Event-related fMRI Analysis Research Articles

Adaptive changes in sensorimotor processing in patients with acute low back pain

In low back pain (LBP), primary care and secondary prevention of recurrent and persistent LBP are not always successful. Enhanced understanding of neural mechanisms of sensorimotor processing and pain modulation in patients with acute LBP is mandatory. This explorative fMRI study investigated sensorimotor processing due to mechanosensory stimulation of the lumbar spine. We studied 19 adult patients with acute LBP (< 4 weeks of an acute episode) and 23 healthy controls. On a numeric rating scale, patients reported moderate mean pain intensity of 4.5 out of 10, while LBP-associated disability indicated mild mean disability. The event-related fMRI analysis yielded no between-group differences. However, the computation of functional connectivity resulted in adaptive changes in networks involved in sensorimotor processing in the patient group: Connectivity strength was decreased in the salience and cerebellar networks but increased in the limbic and parahippocampal networks. Timewise, these results indicate that early connectivity changes might reflect adaptive physiological processes in an episode of acute LBP. These findings raise intriguing questions regarding their role in pain persistence and recurrences of LBP, particularly concerning the multiple consequences of acute LBP pain. Advanced understanding of neural mechanisms of processing non-painful mechanosensations in LBP may also improve therapeutic approaches.

The cerebellum contributes to context-effects during fear extinction learning: A 7T fMRI study

The cerebellum is involved in the acquisition and consolidation of learned fear responses. Knowledge about its contribution to extinction learning, however, is sparse. Extinction processes likely involve erasure of memories, but there is ample evidence that at least part of the original memory remains. We asked the question whether memory persists within the cerebellum following extinction training. The renewal effect, that is the reoccurrence of the extinguished fear memory during recall in a context different from the extinction context, constitutes one of the phenomena indicating that memory of extinguished learned fear responses is not fully erased during extinction training. We performed a differential AB-A/B fear conditioning paradigm in a 7-Tesla (7T) MRI system in 31 young and healthy men. On day 1, fear acquisition training was performed in context A and extinction training in context B. On day 2, recall was tested in contexts A and B. As expected, participants learned to predict that the CS+ was followed by an aversive electric shock during fear acquisition training. Skin conductance responses (SCRs) were significantly higher to the CS+ compared to the CS- at the end of acquisition. Differences in SCRs vanished in extinction and reoccurred in the acquisition context during recall indicating renewal. Fitting SCR data, a deep neural network model was trained to predict the correct shock value for a given stimulus and context. Event-related fMRI analysis with model-derived prediction values as parametric modulations showed significant effects on activation of the posterolateral cerebellum (lobules VI and Crus I) during recall. Since the prediction values differ based on stimulus (CS+ and CS-) and context during recall, data provide support that the cerebellum is involved in context-related recall of learned fear associations. Likewise, mean β values were highest in lobules VI and Crus I bilaterally related to the CS+ in the acquisition context during early recall. A similar pattern was seen in the vermis, but only on a trend level. Thus, part of the original memory likely remains within the cerebellum following extinction training. We found cerebellar activations related to the CS+ and CS- during fear acquisition training which likely reflect associative and non-associative aspects of the task. Cerebellar activations, however, were not significantly different for CS+ and CS-. Since the CS- was never followed by an electric shock, the cerebellum may contribute to associative learning related to the CS, for example as a safety cue.

