A comparison of clustering solutions for cognitive heterogeneity in schizophrenia

This study investigated semantic priming for literal (stinging-mosquito) and metaphoric (stinging-insult) associates presented to either the left or right visual fields (RVF/LVF) across stimulus-onset-asynchronies (SOA) of 200 and 800 ms. For the short SOA condition, facilitation was found for metaphorically related targets in both visual fields (VFs) while literally related targets were facilitated only in the RVF. For the long SOA condition, metaphorically related targets were facilitated in the LVF whereas literally related targets were facilitated in the RVF. These results support previous findings indicating an enhanced role of the RH in metaphoric comprehension. In addition, the present results are in accordance with current models of hemispheric semantic processing.     

Visual form discrimination from texture cues: a PET study

With the purpose of localising the cerebral cortical areas participating in the discrimination of visual form generated exclusively by texture cues, we measured changes in regional cerebral blood flow (rCBF) with positron emissions tomography (PET) and 15O-butanol as the tracer. The subjects performed two odd-one-out discrimination tasks: a form-from-texture discrimination task (in which a visual form was defined by differences in texture) and its reference task, the discrimination of texture. During task performance, activated fields were present bilaterally in the primary visual cortex and its immediate extrastriate cortex, the right lateral occipital gyrus, bilaterally in the fusiform and superior temporal gyri and posterior parts of the superior parietal lobules, along the medial bank of the right intraparietal sulcus, and in the right supramarginal gyrus. Other fields were found in the cingulate and prefrontal cortex. The findings demonstrate that the discrimination of visual form as defined by texture engages cortical fields that are widely distributed ion the human brain. In the visual cortex, the activated fields are present in both the occipito-temporal and occipito-parietal visual areas. These results suggest that the perception and discrimination of forms in the visual system requires the joint-activation of neuronal populations in the visual cortex.     

TOUSLED participates in apical tissue formation during gynoecium development in Arabidopsis

Mutations at the TOUSLED (TSL) protein kinase locus in Arabidopsis cause reduced differentiation of apical gynoecial tissues and eliminate the fusion of the style and septum. TSL expression becomes confined to the developing style by stage 13, where it may promote expansion of tissues. Double mutant analysis suggests that ETTIN interacts with TSL, possibly by restricting TSL expression to apical regions. TSL, LEUNIG, and PERIANTHIA appear to participate in pathways of redundant function during the development of specific gynoecial tissues. TSL and LEUNIG most likely function in similar pathways during ovule development. TSL acts independently of the function of the organ identity genes AGAMOUS and APETALA2, and it is required for the formation of specific tissues in ectopic carpels. Mutations in TSL, ETTIN, PERIANTHIA, and LEUNIG all affect floral organ number as well as gynoecium morphology. Their respective wild-type loci must therefore play important roles in early floral meristem development during initiation of organ primordia in addition to their functions during regional differentiation within developing gynoecial primordia.     

Patterns of visual field progression in patients with retinitis pigmentosa

OBJECTIVE: The purpose of the study was to determine whether distinct patterns of visual field progression are present in patients with retinitis pigmentosa (RP) and to evaluate the correlation between these patterns, if present, and different genetic subtypes of RP. DESIGN: A retrospective analysis of patterns of visual field progression in RP was performed. PARTICIPANTS: Visual fields of 162 patients with RP, including 55 with type 2 Usher syndrome, who had at least 3 Goldmann visual field examinations during a period of at least 3 years were reviewed. MAIN OUTCOME MEASURES: Goldmann visual fields. RESULTS: Visual fields of 86 patients could be classified into one of three specific patterns of visual field progression. Pattern I included those patients with a progressive concentric loss of visual fields; pattern II included those with visual field loss that began superiorly and subsequently developed an arcuate scotoma that progressed either from the nasal (IIA) or the temporal (IIB and IIC) side; and pattern III included patients whose visual field loss was characterized initially by a complete or incomplete midperipheral "ring scotoma" that broke through into the periphery. The end stage of all these patterns was a residual central visual field, sometimes also associated with a small peripheral island. In 53 of the 162 patients, the pattern of visual field loss could not be categorized because of an advanced stage of field loss at the time of the initial examination. CONCLUSIONS: Distinctive patterns of visual field progression can be observed in patients with retinitis pigmentosa and type 2 Usher syndrome. There were no intrafamilial variations in the pattern of visual field loss in our data on 24 patients from 11 families. Within certain genetic subtypes, there was a predilection for a preponderance of a specific pattern of visual field progression. Future studies may be able to correlate these patterns of visual field loss with different genetic mutations. A greater understanding as to why certain patterns of field loss exist could potentially provide greater insight into the various pathogenetic mechanism(s) by which photoreceptor cells degenerate in this group of patients.     

