Axis-alignment affects perceptual grouping: evidence from simultanagnosia

We examined the effect of grouping by the alignment of implicit axes on the perception of multiple shapes, using a patient (GK) who shows simultanagnosia as part of Blint's syndrome. Five experiments demonstrated that: (1) GK was better able to judge the orientation of a global configuration if the constituent local shapes were aligned with their major axes than if they were aligned with their edges; (2) this axis information was used implicitly, since GK was unable to discriminate between configurations of axis-aligned and edge-aligned shapes; (3) GK's sensitivity to axis-alignment persisted even when the orientations of local shapes were kept constant, indicating some form of cooperative effect between the local elements; (4) axis-alignment of shapes also facilitated his ability to discriminate single-item from multi-item configurations; (5) the effect of axis-alignment could be attributed, at least partially, to the degree to which there was matching between the orientations of local shapes and the global configuration. Taken together, the results suggest that axis-based grouping can support the selection of multiple objects.

Axis-based grouping reduces visual extinction

We examined the effects on extinction of grouping by collinearity of edges and grouping by alignment of internal axes of shapes, in a patient (GK) with simultanagnosia following bilateral parietal brain damage. GK’s visual extinction was reduced when items (equilateral triangles and angles) could be grouped by base alignment (i.e., collinearity) or by axis alignment, relative to a condition in which items were ungrouped. These grouping effects disappeared when inter-item spacing was increased, though factors such as display symmetry remained constant. Overall, the results suggest that, under some conditions, grouping by alignment of axes of symmetry can have an equal beneficial effect on visual extinction as edge-based grouping; thus, in the extinguished field, there is derivation of axis-based representations from the contours present.

Neural networks for perpetual grouping

A number of researchers have investigated the application of neural networks to visual recognition, with much of the emphasis placed on exploiting the network's ability to generalise. However, despite the benefits of such an approach it is not at all obvious how networks can be developed which are capable of recognising objects subject to changes in rotation, translation and viewpoint. In this study, we suggest that a possible solution to this problem can be found by studying aspects of visual psychology and in particular, perceptual organisation. For example, it appears that grouping together lines based upon perceptually significant features can facilitate viewpoint independent recognition. The work presented here identifies simple grouping measures based on parallelism and connectivity and shows how it is possible to train multi-layer perceptrons (MLPs) to detect and determine the perceptual significance of any group presented. In this way, it is shown how MLPs which are trained via backpropagation to perform individual grouping tasks, can be brought together into a novel, large scale network capable of determining the perceptual significance of the whole input pattern. Finally the applicability of such significance values for recognition is investigated and results indicate that both the NILP and the Kohonen Feature Map can be trained to recognise simple shapes described in terms of perceptual significances. This study has also provided an opportunity to investigate aspects of the backpropagation algorithm, particularly the ability to generalise. In this study we report the results of various generalisation tests. In applying the backpropagation algorithm to certain problems, we found that there was a deficiency in performance with the standard learning algorithm. An improvement in performance could however, be obtained when suitable modifications were made to the algorithm. The modifications and consequent results are reported here.

Auditory grouping in cochlear implant listeners

This thesis describes a series of experiments investigating both sequential and concurrent auditory grouping in implant listeners. Some grouping cues used by normal-hearing listeners should also be available to implant listeners, while others (e.g. fundamental frequency) are unlikely to be useful. As poor spectral resolution may also limit implant listeners’ performance, the spread of excitation in the cochlea was assessed using Neural Response Telemetry (NRT) and the results were related to those of the perceptual tasks. Experiment 1 evaluated sequential segregation of alternating tone sequences; no effect of rate or evidence of perceptual ambiguity was found, suggesting that automatic stream segregation had not occurred. Experiment 2 was an electrode pitch-ranking task; some relationship was found between pitch-ranking judgements (especially confidence scores) and reported segregation. Experiment 3 used a temporal discrimination task; this also failed to provide evidence of automatic stream segregation, because no interaction was found between the effects of sequence length and electrode separation. Experiment 4 explored schema-based grouping using interleaved melody discrimination; listeners were not able to segregate targets and distractors based on pitch differences, unless accompanied by substantial level differences. Experiment 5 evaluated concurrent segregation in a task requiring the detection of level changes in individual components of a complex tone. Generally, large changes were needed and abrupt changes were no easier to detect than gradual ones. In experiment 6, NRT testing confirmed substantially overlapping simulation by intracochlear electrodes. Overall, little or no evidence of auditory grouping by implant listeners was found.