Individual slow wave events give rise to macroscopic fMRI signatures and drive the strength of the BOLD signal in human resting-state EEG-fMRI recordings

The slow wave state is a general state of quiescence interrupted by sudden bursts of activity or so-called slow wave events (SWEs). Recently, the relationship between SWEs and blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals was assessed in rodent models which revealed cortex-wide BOLD activation. However, it remains unclear which macroscopic signature corresponds to these specific neurophysiological events in the human brain. Therefore, we analyzed simultaneous electroencephalographic (EEG)-fMRI data during human non-REM sleep. SWEs individually detected in the EEG data were used as predictors in event-related fMRI analyses to examine the relationship between SWEs and fMRI signals. For all 10 subjects we identified significant changes in BOLD activity associated with SWEs covering substantial parts of the gray matter. As demonstrated in rodents, we observed a direct relation of a neurophysiological event to specific BOLD activation patterns. We found a correlation between the number of SWEs and the spatial extent of these BOLD activation patterns and discovered that the amplitude of the BOLD response strongly depends on the SWE amplitude. As altered SWE propagation has recently been found in neuropsychiatric diseases, it is critical to reveal the brain's physiological slow wave state networks to potentially establish early imaging biomarkers for various diseases long before disease onset.

The Function of the Hippocampus in Bridging Functional and Temporal Discontiguity.

Theoretical assessment of the function of the hippocampus has suggested that given certain physiological constraints at both the neuronal and cortical level, the hippocampus is best suited to associate discontiguous items that occur in different temporal or spatial positions. Conceptually, “discontiguous” refers to events that are to be associated with one another but do not temporally or spatially overlap. However, given that humans can actively maintain information “online” by rehearsing it, even when the information is no longer being presented to the sensory system, the right way to experimentally define “discontiguity” is still a question. Does it refer to a “gap” in the presentation of information (temporal discontiguity) or to an “interruption” of the active maintenance of working memory (WM) information (functional discontiguity)? To assess this, participants were imaged by functional magnetic resonance imaging (fMRI) when making judgments on whether two words were semantically related or not. In contrast with recognition memory that can be carried out through perceptual familiarity heuristics, judgments on semantic relatedness can only be accomplished through associative processing. To assess this experimentally, two words are either (1) presented at the same time (Event AB) or (2) one after the other with an unfilled, cross-viewing delay (Event A_B) (the uninterrupted discontiguity) or (3) presented one after the other, between which participants are required to perform a calculation task (Event A#B) (the interrupted discontiguity). Results of event-related fMRI analysis revealed that relative to Event AB, Event A_B was not associated with more hippocampal activity, whereas Event A#B was. The direct contrast of Event A#B relative to Event A_B also revealed significant hippocampal and parahippocampal activity. This result implied that functional discontiguity (the interruption of online maintenance of the inputted information) could be more apt at engaging the function of the hippocampus.

Similar Neural Correlates of Planning and Execution to Inhibit Continuing Actions.

Inhibition of action is involved in stopping a movement, as well as terminating unnecessary movement during performance of a behavior. The inhibition of single actions, known as response inhibition (Inhibition of the urge to respond before or after actions) has been widely investigated using the go/no-go task and stop signal task. However, few studies focused on phase and volition-related inhibition after an action has been initiated. Here, we used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of planning and execution underlying the voluntary inhibition of ongoing action. We collected fMRI data while participants performed a continuous finger-tapping task involving voluntary and involuntary (externally directed) inhibition, and during the initiation of movement. The results revealed areas of significantly greater activation during the preparation of inhibition of an ongoing action during voluntary inhibition, compared with involuntary inhibition, in the supplementary (SMA) and pre-supplementary motor areas, dorsolateral prefrontal cortex, inferior frontal gyrus (IFG), inferior parietal lobe, bilateral globus pallidus/putamen, bilateral insula and premotor cortex. Focusing on the period of execution of inhibition of ongoing actions, an event-related fMRI analysis revealed significant activation in the SMA, middle cingulate cortex, bilateral insula, right IFG and inferior parietal cortex. Additional comparative analyses suggested that brain activation while participants were planning to inhibit an ongoing action was similar to that during planning to start an action, indicating that the same neural substrates of motor planning may be recruited even when an action is ongoing. The present finding that brain activation associated with inhibiting ongoing actions was compatible with that seen in response inhibition (urge to stop before/after actions) suggests that common inhibitory mechanisms for motor movement are involved in both actual and planned motor action, which makes our behavior keep going seamlessly.