Mutations synthetically lethal with tpm1delta lie in genes involved in morphogenesis

Yeast contains two genes, TPM1 and TPM2, encoding tropomyosins, either of which can provide an essential function in the yeast cytoskeleton. To elucidate more clearly the function of the major tropomyosin, encoded by TPM1, we have isolated mutations that confer synthetic lethality with the null mutant of TPM1. Here we describe a phenotypic and genetic analysis of mutations in TSL1/BEM2, TSL2, TSL3, TSL5, and TSL6 (tropomyosin synthetic lethal). All the mutants exhibit clear morphological and some actin cytoskeletal defects, but are not noticeably defective in secretion, endocytosis, or organelle segregation. The lethality conferred by tsl tpm1delta mutations could be specifically suppressed by either TPM1 or an additional copy of TPM2. This implies that the essential function compromised in the tsl tpm1delta constructs is the same essential function for which Tpm1p or Tpm2p is necessary. Synthetic interactions and unlinked noncomplementation were observed between the tsl mutants, suggesting that they participate in related functions involving morphogenesis. In support of this, tsl6-1 was identified as an allele of the nonessential gene SLT2 or MPK1 whose product is a MAP kinase regulating cell wall synthesis. These results indicate that this synthetic lethality approach provides a sensitive screen for the isolation of mutations affecting morphogenesis, many of which are likely to be in nonessential genes, like BEM2 and SLT2.     

Eye position influence on the parieto-occipital area PO (V6) of the macaque monkey

The aim of this work was to study the effect of eye position on the activity of neurons of area PO (V6), a cortical region located in the most posterior part of the superior parietal lobule. Experiments were carried out on three awake macaque monkeys. Animals sat in a primate chair in front of a large screen, and fixated a small spot of light projected in different screen locations while the activity of single neurons was extracellularly recorded. Both visual and non-visual neurons were found. About 48% of visual and 32% of non-visual neurons showed eye position-related activity in total darkness, while in approximately 61% of visual response was modulated by eye position in the orbit. Eye position fields and/or gain fields were different from cell to cell, going from large and quite planar fields up to peak-shaped fields localized in more or less restricted regions of the animal's field of view. The spatial distribution of fixation point locations evoking peak activity in the eye position-sensitive population did not show any evident laterality effect, or significant top/bottom asymmetry. Moreover, the cortical distribution of eye position-sensitive neurons was quite uniform all over the cortical region studied, suggesting the absence of segregation for this property within area PO (V6). In the great majority of visual neurons, the receptive field 'moved' with gaze according to eye displacements, remaining at the same retinotopic coordinates, as is usual for visual neurons. In some cases, the receptive field did not move with gaze, remaining anchored to the same spatial location regardless of eye movements ('real-position cells'). A model is proposed suggesting how eye position-sensitive visual neurons might build up real-position cells in local networks within area PO (V6). The presence in area PO (V6) of real-position cells together with a high percentage of eye position-sensitive neurons, most of them visual in nature, suggests that this cortical area is engaged in the spatial encoding of extrapersonal visual space. Since lesions of the superior parietal lobule in humans produce deficits in visual localization of targets as well as in arm-reaching for them, and taking into account that the monkey's area PO (V6) is reported to be connected with the premotor area 6, we suggest that area PO (V6) supplies the premotor cortex with the visuo-spatial information required for the visual control of arm-reaching movements.     

