Attention to single letters activates left extrastriate cortex

Brain imaging studies examining the component processes of reading using words, non-words, and letter strings frequently report task-related activity in the left extrastriate cortex. Processing of these linguistic materials involves varying degrees of semantic, phonological, and orthographic analysis that are sensitive to individual differences in reading skill and history. In contrast, single letter processing becomes automatized early in life and is not modulated by later linguistic experience to the same degree as are words. In this study, skilled readers attended to different aspects (single letters, symbols, and colors) of an identical stimulus set during separate sessions of functional magnetic resonance imaging (fMRI). Whereas activation in some portions of ventral extrastriate cortex was shared by attention to both alphabetic and non-alphabetic features, a letter-specific area was identified in a portion of left extrastriate cortex (Brodmann's Area 37), lateral to the visual word form area. Our results demonstrate that while minimizing activity related to word-level lexical properties, cortical responses to letter recognition can be isolated from figural and color characteristics of simple stimuli. The practical utility of this finding is discussed in terms of early identification of reading disability.     

Touch activates human auditory cortex

Vibrotactile stimuli can facilitate hearing, both in hearing-impaired and in normally hearing people. Accordingly, the sounds of hands exploring a surface contribute to the explorer's haptic percepts. As a possible brain basis of such phenomena, functional brain imaging has identified activations specific to audiotactile interaction in secondary somatosensory cortex, auditory belt area, and posterior parietal cortex, depending on the quality and relative salience of the stimuli. We studied 13 subjects with non-invasive functional magnetic resonance imaging (fMRI) to search for auditory brain areas that would be activated by touch. Vibration bursts of 200 Hz were delivered to the subjects' fingers and palm and tactile pressure pulses to their fingertips. Noise bursts served to identify auditory cortex. Vibrotactile-auditory co-activation, addressed with minimal smoothing to obtain a conservative estimate, was found in an 85-mm3 region in the posterior auditory belt area. This co-activation could be related to facilitated hearing at the behavioral level, reflecting the analysis of sound-like temporal patterns in vibration. However, even tactile pulses (without any vibration) activated parts of the posterior auditory belt area, which therefore might subserve processing of audiotactile events that arise during dynamic contact between hands and environment.     

Imagery for shapes activates position-invariant representations in human visual cortex

In this study, we show that top-down control mechanisms engaged during visual imagery of simple shapes (letters X and O) can selectively activate position-invariant perceptual codes in visual areas specialised for shape processing, including lateral occipital complex (LOC). First, we used multivoxel pattern analysis (MVPA) to identify visual cortical areas that code for shape within a position-invariant reference frame. Next, we examined the similarity between these high-level visual codes and patterns elicited while participants imagined the corresponding stimulus at central fixation. Our results demonstrate that imagery engages object-centred codes in higher-level visual areas. More generally, our results also demonstrate that top-down control mechanisms are able to generate highly specific patterns of visual activity in the absence of corresponding sensory input. We argue that a general model of top-down control must account for dynamic modulation of functional connectivity between high-level control centres and overlapping neural codes in visual cortex.     

Head position modulates activity in the human parietal eye fields

For us to interact with our environment we need to know where objects are around us, relative to our body. In monkeys, a body-centered map of visual space is known to exist within the parietal eye fields. This map is formed by the modulation of retinal responses by gain fields to gaze position. In humans, no map of body-centered space has yet been discovered but clinical data suggest that the right parietal lobe is predominantly responsible for visuospatial function. Using functional MRI, we have been able to demonstrate that an area in the intraparietal sulcus of humans has properties very similar to the parietal eye fields of monkeys. This area demonstrates BOLD signal changes related to the visual, saccadic, and memory components of saccade tasks that are analogous to the visual, saccadic, and memory responses of neurons within the parietal eye fields of monkeys. More importantly, the amount of signal change seen in this region is modulated by head position relative to the body, suggesting that a gain field dependent body-centered representation of space exists bilaterally within the parietal lobes in humans.     

