The initial disparity vergence elicited with single and dual grating stimuli in monkeys: evidence for disparity energy sensing and nonlinear interactions

We recorded the initial vertical vergence eye movements elicited in monkeys at short latency ( approximately 70 ms) when the two eyes see one-dimensional (1D) horizontal grating patterns that are identical except for a phase difference (disparity) of one-quarter wavelength. With gratings composed of single sine waves, responses were always compensatory, showing Gaussian dependence on log spatial frequency (on average: peak = 0.75 cycles/deg; SD = 0.74; r(2) = 0.980) and monotonic dependence on log contrast with a gradual saturation well described by the Naka-Rushton equation (on average: n = 0.89; C(50) = 4.1%; r(2) = 0.978). With gratings composed of two sine waves whose spatial frequencies were in the ratio 3:5 and whose disparities were of opposite sign (the 3f5f stimulus), responses were determined by the disparities and contrasts of the two sine-wave components rather than the disparity of the features, consistent with early spatial filtering of the monocular inputs before their binocular combination and mediation by detectors sensitive to disparity energy. In addition, responses to the 3f5f stimulus showed a nonlinear dependence on the relative contrasts of the two sine waves. Thus on average, when the contrast of one sine wave was 2.3 times greater than that of the other, the one with the lower contrast was largely ineffective as though suppressed, and responses were determined almost entirely by the sine wave of higher contrast: Winner-Take-All. These findings are very similar to those published previously on the vertical vergence responses of humans, indicating that the monkey provides a good animal model for studying these disparity vergence responses.

[Hemoptysis one year after video-assisted thoracoscopic bullectomy for spontaneous pneumothorax: report of a case]

A 63-year-old man who had underwent video-assisted thoracoscopic bullectomy for left spontaneous pneumothorax 1 year before developed recurrent hemoptysis. Chest computed tomography showed previous stapling of the subsegmental bronchus in the left apico-posterior segment Bronchial arteriography showed hypervascularization of bronchial artery in the left upper segment and pooling of contrast medium along the staple-suture line. Video-assisted thoracoscopic apico-posterior segmentectomy was performed successfully. Pathological examination revieled hemosiderin lining along the surgical stump of B(1+2)cii, neither with infection nor infarction. These findings suggest that mechanical stapling of B(1+2)cii induced ischemia in the peripheral lung parenchyma causing bronchial hypervascularization. Late onset hemoptysis should be kept in mind as a complication after bullectomy with a mechanical stapler.

[Massive hemoptysis due to traction bronchiectasis caused by thoracic radiotherapy 23 years earlier]

We reported a 72-year-old woman who had a massive hemoptysis due to traction bronchiectasis in the left upper lobe. The patient underwent left radical mastectomy followed by thoracic radiotherapy for left breast cancer. The chest computed tomography showed traction bronchiectasis in the atrophic left upper lobe and the bronchial angiography showed hypervascularization of bronchial and internal thoracic arteries to the left upper lobe. Left upper lobectomy was performed after bronchial embolization for recurrent massive hemoptysis. Postoperative course was uneventful. Pathologic findings showed non-anatomical but clearly-bordered traction bronchiectasis with hypervascularized bronchial artery in the left upper lobe. These lesions were consistent with the field of the previous radiotherapy. Traction bronchiectasis causing massive hemoptysis should be considered as one of pulmonary sequelae after thoracic radiotherapy.

High-resolution analysis of DNA copy number alterations and gene expression in renal clear cell carcinoma

We analysed chromosomal copy number aberrations (CNAs) in renal cell carcinomas by array-based comparative genomic hybridization, using a genome-wide scanning array with 2304 BAC and PAC clones covering the whole human genome at a resolution of roughly 1.3 Mb. A total of 30 samples of renal cell carcinoma were analysed, including 26 cases of clear cell carcinoma (CCC) and four cases of chromophobe renal cell carcinoma (ChCC). In CCCs, gains of chromosomes 5q33.1-qter (58%), 7q11.22-q35 (35%) and 16p12.3-p13.12 (19%), and losses of chromosomes 3p25.1-p25.3 (77%), 3p21.31-p22.3 (81%), 3p14.1-p14.2 (77%), 8p23.3 (31%), 9q21.13-qter (19%) and 14q32.32-qter (38%) were detected. On the other hand, the patterns of CNAs differed markedly between CCCs and ChCCs. Next, we examined the correlation of CNAs with expression profiles in the same tumour samples in 22/26 cases of CCC, using oligonucleotide microarray. We extracted genes that were differentially expressed between cases with and without CNAs, and found that significantly more up-regulated genes were localized on chromosomes 5 and 7, where recurrent genomic gains have been detected. Conversely, significantly more down-regulated genes were localized on chromosomes 14 and 3, where recurrent genomic losses have been detected. These results revealed that CNAs were correlated with deregulation of gene expression in CCCs. Furthermore, we compared the patterns of genomic imbalance with histopathological features, and found that loss of 14q appeared to be a specific and additional genetic abnormality in high-grade CCC. When we compared the expression profiles of low-grade CCCs with those of high-grade CCCs, differentially down-regulated genes tended to be localized on chromosomes 14 and 9. Thus, it is suggested that copy number loss at 14q in high-grade CCC may be involved in the down-regulation of genes located in this region.

