Assessment of neurological manifestations in hospitalized patients with COVID-19.

BACKGROUND AND PURPOSE: The objective of this study was to assess the neurological manifestations in a series of consecutive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive patients, comparing their frequency with a population hospitalized in the same period for flu/respiratory symptoms, finally not related to SARS-CoV-2. METHODS: Patients with flu/respiratory symptoms admitted to Fondazione Policlinico Gemelli hospital from 14 March 2020 to 20 April 2020 were retrospectively enrolled. The frequency of neurological manifestations of patients with SARS-CoV-2 infection was compared with a control group. RESULTS: In all, 213 patients were found to be positive for SARS-CoV-2, after reverse transcriptase polymerase chain reaction on nasal or throat swabs, whilst 218 patients were found to be negative and were used as a control group. Regarding central nervous system manifestations, in SARS-CoV-2-positive patients a higher frequency of headache, hyposmia and encephalopathy always related to systemic conditions (fever or hypoxia) was observed. Furthermore, muscular involvement was more frequent in SARS-CoV-2 infection. CONCLUSIONS: Patients with COVID-19 commonly have neurological manifestations but only hyposmia and muscle involvement seem more frequent compared with other flu diseases.

"Graspability" of objects affects gaze patterns during perception and action tasks.

When grasping an object, our gaze marks key positions to which the fingertips are directed. In contrast, eye fixations during perceptual tasks are typically concentrated on an object's centre of mass (COM). However, previous studies have typically required subjects to either grasp the object at predetermined sites or just look at computer-generated shapes "as a whole". In the current study, we investigated gaze fixations during a reaching and grasping task to symmetrical objects and compared these fixations with those made during a perceptual size estimation task using real (Experiment 1) and computer-generated objects (Experiment 2). Our results demonstrated similar gaze patterns in both perception and action to real objects. Participants first fixated a location towards the top edge of the object, consistent with index finger location during grasping, followed by a subsequent fixation towards the object's COM. In contrast, during the perceptual task to computer-generated objects, an opposite pattern in fixation locations was observed, where first fixations were closer to the COM, followed by a subsequent fixation towards the top edge. Even though differential fixation patterns were observed between studies, the area in which these fixations occurred, between the centre of the object and top edge, was the same in all tasks. These results demonstrate for the first time consistencies in fixation locations across both perception and action tasks, particularly when the same type of information (e.g. object size) is important for the completion of both tasks, with fixation locations increasing relative to the object's COM with increases in block height.

Temporal integration limits of stereovision in reaching and grasping.

Even though there have been extensive investigations of the temporal integration limits of binocular vision in perceptual tasks, relatively little is known about temporal integration limits during the completion of visuomotor tasks. To assess the temporal integration limits of binocular disparity within the action domain, accuracy of reach kinematics in a reaching and grasping task under continuous binocular and monocular viewing conditions were compared with those obtained under alternating monocular viewing conditions with interocular delays ranging from 14 to 58 ms. Even the shortest of the interocular delays resulted in larger grip apertures than those in the continuous monocular and binocular viewing conditions. The short temporal integration interval of stereovision obtained in this study cannot be accounted for by differential visual feedback in the binocular and interocular delay conditions, nor is it likely to be a consequence of visual disruption due to the interocular delays. Our findings suggest that the visuomotor system has little tolerance to interocular delay.

The specificity of learned associations in visuomotor and perceptual processing.

Learned associations between object properties, such as weight and size, allow for quick and accurate manipulations of objects that we encounter repeatedly. This integration of learned sensory information reduces the overall computational load of our visuomotor system when interacting with familiar objects. In the laboratory, even novel associations can be quickly established after only brief training. Haffenden and Goodale in J Cogn Neurosci 12:950-964 (2000) found that learned associations between color and size affected grip scaling for manual estimations of size and visually guided grasping. But, how specific are these learned associations? In the current study, lighter-shaded "untrained" target objects were added to Haffenden and Goodale's color-size association paradigm to determine if the learned associations made by the perception and action systems are equally tolerant to within-category color changes. During perceptual estimations, training was generalized within color categories--manual estimations of size were influenced by both the trained and lighter-shaded untrained colors. In contrast, grasping was not influenced by the untrained colored blocks. These results demonstrate how the perception and action systems differ in their incorporation of learned perceptual information. In contrast to the object specific associations needed for grasping, our perceptual system is more categorical and uses generalized perceptual grouping strategies when relying on learned color information.

