Stephanie Ortigue

Rapid discrimination of visual and multisensory memories revealed by electrical neuroimaging.

Though commonly held that multisensory experiences enrich our memories and that memories influence ongoing sensory processes, their neural mechanisms remain unresolved. Here, electrical neuroimaging shows that auditory-visual multisensory experiences alter subsequent processing of unisensory visual stimuli during the same block of trials at early stages poststimulus onset and within visual object recognition areas. We show this with a stepwise analysis of scalp-recorded event-related potentials (ERPs) that statistically tested (1) ERP morphology and amplitude, (2) global electric field power, (3) topographic stability of and changes in the electric field configuration, and (4) intracranial distributed linear source estimations. Subjects performed a continuous recognition task, discriminating repeated vs. initial image presentations. Corresponding, but task-irrelevant, sounds accompanied half of the initial presentations during a given block of trials. On repeated presentations within a block of trials, only images appeared, yielding two situations-the images prior presentation was only visual or with a sound. Image repetitions that had been accompanied by sounds yielded improved memory performance accuracy (old or new discrimination) and were differentiated as early as approximately 60-136 ms from images that had not been accompanied by sounds through generator changes in areas of the right lateral-occipital complex (LOC). It thus appears that unisensory percepts trigger multisensory representations associated with them. The collective data support the hypothesis that perceptual or memory traces for multisensory auditory-visual events involve a distinct cortical network that is rapidly activated by subsequent repetition of just the unisensory visual component.

Electrical neuroimaging reveals early generator modulation to emotional words

Functional electrical neuroimaging investigated incidental emotional word processing. Previous research suggests that the brain may differentially respond to the emotional content of linguistic stimuli pre-lexically (i.e., before distinguishing that these stimuli are words). We investigated the spatiotemporal brain mechanisms of this apparent paradox and in particular whether the initial differentiation of emotional stimuli is marked by different brain generator configurations using high-density, event-related potentials. Such would support the existence of specific cerebral resources dedicated to emotional word processing. A related issue concerns the possibility of right-hemispheric specialization in the processing of emotional stimuli. Thirteen healthy men performed a go/no-go lexical decision task with bilateral word/non-word or non-word/non-word stimulus pairs. Words included equal numbers of neutral and emotional stimuli, but subjects made no explicit discrimination along this dimension. Emotional words appearing in the right visual field (ERVF) yielded the best overall performance, although the difference between emotional and neutral words was larger for left than for right visual field presentations. Electrophysiologically, ERVF presentations were distinguished from all other conditions over the 100-140 ms period by a distinct scalp topography, indicative of different intracranial generator configurations. A distributed linear source estimation (LAURA) of this distinct scalp potential field revealed bilateral lateral-occipital sources with a right hemisphere current density maximum. These data support the existence of a specialized brain network triggered by the emotional connotation of words at a very early processing stage.

The Neural Basis of Love as a Subliminal Prime: An Event-related Functional Magnetic Resonance Imaging Study

Throughout the ages, love has been defined as a motivated and goal-directed mechanism with explicit and implicit mechanisms. Recent evidence demonstrated that the explicit representation of love recruits subcorticocortical pathways mediating reward, emotion, and motivation systems. However, the neural basis of the implicit (unconscious) representation of love remains unknown. To assess this question, we combined event-related functional magnetic resonance imaging (fMRI) with a behavioral subliminal priming paradigm embedded in a lexical decision task. In this task, the name of either a beloved partner, a neutral friend, or a passionate hobby was subliminally presented before a target stimulus (word, nonword, or blank), and participants were required to decide if the target was a word or not. Behavioral results showed that subliminal presentation of either a beloveds name (love prime) or a passion descriptor (passion prime) enhanced reaction times in a similar fashion. Subliminal presentation of a friends name (friend prime) did not show any beneficial effects. Functional results showed that subliminal priming with a beloveds name (as opposed to either a friends name or a passion descriptor) specifically recruited brain areas involved in abstract representations of others and the self, in addition to motivation circuits shared with other sources of passion. More precisely, love primes recruited the fusiform and angular gyri. Our findings suggest that love, as a subliminal prime, involves a specific neural network that surpasses a dopaminergic-motivation system.

