Evidence for abnormal visuospatial attentional processes in the interictal migraineur.

Research shows decreased brain region activity in the right temporo-parietal junction (rTPJ) in people with migraine headache relative to headache-free controls when performing an orienting visuospatial attention task. Functional inactivation of the rTPJ has been associated with rightward performance deviations on laterality-based attention Landmark (LM) and greyscale (GRE) tasks in individuals with unilateral neglect and heightened activation in the rTPJ is associated with leftward deviation, known as pseudoneglect, in controls on these tasks. Given this, we investigated whether migraineurs would lack the leftward deviation found in headache-free controls on visuospatial attention tasks. 36 migraineurs and 38 controls were presented with LM and GRE tasks. Response bias scores showed a significant difference in responses between groups (p = 0.036) on the GRE, a luminance-based task, but not on the LM, a size-based task (p = 0.826). This study is the first to show laterality-based attentional differences in migraineurs, as compared to controls. Specifically, migraineurs were found to have smaller leftward biases on luminance-based visuospatial attention tasks, as compared to controls, aligning with previous research suggesting that migraine may be having an impact on a variety of attention tasks in migraineurs in between headache attacks.

Reorganized neural activation in motor cortex following subdural fluid collection: an fMRI and DTI study.

We report a patient with a cavernous malformation involving the right lentiform nucleus. Pre-surgical planning included fMRI localization of language, motor, and sensory processing, and DTI of white matter tracts. fMRI results revealed no activation near the planned resection zone. However, post-surgery the patient developed a subdural fluid collection, which applied pressure to the primary motor cortex (M1). Follow-up scans revealed that motor activation had shifted due to pressure, and then shifted to a new location after the fluid collection subsided. This case report suggests that long-term neural reorganization can occur in response to short term compression in the cortex.

Attentional Network Differences Between Migraineurs and Non-migraine Controls: fMRI Evidence.

Migraine is a headache disorder characterized by sensitivity to light and sound. Recent research has revealed abnormal visual-spatial attention in migraineurs in between headache attacks. Here, we ask whether these attentional abnormalities can be attributed to specific regions of the known attentional network to help characterize the abnormalities in migraine. Specifically, the ventral frontoparietal network of attention is involved with assessing the behavioural relevance of unattended stimuli. Given the decreased suppression of unattended stimuli reported in migraineurs, we hypothesized that migraineurs would have abnormal processing in the ventral portion of the frontoparietal network of attention. To address this, we used functional magnetic resonance imaging to assess the attentional control networks during visual spatial-orienting tasks in migraineurs (N = 16) as compared to non-migraine controls (N = 16). We employed two visual orienting paradigms with target discrimination tasks: (1) voluntary orienting to central arrow cues, and (2) reflexive orienting to peripheral flash cues. While both groups showed activation in the key areas of attentional processing networks, migraineurs showed less activation than non-migraine controls in a key area of the ventral frontoparietal network of attention, the right temporal parietal junction (rTPJ), during both voluntary and reflexive visual spatial orienting. Given the role of rTPJ is to assess the visual environment for behaviorally relevant sensory stimuli outside the focus of attention and signal other attentional areas to reorient attention to behaviorally salient stimuli, our findings fit with previous research showing that migraineurs lack suppression of unattended events and have heightened orienting to sudden onset stimuli in peripheral locations.

Inclusion of attentional networks in the pre-surgical neuroimaging assessment of a large deep hemispheric cavernous malformation: an FMRI case report.

BACKGROUND AND IMPORTANCE: Functional magnetic resonance imaging (fMRI) is a noninvasive and reliable tool for mapping eloquent cortex in patients prior to brain surgery. Ensuring intact perceptual and cognitive processing is a key goal for neurosurgeons, and recent research has indicated the value of including attentional network processing in pre-surgical fMRI in order to help preserve such abilities, including reading, after surgery. CLINICAL PRESENTATION: We report a 42-year-old patient with a large cavernous malformation, near the left basal ganglia. The lesion measured 3.8 × 1.7 × 1.8 cm. In consultation with the patient and the multidisciplinary cerebrovascular team, the decision was made to offer the patient surgical resection. The surgical resection involved planned access via the left superior parietal lobule using stereotactic location. The patient declined an awake craniotomy; therefore, direct electrocortical stimulation (ECS) could not be used for intraoperative language localization in this case. Pre-surgical planning included fMRI localization of language, motor, sensory, and attentional processing. The key finding was that both reading and attention-processing tasks revealed consistent activation of the left superior parietal lobule, part of the attentional control network, and the site of the planned surgical access. Given this information, surgical access was adjusted to avoid interference with the attentional control network. The lesion was removed via the left inferior parietal lobule. The patient had no new neurologic deficits postoperatively but did develop mild neuropathic pain in the left hand. CONCLUSION: This case report supports recent research that indicates the value of including fMRI maps of attentional tasks along with traditional language-processing tasks in preoperative planning in patients undergoing neurosurgery procedures.

