Early Left-Hemispheric Dysfunction of Face Processing in Congenital Prosopagnosia: An MEG Study

Congenital prosopagnosia (CP) refers to a lifelong impairment in face processing despite normal visual and intellectual skills. Many studies have suggested that the key underlying deficit in CP is one of a failure to engage holistic processing. Moreover, there has been some suggestion that, in normal observers, there may be greater involvement of the right than left hemisphere in holistic processing. To examine the proposed deficit in holistic processing and its potential hemispheric atypicality in CP, we compared the performance of 8 CP individuals with both matched controls and a large group of non-matched controls on a novel, vertical composite task. In this task, participants judged whether a cued half of a face (either left or right half) was the same or different at study and test, and the two face halves could be either aligned or misaligned. The standard index of holistic processing is one in which the unattended face half influences performance on the cued half and this influence is greater in the aligned than in the misaligned condition. Relative to controls, the CP participants, both at a group and at an individual level, did not show holistic processing in the vertical composite task. There was also no difference in performance as a function of hemifield of the cued face half in the CP individuals, and this was true in the control participants, as well. The findings clearly confirm the deficit in holistic processing in CP and reveal the useful application of this novel experimental paradigm to this population and potentially to others as well.

Understanding how the human visual system recognizes objects is one of the key challenges in neuroscience. Inspired by a large body of physiological evidence, a general class of recognition models has emerged, which is based on a hierarchical organization of visual processing, with succeeding stages being sensitive to image features of increasing complexity. However, these models appear to be incompatible with some well-known psychophysical results. Prominent among these are experiments investigating recognition impairments caused by vertical inversion of images, especially those of faces. It has been reported that faces that differ 'featurally' are much easier to distinguish when inverted than those that differ 'configurally'; a finding that is difficult to reconcile with the physiological models. Here, we show that after controlling for subjects' expectations, there is no difference between 'featurally' and 'configurally' transformed faces in terms of inversion effect. This result reinforces the plausibility of simple hierarchical models of object representation and recognition in the cortex.

ABSTRACTA recent theoretical account posits that, during the acquisition of word recognition in childhood, the pressure to couple visual and language representations in the left hemisphere (LH) results in competition with the LH representation of faces, which consequently become largely, albeit not exclusively, lateralized to the right hemisphere (RH). We explore predictions from this hypothesis using a hemifield behavioural paradigm with words and faces as stimuli, with concurrent event-related potential (ERP) measurement, in a group of adults with developmental dyslexia (DD) or with congenital prosopagnosia (CP) and matched control participants. Behaviourally, the DD group exhibited clear deficits in both word and face processing relative to controls, while the CP group showed a specific deficit in face processing only. This pattern was mirrored in the ERP data too. The DD group evinced neither the normal ERP pattern of RH dominance for faces nor the LH dominance for words. In contrast, the CP group showed the typical ERP superiority for words in the LH but did not show the typical RH superiority for faces. These findings are consistent with the hypothesis that the typical hemispheric organization for words can develop in the absence of typical hemispheric organization for faces but not vice versa, supporting the account of interactive perceptual development.

Congenital prosopagnosia is associated with a genetic variation in the oxytocin receptor (OXTR) gene: An exploratory study

Calcium imaging has been widely adopted for its ability to record from large neuronal populations. To summarize the time course of neural activity, dimensionality reduction methods, which have been applied extensively to population spiking activity, may be particularly useful. However, it is unclear if the dimensionality reduction methods applied to spiking activity are appropriate for calcium imaging. We thus carried out a systematic study of design choices based on standard dimensionality reduction methods. We also developed a method to perform deconvolution and dimensionality reduction simultaneously (Calcium Imaging Linear Dynamical System, CILDS). CILDS most accurately recovered the single-trial, low-dimensional time courses from simulated calcium imaging data. CILDS also outperformed the other methods on calcium imaging recordings from larval zebrafish and mice. More broadly, this study represents a foundation for summarizing calcium imaging recordings of large neuronal populations using dimensionality reduction in diverse experimental settings.

