Independent component analysis: an introduction

Independent component analysis (ICA) is a method for automatically identifying the underlying factors in a given data set. This rapidly evolving technique is currently finding applications in analysis of biomedical signals (e.g. ERP, EEG, fMRI, optical imaging), and in models of visual receptive fields and separation of speech signals. This article illustrates these applications, and provides an informal introduction to ICA.     

Dynamic brain imaging: Event-related optical signal (EROS) measures of the time course and localization of cognitive-related activity

This paper describes the concept of dynamic brain imaging and introduces a new methodology, the event-related optical signal, or EROS. Dynamic brain imaging allows one to study noninvasively the time course of activity in specific brain areas. Brain imaging data can contribute to the analysis of the subcomponents of the human information processing system and of their interactions. Several brain imaging methods provide data that possess spatial and temporal resolution at various degrees and can be used for this purpose. In this paper, we focus on the EROS method, which yields data with millisecond temporal resolution and subcentimeter spatial resolution. We describe the fundamentals of this method and report several examples of the types of data that can be obtained with it. Finally, we discuss the possibility of combining different imaging methods, as well as the advantages and limitations that can be expected in this process.     

The God Beyond

This article is an attempt to describe the structure of imaging God at the adult level At the adult level of religious development, this structure has three interrelated pieces: first, there is an adult self;second, there is unfettered imaging; and third, there is the God the adult self is able to relate to in unfettered imaging, and this is the God Beyond. The article concludes with a brief look at how the adult self hears and speaks about the God Beyond.The author acknowledges with gratitude the invaluable help in writing this article of Neil J. McGettigan, Religious Studies Department, Villanova University, Villanova, PA.     

The Superego God

This article is an attempt to describe the structure of imaging God at the superego level At the superego level of religious development, this structure has three interrelated pieces: first, there is an adolescing self; second, there is fettered imaging; and third, there is the God the adolescing self is able to relate to in fettered imaging, and this is the Superego God. The article concludes with a brief look at how the adolescing self hears and speaks about the Superego God.The author acknowledges with gratitude the invaluable help in writing this article of Neil J. McGettigan, Religious Studies Department, Villanova University, Villanova, PA.     

A linear optical trajectory informs the fielder where to run to the side to catch fly balls

P. McLeod, N. Reed, and Z. Dienes (2002) argued that the linear optical trajectory (LOT) strategy incorrectly cues fielders to run forward for balls headed beyond them. The authors of this article explain that the downward optical curvature found for balls landing beyond the fielder's initial position occurs because the balls reorient the direction the fielder is facing during pursuit. Thus, when downward optical curvature begins, the ball is headed to land in front of where the fielder is facing and running. This investigation of open-loop failure conditions has led to new insights such as the reorientation of the fielder, and it supports the use of maintaining matching rates of vertical and lateral optical ball movement consistent with primacy of the LOT control mechanism even when interception is unachievable.     

视觉选择性注意脑机制研究进展

视觉选择性注意一直是认知心理学的研究热点之一。注意的早晚期选择问题和基于空间与基于客体的选择问题是选择性注意研究中长期争论的两大理论问题。脑成像研究不仅为解决这些争论提供了有力的证据 ,而且深化和拓展了这两大问题的研究。该文介绍了脑成像研究在上述两个领域的主要研究成果 ,并展望了今后相关问题的研究重点。     

Cognitive Emotion Regulation: Insights From Social Cognitive and Affective Neuroscience

ABSTRACT— Recent developments in the study of cognitive emotion regulation illustrate how functional imaging is extending behavioral analyses. Imaging studies have contributed to the development of a multilevel model of emotion regulation that describes the interactions between neural systems implicated in emotion generation and those implicated in emotional control. In this article, we review imaging studies of one type of cognitive emotion regulation: reappraisal. We show how imaging studies have contributed to the construction of this model, illustrate the interplay of psychological theory and neuroscience data in its development, and describe how this model can be used as the basis for future basic and translational research.     

脑功能成像在催眠状态中的研究进展

催眠是一种特殊的意识状态。本文从意识状态、疼痛及精神病理现象三个方面对脑功能成像在催眠状态中的研究进展进行了回顾,并对脑功能成像技术进行了比较。提出国内可以借鉴相应的方法来研究中国气功。     

Image processing for improved eye-tracking accuracy

Video cameras provide a simple, noninvasive method for monitoring a subject’s eye movements. An important concept is that of the resolution of the system, which is the smallest eye movement that can be reliably detected. While hardware systems are available that estimate direction of gaze in real time from a video image of the pupil, such systems must limit image processing to attain real-time performance and are limited to a resolution of about 10 arc minutes. Two ways to improve resolution are discussed. The first is to improve the image processing algorithms that are used to derive an estimate. Offline analysis of the data can improve resolution by at least one order of magnitude for images of the pupil. A second avenue by which to improve resolution is to increase the optical gain of the imaging setup (i.e., the amount of image motion produced by a given eye rotation). Ophthalmoscopic imaging of retinal blood vessels provides increased optical gain and improved immunity to small head movements but requires a highly sensitive camera. The large number of images involved in a typical experiment imposes great demands on the storage, handling, and processing of data. A major bottleneck had been the real-time digitization and storage of large amounts of video imagery, but recent developments in video compression hardware have made this problem tractable at a reasonable cost. Images of both the retina and the pupil can be analyzed successfully using a basic toolbox of image-processing routines (filtering, correlation, thresholding, etc.), which are, for the most part, well suited to implementation on vectorizing supercomputers.     

