Effects of facial lobectomy on goldfish feeding behavior.

The role of the facial lobe (FL) of goldfish in feeding behavior (search, pick up and ingestion) was investigated using the ablation method. Facial lobectomy (FLX) was performed on 10 fish, five of which were also fitted with blinders (BLs). It was found that FLX did not have any apparent effect on feeding behavior; however, this does not rule out some other, undetected and perhaps subtle, role of the FL in the feeding repertoire. A salient aspect of this finding was the observation that food pick up was not blocked, showing that the FL is not necessary for this feeding step. These results are contrary to that reported in catfish. This difference might be explained by the fact that the FLs of the two species are quite different anatomically; yet it does not account for the fact that the current results are at variance with the commonly accepted role of the teleostean FL as reflected in the literature. The use of BLs alone or combined with FLX also indicated no apparent involvement of the FL in feeding, as was able to be measured within the limitations of this investigation.

MRI of knee osteonecrosis in children with leukemia and lymphoma: Part 1, observer agreement.

OBJECTIVE: The aim of this study was to determine whether a new MRI-based staging system for osteonecrosis of the knee in pediatric patients could be used with an acceptable level of intra- and interobserver agreement. MATERIALS AND METHODS: We conducted a retrospective analysis of MRI studies of the knee performed in a single institution between April 1994 and July 2003. Knee osteonecrosis was identified in 168 children with a primary diagnosis of hematologic malignancy. This substantial number prompted us to design a staging system for use with pediatric patients. To assess interobserver reliability of two primary observers in using the system, they reviewed and interpreted the same 36 imaging studies of randomly chosen patients. For the assessment of intraobserver reproducibility, each observer rereviewed 16 studies. A senior observer coded potential causes of disagreement between the primary observers. RESULTS: Interobserver agreement was substantial: the kappa value was 0.66 (95% confidence interval [CI], 0.58-0.75) in locations where the observers had to record only the presence or absence of a lesion, and the weighted kappa value was 0.65 (95% CI, 0.59-0.72) in locations where they had to classify the extent of involvement. The presence of marrow edema, punctate foci of altered signal, and mottled marrow changes was associated with a higher level of disagreement between the primary observers. CONCLUSION: Our proposed classification system, developed specifically for use with MRI, was used with substantial intra- and interobserver agreement. We think its use can contribute to a standardized approach to the interpretation of MRI findings in pediatric osteonecrosis of the knee.

MRI of knee osteonecrosis in children with leukemia and lymphoma: Part 2, clinical and imaging patterns.

OBJECTIVE: This aim of this study was to explore the relationship between MRI findings and clinical symptoms of knee osteonecrosis in children and to determine the significance of this relationship. Such information is important for early diagnosis of this frequent complication and for choosing an appropriate treatment strategy. MATERIALS AND METHODS: Osteonecrotic lesion size and location were determined in a retrospective analysis of MR images of the knee obtained in our institution during the past 10 years. Association between MRI findings and clinical symptoms expressed by the knee scores was tested for a subgroup of our patient population who had clinical evaluation of the knees in the orthopedic clinic within 6 weeks of their MRI studies. RESULTS: In 80% of patients, osteonecrosis was bilateral. Lesions were distributed as follows: femur and tibia, 66% of the knees; femur alone, 26%; and tibia alone, 8%. Clinical symptoms of knee osteonecrosis were associated with lesions involving the articular surface of the distal femur, large lesions, and involvement of any part of the tibia. MR images showed milder osteonecrosis in patients who were less than 10 years old at the time of primary diagnosis. CONCLUSION: Osteonecrosis affecting the knees of children treated for leukemia and lymphoma is mostly asymptomatic. Children who are 10 years old or older have signs of more advanced osteonecrosis. Clinical symptoms often lag MRI presentation and may develop late in the course of the disease. Routine MRI evaluation is recommended for timely diagnosis of treatment-induced osteonecrosis.

Central visual persistences: II. Effects of hand and head rotations.

In an earlier paper, kinesthetic effects on central visual persistences (CPs) were reported, including the ability to move these images by hand following eye closure. While all CPs could be translated anywhere within the frontal field, the present report documents a more selective influence of manual rotations on CPs in the same subjects. When common objects or figures drawn on cards were rotated (while holding one end of the object or one corner of a card between thumb and forefinger), it was found that CPs of larger objects rotated with the hand. By contrast, CPs of smaller objects, parts of objects, and textures remained stable in space as the hand rotated. It is proposed that CPs of smaller stimuli and textures are represented mainly by the ventral stream (temporal cortex) while larger CPs, which rotate, are represented mainly by the dorsal stream (parietal cortex). A second discovery was that CPs of small objects (but not of line segments or textures) could be rotated when the thumb and fingers surrounded the edges of the object. It is proposed that neuronal convergence of visual and tactile information about shape increases parietal responses to small objects, so that their CPs will rotate. Experiments with CPs offer new tools to infer visual coding differences between ventral and dorsal streams in man.

Central visual persistences: I. Visual and kinesthetic interactions.

Phenomena associated with 'central visual persistences' (CPs) are new to both medical and psychological literature. Five subjects have reported similar CPs: positive afterimages following brief fixation of high-contrast objects or drawings and eye closure. CPs duplicate shapes and colors of single objects, lasting for about 15 s. Unlike retinal afterimages, CPs do not move with the eyes but are stable in extrapersonal space during head or body rotations. CPs may reflect sustained neural activity in neurons of association cortex, which mediate object perception. A remarkable finding is that CPs can be moved in any direction by the (unseen) hand holding the original seen object. Moreover, a CP once formed will 'jump' into an extended hand and 'stick' in that hand as it moves about. The apparent size of a CP of a single object is determined by the size of the gap between finger and thumb, even when no object is touched. These CPs can be either magnified or minified via the grip of the extended hand. The felt orientation of the hand-held object will also determine the orientation of the CP seen in that hand. Thus, kinesthetic signals from hand and arm movements can determine perceived location, size, and orientation of CPs. A neural model based on physiological studies of premotor, temporal, parietal, and prefrontal cortices is proposed to account for these novel phenomena.