215 APPLICATION OFA MICROFLUIDIC SPERM SORTER TO THE IN VITRO FERTILIZATION OF PORCINE OOCYTES

In porcine IVF, polyspermy is a persistent obstacle to the efficient production of normal embryos in vitro. A microfluidic sperm sorter (MFSS; Strex Inc., Osaka, Japan) has been developed to isolate motile human spermatozoa (from diluted semen by 2 laminar flows in the microchannel). The motile spermatozoa can gradually accumulate in a chamber of the MFSS. In addition, we have succeeded in reducing the incidence of polyspermic penetration by a transient coincubation of oocytes with spermatozoa in the presence of caffeine, followed by culture of the oocytes in the absence of caffeine (2004 Reproduction 128, 789–800). If porcine oocytes could be cocultured with motile spermatozoa in the chamber of the MFSS, the gradual accumulation of motile spermatozoa might further improve the efficiency of production of monospermic fertilized porcine embryos. The current study was undertaken to apply the MFSS technology to porcine IVF. The sperm-rich fraction from 3 Berkshire boars was diluted at 1 � 108 cells mL–1 with modified Modena containing 20% seminal fluid, cooled to 15�C for 4 h, and kept at the same temperature until use within 2 days. Stored, diluted semen with greater than 80% viability was flowed with Tyrode lactate-HEPES-polyvinyl alcohol medium for 5 or 10 min at room temperature. The concentration and viability of spermatozoa mixed in the flowed medium were determined. In the next experiment, a diluted semen sample was flowed with modified TCM-199 containing 5 mm caffeine for 5 min at room temperature. Before flowing, porcine IVM oocytes were put into the chamber of the MFSS, where motile spermatozoa will accumulate with modified TCM-199 containing 5 mm caffeine. After flowing for 5 min, those oocytes were transferred into a 500-µL droplet of caffeine-free modified TCM-199, and culture was continued for 8 h. Statistical analyses were carried out by ANOVA and Fisher's PLSD post hoc test. After flowing for 5 min, the concentration of spermatozoa recollected from the chamber was 5.7 � 105 cells mL–1. The viability of recollected spermatozoa was significantly higher than the original flowed semen. However, when spermatozoa were flowed for 10 min, the viability of recollected spermatozoa was not different from the original flowed semen, whereas the concentration of recollected spermatozoa was 9.7 � 105 cells mL–1. When IVM oocytes were cocultured with spermatozoa gradually accumulated in the chamber of MFSS for 5 min, 35% (22 to 48%) of oocytes were penetrated, and 95% (90 to 100%) of the penetrated oocytes were monospermic. These observations demonstrate that the MFSS can separate penetrable boar spermatozoa with a high viability and sufficient concentration for IVF. Furthermore, the current data suggest the possibility of improving the efficiency of monospermic fertilization of porcine IVM oocytes by a transient coculture with MFSS.

Evaluation of the basic properties of the BANGkit gel dosimeter

We evaluated the basic properties of a commercially available BANGkit gel dosimeter, which is a normoxic type of BANG gel. This gel-kit has the same composition as the BANG 3 gel, but is fully oxygenated. To exclude oxygen, oxygen scavenging ascorbic acid and copper sulfate as a catalyst are used. The properties that we examined are the effects of the concentrations of copper sulfate and ascorbic acid on the response, the reproducibility, the long-term stability, the temperature effect at irradiation and the dose-rate effect. In our results, the excellent linear fit of the R2-dose response in a dose range for clinical use and its reproducibility were observed. The precision of a linear fit was preserved for about 3 weeks. The temperature at irradiation showed a significant effect on the dose response. Although the dose-rate dependence in the high-dose range was observed, it was negligible for the clinical dose range up to 270 cGy. In conclusion, this gel dosimeter is thought to be utilizable in clinical practice, while we have to pay attention to the temperature during the entire measurement processes, and additionally there is room for improvement in the linearity and the dose-rate dependence in the high-dose range.

