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At least 343 records · Page 19Linked to original sources
PubMed1988

The neurogenesis of the callosal population of cortical cells in hamsters.

The neurogenesis of the callosal subpopulation of cortical cells was determined in hamsters by associating incorporation of [3H]-thymidine injected on different embryonic days with horseradish peroxidase retrograde labelling in adulthood. Despite the great radial dispersion of migratory destinations of neurons born simultaneously, it was found that callosal birthdates in cortical area 6 extend from day E13 to day E15, a period that corresponds to the neurogenesis of layers III-V, where most callosal neurons come to be located in adults.

Animals↗
PubMed1986

[Various functional features of the contra- and ipsilateral endings of callosal neurons in the cerebral cortex].

Paired stimulation of callosal neurons in the lateral gyrus causes inhibition of the second EP in every part of the cortex with callosal connections. Paired stimulation of callosal neurons in the suprasylvian gyrus causes facilitation of the second EP in the contra- as well as ipsilateral cortex. The possible role of recurrent collaterals in brain functioning is discussed.

Animals↗
PubMed1984

[Modular organization of callosal neurons in the sensomotor area of the cerebral cortex in the rabbit].

The density of distribution of callosal neurons in rabbit sensorimotor cortex was studied by means of horseradish peroxidase injection into the homotopic cortical area. The irregularity of density was evaluated visually and/or computed. Labelled callosal units were mostly small and medium-size pyramidal cells located primarily in layer III-IV and more rarely in layers V and VI. Layer III-IV revealed different patterns of labelled units grouping: in pairs, in 5-8 vertically situated cells, in clusters 120-200 micron wide, separated by areas with decreased density. The obtained results confirm previously made conclusion based on electrophysiological studies about the modular organization of callosal connections in sensorimotor cortex of rabbits.

Animals↗
PubMed1984

A corpus callosal deficit in sequential analysis by schizophrenics.

This preliminary study evaluated interhemispheric (i.e., corpus callosal) information processing by chronic schizophrenic and normal subjects. In right-handed normals the left hemisphere has been reported to be superior in temporal sequential analysis. Consequently temporal information presented to the right hemisphere requires time to cross to the left hemisphere for analysis. Measurement of hemispheric laterality and corpus callosal transfer time were evaluated by a two-pulse temporal discrimination task. Two dot stimuli were presented with decreasing temporal separation during bilateral and unilateral conditions. Subjects were required to judge perceived simultaneity and nonsimultaneity of dot onset. The results indicate that left hemisphere function in chronic schizophrenic and normal controls is superior to the right hemisphere in temporal analysis. Corpus callosal transfer time was significantly slower for chronic schizophrenics than for normal controls.

Adult↗
PubMed1987

Autosomal dominant painful plantar callosities.

We describe large kindred with an autosomal dominant condition characterized by painful callosities that develop over the pressure points of the soles. These callosities are not congenital; they arise with upright ambulation.

Callosities↗
PubMed2004

Debridement of plantar callosities in rheumatoid arthritis: a randomized controlled trial.

OBJECTIVE: To compare forefoot pain, pressure and function before and after normal and sham callus treatment in rheumatoid arthritis (RA). PATIENTS AND METHODS: Thirty-eight RA patients were randomly assigned to normal (NCT group) or sham (SCT) scalpel debridement. The sham procedure comprised blunt-edged scalpel paring of the callus which delivered a physical stimulus but left the hyperkeratotic tissue intact, the procedure being partially obscured from the patient. Forefoot pain was assessed using a 100 mm visual analogue scale (VAS), pressure using a high-resolution foot pressure scanner and function using the spatial-temporal gait parameters measured on an instrumented walkway. Radiographic scores of joint erosion were obtained for metatarsophalangeal (MTP) joints with and without overlying callosities. The trial consisted of a randomized sham-controlled phase evaluating the immediate same-day treatment effect and an unblinded 4-week follow-up phase. RESULTS: During the sham-controlled phase, forefoot pain improved in both groups by only 3 points on a VAS and no statistically significant between-group difference was found (P = 0.48). When data were pooled during the unblinded phase, the improvement in forefoot pain reached a peak after 2 days and gradually lessened over the next 28 days. Following debridement, peak pressures at the callus sites decreased in the NCT group and increased in the SCT group, but there was no statistically significant between-group difference (P = 0.16). The area of and duration of contact of the callus site on the ground remained unchanged following treatment in both groups. Following debridement, walking speed was increased, the stride-length was longer and the double-support time shorter in both groups; however, between-group differences did not reach levels of statistical significance. MTP joints with overlying callus were significantly more eroded than those without (P = 0.02). CONCLUSIONS: Treatment of painful plantar callosities in RA using scalpel debridement lessened forefoot pain but the effect was no greater than sham treatment. Localized pressure or gait function was not significantly improved following treatment.