Quantifying the reliability of image replication studies: The image intraclass correlation coefficient (I2C2)

This article proposes the image intraclass correlation (I2C2) coefficient as a global measure of reliability for imaging studies. The I2C2 generalizes the classic intraclass correlation (ICC) coefficient to the case when the data of interest are images, thereby providing a measure that is both intuitive and convenient. Drawing a connection with classical measurement error models for replication experiments, the I2C2 can be computed quickly, even in high-dimensional imaging studies. A nonparametric bootstrap procedure is introduced to quantify the variability of the I2C2 estimator. Furthermore, a Monte Carlo permutation is utilized to test reproducibility versus a zero I2C2, representing complete lack of reproducibility. Methodologies are applied to three replication studies arising from different brain imaging modalities and settings: regional analysis of volumes in normalized space imaging for characterizing brain morphology, seed-voxel brain activation maps based on resting-state functional magnetic resonance imaging (fMRI), and fractional anisotropy in an area surrounding the corpus callosum via diffusion tensor imaging. Notably, resting-state fMRI brain activation maps are found to have low reliability, ranging from .2 to .4. Software and data are available to provide easy access to the proposed methods.     

Seeing with the skin

A system for converting an optical image into a tactile display has been evaluated to see what promise it has as a visual substitution system. After surprisingly little training, Ss are able to recognize common objects and to describe their arrangement in three-dimensional space. When given control of the sensing and imaging device, a television camera, Ss quickly achieve external subjective localization of the percepts. Limitations of the system thus far appear to be more a function of display resolution than limitations of the skin as a receptor surface. The acquisition of skill with the device has been remarkably similar for blind and sighted Ss.     

Does functional neuroimaging solve the questions of neurolinguistics?

Neurolinguistic research has been engaged in evaluating models of language using measures from brain structure and function, and/or in investigating brain structure and function with respect to language representation using proposed models of language. While the aphasiological strategy, which classifies aphasias based on performance modality and a few linguistic variables, has been the most stable, cognitive neurolinguistics has had less success in reliably associating more elaborately proposed levels and units of language models with brain structure. Functional imaging emerged at this stage of neurolinguistic research. In this review article, it is proposed that the often-inconsistent superfluity of outcomes arising from functional imaging studies of language awaits adjustment at both "ends" of the process: model and data. Assumptions that our current language models consistently and reliably represent implicit knowledge within human cerebral processing are in line for major revision; and the promise of functional brain imaging to reveal any such knowledge structures must incorporate stable correlates of the imaging signal as dependent variable.     

小儿巨大肾积水的循证诊疗策略与思考

通过典型的病例分析,分别从小儿巨大肾积水的概念、影像学诊断、无功能肾脏的判断以及治疗方式的选用等方面入手,结合循证医学实践的三大要素,包括利用最佳的临床研究证据、注重医生的专业技能和经验、尊重患者的期望和权利。简述临床上治疗小儿巨大肾积水时所应当采用的循证诊疗策略,以及从中引申出来的哲学思考。     

Image Interpretation: Bridging the Gap from Mechanically Produced Image to Representation

There is currently a gap in our understanding of how figures produced by mechanical imaging techniques play evidential roles: several studies based on close examination of scientific practice show that imaging techniques do not yield data whose significance can simply be read off the image. If image-making technology is not a simple matter of nature re-presenting itself to us in a legible way, just how do the images produced provide support for scientific claims? In this article I will first show that there is a distinct question about the semiotics of mechanically produced images that has not yet been answered. I show that my account of visual representations can do so, and I argue that the role of convention involved in my account is compatible with the view that visual representations produced through mechanized imaging techniques can play genuine evidential roles in scientific reasoning.     

The Inner Game of Sport: is Everything in the Brain?

The article deals with the following: (1) Three brain imaging studies on athletes are evaluated. What do these neuroscientific studies tell us about the brain and mind of the athlete? (2) Empirical investigations will need a neuro-theory of mind if they are to make the leap from neural activity to the mental. The article looks at such a theory, Gerald Edelman's ‘Neural Darwinism’. What are the implications of such a theory for sport science and philosophy of sport? (3) The article appreciates some of the neurosciences applications, but questions the hope of giving a complete theory of mind.     

