The subjective visual vertical: validation of a simple test

The study sought to provide norms for a simple test of visual perception of verticality (subjective visual vertical). The study was designed as a cohort study with a balanced design. The setting was the Rehabilitation Department of a University Hospital. Twenty-two healthy adults, of 23-58 years, 11 men (three left handed) and 11 women (three left handed) were enrolled. A luminous bar was displayed on a PC screen, and rotated in steps of 0.4° until the participant perceived it as vertical. A positive sign was attributed to a clockwise rotation of the bar. The detection threshold was set at the angle corresponding to a perceived vertical, which the participant then selected out of three subsequent alternatives (each at +0.4 or -0.4°). The participant's position (sitting vs. standing) and the preset angle of presentation (clockwise vs. counterclockwise) were balanced across sex. The constant or deviation error (dE, in degrees) and the absolute errors (aE, in degrees) were computed. An analysis of variance model tested the dependence of dE on sex, posture, age, handedness, and the preset angle. Both dE and aE were unrelated to sex, posture, handedness, and the preset angle, but were dependent on age (junior, ≤43 years; senior, >43 years). The mean dE was -0.14 ± 0.60 in the junior and 0.42 ± 0.64 in the senior group, respectively. The minimal real difference of the dE was 0.75 and 0.25 in the junior and the senior group, respectively. The overall median aE was 0.4 (5th-95th percentile 0-1.2) in the junior and 0.8 (0.4-1.46) in the senior group, respectively. The whole test took no longer than 15 min in healthy participants, and 25 min in stroke patients. The test was applied to three subacute stroke patients with left hemiparesis, of whom two showed left spatial hemineglect. All three patients presented with a significant clockwise dE. This simple test appears to be valid for the routine assessment of spatial disorders in neurological impairments.     

Neural correlates of individual ratings of emotional salience: a trial-related fMRI study

Accurate appraisal of meaningful environmental signals involves the interpretation of salient information for their intrinsic emotional value and personal relevance. We examined the neural basis for these components of endogenous salience during such appraisals using trial-related functional magnetic resonance imaging (fMRI). Subjects viewed affective pictures and assessed either the emotional intensity or extent of self-relatedness of the content of those pictures. In a parametric factorial design, individualized subjective ratings of these two dimensions were correlated with brain activity. The nucleus accumbens (NAcc) responded to both increasing emotional intensity and self-relatedness. Activity in the amygdala was specifically related to affective judgments and emotional intensity. The volitional act of appraising the extent of personal association specifically engaged the ventral medial prefrontal cortex (MPFC), and additionally recruited dorsal medial frontal regions and insula as the extent of self-relatedness increased. The findings highlight both overlapping and segregated neural representations of intrinsic value and personal relevance during the appraisal of emotional stimuli.     

汉语言自由联想功能磁共振的初步研究

目的设计一种适合汉语言自由联想的脑功能磁共振刺激任务,探索汉语言自由联想脑功能区表现。材料与方法对19名健康汉语志愿者进行任务态自由联想语言功能刺激,同时采集功能性磁共振成像(functional magnetic resonance imaging,f MRI)数据,通过SPM8软件分析获取自由联想任务相关主要脑功能区位置,激活大小及最大激活强度。结果汉语自由联想主效应区位于右颞上回(BA21);左颞枕内侧回、左海马旁回在联想任务中没有激活信号,双侧海马的激活程度较低。结论利用该语言任务能激活正常人自由联想语言功能区;同时血氧水平依赖性功能磁共振成像(blood oxygen level dependent functional magnetic resonance imaging,BOLD-f MRI)可以准确定位激活区,量化激活区大小及最大激活强度,技术稳定可靠,适用于汉语言联想相关脑功能区疾病研究。     

简易气管套管加湿过滤器的制作与应用

介绍了一种简易气管套管加湿过滤器的制作与应用方法.气管切开后由于人体天然保护屏障作用消失,气道湿化和过滤是保持气管切开后呼吸道通畅的一项重要措施.     