Migraine and attention to visual events during mind wandering.

Although migraine is traditionally categorized as a primary headache disorder, the condition is also associated with abnormalities in visual attentional function in between headache events. Namely, relative to controls, migraineurs show both a heightened sensitivity to nominally unattended visual events, as well as decreased habituation responses at sensory and post-sensory (cognitive) levels. Here we used event-related potentials (ERPs) to examine whether cortical hypersensitivities in migraineurs extend to mind wandering, or periods of time wherein we transiently attenuate the processing of external stimulus inputs as our thoughts drift away from the on-going task at hand. Participants performed a sustained attention to response task while they were occasionally queried as to their attentional state-either "on-task" or "mind wandering." We then analyzed the ERP responses to task-relevant stimuli as a function of whether they immediately preceded an on-task versus mind wandering report. We found that despite the commonly reported heightened visual sensitivities in our migraine group, they nevertheless manifest a reduced cognitive response during periods of mind wandering relative to on-task attentional states, as measured via amplitude changes in the P3 ERP component. This suggests that our capacity to attenuate the processing of external stimulus inputs during mind wandering is not necessarily impaired by the class of cortical hypersensitivities characteristic of the interictal migraine brain.

Unique, Shared, and Dominant Brain Activation in Visual Word Form Area and Lateral Occipital Complex during Reading and Picture Naming.

Identifying printed words and pictures concurrently is ubiquitous in daily tasks, and so it is important to consider the extent to which reading words and naming pictures may share a cognitive-neurophysiological functional architecture. Two functional magnetic resonance imaging (fMRI) experiments examined whether reading along the left ventral occipitotemporal region (vOT; often referred to as a visual word form area, VWFA) has activation that is overlapping with referent pictures (i.e., both conditions significant and shared, or with one significantly more dominant) or unique (i.e., one condition significant, the other not), and whether picture naming along the right lateral occipital complex (LOC) has overlapping or unique activation relative to referent words. Experiment 1 used familiar regular and exception words (to force lexical reading) and their corresponding pictures in separate naming blocks, and showed dominant activation for pictures in the LOC, and shared activation in the VWFA for exception words and their corresponding pictures (regular words did not elicit significant VWFA activation). Experiment 2 controlled for visual complexity by superimposing the words and pictures and instructing participants to either name the word or the picture, and showed primarily shared activation in the VWFA and LOC regions for both word reading and picture naming, with some dominant activation for pictures in the LOC. Overall, these results highlight the importance of including exception words to force lexical reading when comparing to picture naming, and the significant shared activation in VWFA and LOC serves to challenge specialized models of reading or picture naming.

Reflexive attentional orienting in migraineurs: The behavioral implications of hyperexcitable visual cortex.

INTRODUCTION: Although migraine is classified as a headache disorder, a key part of migraine pathophysiology is a heightened excitability of visual cortices in between headache events. The goal of our study was to examine the behavioral impact of this visuocortical hyperexcitability, in terms of its effect on reflexive visual attentional orienting. METHODS AND RESULTS: In Experiment 1, using a non-predictive spatial cuing task that relied on sensory-evoked responses in the visual cortex for triggering attentional orienting, we found that migraineurs had greater attentional enhancement of manual target responses, relative to non-migraine controls. In two control experiments we confirmed that this heightened attention effect in migraineurs is not due to exaggerated reflexive orienting responses in general, but rather, it appears to be specifically associated with sensory-evoked attentional triggers. DISCUSSION: Taken together, this confirms that the functional consequences of hyperexcitable visual cortex in migraineurs are not just purely sensory in nature, but directly impact at least some forms of reflexive attention. This provides evidence of at least one cognitive implication of hyperexcitable visual cortical responses in migraineurs, namely heightened reflexive visual-spatial orienting specific to sudden-onset peripheral events.

Effects of trauma-related cues on pain processing in posttraumatic stress disorder: an fMRI investigation.

