A recurrent model of transformation invariance by association.

This paper describes an investigation of a recurrent artificial neural network which uses association to build transform-invariant representations. The simulation implements the analytic model of Parga and Rolls [(1998). Transform-invariant recognition by association in a recurrent network. Neural Computation 10(6), 1507-1525.] which defines multiple (e.g. "view") patterns to be within the basin of attraction of a shared (e.g. "object") representation. First, it was shown that the network could store and correctly retrieve an "object" representation from any one of the views which define that object, with capacity as predicted analytically. Second, new results extended the analysis by showing that correct object retrieval could occur where retrieval cues were distorted; where there was some association between the views of different objects; and where connectivity was diluted, even when this dilution was asymmetric. The simulations also extended the analysis by showing that the system could work well with sparse patterns; and showing how pattern sparseness interacts with the number of views of each object (as a result of the statistical properties of the pattern coding) to give predictable object retrieval performance. The results thus usefully extend a recurrent model of invariant pattern recognition.     

局限型与扩展型枕叶癫痫的临床特点及手术疗效比较

目的 探讨局限型(致痫灶局限于枕叶内)与扩展型(致痫灶同时涉及枕叶外的脑叶)枕叶癫痫的临床特点及不同预后,以期为临床诊疗提供帮助. 方法 回顾性分析北京军区总医院自2011年6月至2013年6月收治的32例枕叶癫痫手术患者的临床资料,根据病灶位置将其分为2组:局限型枕叶癫痫组(14例)、扩展型枕叶癫痫组(18例).分析比较2组患者的基本情况、发作和定位诊断的相关数据,以及预后情况. 结果 (1)局限型与扩展型枕叶癫痫患者的性别、病程、发作类型、术前用药、定位诊断及手术疗效等多数临床资料差异没有统计学意义(P＞0.05).(2)发作特征方面,扩展型枕叶癫痫患者的非视觉性先兆明显多于局限型枕叶癫痫患者,差异有统计学意义(P＜0.05).2种类型患者主要发作类型为复杂部分性发作(31例,97％),继发全身强直阵挛发作18例(44％),且多见于扩展型枕叶癫痫.(3)定位诊断方面,脑电图、MRI等多种诊断方法对于2种类型癫痫患者的诊断效果差异无统计学意义(P＞0.05).但行颅内电极植入后脑电图定位诊断的患者均为扩展型枕叶癫痫,提示其致痫灶定位的难度更大.(4)局限型枕叶癫痫患者中12例(86％)术后达到满意疗效,扩展型中13例(72％)达到满意疗效,差异亦没有统计学意义(P＞0.05). 结论 扩展型枕叶癫痫的定位诊断难于局限型,但通过综合运用包括颅内电极脑电图在内的多种定位诊断方法,准确定位并有效切除致痫灶亦可取得较好疗效.     

Mental rotation versus invariant features in object perception from different viewpoints: an fMRI study

It has been proposed that object perception can proceed through different routes, which can be situated on a continuum ranging from complete viewpoint-dependency to complete viewpoint-independency, depending on the objects and the task at hand. Although these different routes have been extensively demonstrated on the behavioral level, the corresponding distinction in the underlying neural substrate has not received the same attention. Our goal was to disentangle, on the behavioral and the neurofunctional level, a process associated with extreme viewpoint-dependency, i.e. mental rotation, and a process associated with extreme viewpoint-independency, i.e. the use of viewpoint-invariant, diagnostic features. Two sets of 3-D block figures were created that either differed in handedness (original versus mirrored) or in the angles joining the block components (orthogonal versus skewed). Behavioral measures on a same-different judgment task were predicted to be dependent on viewpoint in the rotation condition (same versus mirrored), but not in the invariance condition (same angles versus different angles). Six subjects participated in an fMRI experiment while presented with both conditions in alternating blocks. Both reaction times and accuracy confirmed the predicted dissociation between the two conditions. Neurofunctional results indicate that all cortical areas activated in the invariance condition were also activated in the rotation condition. Parietal areas were more activated than occipito-temporal areas in the rotation condition, while this pattern was reversed in the invariance condition. Furthermore, some areas were activated uniquely by the rotation condition, probably reflecting the additional processes apparent in the behavioral response patterns.     

Parameters of human motor unit twitches obtained by intramuscular microstimulation.

Intramuscular microstimulation of motor axons was used to study twitch responses of 209 motor units (MUs) in the first dorsal interosseus muscle (FDI) of 20 normal subjects. Twitch peak force (TF), maximum rate of rise of force (MRRF), contraction time (CT) and one-half relaxation time (HRT) were determined. The distributions of TF (mean 16.0 mN, median 10.3 mN) and MRRF (mean 0.88 N s-1, median 0.66 N s-1) were skewed to the right with the majority of the values lying in the lower ranges, whereas CT (mean 63 ms, median 62 ms) and HRT (mean 61 ms, median 58 ms) were approximately normally distributed. TF was significantly correlated with MRRF, but not with CT in contrast with studies of cat gastrocnemius muscle. TF values were similar to those obtained by spike-triggered averaging in the same muscle. The method proved to be reliable and appropriate for use in patients. Examples of MU twitch parameters from three patients with chronic partial denervation of the FDI are described.     