Simultaneous ERP and fMRI of the auditory cortex in a passive oddball paradigm

Infrequent occurrences of a deviant sound within a sequence of repetitive standard sounds elicit the automatic mismatch negativity (MMN) event-related potential (ERP). The main MMN generators are located in the superior temporal cortex, but their number, precise location, and temporal sequence of activation remain unclear. In this study, ERP and functional magnetic resonance imaging (fMRI) data were obtained simultaneously during a passive frequency oddball paradigm. There were three conditions, a STANDARD, a SMALL deviant, and a LARGE deviant. A clustered image acquisition technique was applied to prevent contamination of the fMRI data by the acoustic noise of the scanner and to limit contamination of the electroencephalogram (EEG) by the gradient-switching artifact. The ERP data were used to identify areas in which the blood oxygenation (BOLD) signal varied with the magnitude of the negativity in each condition. A significant ERP MMN was obtained, with larger peaks to LARGE deviants and with frontocentral scalp distribution, consistent with the MMN reported outside the magnetic field. This result validates the experimental procedures for simultaneous ERP/fMRI of the auditory cortex. Main foci of increased BOLD signal were observed in the right superior temporal gyrus [STG; Brodmann area (BA) 22] and right superior temporal plane (STP; BA 41 and 42). The imaging results provide new information supporting the idea that generators in the right lateral aspect of the STG are implicated in processes of frequency deviant detection, in addition to generators in the right and left STP.     

The BOLD fMRI refractory effect is specific to stimulus attributes: evidence from a visual motion paradigm

Functional magnetic resonance imaging (fMRI) studies have demonstrated that the blood oxygenation level-dependent (BOLD) hemodynamic response (HDR) to a stimulus is reduced by the previous presentation of a similar stimulus. We investigated the dependence of this refractory effect upon stimulus characteristics using a novel adaptation paradigm while scanning subjects using fMRI at 4 T. The stimuli were composed of horizontal stripes that scrolled up, scrolled down, or remained static, randomly presented for 1-s duration with stimulus-onset asynchronies (SOAs) of 2-7 s. We identified regions of interest (ROI) in lateral temporal--occipital cortex that were activated by motion stimuli, regardless of direction or SOA. We found strong evidence for direction specificity in motion-sensitive lateral temporal-occipital (LTO) cortex. For stimuli whose direction of motion reprised that of the previous stimulus (e.g., up preceded by up), the fMRI response was attenuated at short SOAs (2-4 s) compared to long SOAs (5-7 s). However, for stimuli whose direction of motion was opposite that of the previous stimulus (e.g., up preceded by down), little or no refractory effect was observed. Additionally, examination of activity in pericalcarine cortex indicated a similar pattern. We conclude that the fMRI refractory effect predominantly reflects local stimulus-specific neuronal or neurovascular adaptation and is unlikely to be a nonspecific response of large vessels that support broad functional regions.     

Separating subjective emotion from the perception of emotion-inducing stimuli: an fMRI study

fMRI was used to dissociate neural responses temporally associated with the subjective experience of emotion from those associated with the perception of emotion-inducing stimuli in order to better define the emotion-related functions of the amygdala, lateral orbital frontal cortex (OFC), and hippocampus. Subjects viewed aversive pictures followed by an extended post-stimulus period of sustained subjective emotion. Brain regions showing activation paralleling the period of sustained subjective emotion were distinguished from those showing activation limited to the period of aversive picture presentation. Behavioral results showed that subjective ratings of emotion remained elevated for 20 s after offset of the aversive pictures. fMRI results showed that viewing aversive pictures activated the amygdala, lateral OFC, and hippocampus. Subjective emotion (present both during and after aversive pictures) was temporally associated with activation in the right lateral OFC and left hippocampus but not the amygdala. Ratings of subjective emotion were correlated with activation in the right lateral OFC and left hippocampus. The results support direct amygdala involvement in emotion perception but suggest that amygdala activation is not temporally associated with subjective emotion that occurs after the offset of emotion-related stimuli. The results are consistent with a general role for the lateral OFC in monitoring or reflecting on internal experience and show that hippocampal activation is sustained during a period of subjective emotion, possibly related to enhanced memory encoding for the aversive pictures.     

Hidden Markov multiple event sequence models: A paradigm for the spatio-temporal analysis of fMRI data

This paper presents a novel, completely unsupervised fMRI brain mapping method that addresses the three problems of hemodynamic response function (HRF) variability, hemodynamic event timing, and fMRI response non-linearity. Spatial and temporal information are directly taken into account into the core of the activation detection process. In practice, activation detection at voxel v is formulated in terms of temporal alignment between sequences of hemodynamic response onsets (HROs) detected in the fMRI signal at v and in the spatial neighborhood of v, and the input sequence of stimuli or stimulus onsets. Event-related and epoch paradigms are considered. The multiple event sequence alignment problem is solved within the probabilistic framework of hidden Markov multiple event sequence models (HMMESMs), a new class of hidden Markov models. Results obtained on real and synthetic data significantly outperform those obtained with the popular statistical parametric mapping (SPM2) method without requiring any prior definition of the expected activation patterns, the HMMESM mapping approach being completely unsupervised.     