Cataract and high-pass resolution perimetry

The present study describes the influence of cataract on high-pass resolution perimetry results. Twenty-five otherwise healthy patients were examined before and after cataract surgery. Their preoperative visual acuities ranged from 0.1 to 0.8 and their mean resolution thresholds from 3.9 to 12.3 dB. Both elevated mean thresholds and local visual fields defects were observed. In patients with low-grade cataract, i.e. preoperative visual acuity 0.3 to 0.65, the mean improvement in perimetric results after operation was approximately 1 dB. In patients with higher degrees of lens opacity, visual acuity 0.1 to 0.25, the difference between pre- and postoperative perimetry results showed a wide range, 1.4-6.2 dB. In conclusion, cataract induced different types of visual field defects. The general threshold increase due to low-grade cataract (VA > or = 0.3) could be compensated for by subtracting 1 dB from the measured value.     

Naso-temporal asymmetry of spatial interactions in strabismic amblyopia

PURPOSE: Naso-temporal asymmetries of visual acuity and contrast sensitivity have been reported in strabismic amblyopia and attributed to asymmetries of interocular suppression. In this study, we investigated the naso-temporal asymmetry of cortical spatial interactions in two strabismic amblyopes (one esotrope and one exotrope). METHODS: Length and width Westheimer functions were measured on both amblyopes at the 10 deg retinal eccentricity of both nasal and temporal visual fields. RESULTS: Spatial interactions in the two amblyopic eyes were more degraded in the temporal visual fields than in the nasal visual fields. A comparison with results from the preferred eyes suggested that this asymmetry was caused mainly by a loss of spatial interactions in the temporal visual fields of amblyopic eyes, with those in the nasal visual fields being normal. CONCLUSION: Our results suggest that intracortical connections underlying cortical spatial interactions might have been degraded by amblyopia. This degradation exists not only in the areas of the strabismic visual cortex responding to foveal stimuli but also in those responding to stimuli presented in the temporal visual fields.     

Irrelevant peripheral visual stimuli impair manual reaction times in Parkinson's disease

In three experiments, the effects of irrelevant visual information on the time to initiate and to complete a simple movement of the hand in response to a visual signal were studied in patients with a diagnosis of Parkinson's disease, and in age-matched normal controls. Subjects gazed at the centre of a TV monitor and were instructed to move their preferred hand from one metal plate to another as soon as a blue disc appeared in the centre of the screen. This control condition was compared with other conditions in which the surrounding area of the screen was simultaneously filled with fields of irrelevant discs, which in Experiment 1 were either stationary, or streamed out from or in towards the centre of the screen. Reaction times, but not movement times, were significantly slowed in the patients (but not the controls) by the irrelevant disc fields. When the irrelevant dots were continuously present (between as well as within trials--Experiment 2), they had no effect on RT. When they were present between trials, but turned off as the movement signal was turned on, RT was again slowed in patients. The results are discussed in relation to the akinesia ("freezing") experienced by some patients in confined spaces (such as doorways), and to possible abnormalities of visual cortical and striato-nigro-collicular activity.     