Taurine-deficient cultured cerebellar astrocytes and granule neurons obtained by treatment with guanidinoethane sulfonate.

Mouse cerebellar granule neurons and astrocytes grown in the presence of 2 mM guanidinoethane sulfonate (GES) exhibited a progressive and rapid decrease in taurine concentration. A reduction of 20% was observed as early as 1 hr after exposure to GES and the loss of cell taurine continued until the taurine pool was reduced by about 90%. This remaining taurine persisted without further decrease even after 3 weeks of exposure to GES. Taurine reduction caused by GES was similar in both types of cells. The effect of GES was dose-dependent, with significant decreases in taurine levels already detected at 100 microM. It was selective for taurine, since none of the other free amino acids were affected. Taurine depletion induced by GES was totally reversible. Intracellular taurine was not mobilized by GES. Taurine uptake in both astrocytes and granule neurons, examined at the taurine concentration present in the culture medium, was practically abolished by 2 mM GES. This approach represents an in vitro model of taurine depletion that may be useful to investigate the cell abnormalities responsible for the failure of differentiation and migration of granule cells and astrocytes observed in taurine-deficient cats.     

Rats subjected to extended L-tryptophan restriction during early postnatal stage exhibit anxious-depressive features and structural changes

Serotonin transmission dysfunction has been suggested to play an important role in depression and anxiety. This study reports the results of a series of experiments in which rats were subjected to extended maize-based tortilla diets during early postnatal stages. This diet contains only approximately 20% of the L-tryptophan in normal diets of laboratory rodents. Compared with controls, experimental rats displayed a significant increase of immobility counts in the forced swimming test and exhibited anxiety-like behavior in the elevated plus maze test after 1 month of diet treatment. Low levels of serotonin contents were found in prefrontal cortex, striatum, hippocampus, and brainstem using high-performance liquid chromatography. Immunocytochemical reactions against 5-Bromo-2'-deoxyuridine revealed a significant decrease in the proliferation rate for the subgranular zone of dentate gyrus. c-Fos expression after the forced swimming test was found reduced in prefrontal cortex, dentate gyrus, CA1, and hilus of hippocampus and amygdala. Moreover, dendrite arbor atrophy and decreased spine density were evident in Golgi-Cox-impregnated CA1 pyramidal neurons. Abnormal dendrite swelling in dentate gyrus granule cells was also observed. These findings indicate an involvement of hyposerotoninergia in emotional disturbance produced by L-tryptophan restriction during critical developmental stages and suggest that neuroplasticity changes might underlie these changes.     

Spatial coding and invariance in object-selective cortex

The present study examined the coding of spatial position in object selective cortex. Using functional magnetic resonance imaging (fMRI) and pattern classification analysis, we find that three areas in object selective cortex, the lateral occipital cortex area (LO), the fusiform face area (FFA), and the parahippocampal place area (PPA), robustly code the spatial position of objects. The analysis further revealed several anisotropies (e.g., horizontal/vertical asymmetry) in the representation of visual space in these areas. Finally, we show that the representation of information in these areas permits object category information to be extracted across varying locations in the visual field; a finding that suggests a potential neural solution to accomplishing translation invariance.     

Recognition and reproduction of words by Down's syndrome and non-Down's syndrome retarded children.

Children with Down's syndrome were compared with other severely retarded children on tests of recognition and reproduction of real and nonsense words after 0-, 15-, and 30-seconds delay. The results indicated that Down's syndrome children performed better on the recognition task, but worse on the reproduction task after delay, as compared with the other retarded children. It was hypothesized that the articulatory deficit in the Down's syndrome group is part of a general motor disability due to a difficulty in preprogramming sequences of movements.     

Thumb invariance during prehension movement: effects of object orientation.

The aim of the present study was to examine the contribution of the thumb and index finger during the task of reaching to grasp a cylinder positioned at different orientations. To this end an axis was defined between a marker positioned on the subjects' wrist and the target. For each frame the perpendicular distances of the thumb and index finger from this axis were determined. The perpendicular distance was greater for the index finger than the thumb, confirming a relative stability of the thumb during natural prehension and supporting the notion of the thumb as a guide for the transport component of reaching. Further, index finger perpendicular distance was varied according to object orientation. When the object was positioned at an angle that requires hand pronation, the perpendicular distance for the index finger was the greatest. It is concluded that changes in the index finger distance are necessary to allow the thumb to maintain stability in order to provide appropriate movement guidance.     

