Anomalous global effects induced by 'blind' distractors in visual hemifield defects.

Previous research has revealed that a stimulus presented in the blind visual field of participants with visual hemifield defects can evoke oculomotor competition, in the absence of awareness. Here we studied three cases to determine whether a distractor in a blind hemifield would be capable of inducing a global effect, a shift of saccade endpoint when target and distractor are close to each other, in participants with lesions of the optic radiations or striate cortex. We found that blind field distractors significantly shifted saccadic endpoints in two of three participants with lesions of either the striate cortex or distal optic radiations. The direction of the effect was paradoxical, however, in that saccadic endpoints shifted away from blind field distractors, whereas endpoints shifted towards distractors in the visible hemifields, which is the normal global effect. These results provide further evidence that elements presented in the blind visual field can generate modulatory interactions in the oculomotor system, which may differ from interactions in normal vision.

Auger electron angular distributions from surfaces: direct comparison with isoenergetic photoelectrons.

Angular distribution patterns of Auger electrons and of photoelectrons from a Cu (001) surface were measured at the same electron kinetic energy. These measurements reveal that the low kinetic energy angular distributions for Cu Auger electrons and Cu 3p(3/2) photoelectrons differ substantially. This direct comparison between the photoelectron and Auger electron angular distributions demonstrates that, in some circumstances, the Auger process produces a complicated source wave whose nature must be explored before Auger angular distributions can be used for surface structure analysis.

Unilateral right parietal damage leads to bilateral deficit for high-level motion.

Patients with right parietal damage demonstrate a variety of attentional deficits in their left visual field contralateral to their lesion. We now report that patients with right lesions also show a severe loss in the perception of apparent motion in their "good" right visual field ipsilateral to their lesion. Three tests of attention were conducted, and losses were found only in the contralesional fields for a selective attention and a multiple object tracking task. Losses in apparent motion, however, were bilateral in all cases. The deficit in apparent motion in the parietal patients supports previous claims that this relatively effortless percept is mediated by attention. However, the bilateral deficit suggests that the disruption is due to a bilateral loss in the temporal resolution of attention to transient events that drive the apparent motion percept.

The contribution of the fusiform gyrus and superior temporal sulcus in processing facial attractiveness: neuropsychological and neuroimaging evidence.

Current cognitive models suggest that the processing of dynamic facial attributes, including social signals such as gaze direction and facial expression, involves the superior temporal sulcus, whereas the processing of invariant facial structure such as the individuals' identity involves the fusiform face area. Where facial attractiveness, a social signal that may emerge from invariant facial structure, is processed within this dual-route model of face perception is uncertain. Here, we present two studies. First, we investigated the explicit judgments of facial attractiveness and attractiveness-motivated behavior in patients with acquired prosopagnosia, a deficit in familiar face recognition usually associated with damage to medial occipitotemporal cortex. We found that both abilities were impaired in these patients, with some weak residual ability for attractiveness judgments found only in those patients with unilateral right occipitotemporal or bilateral anterior temporal lesions. Importantly, deficits in attractiveness perception correlated with the severity of the face recognition deficit. Second, we performed a functional magnetic resonance imaging study in healthy subjects that included an implicit and explicit processing of facial attractiveness. We found increased neural activity when explicitly judging facial attractiveness within a number of cortical regions including the fusiform face area, but not the superior temporal sulcus, indicating a potential contribution of the fusiform face area to this judgment. Thus, converging neuropsychological and neuroimaging evidence points to a critical role of the inferior occipitotemporal cortex in the processing of facial attractiveness.

The use of working memory for task prediction: what benefits accrue from different types of foreknowledge?

