Magnitude Of Neural Activity Research Articles

Word recognition and future language skills in 14-month-old infants

Children show remarkable progress in word learning in the second year of life. This language growth coincides with the vocabulary spurt and the development of domain-general cognition, e.g., attention that facilitates perceptual processing. Evidence suggests that language growth depends on increasing processing efficiency and underlying neuronal specialization. We used magnetoencephalography (MEG) to characterize neural activity following familiar and unfamiliar words in 14-month-old infants and related measures of neural activity to prospective measures of vocabulary growth. MEG source modeling revealed a broadly distributed network in bilateral frontal, temporal and parietal cortex that distinguished word classes between 150–900 ms after word onset. Analysis of correlations between outcome measurements and strength of neural activity revealed that in the interval 150–300 ms after word onset, the magnitude of neural activation in the right inferior frontal cortex for familiar words was positively correlated with vocabulary size at 18, 21, 24, 27 and 30 months of age. We argue that increased activity to familiar words may reflect more efficient discriminatory processing by the most skilled language learners who develop a larger vocabulary one year later.Children show remarkable progress in word learning in the second year of life. This language growth coincides with the vocabulary spurt and the development of domain-general cognition, e.g., attention that facilitates perceptual processing. Evidence suggests that language growth depends on increasing processing efficiency and underlying neuronal specialization. We used magnetoencephalography (MEG) to characterize neural activity following familiar and unfamiliar words in 14-month-old infants and related measures of neural activity to prospective measures of vocabulary growth. MEG source modeling revealed a broadly distributed network in bilateral frontal, temporal and parietal cortex that distinguished word classes between 150–900 ms after word onset. Analysis of correlations between outcome measurements and strength of neural activity revealed that in the interval 150–300 ms after word onset, the magnitude of neural activation in the right inferior frontal cortex for familiar words was positively correla...

Probing the Interoceptive Network by Listening to Heartbeats: An fMRI Study.

Exposure to cues of homeostatic relevance (i.e. heartbeats) is supposed to increase the allocation of attentional resources towards the cue, due to its importance for self-regulatory, interoceptive processes. This functional magnetic resonance imaging (fMRI) study aimed at determining whether listening to heartbeats is accompanied by activation in brain areas associated with interoception, particularly the insular cortex. Brain activity was measured with fMRI during cue-exposure in 36 subjects while listening to heartbeats vs. sinus tones. Autonomic markers (skin conductance) and subjective measures of state and trait anxiety were assessed. Stimulation with heartbeat sounds triggered activation in brain areas commonly associated with the processing of interoceptive information, including bilateral insular cortices, the inferior frontal operculum, and the middle frontal gyrus. A psychophysiological interaction analysis indicated a functional connectivity between the middle frontal gyrus (seed region) and bilateral insular cortices, the left amygdala and the supplementary motor area. The magnitude of neural activation in the right anterior insular cortex was positively associated with autonomic arousal. The present findings indicate that listening to heartbeats induced activity in areas of the interoception network as well as changes in psychophysiological arousal and subjective emotional experience. As this approach constitutes a promising method for studying interoception in the fMRI environment, a clinical application in anxiety prone populations should be addressed by future studies.

The magnitude of the somatosensory cortical activity is related to the mobility and strength impairments seen in children with cerebral palsy.

The noted disruption of thalamocortical connections and abnormalities in tactile sensory function has resulted in a new definition of cerebral palsy (CP) that recognizes the sensorimotor integration process as central to the motor impairments seen in these children. Despite this updated definition, the connection between a child's motor impairments and somatosensory processing remains almost entirely unknown. In this investigation, we explored the relationship between the magnitude of neural activity within the somatosensory cortices, the strength of the ankle plantarflexors, and the gait spatiotemporal kinematics of a group of children with CP and a typically developing matched cohort. Our results revealed that the magnitude of somatosensory cortical activity in children with CP had a strong positive relationship with the ankle strength, step length, and walking speed. These results suggest that stronger activity within the somatosensory cortices in response to foot somatosensations was related to enhanced ankle plantarflexor strength and improved mobility in the children with CP. These results provide further support for the notion that children with CP exhibit, not only musculoskeletal deficits, but also somatosensory deficits that potentially contribute to their overall functional mobility and strength limitations.

From image statistics to scene gist: evoked neural activity reveals transition from low-level natural image structure to scene category.