Adult↗
PubMed2001

Surgical treatment for hallux valgus with painful plantar callosities.

We retrospectively reviewed the results of a distal soft-tissue procedure and proximal crescentic osteotomy of the first metatarsal combined with a proximal shortening osteotomy of the second and/or third metatarsal. This was in patients who had hallux valgus with painful plantar callosities. The review covered seven years of procedures (1989-1996) in 12 patients (14 feet) averaging 53 years of age. Average follow-up was 52 months. All patients had pain at the first metatarsophalangeal joint and had metatarsalgia preoperatively. At follow-up, 11 feet had no pain at the first metatarsophalangeal joint, and three had some improvement of pain. Ten feet had no metatarsalgia, two had improvement of metatarsalgia, and two feet had transfer lesions postoperatively and required reoperation. The angle of hallux valgus averaged 40 degrees preoperatively and 13 degrees postoperatively. The intermetatarsal angle averaged 18 degrees preoperatively and 6 degrees postoperatively. Mean decreases in length of the second and third metatarsal after surgery were 5.4 mm and 4.8 mm, respectively. Our results suggested that this combined procedure for hallux valgus with painful plantar callosities may be successful, in carefully selected patients.

Adult↗
PubMedDate not supplied

A dorsal wedge V osteotomy for painful plantar callosities.

A dorsal closing wedge proximal V metatarsal osteotomy is described for treatment of painful plantar callosities due to prominence of any of the five metatarsal heads. Forty-one osteotomies were performed over a 3-year period. In all patients so treated relief of symptoms was achieved, plantar callosities were resolved, and no significant complications occurred.

Adolescent↗
PubMed2001

A center's callosities.

We present a case report of a 14-year-old white male who developed hyperkeratotic plaques on the distal aspects of 2 toes. He was referred by his primary care physician for the treatment of onychomycosis. With questioning, the patient stated that he played center for his high school basketball team. After physical examination, he was diagnosed with callosities caused by his basketball activities. Proper nail hygiene and wearing of larger footwear resulted in improvement of his callosities. Sports-related cutaneous injuries should be included in the differential diagnosis of nail and toe abnormalities.

Adolescent↗
PubMed1975

The long-term effects of callosal sectioning. Report of a second case.

Testing a patient 32 years after callosal sectioning revealed defects in transfer of learning and crossed (mixed modality) matching. This points out that defects may persist long after such surgery and that early reports of negative results of callosal section in patients were probably not correct.

Adolescent↗
PubMed2000

Expression of L1 and TAG-1 in the corticospinal, callosal, and hippocampal commissural neurons in the developing rat telencephalon as revealed by retrograde and in situ hybridization double labeling.

In the telencephalon, the corticospinal (CS), callosal, and hippocampal commissural neurons are the major types of neurons that have axons crossing the midline of the brain. To understand the mechanisms involved in crossing the midline structure and to examine whether the expression patterns of L1 and TAG-1 in the commissural neurons are similar to those in the spinal cord, we investigated L1 and TAG-1 expression in these neurons in rats by using a double-labeling technique involving retrograde labeling and in situ hybridization. Expression of L1 messenger RNA was detected in the retrogradely labeled CS projection neurons by 1,1;-dioctadecyl-3,3, 3;,3;-tetramethylindocarbocyanine perchlorate (DiI) injection into the pons at embryonic day (E) 19, but expression of TAG-1 messenger RNA was not detected in these neurons. Also, after their axons crossed the pyramidal decussation, continued expression of L1 but no expression of TAG-1 in the CS projection neurons was shown by an additional double-labeling experiment involving DiI injection into the spinal cord at postnatal day (P) 1. An immunohistochemical study showed that L1 was continuously present in each level of the CS tract at E21 and P3, but TAG-1 immunoreactivity was not found in any level at any stage. Finally, we examined the expression of L1 and TAG-1 messenger RNAs in the callosal and hippocampal commissure neurons after their axons had crossed the midline by using the double-labeling technique. In both cases, hybridization signals of the L1 and TAG-1 messenger RNAs were observed in the retrogradely labeled neurons at P3. These results suggest that the roles of L1 and TAG-1 in the formation of the commissures in the forebrain are different from their roles in the spinal cord.

Animals↗
PubMed1991

Osteochondrodysplasia with rhizomelia, platyspondyly, callosal agenesis, thrombocytopenia, hydrocephalus, and hypertension.