The assumption that the deployment of executive processes invariably improves task performance is implicit to cognitive theory. In particular, working memory can be used to retain and update historical information about predictable trial sequences (foreknowledge) so that subjects can anticipate and prepare for the upcoming trial more effectively. We review the effects of different types of foreknowledge on response accuracy and latency, particularly in relation to experiments investigating saccadic eye movements in humans. While it is possible to make all aspects of an impending trial predictable, varying the predictability of different components of the trial independently can reveal which cognitive operations are potentially modifiable by foreknowledge. These operations include stimulus processing, retrieval of task-set rules, and response preparation, among others. The available data suggest that, while response preparation can be completed and the response even executed before the stimulus appears (i.e. anticipation) when the subject possesses complete task-foreknowledge (knowing both the stimulus to appear and the response required), foreknowledge of the task-set alone does not permit advance configuration of the task-set rules. A taxonomy for foreknowledge is proposed, including foreknowledge for timing, stimulus, set, response, and task. Work on differentiating these effects in neurophysiology, neuroimaging, and neuropsychology is still in the early stages.

Reduced Myelin Water in the White Matter Tracts of Patients with Niemann-Pick Disease Type C.

Previous studies using diffusion tensor imaging to examine white matter in Niemann-Pick disease type C have produced mixed results. However, diffusion tensor imaging does not directly measure myelin and may be affected by other structural changes. We used myelin water imaging to more directly examine demyelination in 2 patients with Niemann-Pick disease type C. The results suggest that this technique may be useful for identifying regional changes in myelination in this condition.

Induction chemotherapy with docetaxel, cisplatin, fluorouracil, and leucovorin for squamous cell carcinoma of the head and neck: a phase I/II trial.

PURPOSE: A phase I/II trial of docetaxel, cisplatin, fluorouracil (5-FU), and leucovorin (TPFL5) induction chemotherapy for patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS: Twenty-three previously untreated patients with stage III or IV SCCHN and Eastern Cooperative Oncology Group functional status less than or equal to 2 were treated with TPFL5. Postchemotherapy home support included intravenous fluids, prophylactic antibiotics, and granulocyte colony-stimulating factor (G-CSF). Docetaxel dose was escalated to determine the maximum-tolerated dose (MTD). Fifteen patients were treated with three cycles of TPFL5 at MTD. Patients who achieved either a partial response (PR) or complete response (CR) to three cycles of TPFL5 then received definitive twice-daily radiation therapy. Toxicity and clinical and pathologic response to TPFL5 were assessed. RESULTS: Twenty-three patients received a total of 69 cycles of TPFL5. The MTD was determined to be docetaxel 60 mg/m2. Dose-limiting toxicity (DLT) was neutropenia. Additional significant toxicities at MTD were nausea, mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The overall response rate to TPFL5 was 100%, which included 14 of 23 (61%) clinical CRs and nine of 23 (39%) clinical PRs. Primary-site clinical and pathologic CR rates were 19 of 22 (86%) CRs and 20 of 22 (91%) CRs, respectively. Eight patients had less than a CR in the neck to chemotherapy and, therefore, had postradiation neck dissections, four of which were positive for residual tumor. CONCLUSION: TPFL5 is a tolerable induction regimen in patients with good performance status. The DLT is neutropenia with significant mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The high response rates to TPFL5 justify further evaluation of this combination of agents in the context of formal clinical trials.

Blink- and saccade-induced seesaw nystagmus.

A 29-year-old woman with bitemporal hemianopia persisting after a suprasellar germinoma was resected twelve years previously had brief periods of pendular seesaw nystagmus after blinks and horizontal or vertical saccades. Nystagmus may have been suppressed during fixation, and escaped only when fixation was interrupted by blinks or saccades.

Motion perception in optic neuropathy.

We tested motion perception in 15 eyes of 13 patients with optic neuropathy. Eleven of the eyes had optic neuritis. The motion perception paradigm tested subjects' ability to discriminate the direction of a global coherent motion signal amid varying levels of background noise. The results showed defective motion processing in eight of the 15 eyes. This defect was not due to low visibility (poor spatial resolution), since 11 of the 15 eyes had Snellen acuities of 20/20 or better. Neither was impaired motion perception due to decreased luminance sensitivity, since attenuating the display signal by 2.1 log units (0.6 units more than the worst relative afferent pupillary defect in any patient) in five normal eyes had no effect. Motion perception and critical flicker fusion were independent of each other. Given proposals that both depend exclusively on the same M, or transient, channel, we had not predicted this double dissociation between flicker and motion perception.