Early clinical outcomes of 3D-conformal radiotherapy using accelerated hyperfractionation without intracavitary brachytherapy for cervical cancer

PURPOSE/OBJECTIVE

To evaluate the outcome of cervical cancer patients unable to undergo conventional intracavitary brachytherapy (ICBT) treated with 3D-conformal radiotherapy (3DCRT) alone using accelerated hyperfractionation (AHF).

METHODS AND MATERIALS

We reviewed the records of 7 patients who had received definitive radiotherapy with 3DCRT alone using AHF for cervical cancer between 2002 and 2005. FIGO stage was IB (1), IIB (2), IIIA (1), IIIB (2), and IVA (1). The reason we did not perform ICBT was due to patient refusal. In 1 patient with stage IB, a total dose of 65.4 Gy was delivered by local irradiation (LI) only. In 1 patient with stage IIIA, a total dose of 60 Gy was delivered by LI only. In 5 patients with Stage IIB-IV, a median total dose of 70.8 Gy was delivered by combination of whole pelvic irradiation (median dose of 45 Gy) with LI. Median overall treatment time was 42 days.

RESULTS

Median follow-up for survival patients was 17 months. Out of 7 patients, 6 patients had CR and 1 patient had PR. The response rate was 100%. The 2-year local control rate was 85.7%. Of these patients, 5 are alive without disease and 1 is alive with lung metastasis.

CONCLUSIONS

Our outcomes suggest that 3DCRT using AHF may be a promising as a definitive treatment for cervical cancer when ICBT is not able to be performed.

Antisense and nonantisense effects of antisense Bcl-2 on multiple roles of Bcl-2 as a chemosensitizer in cancer therapy

Bcl-2 is an oncoprotein that plays a critical role in inhibiting apoptotic cell death in the mitochondria-dependent pathway in cancer chemotherapy. As a strategy for blocking Bcl-2 for enhancement of the chemotherapeutic effect, antisense Bcl-2 (AS Bcl-2; G3139, oblimersen sodium, Genasense) has shown promise, and there are several ongoing clinical studies with hematological malignancies as well as solid tumors. Although several preclinical and clinical studies have shown the therapeutic efficacy of Bcl-2 in combination with an anticancer drug as a chemosensitizer, in clinical trials the downregulation of Bcl-2 has not been observed with a high frequency in tumor cells. Nevertheless, previous studies showed nonantisense effects such as production of reactive oxygen species and immunostimulatory action through cytosine-phosphate-guanosine-motif in the antisense oligodeoxynucleotides. Further, Bcl-2 is able to inhibit Beclin 1-dependent autophagic cell death, which is a nonapoptotic cell death. The current status and future directions of AS Bcl-2 and the potential mechanisms for multiple roles that Bcl-2 has in cancer therapy are reviewed.

Assessment of efficacy of a live oral poliovirus vaccine for virulent Sabin-like poliovirus 1 strains in Japan

Virulent Sabin-like poliovirus (VSLP) was isolated from river and sewage waters between October 1993 and September 1995 in Toyama Prefecture, Japan (Yoshida et al., Lancet 356, 1461-1463, 2000). In this study, to assess the possibility of an epidemic of poliomyelitis caused by a VSLP in Japan under the current vaccination policy of administration of live attenuated oral poliovirus vaccine (OPV), we determined titers of serum neutralizing antibodies to poliovirus 1 (PV-1) strains Sabin (vaccine strain), Mahoney (wild-type strain) and G4-12 (VSLP) in various groups of residents of Toyama Prefecture, Japan. The seropositivity and geometric mean neutralizing antibody titers against these strains in the individuals who obtained two doses of OPV were 99.1%, 94.5% and 95.5%, respectively, and 564, 186 and 194, respectively. Although the antibody titers to G4-12 were lower compared with those to Sabin, these results indicate that the OPV vaccination policy in Japan has been effective in preventing poliomyelitis caused by VSLPs. These results also suggest that (i) an epidemic of poliomyelitis caused by a VSLP has not occurred in Japan due to herd immunity, and (ii) the possibility of reemergence of VSLPs will be prevented if sufficient herd immunity is acquired immediately after completion of the OPV vaccination in accordance with the poliomyelitis eradication program.

