its strength where the other one has limits: The spatial resolution is thus in the range of millimeters with fMRI and the time resolution is in the range of milliseconds with EEG. For a comprehensive understanding of brain activity in target detection, nine healthy subjects (age 24.2 ± 2.9) were investigated with simultaneous EEG (27 electrodes) and fMRI using an auditory oddball paradigm. As a first step, event-related potentials, measured inside the scanner, have been compared with the potentials recorded in a directly preceding session in front of the scanner. Attenuated amplitudes were found inside the scanner for the earlier N1/P2 component but not for the late P300 component. Second, an independent analysis of the localizations of the fMRI activations and the current source density as revealed by low resolution electromagnetic tomography (LORETA) has been done. Concordant activations were found in most regions, including the temporoparietal junction (TPJ), the supplementary motor area (SMA)/anterior cingulate cortex (ACC), the insula, and the middle frontal gyrus, with a mean Euclidean distance of 16.0 ± 6.6 mm between the BOLD centers of gravity and the LORETA-maxima. Finally, a time-course analysis based on the current source density maxima was done. It revealed different time-course patterns in the left and right hemisphere with earlier activations in frontal and parietal regions in the right hemisphere. The results suggest that the combination of EEG and fMRI permits an improved understanding of the spatiotemporal dynamics of brain activity.

Development of the time course for processing conflict: an event-related potentials study with 4 year olds and adults

BackgroundTasks involving conflict are widely used to study executive attention. In the flanker task, a target stimulus is surrounded by distracting information that can be congruent or incongruent with the correct response. Developmental differences in the time course of brain activations involved in conflict processing were examined for 22 four year old children and 18 adults. Subjects performed a child-friendly flanker task while their brain activity was registered using a high-density electroencephalography system.ResultsGeneral differences were found in the amplitude and time course of event-related potentials (ERPs) between children and adults that are consistent with their differences in reaction time. In addition, the congruency of flankers affected both the amplitude and latency of some of the ERP components. These effects were delayed and sustained for longer periods of time in the children compared to the adults.ConclusionsThese differences constitute neural correlates of children's greater difficulty in monitoring and resolving conflict in this and similar tasks.

Phonological processing in language production: Time course of brain activity

Recent neuroimaging studies provide evidence for a shared neural network for phonological processing in language production and comprehension. The temporal dynamics in this network during comprehension has been investigated by Thierry et al., who showed a primacy for Wernicke's over Broca's area. In the present study, we demonstrate the reversed pattern for language production. These results can be interpreted with respect to the functionality of the different regions within the shared network, with Wernicke's area being the sound form store and Broca's area a processor necessary to extract relevant phonological information from that store.