FUNCTIONAL NETWORK ACTIVITY MEDIATING THE SHIFT OF ATTENTIONAL RESOURCES DURING INATTENTIONAL DEAFNESS IN AN AVIATION PURSUIT TASK

FUNCTIONAL NETWORK ACTIVITY MEDIATING THE SHIFT OF ATTENTIONAL RESOURCES DURING INATTENTIONAL DEAFNESS IN AN AVIATION PURSUIT TASK

Audio-visual speech perception in adult readers with dyslexia: an fMRI study.

Developmental dyslexia is a specific deficit in reading and spelling that often persists into adulthood. In the present study, we used slow event-related fMRI and independent component analysis to identify brain networks involved in perception of audio-visual speech in a group of adult readers with dyslexia (RD) and a group of fluent readers (FR). Participants saw a video of a female speaker saying a disyllabic word. In the congruent condition, audio and video input were identical whereas in the incongruent condition, the two inputs differed. Participants had to respond to occasionally occurring animal names. The independent components analysis (ICA) identified several components that were differently modulated in FR and RD. Two of these components including fusiform gyrus and occipital gyrus showed less activation in RD compared to FR possibly indicating a deficit to extract face information that is needed to integrate auditory and visual information in natural speech perception. A further component centered on the superior temporal sulcus (STS) also exhibited less activation in RD compared to FR. This finding is corroborated in the univariate analysis that shows less activation in STS for RD compared to FR. These findings suggest a general impairment in recruitment of audiovisual processing areas in dyslexia during the perception of natural speech.

Marker-based ballistocardiographic artifact correction improves spike identification in EEG-fMRI of focal epilepsy patients.

Ballistocardiographic (BCG) artifacts resemble interictal epileptic discharges (IEDs) and can lead to incorrect IED identification in EEG-fMRI. This study investigates IEDs marked in EEGs corrected using information from a moiré phase tracking (MPT) marker. EEG-fMRI from 18 patients was processed with conventional methods for BCG removal, while 9 patients used a MPT marker. IEDs were marked first without ECG information. In a second review, suspicious IEDs synchronous with the BCG were discarded. After each review, an event-related fMRI analysis was performed on the marked IEDs. No difference was found in the proportion of suspicious IEDs in the 2 patient groups. However, the distribution of IED timings was significantly related to the cardiac cycle in 11 of 18 patients recorded without MPT marker, but only 2 of 9 patients with marker. In patients recorded without marker, failing to discard suspicious IEDs led to more inaccurate fMRI maps and more distant activations. BCG artifact correction based on MPT recordings allowed a more straightforward identification of IEDs that did not require ECG information in the large majority of patients. Marker-based ballistocardiographic artifact correction greatly facilitates the study of the generators of interictal discharges with EEG-fMRI.

Cerebellar vermis contributes to the extinction of conditioned fear

The cerebellum is known to contribute to the acquisition and retention of conditioned motor and emotional responses. Eyeblink conditioning and fear conditioning have been studied in greatest detail. Whereas a considerable number of studies have shown that the cerebellum is also involved in extinction of conditioned eyeblink responses, the likely contribution of the cerebellum to extinction of conditioned fear responses has largely been ignored. In the present study, we analyzed functional brain imaging data (fMRI) of previous work investigating extinction of conditioned fear in 32 young and healthy men, in which event-related fMRI analysis did not include the cerebellum. This dataset was analyzed using a spatial normalization method optimized for the cerebellum. During fear acquisition, an unpleasant electric shock (unconditioned stimulus; US) was paired with one of two pictures of geometrical figures (conditioned stimulus; CS+), while the other picture (CS−) was never paired with the US. During extinction, CS+ and CS− were presented without the US. During the acquisition phase, the fMRI signal related to the CS+ was significantly higher in hemispheric lobule VI in early compared to late acquisition (p<.05, permutation corrected). During the extinction phase, the fMRI signal related to the contrast CS+>CS− was significantly higher within the anterior vermis in early compared to late extinction (p<.05, permutation corrected). The present data show that the cerebellum is not only associated with the acquisition but also with the extinction of conditioned fear.