Release of Short and Proline-Rich Antihypertensive Peptides from Casein Hydrolysate with an Aspergillus oryzae Protease

Angiotensin-I converting enzyme inhibitory activities were measured after hydrolysis of casein by 9 different commercially available proteolytic enzymes. Among these enzymes, a protease isolated from Aspergillus oryzae showed the highest angiotensin-I converting enzyme inhibitory activity per peptide. The A. oryzae peptide also showed the highest antihypertensive effect in spontaneously hypertensive rats when the systolic blood pressure was measured 5 h after oral administration of 32 mg/kg of various enzymatic hydrolysates. Significant antihypertensive effects were observed with dosages of 9.6, 32, and 96 mg of the A. oryzae peptide/kg of body weight (BW), and the effects were dependent on these peptide dosages. Analysis of peptide length showed the A. oryzae hydrolysate was the shortest of all tested casein hydrolysates; the peptide mixture had an average value of 1.4 amino acids (AA) in the sequence. To further characterize the A. oryzae hydrolysate, we analyzed the AA sequence of the whole peptide mixture. Various AA were detected at the first AA position, however, an increased number of Pro residues were observed at the second and third position of the A. oryzae hydrolysate. No strong signals were detected after the fourth AA position of the A. oryzae hydrolysate. These results suggest that the casein hydrolysate of A. oryzae, which expressed potent antihypertensive effects in spontaneously hypertensive rats, mainly contain short peptides of X-Pro and X-Pro-Pro sequences.

Comparison of computer-assisted instruction (CAI) versus traditional textbook methods for training in abdominal examination (Japanese experience)

PURPOSE

This study aimed to compare the effects of computer-assisted, text-based and computer-and-text learning conditions on the performances of 3 groups of medical students in the pre-clinical years of their programme, taking into account their academic achievement to date. A fourth group of students served as a control (no-study) group.

METHOD

Participants were recruited from the pre-clinical years of the training programmes in 2 medical schools in Japan, Jichi Medical School near Tokyo and Kochi Medical School near Osaka. Participants were randomly assigned to 4 learning conditions and tested before and after the study on their knowledge of and skill in performing an abdominal examination, in a multiple-choice test and an objective structured clinical examination (OSCE), respectively. Information about performance in the programme was collected from school records and students were classified as average, good or excellent. Student and faculty evaluations of their experience in the study were explored by means of a short evaluation survey.

RESULTS

Compared to the control group, all 3 study groups exhibited significant gains in performance on knowledge and performance measures. For the knowledge measure, the gains of the computer-assisted and computer-assisted plus text-based learning groups were significantly greater than the gains of the text-based learning group. The performances of the 3 groups did not differ on the OSCE measure. Analyses of gains by performance level revealed that high achieving students' learning was independent of study method. Lower achieving students performed better after using computer-based learning methods.

CONCLUSION

The results suggest that computer-assisted learning methods will be of greater help to students who do not find the traditional methods effective. Explorations of the factors behind this are a matter for future research.

Insulin regulates the expression of the enhancer of split- and hairy-related protein-2 gene via different pathways in 3T3-L1 adipocytes and L6 myotubes

We investigated the effect of insulin on the expression of the enhancer of split- and hairy-related protein-2 gene in 3T3-L1 adipocytes and L6 myotubes. The level of enhancer of split- and hairy-related protein-2 mRNA was increased by insulin in both cells. While both wortmannin and LY294002 blocked the increase in 3T3-L1 adipocytes, and only PD98059 was effective in L6 myotubes. Although the increase by insulin in these cells was inhibited by treatment with actinomycin D, this was enhanced by treatment with cycloheximide. Furthermore, cyclic AMP increased the level of enhancer of split- and hairy-related protein-2 mRNA in both cells in an additive manner. Thus, we conclude that insulin and cyclic AMP induce the expression of the enhancer of split- and hairy-related protein-2 gene in both 3T3-L1 adipocytes and L6 myotubes, and that the gene expression enhanced by insulin is regulated by the cell type-specific pathway. The former requires a phosphoinositide 3-kinase pathway and the latter a mitogen-activated protein kinase pathway.