Optimizing the experimental design for ankle dorsiflexion fMRI

Compared to motor studies of the upper limb, few experiments have sought a relationship between blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) sensorimotor signals and the resulting lower limb output. In Experiment 1, using an fMRI simulator system, we determined the optimized experimental protocol based on two design types and four behavioral movement types during ankle dorsiflexion. Experiment 2 involved testing the BOLD sensitivity at 1.5 T during ankle movements. Subjects performed large- and small-amplitude dorsiflexion movement types using an event-related design, with the intent of contrasting spatial and temporal features of the BOLD signal. In both experiments, the subject's behavior was guided by visual biofeedback of their ankle flexion angle, using an MR-compatible fiberoptic tape. From Experiment 1, we found electromyography (EMG) difference voltage ratio of approximately 2:1 for large (40 degrees ) and small (15 degrees ) dorsiflexion, 0.13 mV and 0.07 mV, respectively. In Experimental 2, we found the peak BOLD % signal changes of 1.04% and 0.89%, for large (40 degrees ) and small (15 degrees ) dorsiflexion, respectively. In addition, graded dorsiflexion produced graded BOLD signals in the primary sensorimotor and supplementary motor areas in 10 of 12 healthy young subjects, attesting to the feasibility of lower-limb fMRI at 1.5 T. This study provides insight into the cortical network involved in dorsiflexion using an experimental paradigm that is likely to translate effectively to hemiparetic stroke subjects.     

Psychometric validation of a subjective well-being measure for people with spinal cord injuries

Purpose: The researchers examined the factorial validity and the concurrent validity of the Sense of Well-Being Inventory (SWBI) based on a sample of Canadians with spinal cord injuries (SCI) in the community.

Method: One hundred thirty-two participants were recruited from the Alberta, Saskatchewan, Nova Scotia, and Manitoba chapters of the Canadian Paraplegic Association. Mean age of participants was 45.82 years (SD = 15.67), and 77% were men. The participants were asked to complete a research packet containing a demographic questionnaire, the SWBI, and the brief version of the World Health Organization Quality of Life questionnaire (WHOQOL-BREF).

Results: Factor analysis yield four factors (Psychological Well-Being, Financial Well-Being, Social and Family Well-Being, and Physical Well-Being) similar to the original SWBI. In addition, the SWBI factors in the present study correlated moderately well with the corresponding factors in the WHOQOL-BREF and with demographic variables appropriate to the respective subscale.

Conclusions: The factorial validity and the concurrent validity of the SWBI were generally supported. The SWBI, as a subjective well-being measure developed specifically to relate to disability and rehabilitation, appears useful for use with people with SCI in the community.     

The effect of Rapid Induction Analgesia on subjective pain ratings and pain tolerance

The effect of Rapid Induction Analgesia (RIA) on pain tolerance and ratings of mechanically induced pain in the pain-sensitized forearm was investigated in 58 undergraduates. Posthypnotic suggestions of relaxation and analgesia did not influence pain ratings or tolerance, but relaxation ratings increased after RIA. When suggestions for analgesia were made throughout pain testing, ratings of pain unpleasantness at the pain tolerance point decreased more in the RIA group than in the attention control group. However, RIA did not influence pain threshold or tolerance. It was concluded that RIA was more effective in reducing subjective reports of pain (particularly the affective component) than in altering pain tolerance, and that maintenance of hypnotic suggestions was more effective than posthypnotic suggestions of comfort and relaxation in alleviating the affective component of pain.     

Psychometric validation of a subjective well-being measure for people with spinal cord injuries

Purpose:?The researchers examined the factorial validity and the concurrent validity of the Sense of Well-Being Inventory (SWBI) based on a sample of Canadians with spinal cord injuries (SCI) in the community.

Method:?One hundred thirty-two participants were recruited from the Alberta, Saskatchewan, Nova Scotia, and Manitoba chapters of the Canadian Paraplegic Association. Mean age of participants was 45.82 years (SD?=?15.67), and 77% were men. The participants were asked to complete a research packet containing a demographic questionnaire, the SWBI, and the brief version of the World Health Organization Quality of Life questionnaire (WHOQOL-BREF).

Results:?Factor analysis yield four factors (Psychological Well-Being, Financial Well-Being, Social and Family Well-Being, and Physical Well-Being) similar to the original SWBI. In addition, the SWBI factors in the present study correlated moderately well with the corresponding factors in the WHOQOL-BREF and with demographic variables appropriate to the respective subscale.