Saccadic duration and intrasaccadic fatigue in myasthenic and nonmyasthenic ocular palsies.

We measured the duration and amplitude of saccades in three normal subjects, eight patients with myasthenia gravis, and eight patients with nonmyasthenic ocular palsies. Saccades were examined at the start of a repetitive saccade task, after 3 minutes of activity, and 1 minute after administration of edrophonium. The duration of saccades was prolonged initially in both myasthenic and nonmyasthenic palsies. Activity did not produce significant differences among the three groups in either the slope of the duration-amplitude relationship or the predicted durations of saccades of 5 degrees, 10 degrees, or 15 degrees. However, durations decreased in myasthenia but increased in nonmyasthenic palsies after edrophonium. Much of this decrease in myasthenic saccadic duration was due to reduction in deceleration time, indicating resolution of intrasaccadic fatigue after edrophonium administration. However, the relation of deceleration fraction (deceleration time divided by total duration) to total duration remained constant in all subject groups. Analysis of saccadic duration is a useful means of interpreting responses to edrophonium because it incorporates data from saccades of a wide range of amplitudes into a linear relation between duration and amplitude.

Covert recognition in acquired and developmental prosopagnosia.

BACKGROUND: Some patients with prosopagnosia have covert recognition, meaning that they retain some familiarity or knowledge of facial identity of which they are not aware. OBJECTIVE: To test the hypothesis that prosopagnosic patients with right occipitotemporal lesions and impaired face perception lack covert processing, whereas patients with associative prosopagnosia and bilateral anterior temporal lesions possess it. METHODS: Eight patients with prosopagnosia were tested with a battery of four face recognition tests to determine their ability to discriminate between famous and unknown faces. RESULTS: Measures of overt familiarity revealed better residual discrimination in patients with acquired prosopagnosia than in those with the developmental form. With forced-choice methods using famous faces paired with unknown faces, no patient demonstrated covert familiarity. However, when the semantic cue of the name of the famous face was provided, covert processing was present in all five patients with acquired prosopagnosia, including the three with extensive right-sided lesions and impaired perceptual discrimination of facial configuration. Sorting unrecognized faces by occupation was also performed above chance in three of these five patients. In contrast, none of the three patients with developmental prosopagnosia had covert processing, even though two demonstrated flawless performance on similar tests of name (rather than face) recognition. Overt familiarity correlated highly with the degree of covert recognition. CONCLUSIONS: Extensive right occipitotemporal lesions with significant deficits in face perception are not incompatible with covert face processing. Covert processing is absent in developmental prosopagnosia, because this condition likely precludes the establishment of a store of accurate facial memories. The presence of covert processing correlates with the degree of residual overt familiarity, indicating that these are related phenomena.

Spatial representation in the normal visual field: a study of hemifield line bisection.

We examined bisection of lines viewed in only one hemifield by normal subjects. Subjects first performed a traditional version of line bisection, by indicating the perceived midpoint of a line on paper with a penmark. Bisection was accurate when they were allowed to shift their gaze over the stimulus, but it was biased towards the central visual field (centripetally) when gaze was fixed so that the line was seen in only one hemifield. In a second experiment, lines with transectors at various locations were presented briefly on a screen and subjects had to indicate on which side of the perceived midpoint the transector was located. A centripetal bias was still found, indicating that it has a perceptual origin. The interaction between bias and effects of tangent line presentation suggested that subjects were performing an angle bisection rather than a line bisection. Also, there was bias in not only right and left hemifields but also upper and lower hemifields. In a third experiment, increasing the width of the stimulus bars peripherally did not eliminate this bias. Bias was size-invariant along the horizontal meridian. This spatial version of Weber's law was modeled by a magnification function using an exponential equation. The slope of this function is much shallower than those currently known for V1, V4 and V5. We conclude that a centripetal bias exists for hemifield line bisection and that this bias likely contributes to the contralateral bias of line bisection by hemianopic patients found in other studies.