Neural Correlates of Fixation Duration during Real-world Scene Viewing: Evidence from Fixation-related (FIRE) fMRI.

During active scene perception, our eyes move from one location to another via saccadic eye movements, with the eyes fixating objects and scene elements for varying amounts of time. Much of the variability in fixation duration is accounted for by attentional, perceptual, and cognitive processes associated with scene analysis and comprehension. For this reason, current theories of active scene viewing attempt to account for the influence of attention and cognition on fixation duration. Yet almost nothing is known about the neurocognitive systems associated with variation in fixation duration during scene viewing. We addressed this topic using fixation-related fMRI, which involves coregistering high-resolution eye tracking and magnetic resonance scanning to conduct event-related fMRI analysis based on characteristics of eye movements. We observed that activation in visual and prefrontal executive control areas was positively correlated with fixation duration, whereas activation in ventral areas associated with scene encoding and medial superior frontal and paracentral regions associated with changing action plans was negatively correlated with fixation duration. The results suggest that fixation duration in scene viewing is controlled by cognitive processes associated with real-time scene analysis interacting with motor planning, consistent with current computational models of active vision for scene perception.

Cerebellar Contribution to Context Processing in Extinction Learning and Recall.

Whereas acquisition of new associations is considered largely independent of the context, context dependency is a hallmark of extinction of the learned associations. The hippocampus and the prefrontal cortex are known to be involved in context processing during extinction learning and recall. Although the cerebellum has known functional and anatomic connections to the hippocampus and the prefrontal cortex, cerebellar contributions to context processing of extinction have rarely been studied. In the present study, we reanalyzed functional brain imaging data (fMRI) of previous work investigating context effects during extinction in a cognitive associative learning paradigm in 28 young and healthy subjects (Lissek et al. Neuroimage. 81:131-3, 2013). In that study, event-related fMRI analysis did not include the cerebellum. The 3T fMRI dataset was reanalyzed using a spatial normalization method optimized for the cerebellum. Data of seven participants had to be excluded because the cerebellum had not been scanned in full. Cerebellar activation related to context change during extinction learning was most prominent in lobule Crus II bilaterally (p < 0.01, t > 2.53; partially corrected by predetermined cluster size). No significant cerebellar activations were observed related to context change during extinction retrieval. The posterolateral cerebellum appears to contribute to context-related processes during extinction learning, but not (or less) during extinction retrieval. The cerebellum may support context learning during extinction via its connections to the hippocampus. Alternatively, the cerebellum may support the shifting of attention to the context via its known connections to the dorsolateral prefrontal cortex. Because the ventromedial prefrontal cortex (vmPFC) is critically involved in context-related processes during extinction retrieval, and there are no known connections between the cerebellum and the vmPFC, the cerebellum may be less important during extinction recall.

Lennox-Gastaut syndrome and phenotype: secondary network epilepsies.