Effector-specific fields for motor preparation in the human frontal cortex

We investigated the neural correlates of advance motor preparation in two experiments that required a movement in response to a peripheral visual stimulus. In one experiment (the memory delay paradigm), subjects knew the target location during a preparatory 'memory delay' interval; in the other experiment they did not know the target location during a 'gap period' (the gap paradigm). In both experiments we further varied the effector that was instructed, either the eye or the forelimb. An area that codes motor preparation should exhibit increases during the memory delay and gap period and such increases should predict some attribute of performance (planning to use the eye or the forelimb). We first identified the frontoparietal visuomotor areas using standard fMRI block designs. Subjects were then scanned using event-related fMRI. With the exception of primary motor cortex (M1), all areas (putative lateral intraparietal area (putLIP), dorsal premotor cortex (PMd), frontal eye field (FEF), ventral frontal eye field (FEFv), supplementary motor area (SMA)) showed gap and memory delay activation for both saccades and pointing. Gap activity in the frontal areas was higher than in the parietal area(s) investigated. The observation that 'memory delay' activity was equivalent or less than gap activity in all areas suggests that what is commonly considered to be memory-related responses largely represents advance motor preparation. Certain areas showed increased activation during the gap or memory delay intervals for pointing (PMd, FEF, FEFv) or saccades (SMA, putLIP). These observations suggest an important role of the frontal cortex in advance motor preparation.     

颌面部手术3种眼保护法效果研究

颌面部手术的消毒不仅要求达到消毒效果,还应避免消毒液引起色素沉着而影响美观.手术中颌面部常规使用的消毒液为0.5%的氯已定乙醇溶液[1].     

The encoding of saccadic eye movements within human posterior parietal cortex

Over the last few years, several functionally distinct subregions of the posterior parietal cortex (PPC) have been shown to subserve oculomotor control. Since these areas seem to overlap with regions whose activation is related to attention, we used functional magnetic resonance imaging to compare the cerebral activation pattern evoked by eye movements with different attentional loads, i.e., oscillatory saccades with different frequencies, as well as predictable, and unpredictable saccades. Our results show activation in largely overlapping networks with differing strength of activity and symmetry of involved areas. Predictable saccades having the shortest saccadic latency led to the most pronounced cerebral activity both in terms of cortical areas involved and signal intensity. Predictable and unpredictable saccades were dominated by activation within the right hemisphere, whereas oscillatory saccades showing the longest saccadic latency were dominated by activation within the left hemisphere. In all tasks, the centers of gravity of activation occurred within the posterior part of the intraparietal sulcus (IPS), while the predictable saccades additionally activated its anterior part. The enhanced activity during the execution of predictable saccades was probably related to top-down processing and/or the preparation of the upcoming eye movement. The hemispheric difference could arise from a predominant role of the right PPC for shifting spatial attention and the left PPC for shifting temporal attention. The differential encoding of saccadic eye movements within IPS indicates that the PPC splits up into different functional modules related to the particular demands of a saccade.     

Real-time monitoring of eye movements using infrared video-oculography during functional magnetic resonance imaging of the frontal eye fields

Monitoring eye movements is a critical aspect of experimental design for studies of spatial attention and visual perception. However, obtaining online eye-movement recordings has been technologically difficult during functional magnetic resonance (MR) imaging studies. Previous approaches to monitoring eye movements either have distorted the MR images or have shown MR-related interference in the recordings. We report a technique using long-range infrared video-oculography to record eye movements without causing artifacts in the MR images. Analysis of the MR signal from a phantom obtained with the eye-movement equipment turned on or off confirmed the absence of significant additional noise in the MR time series. Eye movements of three subjects were monitored while they performed tasks of covert and overt shifts of spatial attention. Activation of the frontal eye fields during the covert task was seen even when the eye-movement recordings demonstrated no significant difference in saccadic eye movements between the baseline and the active conditions.     

Post-registration education in three fields of clinical practice.

This paper describes some empirical findings about the take-up of post-registration education by a substantial sample of clinical practitioners in three fields of practice--mental illness nursing, mental handicap nursing and midwifery. Some implications of the results are discussed in the context of the UKCC PREPP Report recommendations, as a contribution to the current debate about their implementation.     

Perinatal management of fetal hemolytic disease due to Rh incompatibility combined with fetal alloimmune thrombocytopenia due to HPA-5b incompatibility.

We report out experience in the perinatal management of a complex case of fetal hemolytic disease primarily due to Rhesus incompatibility combined with fetal alloimmune thrombocytopenia. The lowest fetal hemoglobin and platelet levels were 2.6 g/dl and 13,000/microliter, respectively. Intrauterine treatment consisted of six transfusions of packed red cells into the umbilical vein and one transfusion of platelets. The neonate required four transfusions of packed red cells to correct her hyporegenerative erythropoiesis. Postnatal management also included one platelet transfusion, intravenous immunoglobulins and erythropoietin. Although some degree of fetal thrombocytopenia may invariably be found in fetal red cell incompatibility, other rare causes need to be excluded.     