Formant-frequency variation and its effects on across-formant grouping in speech perception

How speech is separated perceptually from other speech remains poorly understood. In a series of experiments, perceptual organisation was probed by presenting three-formant (F1+F2+F3) analogues of target sentences dichotically, together with a competitor for F2 (F2C), or for F2+F3, which listeners must reject to optimise recognition. To control for energetic masking, the competitor was always presented in the opposite ear to the corresponding target formant(s). Sine-wave speech was used initially, and different versions of F2C were derived from F2 using separate manipulations of its amplitude and frequency contours. F2Cs with time-varying frequency contours were highly effective competitors, whatever their amplitude characteristics, whereas constant-frequency F2Cs were ineffective. Subsequent studies used synthetic-formant speech to explore the effects of manipulating the rate and depth of formant-frequency change in the competitor. Competitor efficacy was not tuned to the rate of formant-frequency variation in the target sentences; rather, the reduction in intelligibility increased with competitor rate relative to the rate for the target sentences. Therefore, differences in speech rate may not be a useful cue for separating the speech of concurrent talkers. Effects of competitors whose depth of formant-frequency variation was scaled by a range of factors were explored using competitors derived either by inverting the frequency contour of F2 about its geometric mean (plausibly speech-like pattern) or by using a regular and arbitrary frequency contour (triangle wave, not plausibly speech-like) matched to the average rate and depth of variation for the inverted F2C. Competitor efficacy depended on the overall depth of frequency variation, not depth relative to that for the other formants. Furthermore, the triangle-wave competitors were as effective as their more speech-like counterparts. Overall, the results suggest that formant-frequency variation is critical for the across-frequency grouping of formants but that this grouping does not depend on speech-specific constraints.

Rhythmic masking release:effects of asynchrony, temporal overlap, harmonic relations, and source separation on cross-spectral grouping

The rhythm created by spacing a series of brief tones in a regular pattern can be disguised by interleaving identical distractors at irregular intervals. The disguised rhythm can be unmasked if the distractors are allocated to a separate stream from the rhythm by integration with temporally overlapping captors. Listeners identified which of 2 rhythms was presented, and the accuracy and rated clarity of their judgment was used to estimate the fusion of the distractors and captors. The extent of fusion depended primarily on onset asynchrony and degree of temporal overlap. Harmonic relations had some influence, but only an extreme difference in spatial location was effective (dichotic presentation). Both preattentive and attentionally driven processes governed performance. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Formant-frequency variation and its effects on across-formant grouping in speech perception

How speech is separated perceptually from other speech remains poorly understood. In a series of experiments, perceptual organisation was probed by presenting three-formant (F1+F2+F3) analogues of target sentences dichotically, together with a competitor for F2 (F2C), or for F2+F3, which listeners must reject to optimise recognition. To control for energetic masking, the competitor was always presented in the opposite ear to the corresponding target formant(s). Sine-wave speech was used initially, and different versions of F2C were derived from F2 using separate manipulations of its amplitude and frequency contours. F2Cs with time-varying frequency contours were highly effective competitors, whatever their amplitude characteristics, whereas constant-frequency F2Cs were ineffective. Subsequent studies used synthetic-formant speech to explore the effects of manipulating the rate and depth of formant-frequency change in the competitor. Competitor efficacy was not tuned to the rate of formant-frequency variation in the target sentences; rather, the reduction in intelligibility increased with competitor rate relative to the rate for the target sentences. Therefore, differences in speech rate may not be a useful cue for separating the speech of concurrent talkers. Effects of competitors whose depth of formant-frequency variation was scaled by a range of factors were explored using competitors derived either by inverting the frequency contour of F2 about its geometric mean (plausibly speech-like pattern) or by using a regular and arbitrary frequency contour (triangle wave, not plausibly speech-like) matched to the average rate and depth of variation for the inverted F2C. Competitor efficacy depended on the overall depth of frequency variation, not depth relative to that for the other formants. Furthermore, the triangle-wave competitors were as effective as their more speech-like counterparts. Overall, the results suggest that formant-frequency variation is critical for the across-frequency grouping of formants but that this grouping does not depend on speech-specific constraints. © Springer Science+Business Media New York 2013.