Binocular Deficits Associated With Early Alternating Monocular Defocus. II. Neurophysiological Observations

Experiencing binocularly conflicting signals early in life dramatically alters the binocular responses of cortical neurons. Because visual cortex is highly plastic during a critical period of development, cortical deficits resulting from early abnormal visual experience often mirror the nature of interocular decorrelation of neural signals from the two eyes. In the preceding paper, we demonstrated that monkeys that experienced early alternating monocular defocus (–1.5, –3.0, or –6.0 D) show deficits in stereopsis that generally reflected the magnitude of imposed monocular defocus. Because these results indicated that alternating monocular defocus affected the higher spatial frequency components of visual scenes more severely, we employed microelectrode recording methods to investigate whether V1 neurons in these lens-reared monkeys exhibited spatial-frequency-dependent alterations in their binocular response properties. We found that a neuron's sensitivity to interocular spatial phase disparity was reduced in the treated monkeys and that this reduction was generally more severe for units tuned to higher spatial frequencies. In the majority of the affected units, the disparity-sensitivity loss was associated with interocular differences in monocular receptive field properties. The present results suggest that the behavioral deficits in stereopsis produced by abnormal visual experience reflect at least in part the constraints imposed by alterations at the earliest stages of binocular cortical processing and support the hypothesis that the local disparity processing mechanisms in primates are spatially tuned and can be independently compromised by early abnormal visual experience.

Mouse soluble CD14 truncated at amino acid 71 in transgenic mice: preventive effect on endotoxin-mediated toxic shock

Mouse soluble CD14 truncated at amino acid 71 (N71) contains the lipopolysaccharide (LPS)-binding sequence. Transgenic mice carrying alpha1-antitrypsin (AT) promoter-N71 fusion genes, designated AT363-1 and AT363-2, were produced. These mice constitutively produced elevated levels of N71. The concentration of LPS in sera after intraperitoneal LPS injection was lower in AT363-1 mice than in nontransgenic mice. The expression of N71 mRNA was enhanced by subcutaneous turpentine oil injection. The levels of serum LPS and tumor necrosis factor-alpha (TNF-alpha) after intraperitoneal LPS injections were lower in AT363-1 mice than in nontransgenic mice. Cell surface TNF-alpha and CD14 expression in exudate peritoneal macrophages prepared by intraperitoneal injection of proteose peptone and then LPS were higher in AT363-1 mice than in nontransgenic mice. Neutrophil infiltration in the liver after induction of the generalized Shwartzman reaction was lower in AT363-1 mice than in nontransgenic mice. Lethality of the Shwartzman reaction was significantly lower in AT363-1 than in nontransgenic mice. These findings suggest that the endotoxin-binding protein (N71) from CD14 prevents endotoxin-mediated toxic shock.

Regulation of circulating immune complexes by complement receptor type 1 on erythrocytes in chronic viral liver diseases

BACKGROUND AND AIM

Complement receptor type 1 (CR1) is a transmembrane protein, and human erythrocyte CR1 (E-CR1) is involved in the transport of circulating immune complexes (IC) from the circulation to the reticuloendothelial system, including the liver and spleen. In chronic viral hepatitis, increased levels of IC containing viral particles and an association with various extrahepatic manifestations have been reported. However, regulatory mechanisms for IC levels are not fully understood. PATIENTS/SUBJECTS AND METHODS: We analysed IC, E-CR1, and quantitative polymorphism of the CR1 gene in 149 patients with chronic viral liver diseases and in 64 normal blood donors using an enzyme linked immunosorbent assay, radioimmunoassay, and polymerase chain reaction-restriction fragment length polymorphism, respectively. We also analysed the effect of CR1 gene polymorphism on IC binding to E-CR1 using molecular methods.

RESULTS

E-CR1 levels in patients with chronic hepatitis and chronic viral liver diseases as a whole correlated inversely with increased levels of IC. Moreover, significantly high levels of IC were observed in patients with chronic hepatitis C (CH-C) who were homozygous for the E-CR1 low density allele. We also found low levels of E-CR1 in liver cirrhosis and CH-C but not in CH-B. Low levels of E-CR1 in CH-C were observed, even after considering the polymorphism of the CR1 gene. Finally, we demonstrated CR1 gene polymorphism dependent binding of hepatitis virus containing IC.

CONCLUSIONS

Our results emphasise the important role of E-CR1 in clearance of IC from the circulation and the acquired, rather than inherited, decrease in E-CR1 in chronic viral liver diseases, especially of type C.