Shedding light on brain function: the event-related optical signal

One of the basic goals of cognitive psychology is the analysis of the covert processes that occur between stimulus and response. In the past 20-30 years, the tools available to cognitive psychologists have been augmented by a number of imaging techniques for studying the 'brain in action' in a non-invasive manner. These techniques have their strength in either temporal or spatial information, but not both. We review here recent advances of a new approach, the event-related optical signal (EROS). This method allows measurements of the time course of neural activity in specific cortical structures, thus combining good spatial and temporal specificity. As an example, we show how EROS can be used to distinguish between serial and parallel models of information processing.     

Mental rotation and the parietal question in functional neuroimaging: A discussion of two views

This review addresses the meaning of parietal activation in functional imaging studies of mental rotation. It focuses on parietal activity with primary reference to the 3‐D cube array task. Key functional imaging studies of mental rotation are surveyed to bring forth two current perspectives on the meaning of parietal activation: (1) a dominant mechanism for whole‐object coordinate transformation which accounts for the parietal‐based “bulk” of mental rotation, and (2) various visuospatial parietal mechanisms including but not dominated by a coordinate transformational mechanism, which only together account for the strength of parietal activation. The centrality of coordinate transformations, particularly to the first perspective, is highlighted. Many basic questions about rotational coordinate mechanics are posed—suggesting some specific issues for future work on functional imaging of mental rotation. This article simply attempts to lay out the dominant perspectives of parietal activation in mental rotation, how they have gained validity, and the complications they face when discrete computations on which they hinge, are factored in.     

Synchronising self-displacement with a cross-traffic gap: How does the size of traffic vehicles impact continuous speed regulations?

In this article, we investigated what visual information is used by drivers at a road crossing when they want to synchronize their displacement with that of an incoming traffic train. We made the hypothesis that synchronizing self-displacement with that of a traffic gap shares the same perceptual-motor basis as interception tasks. While a large body of literature demonstrates that bearing angle is used to control interception, another range of studies points to optical size and expansion as playing a critical role in collision avoidance. In order to test the hypothesis of the exclusive use of bearing angle in road crossing task, we manipulated the optical size and expansion of oncoming traffic elements independently of bearing angle variations. We designed a driving simulator study in which participants were to adjust their approach speed in order to cross a road junction within a moving traffic gap. We manipulated the initial offset of participants with the traffic gap, the geometry of the road junction and the way optical size of oncoming traffic elements evolves over the course of a trial. Our results showed an effect of optical size and optical expansion manipulations eventhough, we also found similar displacement profiles as in interception studies. This demonstrates that bearing angle could not explain alone the control of such a complex perceptual-motor task. We discuss these results with regard to similar results in other fields of literature.     

Spatiotemporal dynamics of long-term potentiation in rat insular cortex revealed by optical imaging

Long-term potentiation (LTP) of the gustatory cortex (GC), a part of the insular cortex (IC) around the middle cerebral artery, is a key process of gustatory learning and memory, including conditioned taste aversion learning. The rostral (rGC) and caudal GC (cGC) process different tastes; the rGC responds to hedonic and the cGC responds to aversive tastes. However, plastic changes of spatial interaction of excitatory propagation between the rGC and cGC remain unknown. The present study aimed to elucidate spatiotemporal profiles of excitatory propagation, induced by electrical stimulation (five train pulses) of the rGC/cGC before and after LTP induction, using in vivo optical imaging with a voltage-sensitive dye. We demonstrated that tetanic stimulation of the cGC induced long-lasting expansion of the excitation responding to five train stimulation of the cGC, and an increase in amplitude of optical signals in the IC. Excitatory propagation after LTP induction spread preferentially toward the rostral IC: the length constant (λ) of excitation, obtained by fitting optical signals with a monoexponential curve, was increased to 121.9% in the rostral direction, whereas λ for the caudal, dorsal, and ventral directions were 48.9%, 44.2%, and 62.5%, respectively. LTP induction was prevented by pre-application of D-APV, an NMDA receptor antagonist, or atropine, a muscarinic receptor antagonist, to the cortical surface. In contrast, rGC stimulation induced only slight LTP without direction preference. Considering the different roles of the rGC and cGC in gustatory processing, these characteristic patterns of LTP in the GC may be involved in a mechanism underlying conversion of palatability.     

Advances in magnetic resonance imaging methods for the evaluation of bipolar disorder

This article reviews the current state of magnetic resonance imaging techniques as applied to bipolar disorder. Addressed are conventional methods of structural neuroimaging and recently developed techniques. This latter group comprises volumetric analysis, voxel-based morphometry, the assessment of T2 white matter hyperintensities, shape analysis, cortical surface-based analysis, and diffusion tensor imaging. Structural analysis methods used in magnetic resonance imaging develop exponentially, and now present opportunities to identify disease-specific neuroanatomic alterations. Greater acuity and complementarity in measuring these alterations has led to the generation of further hypotheses regarding the pathophysiology of bipolar disorder. Included in the summary of findings is consideration of a resulting neuroanatomic model. Integrative issues and future directions in this relatively young field, including multi-modal approaches enabling us to produce more comprehensive results, are discussed.