Estudio comparativo de anastomosis de intestino delgado entre: la técnica de sutura monoplano extramucosa y la técnica de sutura en dos planos

Parte de la hipótesis de que la sutura monoplano extra mucosa es mejor que la sutura en dos planos porque la cicatrización estaría favorecida por respetar la red vascular submucosa. La complicación post operatoria de estenosis sería menor ya que la cantidad de tejido que se incluye en la sutura es mínima, el riesgo dehiscencia sería inferior porque la coaptación de los bordes sería mejor. Se presenta entonces el objetivo de evaluar comparativamente las ventajas y desventajas de estos dos tipos de sutura. El trabajo experimental se realiza en 20 perros de raza mestiza (fotos) con edad y peso promedio de dos años y dos meses y 10,4 kg. Divididos en dos grupos de 10 cada uno. A un grupo se le aplicó la sutura monoplano extra mucosa en intestino delgado y al otro la sutura en dos planos en intestino delgado. Cada uno de ellos fue re intervenido a los cinco, diez y veinte días post operatorios, divididos en tres subgrupos de seis, ocho y seis animales, los mismos que en primer subgrupo corresponden a tres con sutura monoplano y tres en dos planos; el segundo grupo: cuatro con monoplano y cuatro en dos planos; y el tercero: tres de monoplano y tres de dos planos. Mediante la observación se analizó las complicaciones intraoperatorias, las complicaciones post operatorias y el grado de cicatrización. Los resultados fueron: No hubo complicaciones intraoperatorias; 2 Las complicaciones post operatorias se dividieron en mediatas e inmediatas, inmediatas no existieron; y en las mediatas se tiene adherencias, estenosis; obstrucción no se presentó

The Integration of Foreign Students in the Portuguese School of the 1st Cycle of Basic Education: the Case of a School Grouping in the Municipality of Viseu

The present study aims to understand whether the foreign students who have different nationalities but the Portuguese are integrated into the school of the 1st Cycle of Basic Education. With this purpose, a descriptive and phenomenological research was conducted, making use of documental analysis, as well as semi-structured interviews and sociometric tests. These two data collecting tools were applied to students attending from the 1st to the 4th school years, in three 1st Cycle of Basic Education schools, within a school grouping in Viseu. The data obtained through the interviews allow us to conclude that foreign students, in general, feel integrated both in the school and in the class they belong to. However, the analysis of the results of the sociometric tests reveals other data, allowing us to conclude that one of the students is neither integrated in the school, nor in the class he is part of.

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis

To evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve. Method: Eleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A control group comprised seven normal people and seven patients with a complete Bell's facial palsy; in this group, responses on the sternocleidomastoideus (SCM) muscles were studied after supraorbital nerve stimulation. Results: All the patients with AFA showed a consistent degree of facial reinnervation. Ten out of the 11 patients with AFA showed reflex responses; in six, responses were configured by a double component pattern, resembling the R1 and R2 components of the blink reflex; three patients had an R1-like response and one patient showed a unique R2 component. Mean values of latencies were 15.2 (SD 4.6) ms for the R1 and 85.3 (SD 9.6) ms for the R2. In the control group, eight out of 14 people had evidence of reflex responses in the SCM muscles; these were almost exclusively configured by a bilateral late component (mean latency 63.5 (SD 15.9) ms) and only one of the subjects showed an early response at 11 ms. Conclusion: The trigemino-accessory reflex response in the pathological group was more complex and of a significantly higher incidence than in the control group. These differences could be tentatively explained by a mechanism of synaptic plasticity induced by the impairment of the efferent portion of the reflex. This could unmask the central linking between the trigeminal and the accessory limbs of the reflex. The findings described could be a demonstration of neurobionomic function in the repairing process of the nervous system.