BACKGROUND: Imaging studies of pain processing in primary psychiatric disorders are just emerging. This study explored the neural correlates of stress-induced analgesia in individuals with posttraumatic stress disorder (PTSD). It combined functional magnetic resonance imaging (fMRI) and the traumatic script-driven imagery symptom provocation paradigm to examine the effects of trauma-related cues on pain perception in individuals with PTSD. METHODS: The study included 17 patients with PTSD and 26 healthy, trauma-exposed controls. Participants received warm (nonpainful) or hot (painful) thermal stimuli after listening to a neutral or a traumatic script while they were undergoing an fMRI scan at a 4.0 T field strength. RESULTS: Between-group analyses revealed that after exposure to the traumatic scripts, the blood oxygen level-dependent (BOLD) signal during pain perception was greater in the PTSD group than the control group in the head of the caudate. In the PTSD group, strong positive correlations resulted between BOLD signal and symptom severity in a number of brain regions previously implicated in stress-induced analgesia, such as the thalamus and the head of the caudate nucleus. Trait dissociation as measured by the Dissociative Experiences Scale correlated negatively with the right amygdala and the left putamen. LIMITATIONS: This study included heterogeneous traumatic experiences, a different proportion of military trauma in the PTSD versus the control group and medicated patients with PTSD. CONCLUSION: These data indicate that in patients with PTSD trauma recall will lead in a state-dependent manner to greater activation in brain regions implicated in stress-induced analgesia. Correlational analyses lend support to cortical hyperinhibition of the amygdala as a function of dissociation.

The Effect of Tumor Neovasculature on Functional Magnetic Resonance Imaging Blood Oxygen Level-Dependent Activation.

BACKGROUND: We report the case of a 40-year-old patient with a large, World Health Organization grade III oligodendroglioma in the left parietal lobe. CASE DESCRIPTION: Presurgical planning included functional magnetic resonance imaging (fMRI) localization of language, motor, and somatosensory processing. fMRI results for motor and somatosensory tasks revealed activation in perilesional regions near the surgical resection as well as deactivation in the tumor for the sensory task, suggesting decreased autoregulation in the region owing to the glioma. fMRI results showed left-hemisphere dominance for language and activation in perilesional regions for all 3 speech tasks (i.e., word reading, picture naming, and semantic questions). In addition, the results demonstrated that the high vascularity of the lesion altered the blood oxygen level-dependent function, resulting in false-positive and false-negative activation in the semantic questions and leg/foot rubbing task, respectively. Intraoperative direct cortical stimulation was conducted in the regions corresponding to fMRI activation while the patient performed motor, sensory, and language tasks and showed no loss of function. Follow-up fMRI revealed that there was no longer activation in the tumor or in perilesional regions, presumably owing to the resection of the vascularized tumor. CONCLUSIONS: This case highlights the importance of presurgical fMRI to inform the neurosurgical approach and emphasizes the need for careful interpretation of fMRI data, especially in cases of malignant glioma, which can decrease autoregulation in surrounding regions, affecting fMRI blood oxygen level-dependent signal.

Pre-Surgical Integration of fMRI and DTI of the Sensorimotor System in Transcortical Resection of a High-Grade Insular Astrocytoma.

Herein we report on a patient with a WHO Grade III astrocytoma in the right insular region in close proximity to the internal capsule who underwent a right frontotemporal craniotomy. Total gross resection of insular gliomas remains surgically challenging based on the possibility of damage to the corticospinal tracts. However, maximizing the extent of resection has been shown to decrease future adverse outcomes. Thus, the goal of such surgeries should focus on maximizing extent of resection while minimizing possible adverse outcomes. In this case, pre-surgical planning included integration of functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), to localize motor and sensory pathways. Novel fMRI tasks were individually developed for the patient to maximize both somatosensory and motor activation simultaneously in areas in close proximity to the tumor. Information obtained was used to optimize resection trajectory and extent, facilitating gross total resection of the astrocytoma. Across all three motor-sensory tasks administered, fMRI revealed an area of interest just superior and lateral to the astrocytoma. Further, DTI analyses showed displacement of the corona radiata around the superior dorsal surface of the astrocytoma, extending in the direction of the activation found using fMRI. Taking into account these results, a transcortical superior temporal gyrus surgical approach was chosen in order to avoid the area of interest identified by fMRI and DTI. Total gross resection was achieved and minor post-surgical motor and sensory deficits were temporary. This case highlights the utility of comprehensive pre-surgical planning, including fMRI and DTI, to maximize surgical outcomes on a case-by-case basis.

