TMS over V5 disrupts motion prediction

Given the vast amount of sensory information the brain has to deal with, predicting some of this information based on the current context is a resource-efficient strategy. The framework of predictive coding states that higher-level brain areas generate a predictive model to be communicated via feedback connections to early sensory areas. Here, we directly tested the necessity of a higher-level visual area, V5, in this predictive processing in the context of an apparent motion paradigm. We flashed targets on the apparent motion trace in-time or out-of-time with the predicted illusory motion token. As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets. However, when we applied functional magnetic resonance imaging-guided, double-pulse transcranial magnetic stimulation (TMS) over left V5 at 13–53 ms before target onset, the detection advantage of in-time targets was eliminated; this was not the case when TMS was applied over the vertex. Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010). Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framework

Mirror Neurons System Engagement in Late Adolescents and Adults While Viewing Emotional Gestures

International audienceObserving others' actions enhances muscle-specific cortico-spinal excitability, reflecting putative mirror neurons activity. The exposure to emotional stimuli also modulates cortico-spinal excitability. We investigated how those two phenomena might interact when they are combined, i.e., while observing a gesture performed with an emotion, and whether they change during the transition between adolescence and adulthood, a period of social and brain maturation. We delivered single-pulse transcranial magnetic stimulation (TMS) over the hand area of the left primary motor cortex of 27 healthy adults and adolescents and recorded their right first dorsal interossus (FDI) muscle activity (i.e., motor evoked potential – MEP), while they viewed either videos of neutral or angry hand actions and facial expressions, or neutral objects as a control condition. We reproduced the motor resonance and the emotion effects – hand-actions and emotional stimuli induced greater cortico-spinal excitability than the faces/control condition and neutral videos, respectively. Moreover, the influence of emotion was present for faces but not for hand actions, indicating that the motor resonance and the emotion effects might be non-additive. While motor resonance was observed in both groups, the emotion effect was present only in adults and not in adolescents. We discuss the possible neural bases of these findings

TMS Over V5 Disrupts Motion Prediction

Given the vast amount of sensory information the brain has to deal with, predicting some of this information based on the current context is a resource-efficient strategy. The framework of predictive coding states that higher-level brain areas generate a predictive model to be communicated via feedback connections to early sensory areas. Here, we directly tested the necessity of a higher-level visual area, V5, in this predictive processing in the context of an apparent motion paradigm. We flashed targets on the apparent motion trace in-time or out-of-time with the predicted illusory motion token. As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets. However, when we applied functional magnetic resonance imaging-guided, double-pulse transcranial magnetic stimulation (TMS) over left V5 at 13-53 ms before target onset, the detection advantage of in-time targets was eliminated; this was not the case when TMS was applied over the vertex. Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010). Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framewor

Development of functional connectivity during adolescence:A longitudinal study using an action-observation paradigm

Successful interpersonal interactions rely on an ability to read the emotional states of others and to modulate one's own behavior in response. The actions of others serve as valuable social stimuli in this respect, offering the observer an insight into the actor's emotional state. Social cognition continues to mature throughout adolescence. Here we assess longitudinally the development of functional connectivity during early adolescence within two neural networks implicated in social cognition: one network of brain regions consistently engaged during action observation and another one associated with mentalizing. Using fMRI, we reveal a greater recruitment of the social-emotional network during the observation of angry hand actions in male relative to female adolescents. These findings are discussed in terms of known sex differences in adolescent social behavior

Patterns of Activity in the Human Frontal and Parietal Cortex Differentiate Large and Small Saccades

A vast literature indicates that small and large saccades, respectively, subserve different perceptual and cognitive strategies and may rely on different programming modes. While it is well established that in monkeys’ main oculomotor brain regions small and large eye movements are controlled by segregated neuronal populations, the representation of saccade amplitude in the human brain remains unclear. To address this question we used functional magnetic resonance imaging (fMRI) to scan participants while they performed saccades towards targets at either short (4 degrees) or large (30 degrees) eccentricity. A regional multivoxel pattern analysis (MVPA) reveals that patterns of activity in the frontal (FEF) and parietal eye fields discriminate between the execution of large or small saccades. This was not the case in the supplementary eye fields nor in the inferior precentral cortex. These findings provide the first evidence of a representation of saccadic eye movement size in the fronto-parietal occulomotor circuit. They shed light on the respective roles of the different cortical oculomotor regions with respect to space perception and exploration, as well as on the homology of eye movement control between human and non-human primates

Subjective and neurophysiological perspectives on emotion perception from dance

Emotional engagement and aesthetic appreciation can be prime motivations for engaging with dance. Dance can therefore offer a valuable tool for the neuroscientific study of emotion processing. This idea underpinned the project Watching Dance, which investigated the neural correlates of subjective emotional response. Participants watched a four-minute video of contemporary dance involving two dancers and three music segments. Subjective emotional response was measured by continuous rating with a slider on an analogue scale, and structured interviews prompted participants to reflect on their ratings. The neural correlates were measured using functional brain imaging complemented by a brain interference study to investigate a causal link between regional brain activity and the subjective emotional response. A pattern of emotional rating emerged that was strongly influenced by both music and movement, as confirmed by the qualitative investigation. A direct link was established between posterior parietal cortex activity and emotional reaction to dance

