Neuronal correlates of real and illusory contour perception: functional anatomy with PET

Illusory contours provide a striking example of the visual system's ability to extract a meaningful representation of the surroundings from fragmented visual stimuli. Psychophysical and neurophysiological data suggest that illusory contours are processed in early visual cortical areas, and neuroimaging studies in humans have shown that Kanizsa-type illusory contours activate early retinotopic visual areas that are also activated by real contours. It is not known whether other types of illusory contours are processed by the same mechanisms, nor is it clear to what extent attentional effects may have influenced these results, as no attempt was made to match the salience of real and illusory stimuli in previous imaging studies. It therefore remains an open question whether there are any brain regions specifically involved in the perception of illusory contours. To address these questions, we have used 15O-butanol positron emission tomography (PET) and a novel kind of illusory contour stimulus that is induced only by aligned line ends. By employing a form discrimination task that was matched for attention and stimulus salience across conditions we were able to directly contrast perception of real and illusory contours. We found that the regions activated by illusory contour perception were the same as those activated by real contours. Only one region, located in the right fusiform gyrus, was significantly more strongly activated by perception of illusory contours than by real contours. In addition, a principal component analysis suggested that illusory contour perception is associated with a change in the correlation between V1 and V2. We conclude that different kinds of illusory contours are processed by the same cortical regions and that these regions overlap extensively with those involved in processing of real contours. At the regional level, perception of illusory contours thus appears to differ from perception of real contours by the degree of involvement of higher visual areas as well as by the nature of interaction between early visual areas.     

Evidence for curvilinear interpolation from dot alignment judgements

Visual interpolation between dots responsible for rectilinear versus curvilinear contour interpretation was examined with the psychophysical forced directional response (FDR) paradigm. Regular four-dot polygon segments, together with a target dot, were presented to the subjects for 150 ms. Subjects were required to indicate the direction of deviation of the target dot from the midpoint of the intermediate line segment. Crucial variables were the outer angle of the line segments and symmetry axis orientation of the polygon segment. Logistic regression analyses showed that curvilinear interpolation occurred for angles up to 30 degrees, but emerged more pervasively under the vertical symmetry axis orientation for angles up to 60 degrees.     

Familiar Face and Voice Matching and Recognition in Children with Autism

Relatively able children with autism were compared with age- and language-matched controls on assessments of (1) familiar voice-face identity matching, (2) familiar face recognition, and (3) familiar voice recognition. The faces and voices of individuals at the children's schools were used as stimuli. The experimental group were impaired relative to the controls on all three tasks. Face recognition and voice recognition correlated significantly with voice-face identity matching, but not with each other, suggesting that the recognition impairments jointly cause the matching impairment. Neither chronological age nor verbal mental age were consistently related to the recognition and matching impairments.     

人工耳蜗植入者音乐感知能力的初步研究

目的　建立测试人工耳蜗植入者音乐感知能力的体系 ,研究语后聋成人和语前聋儿童人工耳蜗植入后对音乐感知的能力。方法　构建测试用的标准钢琴音调和乐曲测试素材库 ,运用该素材库在CakewalkPro 8.0平台上进行音调和乐曲的感知能力测试 ,测试对象包括已植入多导人工耳蜗的 2名语后聋成人、8名语前聋儿童和各自的正常对照组。结果　建立了一个可用于人工耳蜗植入者音乐感知能力测试的系统。音调差异感知阈 (df/f)在植入人工耳蜗的语后聋成人和语前聋儿童分别为 7.78%± 6 .6 3%和 14 .4 9%± 11.2 0 % ,与各自正常人对照组比较有显著性差异 ;但两组间无显著性差异。植入人工耳蜗的语后聋成人在熟悉乐曲测试中 ,对正确乐曲的感知差异度为 - 2 .75± 0 .35 (半音 ) ,离散度为 1.5 0± 0 .71(半音 ) ,都与正常成人有显著性差异。结论　运用数字音乐技术和MIDI软件建立的这一测试系统能够方便的测试人工耳蜗植入者的音乐感知能力。人工耳蜗植入者音乐感知能力不及正常人     

机动车驾驶员视觉功能与道路交通安全

现行的交通法规对驾驶员的视觉功能有特殊要求,但其标准有待规范。本文对关系到安全驾驶的视觉功能如视力、视野、立体视觉、色觉、视觉适应等因素从原理、流行病学调查以及一些相关措施方面加以讨论。最后指出,我们对汽车驾驶员的视觉功能要求应该做进一步的划分达到有针对性地约束其驾驶行为。     

Effects of irradiation on nasal mucociliary clearance in head and neck cancer patients

A prospective longitudinal study was conducted on fifty patients of histopathologically confirmed head and neck cancer with the main aim to assess the nasal mucociliary clearance, pre-and post-irradiation; and to compare the findings with the healthy non-irradiated age and sex-matched controls. All the patients underwent saccharin particle test for nasal mucociliary clearance before commencement of radiation therapy and again within 6 months of completion of radiation therapy. The difference between the saccharin perception times of nasal mucosa in the healthy non-irradiated controls and the pre-irradiated head and neck cancer patients were statistically inssignificant (P>0.05). But, the difference between the saccharin perception times of nasal mucosa in the pre-and post-irradiated head and neck cancer patients was found to be statistically significant (P=0). It is concluded that even indirect irradiation of nasal mucosa in head and neck cancer patients significantly affect its ciliary activity. Significance of total radiation dosage along with chemotherapy in some cases was also studied.     

Psychosocial effect of mastectomy versus conservative surgery in patients with early breast cancer

Purpose To compare the quality-of-life (QoL) and psycho-social changes in a group of patients with early breast cancer who underwent conservative surgery (BCS) or modified radical mastectomy (MRM). Methods Self-administered questionnaire assessing body image perception, social habits, sexual attraction and self-consciousness with relatives/friends, was randomly assigned to 125 patients (61 BCS, 64 MRM; aged 53±8 and 50±9 years, respectively, p=NS). Results MRM patients reported a significantly higher frequency of changes in body image perception and other related social behaviour such as avoiding going to the beach or using low-cut clothes, and reticence with friends. Conversely, no differences were found regarding sexuality, denial of the disease by the husband/partner, or concealing the disease from family members. Also, no significant differences were found between patients above and below the age of 50 years, for all variables studied after adjustment for surgical procedure. Conclusions Modified radical mastectomy has a negative effect on body image perception and in social behaviour patterns of patients and with a concomitant decrease in QoL. The sexuality of the patient is not significantly affected.