The visual system processes natural scenes in a split second. Part of this process is the extraction of "gist," a global first impression. It is unclear, however, how the human visual system computes this information. Here, we show that, when human observers categorize global information in real-world scenes, the brain exhibits strong sensitivity to low-level summary statistics. Subjects rated a specific instance of a global scene property, naturalness, for a large set of natural scenes while EEG was recorded. For each individual scene, we derived two physiologically plausible summary statistics by spatially pooling local contrast filter outputs: contrast energy (CE), indexing contrast strength, and spatial coherence (SC), indexing scene fragmentation. We show that behavioral performance is directly related to these statistics, with naturalness rating being influenced in particular by SC. At the neural level, both statistics parametrically modulated single-trial event-related potential amplitudes during an early, transient window (100-150 ms), but SC continued to influence activity levels later in time (up to 250 ms). In addition, the magnitude of neural activity that discriminated between man-made versus natural ratings of individual trials was related to SC, but not CE. These results suggest that global scene information may be computed by spatial pooling of responses from early visual areas (e.g., LGN or V1). The increased sensitivity over time to SC in particular, which reflects scene fragmentation, suggests that this statistic is actively exploited to estimate scene naturalness.

Incorporating fMRI Functional Networks in EEG Source Imaging: A Bayesian Model Comparison Approach

Brain functional networks extracted from fMRI can improve the accuracy of EEG source localization. However, the coupling between EEG and fMRI remains poorly understood, i.e., whether fMRI networks provide information about the magnitude of neural activity, and whether neural sources demonstrate temporal correlations within each network. In this paper, we present an improved version of the NEtwork-based SOurce Imaging method (iNESOI) through Bayesian model comparison. Different models correspond to various matching between EEG and fMRI, and the appropriate one is selected by data with the model evidence. Synthetic and real data tests show that iNESOI has potential to select the appropriate fMRI priors to reach a better source reconstruction than some other typical approaches.

The Sensory Representation of Time

The Sensory Representation of Time

Attention-Dependent Representation of a Size Illusion in Human V1

One of the most fundamental properties of human primary visual cortex (V1) is its retinotopic organization, which makes it an ideal candidate for encoding spatial properties, such as size, of objects. However, three-dimensional (3D) contextual information can lead to size illusions that are reflected in the spatial pattern of activity in V1 [1]. A critical question is how complex 3D contextual information can influence spatial activity patterns in V1. Here, we assessed whether changes in the spatial distribution of activity in V1 depend on the focus of attention, which would be suggestive of feedback of 3D contextual information from higher visual areas. We presented two 3D rings at close and far apparent depths in a 3D scene. When subjects fixated its center, the far ring appeared to be larger and occupy a more eccentric portion of the visual field, relative to the close ring. Using functional magnetic resonance imaging, we found that the spatial distribution of V1 activity induced by the far ring was also shifted toward a more eccentric representation of the visual field, whereas that induced by the close ring was shifted toward the foveal representation, consistent with their perceptual appearances. This effect was significantly reduced when the focus of spatial attention was narrowed with a demanding central fixation task. We reason that focusing attention on the fixation task resulted in reduced activity in--and therefore reduced feedback from--higher visual areas that process the 3D depth cues.

Sex Differences in Brainstem Neural Activation after Injury to the TMJ Region

The basis for a higher prevalence of painful temporomandibular disorders (TMD) among women than men is not known. The present study used Fos-like immunoreactivity (Fos-LI) to quantify the pattern and magnitude of neural activation within the trigeminal brainstem complex of male and female rats caused by acute inflammatory injury to the temporomandibular joint (TMJ) region. Also, Fos-LI was assessed in animals given morphine, a preferential mu opioid receptor agonist, or U50,488H, a selective kappa opioid agonist, prior to TMJ injury to determine if opioid modulation of neural activation was similar in males and females. The general pattern of Fos-LI after TMJ injury was similar in males and females. This pattern was characterized by a high density of Fos-positive neurons in the dorsal paratrigeminal nucleus (dPa5), subnucleus interpolaris/caudalis transition region (Vi/Vc-vl), and in the superficial laminae at the subnucleus caudalis/upper cervical spinal cord (Vc/C2) junction ipsilateral to TMJ injury. In contrast to other regions the number of Fos-positive neurons produced at the Vc/C2 junction was proportional to the concentration of mustard oil injected into the TMJ region. In addition, proestrus females produced higher levels of Fos-LI at the Vc/C2 junction than diestrus females or males. Morphine caused a greater dose-related reduction in Fos-LI at the dPa5 and Vc/C2 junction in males than females. By contrast, U50,488H caused a dose-related reduction in Fos-LI only at the Vc/C2 junction of proestrus females. These results support the hypothesis that the Vc/C2 junction region plays a critical role in the integration of pain signals originating from the TMJ region and may underlie sex differences in sensory processing related to TMJ pain.