Cortical activation and functional connectivity in visual-cognitive-motor networks during motor-cognitive exercise.

The main goal of monolingual models of sentence processing is to explain how the syntactic processor (or parser) assigns structure to an incoming string of words. The theoretical divide in the field has been about whether the architecture and mechanisms of the human sentence processor are modular—and computations are carried out serially—or whether it is interactive and computations are carried out in parallel. The debate about bilingual sentence processing has, instead, focused on whether bilingual speakers process their second language in a manner similar to monolingual speakers of the target language. Proposals rooted in generative approaches to language acquisition argue that adult second language (L2) learners lack access to the universal principles or the ability to reset parameters that guide language acquisition and language processing in their L2. Models grounded in neurocognitive approaches to memory hold that late bilinguals recruit different memory systems compared to native speakers of the target language. Other models have argued that differences in first and second language processing result largely from capacity differences, differences in susceptibility to interference, or lack of predictive ability. More recently, several studies have turned toward more experience-driven accounts, eschewing the earlier assumption that the first language is static and unchanging, and instead focusing on the interactive and interconnected nature of the bilingual linguistic system. These studies have revealed that not only does the first language (L1) affect L2 syntactic processing, but experience with the L2 can have ramifications for processing in the native language. A range of experimental techniques are employed to investigate how monolingual and bilingual speakers process language at the sentence level. Eye-tracking techniques allow measurement of responses, such as eye movements and pupil dilation, to study written and auditory language processing. Such measures permit insight into the cognitive processes that are engaged when individuals read written text or inspect visual scenes. Electrophysiological measures are particularly helpful for understanding the time course of neural activity associated with language and cognitive processes. Event-related potentials (ERPs) are obtained by recording and averaging across brain potentials associated with time-locked events (e.g., a word in a sentence). Electrophysiological measures are used to determine which stages of processing are affected by the experimental manipulation. Neuroimaging provides information about changes in brain structure and function. For example, the functional magnetic resonance imaging (fMRI) technique can be used to visualize which brain regions are engaged in processing a particular type of sentence. Although neuroimaging is a relatively-new methodology, it holds great promise for increasing our understanding of the dynamic processes in the brain related to language. The writing of this bibliography was supported in part by National Science Foundation (NSF) grant BCS-1535124 and OISE 1545900 to Paola E. Dussias.

Evidence is mixed whether fluid intelligence (Gf) is associated with increased or decreased alpha and beta band activity (7–30 Hz). Moreover, the Gf relationship with the delta and theta band activity (1–7 Hz) is unknown. We recorded electroencephalographic (EEG) data in 160 healthy adults solving Raven's Advanced Progressive Matrices with a randomized item order to control for item difficulty unaffected by sequential effects. The participants studied each matrix for 30 s before the response bank onset, so we could track the time course of neural activity during problem solving. We measured Gf using six tests. Gf positively correlated with the delta band power, while there was no correlation with the theta band power. For almost all of the participants, we identified the specific slow rhythm frequency, which varied in power as a function of item difficulty. We observed that the lower this frequency, the higher Gf, but only in men. Finally, the alpha and low-beta activity correlated negatively with Gf after we had filtered out the activity during idle intervals (the latter reflecting waiting for the response bank). Overall, the brain activity in the delta, alpha, and beta bands explained 22.6% of Gf variance.

In this paper a new Lanczos-tau method for solving linear functional differential equations is introduced. The scheme has infinite order of accuracy both in time and in the delayed argument. The high accuracy in time is obtained without increasing the computational work and memory space which is needed for a one-step explicit difference scheme. The article demonstrates how to implement the algorithm in a robust and efficient manner and to treat problems with piecewise continuous initial function. Numerical results illustrating the behavior of the method when faced with difficult problems are presented and the numerical results are compared to those obtained by using two other methods.