Intestinal microbiome in chronic intestinal failure and associations with intestinal failure associated liver disease

Background and Aims: Intestinal dysbiosis has been described in children with chronic intestinal failure (CIF) and in adults with short bowel syndrome (SBS), mostly with jejunocolic anastomosis (SBS-2) and jejuno-ileal anastomosis (SBS-3), linked to generic data with the pathogenesis of Intestinal Failure Associated Liver Disease (IFALD). Little is known about gut microbiome of adults with end-jejunostomy (SBS-1) and in CIF other than SBS and any specific associations with the onset of IFALD. We aimed to describe the fecal microbiome of adult patients with different mechanisms of CIF and any possible associations with the development of IFALD. Material and methods: Fecal samples from 61 patients with benign CIF. Phylogenetic characterization of the microbiome by amplification of the hypervariable regions V3 and V4 of the bacterial gene encoding 16S rRNA, and subsequent grouping of sequences in amplicon sequence variants (ASVs). Patient samples comparison to microbiome sequences from 61 healthy subjects, matched for sex and age, selected from the healthy subjects library of the Laboratory of the Microbial Ecology of Health Unit, Department of Pharmacy and Biotechnology, of the University of Bologna. IFALD was assessed by the diagnostic criteria of IFALD-cholestasis, IFALD-steatosis, IFALD-fibrosis. Results: Decreased bacterial α-diversity in CIF patients (increase of Proteobacteria and Actinobacteria and decrease in Bacteroidetes). Identification of microbial family-level signatures specific for CIF mechanisms (increase in Actinomycetaceae and Streptococcaceae in SBS-1, Bifidobacteriaceae and Lactobacillaceae in SBS-2, Bacteroidaceae and Porphyromonadaceae in dysmotility). Abundance of Lactobacillus and Lactobacillaceae strongly associated with IFALD-cholestasis and IFALD–fibrosis for SBS-1; Peptostreptococcus, Prevotellaceae (Prevotella) and Pasteurellaceae (Haemophilus) significantly increased in IFALD-fibrosis for other CIF mechanisms. Conclusions: CIF patients had a marked intestinal dysbiosis with microbial family-level signatures specific to the pathophysiological mechanism. Specific characteristics of microbiome may contribute to the pathogenesis of IFALD. Intestinal microbiome could become a therapeutic target in patients with CIF.

Plastias de estenoses de intestino delgado na doença de Crohn: resultados imediatos e tardios

BACKGROUND: Strictureplasty is an alternative surgical procedure for Crohn?s disease, particulary in patients with previous resections or many intestinal stenosis. AIM: To analyze surgical complications and clinical follow-up in patients submitted to strictureplasty secondary to Crohn?s disease. METHODS: Twenty-eight patients (57.1% male, mean age 33.3 years, range 16-54 years) with Crohn?s disease and intestinal stenosis (small bowel, ileocecal region and ileocolic anastomosis) were submitted to strictureplasty, at one institution, between September 1991 and May 2004. Thirteen patients had previous intestinal resections. The mean follow-up was 58.1 months. A total of 116 strictureplasties were done (94 Heineke-Mikulicz - 81%, 15 Finney - 13%, seven side-to-side ileocolic strictureplasty - 6%). Three patients were submitted to strictureplasty at two different surgical procedures and two in three procedures. RESULTS: Regarding to strictureplasty, postoperative complication rate was 25% and mortality was 3.6%. Early local complication rate was 57.1%, with three suture leaks (10.7%) and late complication was present in two patients, both with incisional hernial and enterocutaneous fistulas (28.6%). Patients remained hospitalized during a medium time of 12.4 days. Clinical and surgical recurrence rates were 63% and 41%, respectively. Among the patients submitted to another surgery, two patients had two more operations and one had three. Recurrence rate at strictureplasty site was observed in 3.5%, being Finney technique the commonest one. Presently, 19 patients had been asymptomatic with the majority of them under medical therapy. CONCLUSION: Strictureplasties have low complication rates, in spite of having been done at compromised site, with long term pain relief. Considering the clinical course of Crohn?s disease, with many patients being submitted to intestinal resections, strictureplasties should be considered as an effective surgical treatment to spare long intestinal resections.