Blindsight in subjects with homonymous visual field defects

Brain damage in the visual system can lead to apparently blind visual areas. However, more elaborate testing indicates that some visual ability may still exist for specific stimuli in the otherwise blind regions. This phenomenon is called 'blindsight' if subjects report no conscious awareness of visual stimuli but when forced to guess, nevertheless perform better than chance. It has mainly been suggested that secondary visual pathways are responsible for this phenomenon. However, no published study has clearly shown the neural mechanism responsible for blindsight. Furthermore, experimental artifacts may have been responsible for the appearance of the phenomenon in some subjects. In the present study, the visual fields of nine subjects were mapped and residual visual performance was examined in many areas using three different experimental procedures. Artifacts such as stray light or eye movements were well controlled. In addition, confidence ratings were required after each trial in the forced-choice tests. The results show that only one subject with a lesion in the optic radiation had blindsight in two discrete areas of the affected visual field. Spared optic radiation fibers of the main (primary) geniculo-striate visual pathway were most likely to account for this finding.     

Visuospatial properties of ventral premotor cortex

In macaque ventral premotor cortex, we recorded the activity of neurons that responded to both visual and tactile stimuli. For these bimodal cells, the visual receptive field extended from the tactile receptive field into the adjacent space. Their tactile receptive fields were organized topographically, with the arms represented medially, the face represented in the middle, and the inside of the mouth represented laterally. For many neurons, both the visual and tactile responses were directionally selective, although many neurons also responded to stationary stimuli. In the awake monkeys, for 70% of bimodal neurons with a tactile response on the arm, the visual receptive field moved when the arm was moved. In contrast, for 0% the visual receptive field moved when the eye or head moved. Thus the visual receptive fields of most "arm + visual" cells were anchored to the arm, not to the eye or head. In the anesthetized monkey, the effect of arm position was similar. For 95% of bimodal neurons with a tactile response on the face, the visual receptive field moved as the head was rotated. In contrast, for 15% the visual receptive field moved with the eye and for 0% it moved with the arm. Thus the visual receptive fields of most "face + visual" cells were anchored to the head, not to the eye or arm. To construct a visual receptive field anchored to the arm, it is necessary to integrate the position of the arm, head, and eye. For arm + visual cells, the spontaneous activity, the magnitude of the visual response, and sometimes both were modulated by the position of the arm (37%), the head (75%), and the eye (58%). In contrast, to construct a visual receptive field that is anchored to the head, it is necessary to use the position of the eye, but not of the head or the arm. For face + visual cells, the spontaneous activity and/or response magnitude was modulated by the position of the eyes (88%), but not of the head or the arm (0%). Visual receptive fields anchored to the arm can encode stimulus location in "arm-centered" coordinates, and would be useful for guiding arm movements. Visual receptive fields anchored to the head can likewise encode stimuli in "head-centered" coordinates, useful for guiding head movements. Sixty-three percent of face + visual neurons responded during voluntary movements of the head. We suggest that "body-part-centered" coordinates provide a general solution to a problem of sensory-motor integration: sensory stimuli are located in a coordinate system anchored to a particular body part.     

The favorable effect of topical betaxolol and timolol on glaucomatous visual fields: a 2-year follow-up study

BACKGROUND: It has been suggested that beta-adrenergic antagonists might have mechanisms of action other than ocular hypotensive effects affecting the visual function in glaucoma patients and that betaxolol might protect the visual field better than others. A randomized, double-blind study was conducted to compare the effects of betaxolol and timolol on visual fields of glaucoma patients. METHODS: Sixty-four glaucoma patients were treated with either 0.5% betaxolol or 0.25% timolol eyedrops twice daily. The Octopus visual field performance was followed up for 2 years and analyzed to find diffuse and localized changes. We analyzed the change in the mean sensitivity (MS) and performed a cluster analysis and clinical assessment of the visual fields in both treatment groups. RESULTS: The mean sensitivity (MS) improved significantly and equally in both treatment groups. There was a tendency towards more improved clusters in the betaxolol group than in the timolol group and more worsened cluster in the timolol group than in the betaxolol group, but the difference was not statistically significant. The clinical assessment also showed no statistically significant difference between the two groups. CONCLUSION: In the present study both betaxolol and timolol had a favorable effect on the visual fields of glaucoma patients. There was no statistically significant difference between betaxolol- and timolol-treated patients either in the change in mean retinal sensitivity or in the change in localized scotomatous areas.     