Schizophrenia patients have abnormalities of auditory information processing, theoretically associated with dysfunction of neuronal excitation. Auditory paired-stimuli (S1-S2) paradigms are used to evaluate the nature of these abnormalities. It is unknown whether patients' abnormalities during S1-S2 paradigms are attributable to specific hemispheric differences in cortical processing. The present studies used whole head magnetoencephalography and monaural or binaural versions of the paired-stimuli paradigm to evaluate auditory processing among 38 schizophrenia and 38 normal subjects. The strengths of auditory-evoked brain responses over time were quantified using distributed source reconstructions with L2 minimum norm constraint and realistic head models. For left ear stimuli, schizophrenia and normal groups did not differ on either left or right hemisphere activity over auditory cortex. For right ear and binaural stimuli, schizophrenia patients had less activity over left auditory cortex from 80 to 120 ms post-stimulus but did not differ from normal on activity over right auditory cortex. Additionally, in response to monaural stimulation, schizophrenia patients had significantly less activity than normal over right temporal parietal junction from 60 to 120 ms post-stimulus. These data are consistent with four propositions about schizophrenia: (i). right auditory cortex is functioning normally; (ii). processing of simple auditory stimuli is abnormal in left auditory cortex, probably specifically in supra-granular layers; (iii). auditory localization abilities are deficient; and (iv). auditory cortex abnormalities are not a function of deficient hemispheric communication because they are evident early in processing as long as stimuli are delivered directly to left hemisphere.

Emotional reactions are sometimes observed during the intracarotid sodium amobarbital test. For instance, euphoric/indifference reactions can be seen during right hemisphere inactivation and catastrophic reactions may accompany left hemisphere inactivation. Less dramatic changes can also be detected in affective self-report during left and right hemisphere amobarbital tests, with more negative affect reported during left hemisphere inactivation and either neutral or mildly positive affective states reported during right hemisphere inactivation. The current study not only replicated this effect, but in addition, found significant group differences. The first group (right way) showed a pattern of affective self-report during left and right amobarbital tests entirely consistent with prior findings, while a second group (wrong way) showed results that behaved in a diametrically opposite fashion. A third group (no change) showed little, if any, difference in affective self-report during left and right amobarbital tests. The major factor distinguishing the wrong way group from the other two appeared to be an asymmetrical distribution of left and right temporal lobe lesions in the former group. In contrast, the factor differentiating the right way group from the no change group appeared to be the relative degree of left hemisphere inactivation during the left hemisphere amobarbital test. The results are discussed not only in terms of their impact on theories of cerebral lateralization for emotion, but also in terms of methodological issues in this field.

ABSTRACTFor the one-stage third-order gas-kinetic scheme (GKS), successful applications have been achieved for the three-dimensional compressible flows [Pan, L., K. Xu, Q. Li, and J. Li. 2016. “An Efficient and Accurate Two-stage Fourth-order Gas-kinetic Scheme for the Navier-Stokes Equations.” Journal of Computational Physics 326: 197–221]. The high-order accuracy of the scheme is obtained by integrating a multidimensional time-accurate gas distribution function over the cell interface within a time step without using Gaussian quadrature points and Runge-Kutta time-stepping technique. However, to the further increase of the order of the scheme, such as the fourth-order one, the one step formulation becomes very complicated for the multidimensional flow. Recently, a two-stage fourth-order GKS with high efficiency has been constructed for two-dimensional inviscid and viscous flow computations ([Li, J., and Z. Du. 2016. “A Two-stage Fourth Order Time-accurate Discretization for Lax-Wendroff Type Flow Solvers I. Hyperbolic Conservation Laws.” SIAM Journal on Scientific Computing 38: 3046–3069]; Pan et al. 2016), and the scheme uses the time accurate flux function and its time derivatives. In this paper, a fourth-order GKS is developed for the three-dimensional flows under the two-stage framework. Based on the three-dimensional WENO reconstruction and flux evaluation at Gaussian quadrature points on a cell interface, the high-order accuracy in space is achieved first. Then, the two-stage time stepping method provides the high accuracy in time. In comparison with the formal third-order GKS [Pan, L., and K. Xu. 2015. “A Third-order Gas-kinetic Scheme for Three-dimensional Inviscid and Viscous Flow Computations.” Computers & Fluids 119: 250–260], the current fourth-order method not only improves the accuracy of the scheme, but also reduces the complexity of the gas-kinetic flux solver greatly. More importantly, the fourth-order GKS has the same robustness as the second-order shock capturing scheme [Xu, K. 2001. “A Gas-kinetic BGK Scheme for the Navier-Stokes Equations and its Connection with Artificial Dissipation and Godunov Method.” Journal of Computational Physics 171: 289–335]. Numerical results validate the outstanding reliability and applicability of the scheme for three-dimensional flows, such as the cases related to turbulent simulations.