Lennox-Gastaut syndrome (LGS) is a severe epilepsy phenotype with characteristic electroclinical features despite diverse etiologies. We previously found common cerebral networks involved during slow spike-and-wave (SSW) and generalized paroxysmal fast activity (PFA), characteristic interictal discharges. Some patients have a Lennox-Gastaut-like phenotype and cortical lesions. We wished to explore the interaction between cerebral networks and lesions in this group. 3 Tesla electroencephalography-functional magnetic resonance imaging (EEG-fMRI) on six subjects with Lennox-Gastaut phenotype and a structural lesion. Timings of SSW and PFA events were used in an event-related fMRI analysis, and to estimate the time course of the hemodynamic response from key regions. (1) PFA-robust fMRI signal increases were observed in frontal and parietal association cortical areas, thalamus, and pons, with simultaneous increases in both "attention" and resting-state (default mode) networks, a highly unusual pattern. (2) SSW showed mixed increased and decreased fMRI activity, with preevent increases in association cortex and thalamus, and then prominent postevent reduction. There was decreased fMRI activity in primary cortical areas. (3) Lesion-variable fMRI increases were observed during PFA and SSW discharges. Three subjects who proceeded to lesionectomy are >1 year seizure-free. We conceptualize Lennox-Gastaut phenotype as a being a network epilepsy, where key cerebral networks become autonomously unstable. Epileptiform activity in Lennox-Gastaut phenotype, and by implication in LGS, appears to be amplified and expressed through association cortical areas, possibly because the attention and default-mode networks are widely interconnected, fundamental brain networks. Seizure freedom in the subjects who proceeded to lesionectomy suggests that cortical lesions are able to establish and maintain this abnormal unstable network behavior. LGS may be considered a secondary network epilepsy because the unifying epileptic manifestations of the disorder, including PFA and SSW, reflect network dysfunction, rather than the specific initiating process.

Functional imaging of NREM recovery sleep slow waves in young and older subjects : preliminary results

Introduction During non-rapid eye movement (NREM) sleep, the level of neural synchronization is mainly reflected on the electroencephalogram (EEG) by large-amplitude slow waves (SW). Factors such as age and sleep homeostasis modify SW characteristics and their underlying neural processes. Recent neuroimaging studies have identified brain regions recruited by SW mechanisms in young, non-sleep-deprived humans. In these preliminary analyses, we aimed to identify brain regions implicated in SW onset and SW amplitude in young and older subjects during a recovery morning sleep following prolonged wakefulness. Materials and methods Thirty-one healthy, right-handed volunteers were divided in two age groups: young ( n = 16; 7 females; 20–30 years, M = 23.06, SD = 3.34) and older ( n = 15; 9 females; 52–69 years, M = 59.47, SD = 5.89). Subjects underwent 26 h of sleep deprivation before the recording session. Sleep was recorded in the morning for a maximum of 90 min, using simultaneous EEG and fMRI acquisitions. EEG data were corrected for gradient and ballistocardiographic artifacts, sleep stages were identified, and SW were detected using an automatic algorithm. Event-related fMRI analyses were performed on functional volumes corresponding to periods of uninterrupted N2 and N3 sleep. SW events were modeled as one onset regressor and one parametric modulator accounting for the wave’s amplitude, both convolved with the hemodynamic response function basis set. Individual t -maps (first level analysis) were included in an ANOVA with basis set and age group as factors (second level analysis). Significant voxels ( p p Results In young subjects, SW onset was associated to significant BOLD changes in the cerebellum, whereas older participants showed BOLD changes in the pons, thalamus, caudate nucleus and putamen. SW amplitude significantly modulated BOLD changes in the insula and in frontal, temporal and supramarginal regions in older subjects, but not in the young. Conclusion After prolonged wakefulness, SW onsets in young and older subjects are mostly associated to changes in subcortical brain regions. SW amplitudes in older subjects modulate neural activity in several cortical and subcortical areas. Acknowledgements This work was supported by the Canadian Institutes of Health Research and the Fonds de Recherche en Sante du Quebec.

How Embodied Is Perceptual Decision Making? Evidence for Separate Processing of Perceptual and Motor Decisions

The extent to which different cognitive processes are "embodied" is widely debated. Previous studies have implicated sensorimotor regions such as lateral intraparietal (LIP) area in perceptual decision making. This has led to the view that perceptual decisions are embodied in the same sensorimotor networks that guide body movements. We use event-related fMRI and effective connectivity analysis to investigate whether the human sensorimotor system implements perceptual decisions. We show that when eye and hand motor preparation is disentangled from perceptual decisions, sensorimotor areas are not involved in accumulating sensory evidence toward a perceptual decision. Instead, inferior frontal cortex increases its effective connectivity with sensory regions representing the evidence, is modulated by the amount of evidence, and shows greater task-positive BOLD responses during the perceptual decision stage. Once eye movement planning can begin, however, an intraparietal sulcus (IPS) area, putative LIP, participates in motor decisions. Moreover, sensory evidence levels modulate decision and motor preparation stages differently in different IPS regions, suggesting functional heterogeneity of the IPS. This suggests that different systems implement perceptual versus motor decisions, using different neural signatures.