Predictors of the discrepancy between time needed and time spent in learning among boys exhibiting behavior problems.

Tested 96 3rd- and 4th-grade boys, who were referred to a summer camp because of classroom behavior problems, on a task in which they were required to read and reread a passage until 100% accuracy was achieved on a criterion test. They were also permitted to self-regulate learning trials and stop rereading an alternate passage when they felt the material had been mastered. Attempts were made to identify factors that explain the discrepancy between time needed for learning (TTL) and time actually spent in learning (TSL). Reading achievement, attention deficits, low self-concept, locus of control, interest level, and IQ were used to predict the discrepancy between the number of trials needed (TTL) and the number spent (TSL) in learning passage material. The 6 variables together accounted for 63% of the variability in TTL–TSL discrepancy, with reading achievement explaining about 35%. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of TSL and PSL in Al^3＋-Doped BaFBr：Eu^2＋ at Difference Synthesis Conditions

Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al^3 -doped BaFBr:Eu^2 in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al^3 -doped BaFBr:Eu^2 by different synthetic conditions. The relationship of color center‘s energy and different synthetic conditions is discussed.     

Right Hemisphere Sensitivity to Word- and Sentence-Level Context: Evidence From Event-Related Brain Potentials.

Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical implications of intra- and inter-reader agreement in four different automated visual fields

BACKGROUND: This study was designed and conducted to examine the degree of inter- and intra-reader agreement when four readers evaluate visual fields in patients known to have glaucoma and patients known to not have glaucoma. METHODS: Fifty-three patients known to have glaucoma and 60 patients known not to have glaucoma were selected randomly from a population at the University of Alabama at Birmingham School of Optometry. Four visual fields were performed on each patient, non-dilated, with the proper correction in place. The fields were performed on three different instruments by technicians who were unaware of the diagnostic status of the patient. Four independent (blinded) clinicians read the visual fields and judged them as: "glaucoma field defect," "no glaucoma field defect," and "poor reliability-cannot judge." RESULTS: Statistical analysis revealed that a single reader's interpretation of four different types of visual fields are very different from, are poorer than, and are more consistent than are the four readers' interpretations of a single type of visual field. The analysis also shows that the readers consistently underestimated the number of glaucoma patients with one instrument and overestimated the number with another. CONCLUSIONS: This results suggest that a single visual field will discriminate patients with glaucoma with an accuracy in the 70 to 75 percent range. For one of the instruments, the shorter protocol was almost as effective in discriminating glaucomatous fields as the longer protocol. This study also suggests that repeating the visual fields or analysis of a single field by two readers improves reliability.     

Morphological variation of layer III pyramidal neurones in the occipitotemporal pathway of the macaque monkey visual cortex

We compared the morphological characteristics of layer III pyramidal neurones in different visual areas of the occipitotemporal cortical 'stream', which processes information related to object recognition in the visual field (including shape, colour and texture). Pyramidal cells were intracellularly injected with Lucifer Yellow in cortical slices cut tangential to the cortical layers, allowing quantitative comparisons of dendritic field morphology, spine density and cell body size between the blobs and interblobs of the primary visual area (V1), the interstripe compartments of the second visual area (V2), the fourth visual area (V4) and cytoarchitectonic area TEO. We found that the tangential dimension of basal dendritic fields of layer III pyramidal neurones increases from caudal to rostral visual areas in the occipitotemporal pathway, such that TEO cells have, on average, dendritic fields spanning an area 5-6 times larger than V1 cells. In addition, the data indicate that V1 cells located within blobs have significantly larger dendritic fields than those of interblob cells. Sholl analysis of dendritic fields demonstrated that pyramidal cells in V4 and TEO are more complex (i.e. exhibit a larger number of branches at comparable distances from the cell body) than cells in V1 or V2. Moreover, this analysis demonstrated that the dendrites of many cells in V1 cluster along specific axes, while this tendency is less marked in extrastriate areas. Most notably, there is a relatively large proportion of neurones with 'morphologically orientation-biased' dendritic fields (i.e. branches tend to cluster along two diametrically opposed directions from the cell body) in the interblobs in V1, as compared with the blobs in V1 and extrastriate areas. Finally, counts of dendritic spines along the length of basal dendrites revealed similar peak spine densities in the blobs and the interblobs of V1 and in the V2 interstripes, but markedly higher spine densities in V4 and TEO. Estimates of the number of dendritic spines on the basal dendritic fields of layer III pyramidal cells indicate that cells in V2 have on average twice as many spines as V1 cells, that V4 cells have 3.8 times as many spines as V1 cells, and that TEO cells have 7.5 times as many spines as V1 cells. These findings suggest the possibility that the complex response properties of neurones in rostral stations in the occipitotemporal pathway may, in part, be attributed to their larger and more complex basal dendritic fields, and to the increase in both number and density of spines on their basal dendrites.     