Conclusions:?The factorial validity and the concurrent validity of the SWBI were generally supported. The SWBI, as a subjective well-being measure developed specifically to relate to disability and rehabilitation, appears useful for use with people with SCI in the community.     

The effect of rapid induction analgesia on subjective pain ratings and pain tolerance

The effect of Rapid Induction Analgesia (RIA) on pain tolerance and ratings of mechanically induced pain in the pain-sensitized forearm was investigated in 58 undergraduates. Posthypnotic suggestions of relaxation and analgesia did not influence pain ratings or tolerance, but relaxation ratings increased after RIA. When suggestions for analgesia were made throughout pain testing, ratings of pain unpleasantness at the pain tolerance point decreased more in the RIA group than in the attention control group. However, RIA did not influence pain threshold or tolerance. It was concluded that RIA was more effective in reducing subjective reports of pain (particularly the affective component) than in altering pain tolerance, and that maintenance of hypnotic suggestions was more effective than posthypnotic suggestions of comfort and relaxation in alleviating the affective component of pain.     

Artful design: writing the proposal for research in the naturalist paradigm

The preparation of the research proposal for a study that involves an emergent research design compels the investigator to negotiate the paradox of planning what should not be planned in advance. This paper is a guide to writing the proposal for research in the naturalist paradigm, and includes illustrative sections of a proposal recently funded by the National Center for Nursing Research.     

The correlates of subjective perception of identity and expression in the face network: an fMRI adaptation study

The recognition of facial identity and expression are distinct tasks, with current models hypothesizing anatomic segregation of processing within a face-processing network. Using fMRI adaptation and a region-of-interest approach, we assessed how the perception of identity and expression changes in morphed stimuli affected the signal within this network, by contrasting (a) changes that crossed categorical boundaries of identity or expression with those that did not, and (b) changes that subjects perceived as causing identity or expression to change, versus changes that they perceived as not affecting the category of identity or expression. The occipital face area (OFA) was sensitive to any structural change in a face, whether it was identity or expression, but its signal did not correlate with whether subjects perceived a change or not. Both the fusiform face area (FFA) and the posterior superior temporal sulcus (pSTS) showed release from adaptation when subjects perceived a change in either identity or expression, although in the pSTS this effect only occurred when subjects were explicitly attending to expression. The middle superior temporal sulcus (mSTS) showed release from adaptation for expression only, and the precuneus for identity only. The data support models where the OFA is involved in the early perception of facial structure. However, evidence for a functional overlap in the FFA and pSTS, with both identity and expression signals in both areas, argues against a complete independence of identity and expression processing in these regions of the core face-processing network.     

Performance and validation of a simplified postoperative atrial fibrillation risk score

Background

Postoperative atrial fibrillation (POAF) occurs in 20–40% patients who received isolated coronary artery cardiac bypass surgery (CABG). Several POAF risk prediction models have been developed, but none of them is widely adopted in practice. Our objective was to derive and validate a simple scoring system to estimate POAF risk after isolated CABG, using easily available clinical information.

Methods

Medical records of 1,000 consecutive patients undergoing isolated CABG were reviewed. The data of first 700 patients were used for model derivation and data of the remaining 300 patients were used for model validation. Discrimination and calibration of the newly developed model were assessed.

Results

POAF incidence in both the derivation and validation cohorts was 27.3%. Age ≥65, history of hypertension, heart failure, and myocardial infarction were independently associated with POAF risk. Risk scores were calculated by summing weighting points for each independent predictor. The score ≥3 was associated with high POAF incidence (41.1% in the derivation cohort and 44.3% in the validation cohort). The positive and negative POAF predictive value was 41.1% and 78.5%, respectively, in the derivation cohort, and 44.3% and 80.8%, respectively, in the validation cohort, when the cut‐point score ≥3 was used. The Hosmer–Lemeshow goodness‐of‐fit test P‐values were 0.917 and 0.894 in the derivation cohort and validation cohort, respectively.

Conclusions

This POAF risk following isolated CABG can be predicted with simple patient characteristic during the preoperative period. Patients with high risk scores (≥3) may constitute a target population for POAF prevention and prolonged postoperative surveillance.

     

The emergence of doing "nothing" as a viable paradigm design

Resting state fMRI has become widely accepted as a viable technique for investigating functional connectivity of the human brain. I review from a personal perspective the events of the first 8-10 years after the initial report of resting state functional connectivity, focusing on the events that led to eventual acceptance of the method. During this time there were important studies, both in MRI and other modalities, that were critical to the eventual acceptance of the resting state as a viable research tool in fMRI.