Spatial transformations for eye-hand coordination.

Eye-hand coordination is complex because it involves the visual guidance of both the eyes and hands, while simultaneously using eye movements to optimize vision. Since only hand motion directly affects the external world, eye movements are the slave in this system. This eye-hand visuomotor system incorporates closed-loop visual feedback but here we focus on early feedforward mechanisms that allow primates to make spatially accurate reaches. First, we consider how the parietal cortex might store and update gaze-centered representations of reach targets during a sequence of gaze shifts and fixations. Recent evidence suggests that such representations might be compared with hand position signals within this early gaze-centered frame. However, the resulting motor error commands cannot be treated independently of their frame of origin or the frame of their destined motor command. Behavioral experiments show that the brain deals with the nonlinear aspects of such reference frame transformations, and incorporates internal models of the complex linkage geometry of the eye-head-shoulder system. These transformations are modeled as a series of vector displacement commands, rotated by eye and head orientation, and implemented between parietal and frontal cortex through efficient parallel neuronal architectures. Finally, we consider how this reach system might interact with the visually guided grasp system through both parallel and coordinated neural algorithms.

Patient Schn: has Goldstein and Gelb's case withstood the test of time?

The current manuscript takes a critical look at the case of Goldstein and Gelb's patient, Schn, reported to be the first well-defined example of apperceptive visual agnosia. While doubts have been cast on the validity of the original investigations, we propose that perhaps the case of Schn should be reclassified as an example of integrative agnosia. Be that as it may, what is not in doubt is that the case of Schn has had a lasting impact on the development of neuropsychological theorem.

Kinematic rules for upper and lower arm contributions to grasp orientation.

The purpose of the current study was to investigate the contribution of upper and lower arm torsion to grasp orientation during a reaching and grasping movement. In particular, we examined how the visuomotor system deals with the conflicting demands of coordinating upper and lower arm torsion and maintaining Donders' Law of the upper arm (a behavioral restriction of the axes of arm rotation to a two-dimensional "surface"). In experiment 1, subjects reached out and grasped a target block that was presented in one of 19 orientations (5 degrees clockwise increments from horizontal to vertical) at one position in a vertical presentation board. In experiment 2, target blocks were presented in one of three orientations (horizontal, three-quarter, and vertical) at nine different positions in the presentation board. If reach and grasp commands control the proximal and distal arms separately, then one would only expect the lower arm to contribute to grasp orientations and that Donders' Law would hold for the upper arm-independent of grasp orientations. Instead, as the required grasp orientation increased from horizontal to vertical, there was a significant clockwise torsional rotation in the upper arm, which accounted for 9% of the final vertical grasp orientation, and the lower arm, which accounted for 42%. A linear relationship existed between the torsional rotations of the upper and lower arm, which indicates that the components of the arm rotate in coordination with one another. The location-dependent aspects of upper and lower arm torsion remained invariant, however, yielding consistently shaped Donders' "surfaces" (with different torsional offsets) for different grasp orientations. These observations suggest that the entire arm-hand system contributes to grasp orientation, and therefore, the reach/grasp distinction is not directly reflected in proximal-distal kinematics but is better reflected in the distinction between these coordinated orienting rules and the location-dependent kinematic rules for the upper arm that result in Donders' Law for one given grasp orientation.

Hemispatial neglect: its effects on visual perception and visually guided grasping.