Predicting perceptual events activates corresponding motor schemes in lateral premotor cortex: an fMRI study

The ability to recognize sequential patterns of external events enables us to predict their future course and thus to plan and execute actions based on current perceptions and previous experiences. Here we show with functional magnetic resonance imaging that even in the absence of movement the prediction of sequential patterns activates brain areas involved in the representation of specific motor schemas. Particularly, the prediction of size engages premotor areas involved in hand movements (superior part of the ventrolateral premotor cortex), whereas the prediction of pitch engages premotor areas involved in articulation (inferior most ventrolateral premotor cortex). The findings indicate that events are mapped onto somatotopically corresponding motor schemes whenever we predict sequential perceptions.     

Enterobacterial tetracycline resistance in relation to plasmid incompatibility.

Sixty-eight well-characterized antibiotic resistance (R) plasmids belonging to 19 Incompatibility groups were screened with probes representing heterologous classes (A-E) of the enterobacterial tetracycline resistance (TcR) determinant. The Class B determinant was shown to be predominant in the IncF and IncH complexes and the IncC group. The Class A determinant was shown to be predominant in the IncP and IncM groups. There was no correlation between distribution of the class of TcR gene and the genus or the species of the host bacterial strain. The plasmids R714a (IncFI) and pHH1465 (IncC) contained TcR determinants which had no homology with any of these five probes.     

Retrieving autobiographical memories of painful events activates the anterior cingulate cortex and inferior frontal gyrus.

Patients will often reflect on the meaning of a painful episode, as, for example, when completing questionnaire measures of subjective pain experience or in clinical interviews. Neuroimaging studies of the human cortical and subcortical physical pain response have identified a neural network consistently referred to as the "pain matrix." We used functional magnetic resonance imaging to investigate whether the pain matrix could be activated through the retrieval of memories relating to previously painful events, in the absence of any direct peripheral noxious input. Fourteen pain-free participants were explicitly instructed to recall autobiographical memories of painful episodes in response to pain-related words and non-painful episodes in response to equally salient but non-pain words. Memories triggered by pain-related words produced significantly greater activation of left caudal anterior cingulate cortex (BA32'), and left inferior frontal gyrus (BA44, extending to BA47/45) more than memories triggered by equally salient but non-pain words. We suggest that these activations demonstrate a semantic retrieval process for pain-related memories, which may provide a means of cognitively reappraising the memory of the painful episode, thus allowing the person to elaborate on the circumstances surrounding the event, without physically re-experiencing it. PERSPECTIVE: The present study reveals a putative neural mechanism for the retrieval of autobiographical memories of previously painful events, which may provide a means of cognitively reappraising a painful episode, without physically re-experiencing it. This finding has implications for understanding disease mechanisms of chronic pain and their impact on subsequent treatment.     

食管癌三野清扫术围术期护理

[目的]探讨食管癌三野清扫术病人围术期护理，促进病人早期康复。[方法]对15例食管癌行三野清扫术的病人加强围术期护理，密切观察病情变化，加强管道护理、呼吸道管理、营养支持、疼痛护理及并发症的观察与护理。[结果]术后病人出现肺部感染4例，心律失常3例，声音嘶哑3例，颈部吻合口瘘2例，经积极治疗和护理，均康复出院。[结论]加强围术期护理，对减少并发症的发生，促进病人早日康复有重要的意义。     

食管癌三野清扫术围术期护理

[目的]探讨食管癌三野清扫术病人围术期护理,促进病人早期康复.[方法]对15例食管癌行三野清扫术的病人加强围术期护理,密切观察病情变化,加强管道护理、呼吸道管理、营养支持、疼痛护理及并发症的观察与护理.[结果]术后病人出现肺部感染4例,心律失常3例,声音嘶哑3例,颈部吻合口瘘2例,经积极治疗和护理,均康复出院.[结论]加强围术期护理,对减少并发症的发生,促进病人早日康复有重要的意义.     

A rapid topographic mapping and eye alignment method using optical imaging in Macaque visual cortex

In optical imaging experiments, it is often advantageous to map the field of view and to converge the eyes without electrophysiological recording. This occurs when limited space precludes placement of an electrode or in chronic optical chambers in which one may not want to introduce an electrode each session or for determining eye position in studies of ocular disparity response in visual cortex of anesthetized animals. For these purposes, we have developed a spot imaging method that can be conducted rapidly and repeatedly throughout an experiment. Using small 0.2°–0.5° spots, the extent of the imaged field of view is mapped by imaging cortical response to single spots, placed at different positions (0.2° steps) in either the horizontal or vertical axes. By shifting the relative positions of two spots, one presented to each eye, eye convergence can be assessed to within 0.1° resolution. Once appropriate eye alignment is determined, stimuli for further optical imaging procedures (e.g. imaging random dot stimuli for study of disparity responses) can then be confidently placed. This procedure can be quickly repeated throughout the experiment to ensure maintained eye alignment.