NEUROCIRCUITRY OF GENERALIZED ANXIETY DISORDER IN ADOLESCENTS: A PILOT FUNCTIONAL NEUROIMAGING AND FUNCTIONAL CONNECTIVITY STUDY

Dysfunction of neural systems responsible for the processing of emotional stimuli is hypothesized to be involved in the pathophysiology of generalized anxiety disorder (GAD) in adolescents. We used standard fMRI and functional connectivity analyses to examine the functional neurocircuitry of GAD in adolescents. Ten adolescents with GAD and 10 healthy comparison subjects underwent fMRI while performing a continuous performance task with emotional and neutral distractors. Standard event-related voxel-wise fMRI and steady-state functional connectivity analyses were performed. Increased activation was observed in the left medial prefrontal cortex and right ventrolateral prefrontal cortex (VLPFC) in response to emotional images compared to neutral imagines in youth with GAD. Connectivity analyses using the right VLPFC seed region suggested decreased connectivity between this region and the bilateral medial prefrontal cortex. Connectivity analyses using the right amygdala seed region revealed decreased correlation with the posterior cingulate cortex in adolescents with GAD. The left amygdala seed region demonstrated increased connectivity with the ipsilateral precuneus in youth with GAD compared to healthy subjects. In addition to increased activation of the medial prefrontal cortex and right VLPFC, we observed altered connectivity between the amygdala or VLPFC and regions, which subserve mentalization (e.g. posterior cingulate cortex, precuneus, and medial prefrontal cortex). This suggests that structures that regulate emotion and affect interact abnormally with key structures that are involved in mentalization, a process known to be disrupted in GAD.

Functional brain networks underlying perceptual switching: auditory streaming and verbal transformations

Recent studies have shown that auditory scene analysis involves distributed neural sites below, in, and beyond the auditory cortex (AC). However, it remains unclear what role each site plays and how they interact in the formation and selection of auditory percepts. We addressed this issue through perceptual multistability phenomena, namely, spontaneous perceptual switching in auditory streaming (AS) for a sequence of repeated triplet tones, and perceptual changes for a repeated word, known as verbal transformations (VTs). An event-related fMRI analysis revealed brain activity timelocked to perceptual switching in the cerebellum for AS, in frontal areas for VT, and the AC and thalamus for both. The results suggest that motor-based prediction, produced by neural networks outside the auditory system, plays essential roles in the segmentation of acoustic sequences both in AS and VT. The frequency of perceptual switching was determined by a balance between the activation of two sites, which are proposed to be involved in exploring novel perceptual organization and stabilizing current perceptual organization. The effect of the gene polymorphism of catechol-O-methyltransferase (COMT) on individual variations in switching frequency suggests that the balance of exploration and stabilization is modulated by catecholamines such as dopamine and noradrenalin. These mechanisms would support the noteworthy flexibility of auditory scene analysis.