Neuroimaging of Love: fMRI Meta‐Analysis Evidence toward New Perspectives in Sexual Medicine

INTRODUCTION Brain imaging is becoming a powerful tool in the study of human cerebral functions related to close personal relationships. Outside of subcortical structures traditionally thought to be involved in reward-related systems, a wide range of neuroimaging studies in relationship science indicate a prominent role for different cortical networks and cognitive factors. Thus, the field needs a better anatomical/network/whole-brain model to help translate scientific knowledge from lab bench to clinical models and ultimately to the patients suffering from disorders associated with love and couple relationships. AIM The aim of the present review is to provide a review across wide range of functional magnetic resonance imaging (fMRI) studies to critically identify the cortical networks associated with passionate love, and to compare and contrast it with other types of love (such as maternal love and unconditional love for persons with intellectual disabilities). METHODS Retrospective review of pertinent neuroimaging literature. MAIN OUTCOME MEASURES Review of published literature on fMRI studies of love illustrating brain regions associated with different forms of love. RESULTS Although all fMRI studies of love point to the subcortical dopaminergic reward-related brain systems (involving dopamine and oxytocin receptors) for motivating individuals in pair-bonding, the present meta-analysis newly demonstrated that different types of love involve distinct cerebral networks, including those for higher cognitive functions such as social cognition and bodily self-representation. CONCLUSIONS These metaresults provide the first stages of a global neuroanatomical model of cortical networks involved in emotions related to different aspects of love. Developing this model in future studies should be helpful for advancing clinical approaches helpful in sexual medicine and couple therapy.

Understanding Actions of Others: The Electrodynamics of the Left and Right Hemispheres. A High-Density EEG Neuroimaging Study

Background When we observe an individual performing a motor act (e.g. grasping a cup) we get two types of information on the basis of how the motor act is done and the context: what the agent is doing (i.e. grasping) and the intention underlying it (i.e. grasping for drinking). Here we examined the temporal dynamics of the brain activations that follow the observation of a motor act and underlie the observers capacity to understand what the agent is doing and why. Methodology/Principal Findings Volunteers were presented with two-frame video-clips. The first frame (T0) showed an object with or without context; the second frame (T1) showed a hand interacting with the object. The volunteers were instructed to understand the intention of the observed actions while their brain activity was recorded with a high-density 128-channel EEG system. Visual event-related potentials (VEPs) were recorded time-locked with the frame showing the hand-object interaction (T1). The data were analyzed by using electrical neuroimaging, which combines a cluster analysis performed on the group-averaged VEPs with the localization of the cortical sources that give rise to different spatio-temporal states of the global electrical field. Electrical neuroimaging results revealed four major steps: 1) bilateral posterior cortical activations; 2) a strong activation of the left posterior temporal and inferior parietal cortices with almost a complete disappearance of activations in the right hemisphere; 3) a significant increase of the activations of the right temporo-parietal region with simultaneously co-active left hemispheric sources, and 4) a significant global decrease of cortical activity accompanied by the appearance of activation of the orbito-frontal cortex. Conclusions/Significance We conclude that the early striking left hemisphere involvement is due to the activation of a lateralized action-observation/action execution network. The activation of this lateralized network mediates the understanding of the goal of object-directed motor acts (mirror mechanism). The successive right hemisphere activation indicates that this hemisphere plays an important role in understanding the intention of others.

Pure representational neglect after right thalamic lesion

After a right thalamic stroke, an 86‐year‐old man presented an acute pure left representational neglect in the absence of any perceptual neglect. On spatial mental imagery tasks, the patient systematically omitted items located on his left side, but only when a vantage point was given. This suggests that (1) pure representational neglect is not just a residual finding after recovery from global (perceptual and representational) neglect; (2) space representation can be coded by two independent processes: in viewer‐centered or world‐based (allocentric) coordinates; and (3) the right thalamus serves as a relay in the processing of spatial visual imagery.

Correlation between insula activation and self-reported quality of orgasm in women.

Current multidimensional models of womens sexual function acknowledge the implicit impact of psychosocial factors on womens sexual function. Interaction between human sexual function and intensity of love has been also assumed, even if love is not an absolute condition. Yet, whereas great insights have been made in understanding the central mechanisms of the peripheral manifestations of womens sexual response, including orgasm, the cerebral correlates sustaining the interaction between womens sexual satisfaction and the unconscious role of the partner in this interpersonal experience remain unknown. Using functional imaging, we assessed brain activity elicited when 29 healthy female volunteers were unconsciously exposed to the subliminal presentation of their significant partners name (a task known to elicit a partner-related neural network) and correlated it with individual scores obtained from different sexual dimensions: self-reported partnered orgasm quality (ease, satisfaction, frequency), love intensity and emotional closeness with that partner. Behavioral results identified a correlation between love and self-reported partnered orgasm quality. The more women were in love/emotionally close to their partner, the more they tended to report being satisfied with the quality of their partnered orgasm. However, no relationship was found between intensity of love and partnered orgasm frequency. Neuroimaging data expanded these behavioral results by demonstrating the involvement of a specific left-lateralized insula focus of neural activity correlating with orgasm scores, irrespective of dimension (frequency, ease, satisfaction). In contrast, intensity of being in love was correlated with a network involving the angular gyrus. These findings strongly suggest that intimate and sexual relationships are sustained by partly different mechanisms, even if they share some emotional-related mechanisms. The critical correlation between self-reports of orgasm quality and activation of the left anterior insula, a part of the partner-related neural network known to play a pivotal role in somatic processes, suggests the importance of somatic information in the integration of sexual experience. On the other hand, the correlation between activation of the angular gyrus and love intensity reinforces the assumption that the representation of love calls for higher order cognitive levels, such as those related to the generation of abstract concepts. By highlighting the specific role of the anterior insula in the way women integrate components of physical satisfaction in the context of an intimate relationship with a partner, the current findings take a step in the understanding of a womans sexual pleasure.