Impaired visual search in patients with unilateral neglect: an oculographic analysis.

The attentional deficit underlying hemispatial neglect was examined through a detailed analysis of the eye movement performance of a group of neglect patients. Relative to normal subjects and to patients with hemianopia without neglect, patients with left neglect make fewer fixations and have shorter inspection time on the contralesional left side. They also start their search to the right of the midline and make significantly more fixations and longer fixations on the ipsilesional right side. A positive linear relationship between horizontal location and frequency of fixations was noted for the neglect group as a whole, as well as for most of the individual patients. These findings strongly endorse the view that the attentional deficit in neglect follows a left right gradient. The peak of the maximum fixations, however, is not on the extreme right, as might be predicted by a strict gradient account, and is more consistent with recent views that the midsagittal plane of the viewer is redirected rightwards. These findings provide a detailed analysis of the eye movement patterns in neglect patients and demonstrate the robustness of oculographic analysis for examining their altered spatial representation.

The eye movements of pure alexic patients during reading and nonreading tasks.

We compared the eye-movements of two patients who read letter-by-letter (LBL) following a left occipital lobe lesion with those of normal control subjects and of hemianopic patients in two tasks: a nonreading visual search task and a text reading task. Whereas the LBL readers exhibited similar eye-movement patterns to those of the other two groups on the nonreading task, their eye movements differed significantly during reading, as reflected in the disproportionate increase in the number and duration of fixations per word and in the regressive saccades per word. Importantly, relative to the two control groups, letter-by-letter readers also made more fixations per word as word length increased, especially as word frequency and word imageability decreased. Two critical results emerged from these experiments: First, the alteration in the oculomotor behavior of the LBL readers during reading is similar to that seen in normal readers under difficult reading conditions, as well as in beginning readers and in those with developmental dyslexia, and appears to reflect difficulties in processing the visual stimulus. Second, the interaction of length with frequency and with imageability in determining the eye movement pattern is consistent with an interactive activation model of normal word recognition in which weakened activation of orthographic input can nevertheless engage high-level lexical factors.

'Saccadic jitter' is a quantitative ocular sign in myasthenia gravis.

PURPOSE: To examine the variability of saccadic peak-velocity amplitude relationships in myasthenic and nonmyasthenic ocular palsies. METHODS: The authors measured centrifugal saccades in nine patients with myasthenia gravis, nine patients with proven nonmyasthenic ocular palsies, and three normal subjects. Patients made repetitive saccades for 8 minutes. Saccades were analyzed at the start of the task, after 3 minutes of the task (fatigue), and at 1 minute after edrophonium. The authors fitted an exponential function to individual data and averages for amplitude bins and calculated the root mean square error of the curves. They then subtracted the root mean square error of curves fitted to bin averages from that of curves fitted to individual saccades: The result was an index of the variability of saccadic peak velocity, which they called saccadic jitter. RESULTS: Compared to those without myasthenia, the saccades of patients with myasthenia showed more variability in the initial and the fatigue periods. The change induced by edrophonium did not distinguish between the groups. CONCLUSIONS: Signal detection analysis indicated that saccadic jitter has little value as a screening tool but is a useful diagnostic sign in 42% of myasthenic saccadic analyses.

Pediatrician attendance at cesarean delivery: necessary or not?

OBJECTIVE: To determine whether it is necessary for a pediatrician to attend all cesarean deliveries. METHODS: We analyzed a database of 17,867 consecutive deliveries to determine the rates of low Apgar scores in the following three groups of patients: those with vaginal delivery, cesarean delivery using regional anesthesia without fetal indication, and cesarean delivery for fetal indications or using general anesthesia. RESULTS: There was a significantly higher rate of low Apgar scores in the fetal indications or general anesthesia group when compared with vaginal deliveries. Specifically, 35 (5.8%) of 596 cesareans for fetal heart rate abnormality or using general anesthesia had 1-minute Apgars under 4 in contrast to 115 of 10,270 (1.1%) of vaginal deliveries. There was no significantly increased risk for low Apgar scores in the group of cesareans using regional anesthesia for nonfetal indications (33 of 2057, 1.6%). Results were similar for Apgar scores under 7 at 5 minutes. CONCLUSION: Because there is no higher incidence of low Apgar scores in cesarean deliveries using regional anesthesia for nonfetal indications compared with vaginal deliveries, there is no convincing need for pediatrician attendance at such deliveries.