Complicações imediatas e tardias após cirurgia de reservatório ileal na polipose adenomatosa familiar

BACKGROUND: Restorative proctocolectomy is the procedure of choice to treat familial adenomatous polyposis, however it can be associated to short-term and long-term postoperative complications. AIM: To evaluate the occurrence of complications related to the surgical treatment of familial adenomatous polyposis with ileal pouch technique. METHODS: Retrospective study of 69 patients with familial adenomatous polyposis after rectocolectomy with ileal reservoir between 1984 and 2006, operated on Coloproctology Group, Medical Sciences Faculty, State University of Campinas, Campinas, SP, Brazil. The median follow-up period was 82 (2-280) months. Data obtained were surgical techniques and postoperative complications. RESULTS: The morbidity and mortality were 63.8% and 2.9%, respectively. The most frequent complications were small-bowel obstruction (17.4%), anastomotic stricture (15.9%) and pelvic sepsis (10.1%). Acute ischemia of the ileal pouch (4.3%), pouchitis (2.9%) and ileal pouch-related fistula (2.9%) had poorer frequency than others. CONCLUSIONS: The morbid-mortality was similar to the literature?s data and it is acceptable for a complex surgery in two terms like the ileal reservoir-anal anastomosis. The small-bowel obstruction was the most frequent complication. However, ischemia of the reservoir, pouchitis and pelvic sepsis were important complications and was related to the failure of the ileal reservoir.

Resultados da cirurgia de reservatórios ileais em pacientes com doença de Crohn

BACKGROUND: Total rectocolectomy and ileal pouch-anal anastomosis is the choice surgical procedure for patients with ulcerative colitis. In cases of Crohn's disease post-operative diagnosis, it can be followed by pouch failure. AIM: To evaluate ileal pouch-anal anastomosis long-term outcome in patients with Crohn's disease. METHODS: Between February 1983 and March 2007, 151 patients were submitted to ileal pouch-anal anastomosis by Campinas State University Colorectal Unit, Campinas, SP, Brazil, 76 had pre-operative ulcerative colitis diagnosis and 11 had post-operative Crohn's disease diagnosis. Crohn's disease diagnosis was made by histopathological biopsies in nine cases, being one in surgical specimen, two cases in rectal stump, small bowel in two cases, ileal pouch in three and in perianal abscess in one of them. The median age was 30.6 years and eight (72.7%) were female. RESULTS: All patients had previous ulcerative colitis diagnosis and in five cases emergency colectomy was done by toxic megacolon. The mean time until of Crohn's disease diagnosis was 30.6 (6-80) months after ileal pouch-anal anastomosis. Ileostomy closure was possible in 10 cases except in one that had ileal pouch fistula, perianal disease and small bowel involvement. In the long-term follow-up, three patients had perineal fistulas and one had also a pouch-vaginal fistula. All of them were submitted to a new ileostomy and one had the pouch excised. Another patient presented pouch-vaginal fistula which was successfully treated by mucosal flap. Three patients had small bowel involvement and three others, pouch involvement. All improved with medical treatment. Presently, the mean follow-up is 76.5 months and all patients are in clinical remission, and four have fecal diversion. The remaining patients have good functional results with 6-10 bowel movements/day. CONCLUSION: Crohn's disease diagnosis after ileal pouch-anal anastomosis for ulcerative colitis may be usual and later complications such fistulas and stenosis are common. However, when left in situ ileal pouch is associated with good function.