Morphological study of the regeneration mechanism of acetic acid-injured colon crypts in the rat

The regeneration mechanism of injured rat colonic mucosa with 1% acetic acid was certified in this study. The injured colons were studied periodically on experimental days 1, 3, 5, 7, 15, and 20 with light and scanning electron microscopy. Specimens were examined in paraffin sections stained with hematoxylin and eosin; crypts were isolated with the HCl digestion method; and three-dimensional stromal collagen tissue was prepared with the NaOH cell maceration method. Damage to the mucosal and submucosal layers peaked between the 1st and 3rd days with edema, regeneration, necrosis, and inflammation. The edema and inflammation subsided, and mucosal atrophy and crypt reduction remained at around 1 week. At 2 weeks the mucosa became thick, and crypts showed many branches in their lower two-thirds; and by 3 weeks the mucosa had recovered to almost normal. The ratio of number of crypts at the base and surface was almost 1.5 on the 15th day and 1.0 on the 20th day, suggesting that each branch progresses upward to create an independent crypt. We believe that the fission mechanism plays an important role in crypt repair after acetic acid injury of the colonic mucosa. As the proliferative zone of the colonic crypt is localized at the crypt base, fission of the crypt starting at the base and progressing up to the surface is the most reasonable and efficient mechanism for repair by increasing the number of crypts.

An immunohistochemical and ultrastructural study of a follicle-stimulating hormone-secreting gonadotroph adenoma occurring in a 10-year-old girl

Female gonadotroph adenomas with endocrinological symptoms are uncommon. Six cases of such adenomas have been reported in the literature: two were girls who presented with precocious puberty and four were premenopausal women with accompanying multiple ovarian cysts. We describe here a 10-year-old Japanese girl with a gonadotroph macroadenoma and present detailed morphological findings of the tumor. The patient's chief complaints were nausea, abdominal distention, and abdominal pain. Abdominopelvic ultrasonography and magnetic resonance imaging (MRI) revealed bilateral multiple ovarian cysts. Endocrinological assays showed elevated serum follicle-stimulating hormone (FSH) (33.7 mIU/ml) and estradiol (3840 pg/ml). MRI of the head showed a large pituitary tumor. Two transsphenoidal operations and subsequent radiation therapy were performed. Immunohistochemically, more than half the tumor cells were positive for anti-FSH-beta monoclonal antibody. Ultrastructurally, the tumor cells exhibited a fairly uniform picture of rounded cells. Their nuclei were slightly irregular and contained heterochromatin, and their cytoplasm contained many round, dense core granules, measuring 140-260 nm in diameter, together with well-developed organelles. An in vitro study showed that the tumor cells in primary culture produced FSH (1089.0 mIU/ml). To our knowledge, this is the first immunohistochemical and ultrastructural study of an FSH-secreting gonadotroph adenoma occurring in childhood.

Effects of the duration of early strabismus on the binocular responses of neurons in the monkey visual cortex (V1)

PURPOSE

To determine how the duration of early strabismus influences the severity of loss of disparity sensitivity in V1 neurons and the effects of extensive poststrabismus visual experience on the maintenance of functional binocular connections.

METHODS

Concomitant strabismus was optically simulated in 10 rhesus monkeys using a prism-rearing procedure. The onset of strabismus was kept constant at 4 weeks of age and the duration was maintained for 2, 4, or 8 weeks. In one group of monkeys (infants), the neurophysiological experiments were conducted immediately after the period of rearing with prisms. In another group (adults), after the termination of the prism-rearing regimen at either 8 or 12 weeks of age, the monkeys were kept in a normal housing environment until maturity and behavioral testing was conducted before the recording experiments to determine the animal's monocular and binocular visual capacities. To assess the effects of the period of early strabismus on binocular interactions in V1, extracellular single-unit recording methods were used in anesthetized and paralyzed monkeys, and dichoptic sine-wave gratings were used as stimuli.

RESULTS

In all strabismic monkeys, the sensitivity of V1 units to interocular spatial phase disparity (disparity sensitivity) was significantly reduced, and the prevalence of binocular suppression was higher than that found in age-matched control animals. Although 8 weeks of strabismus resulted in a slightly larger loss of disparity sensitivity, the overall effects of the duration of strabismus were surprisingly small in infant strabismic monkeys. After poststrabismus visual experience, a small but significantly higher degree of disparity sensitivity was noted in V1 if prism-rearing was terminated after 4 weeks of strabismus (i.e., at 8 weeks of age), but not after 8 weeks of strabismus (i.e., at 12 weeks of age).

CONCLUSIONS

A brief period (2 weeks) of misalignment after the emergence of stereopsis is sufficient to drastically reduce the functional binocular connections in V1, and longer periods of strabismus result in little additional loss in disparity sensitivity. Clinically, these results suggest that taking corrective measures for infantile esotropes before the known onset age for stereopsis may be important for maintaining better binocular sensory function and better interocular alignment at later stages of development.