Abnormalities of lexical and semantic processing in left temporal lobe epilepsy: An fMRI study

We examined the efficiency of lexical and semantic processing and associated brain activation using functional magnetic resonance imaging (fMRI) in patients with left temporal lobe epilepsy (TLE). Twenty patients with left TLE (10 with hippocampal sclerosis, the HS group; and 10 with nonlesional MR scans, the NL group) and 12 healthy controls underwent an event-related fMRI analysis during a lexical decision task (LDT). Lexical and semantic processing were examined by comparing behavioral and imaging data associated with words and nonwords (lexicality) or with concrete and abstract words (concreteness). Although the control group showed greater activation associated with word stimuli than with nonword stimuli in a bilateral language network, both TLE groups showed greater activation for nonword stimuli than word stimuli, including greater activation of inferior frontal language areas (bilaterally in the HS group and left-lateralized in the NL group). The TLE groups also exhibited differential activation patterns during the processing of abstract and concrete words compared to controls, and compared to each other. For abstract words, in particular, the HS group showed activation of frontal areas typically associated with executive functions, whereas the NL group showed activation of more posterior semantic processing regions. These results suggest that left TLE is associated with altered functional organization of cortical networks involved in lexical and semantic processing. In addition, the organization observed varies as a function of hippocampal pathology.

Fixation based event‐related fmri analysis: Using eye fixations as events in functional magnetic resonance imaging to reveal cortical processing during the free exploration of visual images

Eye movements, comprising predominantly fixations and saccades, are known to reveal information about perception and cognition, and they provide an explicit measure of attention. Nevertheless, fixations have not been considered as events in the analyses of data obtained during functional magnetic resonance imaging (fMRI) experiments. Most likely, this is due to their brevity and statistical properties. Despite these limitations, we used fixations as events to model brain activation in a free viewing experiment with standard fMRI scanning parameters. First, we found that fixations on different objects in different task contexts resulted in distinct cortical patterns of activation. Second, using multivariate pattern analysis, we showed that the BOLD signal revealed meaningful information about the task context of individual fixations and about the object being inspected during these fixations. We conclude that fixation-based event-related (FIBER) fMRI analysis creates new pathways for studying human brain function by enabling researchers to explore natural viewing behavior.

The BOLD correlates of the visual P1 and N1 in single-trial analysis of simultaneous EEG-fMRI recordings during a spatial detection task

Simultaneous EEG-fMRI measurements can combine the high spatial resolution of fMRI with the high temporal resolution of EEG. Therefore, we applied this approach to the study of peripheral vision. More specifically, we presented visual field quadrant fragments of checkerboards and a full central checkerboard in a simple detection task. A technique called “integration-by-prediction” was used to integrate EEG and fMRI data. In particular, we used vectors of single-trial ERP amplitude differences between left and right occipital electrodes as regressors in an ERP-informed fMRI analysis. The amplitude differences for the regressors were measured at the latencies of the visual P1 and N1 components. Our results indicated that the traditional event-related fMRI analysis revealed mostly activations in the vicinity of the primary visual cortex and in the ventral visual stream, while both P1 and N1 regressors revealed activation of areas in the temporo-parietal junction. We conclude that simultaneous EEG-fMRI in a spatial detection task can separate visual processing at 100–200ms from stimulus onset from the rest of the information processing in the brain.

Temporal pole activity during understanding other persons' mental states correlates with neuroticism trait

Comprehension of other persons' mental states is one of the representative cognitive functions involved in social situations. It has been suggested that this function sometimes recruits emotional processes. The present fMRI study examined the neural mechanisms associated with understanding others' mental states, and the conditions that determine the recruitment of the emotional processes. The false belief paradigm, a traditional behavioral paradigm to investigate comprehension of others, was applied to an event-related fMRI analysis, allowing for the extraction of brain activity time-locked to successful understanding of others' mental states. Prominent brain activity was observed in multiple cortical regions including the medial prefrontal cortex, temporo-parietal junction, precuneus, and temporal pole. Then, correlational analyses were performed between the activations and individuals' scores of neuroticism, a personality trait that reflects emotional instability in daily life. It was revealed that the neuroticism scores were positively correlated with the activity in the temporal pole region, but not in the other regions. These results suggest that the emotional processes implemented in the temporal pole are recruited during successful understanding of other persons' mental states, and that the recruitment may be modulated by an emotional personality trait of individual subjects.