钙铁橄榄石渣系在铜锍顶吹吹炼工艺的应用

侯马冶炼厂使用铜锍顶吹吹炼工艺生产粗铜,生产初期采用常规的铁橄榄石渣系,在实际生产中因为铁橄榄石炉渣在高氧势条件下磁铁含量高,易导致炉渣泡沫化,甚至造成严重的安全生产隐患。为了有效控制炉渣泡沫化,在顶吹吹炼炉试验了钙铁橄榄石渣系,试验证明,钙铁橄榄石渣系对固态磁铁的析出能够起到很好的控制作用。     

Influence of spontaneous activity and visual experience on developing retinal receptive fields

BACKGROUND: The role played by early neural activity in shaping retinal functions has not yet been established. In the developing vertebrate retina, ganglion cells fire spontaneous bursts of action potentials before the onset of visual experience. This spontaneous bursting disappears shortly after birth or eye opening. In the present study, we have investigated whether the outgrowth of receptive fields in turtle retinal ganglion cells is affected by early spontaneous bursting or by early visual experience. RESULTS: Ganglion cells normally stop bursting spontaneously 2-4 weeks post-hatching, the time when receptive-field areas reach adult size. When turtles are reared in the dark, the spontaneous bursting persists. Concomitantly, receptive-field areas expand to more than twice those observed in normal adults. To test whether chronic blockade of spontaneous bursting inhibits the expansion of developing receptive-field areas, we have exposed the retina to curare, a nicotinic cholinergic antagonist, because spontaneous bursting by ganglion cells requires acetylcholine. Curare was released from Elvax, a slow-release polymer that was implanted in the eye. When spontaneous bursting was chronically blocked with curare in hatchlings, dark-induced expansion of receptive fields was abolished. Moreover, receptive fields of ganglion cells exposed to curare in hatchlings reared in normal light and dark cycles were smaller than normal. CONCLUSIONS: These results strongly suggest that early, acetylcholine-dependent spontaneous bursts of activity control the outgrowth of receptive-field areas in retinal ganglion cells. The onset of visual experience induces the disappearance of the immature spontaneous bursts, resulting in the stabilization of receptive-field areas to their mature size.     

Positional firing properties of perirhinal cortex neurons

Neuronal activity in the perirhinal cortex was recorded while rats performed a spatial task on a four arm radial maze. The maze was defined by proximal multisensory cues on the arm surfaces and distal complex visual cues at the surround. During each recording session, rats were run in three conditions: baseline, a condition in which proximal and distal cues were manipulated, and a second baseline. Compared with the activity of hippocampal neurons in the same paradigm, a much smaller proportion of perirhinal neurons exhibited spatial selectivity and perirhinal place fields were larger than hippocampal place fields. Although perirhinal place fields exhibited a high degree of spatial tuning and reliability within a condition, they were not stable across conditions.