Mode of delivery and risk of respiratory diseases in newborns.

OBJECTIVE: To determine whether there is an increased incidence of persistent pulmonary hypertension in neonates delivered by cesarean, with or without labor, compared with those delivered vaginally. METHODS: We did a computerized retrospective review of 29,669 consecutive deliveries over 7 years (1992-1999). The incidences of persistent pulmonary hypertension of the newborn, transient tachypnea of the newborn, and respiratory distress syndrome (RDS) were tabulated for each delivery mode. Cases of persistent pulmonary hypertension were reviewed individually to determine delivery method and whether labor had occurred. The three groups defined were all cesarean deliveries, all elective cesareans, and all vaginal deliveries. RESULTS: Among 4301 cesareans done, 17 neonates had persistent pulmonary hypertension (four per 1000 live births). Among 1889 elective cesarean deliveries, seven neonates had persistent pulmonary hypertension (3.7 per 1000 live births). Among 21,017 vaginal deliveries, 17 neonates had persistent pulmonary hypertension (0.8 per 1000 live births). chi2 analysis showed an odds ratio 4.6 and P <.001 for comparison of elective cesarean and vaginal delivery for that outcome. CONCLUSION: The incidence of persistent pulmonary hypertension of the newborn was approximately 0.37% among neonates delivered by elective cesarean, almost fivefold higher than those delivered vaginally. The findings have implications for informed consent before cesarean and increased surveillance of neonates after cesarean.

Ureterouterine fistula as a complication of elective abortion.

A rare case of ureterouterine fistula following a uterine curettage for elective abortion is presented. Review of the literature and management of the present case outlines two different methods of managment of this complication of surgery. Attention is called to the possibility of this complication occurring following uterine curettage for elective abortion.

Small retinal hemorrhages as the only sign of an intracranial aneurysm.

PURPOSE: To report a woman with two small circumpapillary and nerve fiber layer hemorrhages found on routine examination. METHODS: Case report. The patient had a history of severe headache 2 weeks previously but no other symptoms or signs. RESULT: Magnetic resonance imaging showed an intracranial aneurysm. CONCLUSIONS: This potentially lethal abnormality should be considered with small unexplained retinal hemorrhages, even when the neurologic examination is normal. A history of recent headache should be sought.

Quantitative ocular tests for myasthenia gravis: a comparative review with detection theory analysis.

Many reports in the literature describe a variety of ocular signs in myasthenia gravis. To determine the utility of laboratory recordings of ocular signs in the evaluation for myasthenia, we reviewed all previous studies of quantitative measures of eye movements or intra-ocular pressures. We selected those studies with data presented for both myasthenic and non-myasthenic ocular palsies. Signal detection theory was used to evaluate the discriminative power of each variable. The characteristics of saccades and quick phases of optokinetic nystagmus at the start of recording were poor at distinguishing between myasthenic and non-myasthenic palsies, except when the comparison was solely between myasthenia and chronic progressive external ophthalmoplegia. The effects of fatigue on saccadic parameters were also not discriminative, though there was insufficient data to evaluate this adequately. Changes induced by edrophonium in the amplitude or peak velocity of saccades or optokinetic quick phases were good diagnostic tests, retaining high sensitivities when criteria were set to yield a specificity of 95%. Most of these parameters were less efficient as screening tests, with modest specificities when criteria were set to yield a sensitivity of 95%. The change in optokinetic quick phase amplitude recorded by infrared oculography was the best test, with ideal characteristics of 97% specificity and sensitivity at a criterion of zero change. This analysis suggests that eye movement recordings of saccades or optokinetic nystagmus have potential as useful and inexpensive tests for myasthenia, and warrant further study.