Hemispatial neglect is a neurological disorder characterized by a failure to represent information appearing in the hemispace contralateral to a brain lesion. In addition to the perceptual consequences of hemispatial neglect, several authors have reported that hemispatial neglect impairs visually guided movements. Others have reported that the extent of the impairment depends on the type of visually guided task. Finally, in some cases, neglect has been shown to impair visual perception without affecting visuomotor control in relation to the very same stimuli. While neglect patients may be able to successfully pick up an object they have difficulty perceiving in its entirety, it does not mean that they are picking up the object in the same way that a neurologically intact individual would. In the current study, patients with hemispatial neglect were presented with irregularly shaped objects, directly in front of them, that lacked clear symmetry and required an analysis of their entire contour in order to calculate stable grasp points. In a perceptual discrimination task, the neglect patients had difficulty distinguishing one object from another on the basis of their shape. In a grasping task, the neglect patients showed more variance in the position of their grasp on the target objects than their control subjects, with an overall shift to the relative right side of the presented objects. The perceptual and visuomotor deficits seen in patients with hemispatial neglect deficits may be the result of an inability to form good structural representations of the entire object for use in visual perception and visuomotor control.

The effects of rotation and inversion on face processing in prosopagnosia.

The current study investigated the sensitivity of face recognition to two changes of the stimulus, a rotation in depth and an inversion, by comparing the performance of two prosopagnosic patients, RN and CR, with non-neurological control subjects on a face-matching task. The control subjects showed an effect of depth rotation, with errors and reaction times increasing systematically with rotation angle, and the traditional inversion effect, with errors and reaction times increasing under inverted conditions. In contrast, RN showed no effect of rotation or inversion on his error data but did show a less sensitively graded effect of rotation and the traditional inversion effect on reaction times. CR did not show a graded effect of rotation on his errors or reaction times. Although CR showed the traditional inversion effect on his error data, he displayed an inversion superiority effect on his reaction time data, which supports the claim that the damaged holistic processing systems continue to dominate face processing in prosopagnosia even though they are malfunctioning. These results suggest that the damage that occurs to the ventral temporal cortex in prosopagnosia may have forced the patients to rely on sources of information that are not dependent on the view of the face and, moreover, cannot be adapted to deal with rotated faces under both upright and inverted conditions.

A functional MRI study of face recognition in patients with prosopagnosia.

An fMRI investigation was conducted to determine whether patients with impaired face recognition, a deficit known as prosopagnosia, would show functional activation in the fusiform gyrus, the neural substrate for face processing, when viewing faces. While the patients did show activation in the fusiform gyrus, with significantly more voxels in posterior areas than their control subjects, this activation was not sufficient for face processing. In one of the patients, the posterior activation was particularly evident in the left hemisphere, which is thought to be involved in feature-based strategies of face perception. We conclude that an increased reliance on feature-based processing in prosopagnosia leads to a recruitment of neurons in posterior regions of the fusiform gyrus, regions that are not ideally suited for processing faces.

Trends in case-mix-adjusted use of radiology resources at an urban level 1 trauma center.

OBJECTIVE: The objective of our study was to determine the utilization rates of diagnostic radiology services at an urban level 1 trauma center. MATERIALS AND METHODS: This was an observational study of imaging use patterns from 1993 to 1998. Data were segregated by patient type and imaging procedure. Annual hospital admissions were adjusted for severity of illness using the Health Care Financing Administration's case-mix index. Per-patient imaging trends for the emergency department and outpatients were assessed using a ratio of the total number of procedures to the number of patient visits. Linear regression models were used to assess the strength of associations between resource use, measured as relative value units (RVUs), and independent variables (calendar year, patient type, and examination type). RESULTS: The RVUs for all imaging increased 53% for inpatients, 69% for outpatients, and 85% in the emergency department. No significant trend for use was found for the aggregate of inpatient imaging. There was a significant increase in the inpatient MR imaging RVUs (p = 0.04). No significant trend was found for the aggregated outpatient imaging RVUs. The trends were significant for angiography (p = 0.006), MR imaging (p = 0.002), and sonography (p = 0.04). The aggregated emergency room imaging RVUs showed a significant increase over time (p < 0.03). CONCLUSION: The number of imaging procedures increased during the study period. There was no overall trend toward increasing use of imaging in inpatients once an adjustment for severity of illness was made. Increases in patient visit-adjusted emergency department use of CT, sonography, and nuclear medicine procedures resulted from changes in practice patterns. For emergency department and outpatient settings, adjusting for the number of patient visits explains a significant portion of the increase in utilization.