Presurgical language mapping in epilepsy: Using fMRI of reading to identify functional reorganization in a patient with long-standing temporal lobe epilepsy.

We report a 55-year-old, right-handed patient with intractable left temporal lobe epilepsy, who previously had a partial left temporal lobectomy. The patient could talk during seizures, suggesting that he might have language dominance in the right hemisphere. Presurgical fMRI localization of language processing including reading of exception and regular words, pseudohomophones, and dual meaning words confirmed the clinical hypothesis of right language dominance, with only small amounts of activation near the planned surgical resection and, thus, minimal eloquent cortex to avoid during surgery. Postoperatively, the patient was rendered seizure-free without speech deficits.

Cognitive processing of visual images in migraine populations in between headache attacks.

BACKGROUND AND OBJECTIVE: People with migraine headache have altered interictal visual sensory-level processing in between headache attacks. Here we examined the extent to which these migraine abnormalities may extend into higher visual processing such as implicit evaluative analysis of visual images in between migraine events. METHODS: Specifically, we asked two groups of participants--migraineurs (N=29) and non-migraine controls (N=29)--to view a set of unfamiliar commercial logos in the context of a target identification task as the brain electrical responses to these objects were recorded via event-related potentials (ERPs). Following this task, participants individually identified those logos that they most liked or disliked. We applied a between-groups comparison of how ERP responses to logos varied as a function of hedonic evaluation. RESULTS: Our results suggest migraineurs have abnormal implicit evaluative processing of visual stimuli. Specifically, migraineurs lacked a bias for disliked logos found in control subjects, as measured via a late positive potential (LPP) ERP component. CONCLUSIONS: These results suggest post-sensory consequences of migraine in between headache events, specifically abnormal cognitive evaluative processing with a lack of normal categorical hedonic evaluation.

Interictal neurocognitive processing of visual stimuli in migraine: evidence from event-related potentials.

Research has established decreased sensory habituation as a defining feature in migraine, while decreased cognitive habituation has only been found with regard to cognitive assessment of the relative probability of the occurrence of a stimulus event. Our study extended the investigation of interictal habituation in migraine to include cognitive processing when viewing of a series of visually-complex images, similar to those we encounter on the internet everyday. We examined interictal neurocognitive function in migraine from a habituation perspective, using a novel paradigm designed to assess how the response to a series of images changes over time. Two groups of participants--migraineurs (N = 25) and non-migraine controls (N = 25)--were asked to view a set of 232 unfamiliar logos in the context of a target identification task as their brain electrical responses were recorded via event-related potentials (ERPs). The set of logos was viewed serially in each of 10 separate trial blocks, with data analysis focusing on how the ERP responses to the logos in frontal electrodes from 200-600 ms changed across time within each group. For the controls, we found that the amplitude of the late positive potential (LPP) ERP component elicited by the logos had no significant change across trial blocks. In contrast, in migraineurs we found that the LPP significantly increased in amplitude across trial blocks, an effect consistent with a lack of habituation to visual stimuli seen in previous research. Our findings provide empirical support abnormal cognitive processing of complex visual images across time in migraineurs that goes beyond the sensory-level habituation found in previous research.

Top-down control of visual cortex in migraine populations.

The pathophysiology of migraine includes a heightened excitability of visual cortex that persists between headache events and that has been linked to impaired inhibitory intracortical processes. Here we examined the hypothesis that this cortical pathophysiology would affect the top-down attentional control of visual cortex. We asked two groups of participants-migraineurs (N=29) and non-migraine controls (N=29)-to perform a probabilistic spatial orienting task as we measured visual sensory cortical responses via event-related potentials (ERPs). Data were then analyzed as a function of whether the ERP-eliciting stimulus was in the fovea vs. parafovea, and whether the stimulus' location was attended or unattended. In this regard, we found two key between-groups differences in the effect of attention on sensory-evoked visual-cortical activity. First, relative to controls, migraineurs showed a larger attention effect in the visual N1 ERP component for events at the fovea. Second, unlike controls, migraineurs showed no early-phase attention effect in the P1 ERP component for events in the parafovea. Despite these altered ERP responses in migraineurs, however, corresponding behavioral data indicated that they also had heightened response performance. Taken together, our results support the hypothesis that migraineurs have an altered top-down attentional control of visual cortex, with the data suggesting that the effect may be tied to a reduced ability to suppress sensory-evoked activity for unattended events in the visual periphery.