Pros and cons of using the informed basis set to account for hemodynamic response variability with developmental data

Conventional analysis of functional magnetic resonance imaging (fMRI) data using the general linear model (GLM) employs a neural model convolved with a canonical hemodynamic response function (HRF) peaking 5s after stimulation. Incorporation of a further basis function, namely the canonical HRF temporal derivative, accounts for delays in the hemodynamic response to neural activity. A population that may benefit from this flexible approach is children whose hemodynamic response is not yet mature. Here, we examined the effects of using the set based on the canonical HRF plus its temporal derivative on both first- and second-level GLM analyses, through simulations and using developmental data (an fMRI dataset on proprioceptive mapping in children and adults). Simulations of delayed fMRI first-level data emphasized the benefit of carrying forward to the second-level a derivative boost that combines derivative and nonderivative beta estimates. In the experimental data, second-level analysis using a paired t-test showed increased mean amplitude estimate (i.e., increased group contrast mean) in several brain regions related to proprioceptive processing when using the derivative boost compared to using only the nonderivative term. This was true especially in children. However, carrying forward to the second-level the individual derivative boosts had adverse consequences on random-effects analysis that implemented one-sample t-test, yielding increased between-subject variance, thus affecting group-level statistic. Boosted data also presented a lower level of smoothness that had implication for the detection of group average activation. Imposing soft constraints on the derivative boost by limiting the time-to-peak range of the modelled response within a specified range (i.e., 4-6s) mitigated these issues. These findings support the notion that there are pros and cons to using the informed basis set with developmental data

Modulation of task-related electrophysiological responses by socially relevant stimuli

Human faces induce stronger involuntary orienting responses than other visual objects. We recently reported a significant increase in anti-saccade error rates for faces compared to cars and noise patterns, as well as faster pro-saccades compared to the other visual categories (Morand et al., 2010). However, when and where this preferential orienting response is taking place at the neural level remains to be clarified. To address this issue, we investigated the neural dynamics preceding the onset of pro-and anti-saccades elicited by human faces and non-face visual objects normalized for their low-level visual properties (i.e., amplitude spectra and contrast). We simultaneously recorded high-density evoked potentials (ERPs) and eye movements in adult observers as they performed randomly interleaved pro- and anti-saccades to a lateralized target. Pro- and anti-saccades directed to the same visual field significantly modulated the electrophysiological signals within the 100–140 ms time-period following target onset. These amplitude modulations were associated with distinct electrical scalp topographies. Faces triggering pro-saccades directed to the left and anti-saccades directed to the right (presented in the LVF) modulated the neurophysiological signals over the temporo-occipital electrodes (PO8 and P9) at 130–140 ms, which correspond to the right and left counterparts of the face-sensitive N170 component respectively. These neurophysiological modulations were not accompanied with topographic changes, but with an increase in response amplitude for faces. Our data show distinct electrophysiological signatures for pro- and anti-saccades occurring as early as 100 ms after target onset. We believe these to reflect distinct cortical networks, probably recruiting the FEF and DLPFC in their respective role in saccade programming. Critically, faces, compared to other visual objects impact upon saccade programming at several stages by modulating the magnitude of the cortical networks active prior to both pro- and anti-saccades execution. These observations provide the neural dynamics and mapping of the involuntary orienting responses for faces

Co-ordinated structural and functional covariance in the adolescent brain underlies face processing performance

Our ability to process complex social cues presented by faces improves during adolescence. Using multivariate analyses of neuroimaging data collected longitudinally from a sample of 38 adolescents (17 males) when they were 10, 11.5, 13 and 15 years old, we tested the possibility that there exists parallel variations in the structural and functional development of neural systems supporting face processing. By combining measures of task-related functional connectivity and brain morphology, we reveal that both the structural covariance and functional connectivity among 'distal' nodes of the face-processing network engaged by ambiguous faces increase during this age range. Furthermore, we show that the trajectory of increasing functional connectivity between the distal nodes occurs in tandem with the development of their structural covariance. This demonstrates a tight coupling between functional and structural maturation within the face-processing network. Finally, we demonstrate that increased functional connectivity is associated with age-related improvements of face-processing performance, particularly in females. We suggest that our findings reflect greater integration among distal elements of the neural systems supporting the processing of facial expressions. This, in turn, might facilitate an enhanced extraction of social information from faces during a time when greater importance is placed on social interactions

Right temporal TMS impairs voice detection

Functional magnetic resonance imaging (fMRI) research has revealed bilateral cortical regions along the upper banks of the superior temporal sulci (STS) which respond preferentially to voices compared to non-vocal, environmental sounds [1] and [2] . This sensitivity is particularly pronounced in the right hemisphere. Voice perception models imply that these regions, referred to as the temporal voice areas (TVAs), could correspond to a first stage of voice-specific processing in auditory cortex [3] and [4] , after which different types of vocal information are processed in interacting but partially independent functional pathways. However, clear causal evidence for this claim is missing. Here we provide the first direct link between TVA activity and voice detection ability using repetitive transcranial magnetic stimulation (rTMS). Voice/non-voice discrimination ability was impaired when rTMS was targeted at the right TVA compared with a control site. In contrast, a lower-level loudness judgement task was not differentially affected by site of stimulation. Results imply that neuronal computations in the right TVA are necessary for the distinction between human voices and other, non-vocal sounds