Rehabilitation of schizophrenics by the extended family

Patterns of care by extended and nuclear families for their patients were studied in relation to 540 Arab schizophrenic outpatients in Qatar. The extended family differs from the nuclear family not only in its larger size but also in the greater emotional commitment of its members to each other's well being. The extended family is more tolerant of patients' minor behavioural abnormalities and temporary protective withdrawals. It is more helpful in the supervision of patients' medication and their social adjustment and leisure-time occupation. Being more traditionally oriented, the extended family helps patients to understand their illness experiences in terms of cultural belief systems once they lose the components that cannot be contained in these systems. Extended family members are less likely than nuclear family members to tax the patients' emotional resources and limited repertoire of social skills.     

Assessing need for extended psychiatric hospitalization.

The authors developed a set of rating scales to assess a wide range of variables believed by clinicians to influence the optimal length of hospital stay. They report the results of interrater reliability studies, a factor analysis of the scales, and a correlational study of the factors with actual length of stay. They describe the potential applications of the scales to clinical practice and research.     

Human short-latency auditory responses obtained by cross-correlation

Short-latency auditory responses were obtained by cross-correlation of continuous, pseudorandom noise stimuli with averaged scalp potentials from adults with normal hearing. Responses were recorded for spectrum levels of 14-74 dB for noise bandwidths from 800 to 6000 Hz. At the lowest intensity level of broadband noise, all 10 subjects showed replicable cross-correlation functions (CCFs), which were characterized by prominent positive peaks at delays (latencies) of 5-7 msec. Male subjects exhibited longer delays than females. Delay (latency) increased with decreasing stimulus intensity. Very early responses (less than 2 msec) attributable to cochlear microphonic, which were prominent in earlier work on guinea pigs, were not well seen in these human data. CCFs for responses to band-limited stimuli and off-line derivation of band-limited CCFs for responses evoked by broadband stimuli both showed that this technique is most sensitive to frequency-following behavior at low frequencies (less than 800 Hz). However, definite phase-locked responses to even the highest passband (3100-6200 Hz) were seen. These results support the use of the CCF technique as an efficient method of frequency-specific assessment of the auditory system.     

Cross-national invariance of Attention-Deficit/Hyperactivity Disorder factors in Japanese and U.S. university students

Prior research with children generally supports the two-dimensional structure of Attention-Deficit/Hyperactivity Disorder (ADHD; inattentive and hyperactive/impulsive factors) of the DSM-IV-TR as well as invariance of the two-factor structure across nations and cultures. Research with adults supports either a two-factor or three-factor structure depending on reporting source and breadth of symptoms assessed. However, research with adults is limited and there are few studies addressing cross-national invariance in adults. The purposes of this study were to (1) assess relative fit of two- versus three-factor solutions for self-report of childhood and recent ADHD symptoms in adults; and (2) further establish cross-national invariance of factors. Participants included 271 U.S. and 712 Japanese university students who completed a rating scale assessing the 18 DSM-IV-TR ADHD symptoms. Confirmatory factor analysis using Mplus (Version 6) and the mean and variance-adjusted weighted least squares (WLSMV) procedure showed invariance of two- and three-factor models across U.S. and Japanese samples. The two- and three-factor models showed similar fit indices. Neither a two-factor or three-factor model was clearly superior. The two-factor model was favored, however, because it is more parsimonious and consistent with current theory, and because of high correlations between hyperactive and impulsive factors in the three-factor models. Invariance across nations is consistent with previous studies and supports ADHD as a universally valid syndrome rather than a cultural construct. These results add to the limited knowledge of assessment of ADHD symptoms in Japan.     

WHO“癫痫社会控制”方案的扩展性试验研究

本研究对WHO“癫痫的社会控制”提案在山西和宁夏回族自治区农村进行了为期一年的扩展性观察试验。共选定癫痫大发作患者120例作为样本。两地各随机分为二组,一组由经过短期培训的乡村医生治疗,另一组由神经科医生治疗。规定使用同一种药物苯巴比妥。结果表明两组都取得了令人满意的疗效,乡村医生可以按规定方案担当起治疗和管理多数癫痫太发作病人的任务。从而再次证实此方案在我国大部分农村地区是可行的、适用的,值得逐步推广。     

Hydroporencephalus. Clinical features and management

(1) Experiences with a case of progressive porencephaly due to a cyst under tension are presented and reviewed in comparison with the literature on this subject and the term "hydroporencephaly" is suggested to describe this phenomenon. (2) Attention is called to the frequent progressive nature and delayed onset of symptoms in this disease and also to the possibility of effective neurosurgical treatment of some aspects of this disorder. (3) An abnormality of the rectilinear brain scan in porencephaly is described.