Differential Recruitment of Anterior Intraparietal Sulcus and Superior Parietal Lobule during Visually Guided Grasping Revealed by Electrical Neuroimaging

Dorsal parietal cortex is required for visually guided prehension. Transcranial magnetic stimulation to either the anterior intraparietal sulcus (aIPS) or superior parietal lobule (SPL) disrupts on-line adaptive adjustments of grasp when objects are perturbed. We used high-density electroencephalography during grasping to determine the relative timing of these two areas and to test whether the temporal contribution of each site would change when the task goal was perturbed. During object grasping with the right-hand, two distinct evoked responses were present over the 50–100 and 100–200 ms periods after movement onset. Distributed linear source estimation of these scalp potentials localized left lateralized sources, first in the aIPS and then the SPL. The duration of the response from the aIPS area was longer when there was an object perturbation. Initiation of a corrective movement coincided with activation in SPL. These data support a two-stage process: the integration of target goal and an emerging action plan within aIPS and subsequent on-line adjustments within SPL.

Spatio-Temporal Dynamics of Human Intention Understanding in Temporo-Parietal Cortex: A Combined EEG/fMRI Repetition Suppression Paradigm

Inferring the intentions of other people from their actions recruits an inferior fronto-parietal action observation network as well as a putative social network that includes the posterior superior temporal sulcus (STS). However, the functional dynamics within and among these networks remains unclear. Here we used functional magnetic resonance imaging (fMRI) and high-density electroencephalogram (EEG), with a repetition suppression design, to assess the spatio-temporal dynamics of decoding intentions. Suppression of fMRI activity to the repetition of the same intention was observed in inferior frontal lobe, anterior intraparietal sulcus (aIPS), and right STS. EEG global field power was reduced with repeated intentions at an early (starting at 60 ms) and a later (∼330 ms) period after the onset of a hand-on-object encounter. Source localization during these two intervals involved right STS and aIPS regions highly consistent with RS effects observed with fMRI. These results reveal the dynamic involvement of temporal and parietal networks at multiple stages during the intention decoding and without a strict segregation of intention decoding between these networks.

Neural bases of hypoactive sexual desire disorder in women: an event-related fMRI study

INTRODUCTION Although there is an abundant debate regarding the mechanisms sustaining one of the most common sexual complaints among women, i.e., female hypoactive sexual desire disorder (HSDD), little remains known about the specific neural bases of this disorder. AIM The main goal of this study was to determine whether women with HSDD showed differential patterns of activation within the brain network that is active for sexual desire in subjects without HSDD. METHODS A total of 28 right-handed women participated in this study (mean age 31.1±7.02 years). Thirteen out of the 28 women had HSDD (HSDD participants), while 15 women reported no hypoactive sexual desire disorder (NHSDD participants). Using event-related functional magnetic resonance imaging (fMRI), we compared the regional cerebral blood flow responses between these two groups of participants, while they were looking at erotic vs. non-erotic stimuli. MAIN OUTCOME MEASURE Blood-oxygenation level dependent (BOLD) signal changes in response to erotic stimuli (compared with non-erotic stimuli). Statistical Parametric Mapping was used to identify brain regions that demonstrated significant differential activations between stimuli and between groups. RESULTS As expected, behavioral results showed that NHSDD participants rated erotic stimuli significantly higher than HSDD participants did on a 10-point desirable scale. No rating difference was observed for the non-erotic stimuli between NHSDD and HSDD participants. Our functional neuroimaging results extended these data by demonstrating two distinct types of neural changes in participants with and without HSDD. In comparison with HSDD participants, participants without HSDD demonstrated more activation in brain areas involved in the processing of erotic stimuli, including intraparietal sulcus, dorsal anterior cingulate gyrus, and ento/perirhinal region. Interestingly, HSDD participants also showed additional activations in brain areas associated with higher order social and cognitive functions, such as inferior parietal lobule, inferior frontal gyrus, and posterior medial occipital gyrus. CONCLUSION Together, these findings indicate that HSDD participants do not only show a hypo activation in brain areas mediating sexual desire, but also a different brain network of hyper activation, which might reflect differences in subjective, social, and cognitive interpretations of erotic stimuli. Collectively, these data are in line with the incentive motivation model of sexual functioning.