A female infant born at term to phenotypically normal nonconsanguinous parents had hypertension, thrombocytopenia, hydrocephalus, callosal agenesis, and nonlethal rhizomelic osteochondrodysplasia. Her osteochondrodysplasia was characterized roentgenographically by shortening and metaphyseal broadening of long bones, without bowing, and by platyspondyly, with deficient ossification of dorsal and central portions of vertebral bodies. By light microscopy, the iliac crest growth plate showed expansion of the zone of chondrocyte hypertrophy and degeneration, with faulty columnar alignment, sparse vascular ingrowth, and irregular mineralization at the zone of chondroosseous transformation. These findings appear to define a novel osteochondrodysplasia, which in association with hypertension, thrombocytopenia, hydrocephalus, and callosal agenesis may constitute a new syndrome.

Agenesis of Corpus Callosum↗
PubMed2004

Hemispheric mediation of spatial attention: pseudoneglect after callosal stroke.

Study of patients with callosal lesions can provide insight into the mediation of spatial attention-intention by each hemisphere. Two patients with anterior callosal strokes bisected lines to the left of midline with the left hand and to the right of midline with the right in both a visual and tactile bisection task. The patients demonstrated a similar pattern of performance on pointing to body-midline in space. These results are consistent with the notion that each hemisphere supports spatial attention-intention toward contralateral space and that the corpus callosum is critical in the integration of such information.

Aged↗
PubMed1993

Callosal apraxia without agraphia.

We describe a patient with left unilateral ideomotor apraxia without left-sided agraphia caused by a callosal lesion that was demonstrated by magnetic resonance imaging. The clinical features, together with data in the literature, suggest that the callosal fibers for writing are concentrated in the posterior corpus callosum, while those for praxis cross in the more rostral part of the posterior half of the callosum.

Agraphia↗
PubMed1984

Callosal inhibition: the key to the brain code.

A mechanism for interhemispheric communication is proposed based upon the assumption of homotopic callosal inhibition. The implied pattern of cortical activity in each cerebral hemisphere is shown to be the mirror-image and "photographic negative" of the contralateral pattern. Mirror-imagery is a direct consequence of (1) approximate cerebral hemispheric bilateral symmetry and (2) homotopic callosal connections. The photographic negative relationship is a direct consequence of (1) bilaterally symmetrical activation of the cortex via subcortical "attentional" mechanisms and (2) inhibition by a unilaterally established engram of an identical cortical pattern contralaterally. In language generation and understanding, excitation predominantly in the left hemisphere produces on the right inhibition of language-related neurons as well as excitation of all surrounding "contextual" neurons. The suggested dichotomy of verbal and contextual functions of the cerebral hemispheres is shown to be supported by previous findings concerned with cognition in brain-damaged patients. Unlike earlier suggestions of linguistic and paralinguistic specializations in the left and right, the mirror-image negative hypothesis is based upon an explicit physiological process rather than unspecified differences in "information processing."

Animals↗
PubMed1982

The contribution of late-generated neurons to the callosal projection in rat: a study with prenatal x-irradiation.

Studies utilizing horseradish peroxidase tracing methods have suggested that there are species differences in the relative contribution of the different neocortical layers to the callosal projection. The present investigation utilized x-irradiation at different gestational ages to eliminate the late-generated neurons in the rat neocortex. The caudorostral gradient of reduction in the neuronal population of the supragranular layers is closely correlated with the gradient of reduction in the size of the corpus callosum. Furthermore, the callosal projection is absent in anteroposterior cortical segments in which the development of the supragranular layers was prevented without a reduction of the number of neurons in the infragranular layers of the neocortex. These results indicate that late-generated neurons residing primarily in the supragranular layers are essential for the formation of the corpus callosum.

Animals↗
PubMed1975

The effect of chronic protein malnutrition on trans-callosal evoked responses in the rat.

Studies were carried out on the trans-callosal evoked response in rats born of dams fed either a low (8%) or normal (25%) protein diet beginning 5 weeks prior to mating and throughout gestation and lactation. After weaning, pups were fed the same diets as their mothers. Bipolar (surface vs depth) stainless steel stimulating and recording electrodes were positioned at corresponding loci in the right and left sensorimotor cortices. Trans-callosal evoked responses were measured under urethane anesthesia using twice-threshold bipolar pulses of .1 msec duration at ages 13, 21, and 60-66 days. Evoked response latency was significantly greater in malnourished animals at 13 days of age, whereas at adulthood no latency differences were seen. Poststimulation excitability (15-100 msec range) was not significantly affected by the dietary treatment. These results are interpreted as corroborating previous reports on rats undernourished during development using sensory evoked potentials. By avoiding the use of extrinsic sensory stimulation, the present study demonstrates a dietary effect upon ontogeny of cortical evoked potentials independent of any possible effect on sensory receptor mechanisms.

Age Factors↗