This paper reports dielectric recovery property measurements of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and Air arcs under free recovery condition. In these measurements, the arc current and the voltage applied to the free recovery arcs were controlled with a high accuracy in time using power semiconductors. The recovery properties were measured by changing the application delay time t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> of the recovery voltage with a peak of 8.2 kV. As a result, 200 L/min of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas flow needs t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 165 μs to withstand the quasi-TRV application with 50% probability of arc re-ignition; while 200 L/min of Air gas flow requires t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 220 μ for the same purpose.

Cost-effective waveform modeling is the key to practical reverse time migration (RTM) and full-waveform inversion (FWI) implementations. We evaluated an explicit time evolution (ETE) method to efficiently simulate wave propagation in acoustic media with high temporal accuracy. We started from the constant-density acoustic wave equation and obtained an analytical time-marching scheme in the wavenumber domain. We then formulated an ETE scheme in the time-space domain by introducing a cosine function approximation. Although the ETE operator appears to be similar to the second-order temporal finite-difference (FD) operator, the exact nature of the ETE formula ensures high accuracy in time. We further introduced a set of optimum stencils and coefficients by minimizing evolution errors in a least-squares sense. Our numerical tests indicated that ETE can achieve similar waveform accuracy as FD with four times larger time steps. Meanwhile, the compact ETE operator keeps the computation efficient. The efficiency and capability to handle complex velocity field make ETE an attractive engine in acoustic RTM and FWI.

Neuropsychological investigations of patients with Parkinson's disease, schizophrenia, or attention deficit disorder converge with psychopharmacological studies in animals and healthy volunteers to implicate dopamine (DA) pathways in timing. In parallel, single-cell recording and functional neuroimaging studies have highlighted the importance of basal ganglia, prefrontal cortex, and supplementary motor area (SMA) for timing. In a placebo-controlled, within-subject design, we combined event-related functional magnetic resonance imaging with a DA manipulation (acute phenylalanine/tyrosine depletion; APTD) in healthy volunteers to pinpoint the neuroanatomical and functional substrates of the DA modulation of timing. Behaviorally, APTD selectively impaired accuracy of perceptual timing, with no effect on performance of a color-control task matched for difficulty, working memory (WM), and attentional demands. Neurally, APTD attenuated timing-specific activity in the putamen and SMA. Notably, APTD-induced decreases in brain activity were directly correlated to APTD-induced impairments in timing performance. Moreover, APTD modulated timing-specific activity selectively during initial storage of the sample duration, but had no effect during its subsequent retrieval or comparison to a probe. Our results do not simply reflect DA modulation of WM since the color task controlled for the WM updating process necessary for timing of durations in the seconds range. Moreover, preliminary evidence indicated APTD effects on putamen and SMA were greater for subsecond (540 ms) than suprasecond (1080 ms) durations, when WM demands would actually be lower. Instead, we show for the first time in healthy humans that DA manipulation perturbs timing by attenuating the activity in putamen and SMA that mediates initial storage of temporal information into WM.