Role of familiar size in the control of grasping.

The present study examined whether the learned pictorial depth cue of "familiar size" could be used to plan a reaching and grasping movement in the absence of binocular vision. Sixteen right-handed subjects were presented with two different arrays, under monocular and binocular viewing conditions, in which a range of different "grasp-sized" spheres that were lit from within could be presented in an otherwise darkened environment. In the "familiar-size" presentation array, only one "standard" sized sphere was presented, which gave subjects an opportunity to learn the relationship between the standard sphere's retinal image size and its distance. In the "multiple" spheres presentation array, subjects could not learn such a relationship because on any one trial, one of four different sphere sizes could be present. In a second experiment, the effects of this paradigm on six subjects' perceptual reports of distance were examined by having subjects slide their index fingers apart along a horizontal rod to indicate the estimated distance of the spheres. When familiar size could not be used as a cue to distance, subjects produced more on-line corrections in their reaching and grasping movements to the standard-sized spheres--but only under monocular viewing conditions. It appears that subjects are able to exploit the learned relationship between an object's distance and its projected retinal image size to help program and control reaching and grasping movements when binocular vision is not available. Although the influence of familiar size on subjects' perceptual estimates is less clear, it is clear that subjects' perceptual estimates show poor absolute scaling for distance. This result further supports the notion that under normal viewing conditions the visuomotor system uses binocular information to program and control manual prehension, but is able to use pictorial information when binocular vision is denied.

Regionally selective effects of gonadectomy on cortical catecholamine innervation in adult male rats are most disruptive to afferents in prefrontal cortex.

Changes in gonadal hormones induced early in life produce substantial, seemingly permanent decreases in tyrosine hydroxylase (TH)-immunoreactive axon density in sensory, motor and prefrontal regions in the rat cerebral cortex. Less is known, however, about the responsiveness of cortical catecholamines to hormone stimulation during adulthood. In this study we expanded upon an earlier analysis of the effects of acute (4 day) and chronic (28 day) gonadectomy in adult male rats on TH innervation in right hemifield of the cingulate cortex to include assessment of sensorimotor areas previously examined following perinatal gonadectomy, the left cingulate hemifield, and one additional prefrontal area - the dorsal anterior insular cortex. Qualitative and quantitative analyses of immunoreactivity revealed modest, transient declines in innervation in sensorimotor areas 4 days after gonadectomy, and a return to normal innervation densities by 28 days after surgery. In cingulate and insular cortices, however, strikingly depleted axon densities observed following acute gonadectomy rebounded to significantly higher than normal levels of innervation 3 weeks later. All effects were attenuated in gonadectomized animals supplemented with testosterone. Thus, for cortical catecholamine innervation, as for other endpoints of hormone stimulation, gonadal steroid sensitivity appears to change dramatically with lifestage. In adult male rats, this sensitivity is also marked by a seemingly selective vulnerability of catecholamine innervation in prefrontal areas to changes in the hormone environment induced by gonadectomy.

Silicone gel breast implant failure and frequency of additional surgeries: analysis of 35 studies reporting examination of more than 8,000 explants.

Although it is well known that silicone gel breast implants (SGBIs) produce many "local" complications (i.e., pain, hard fibrous capsules, disfigurement, chronic inflammation, implant shell failure) and necessitate frequent surgical revisions, no large cohort retrospective quantitative analysis of clinical data has been reported to date, especially for the prevalence of failures and additional surgeries. Data from 35 different studies that encompass more than 8000 explanted SGBIs have now been analyzed and are reported here. Because examination of a prosthesis when explanted is the definitive method for determining shell integrity, the only studies that were used were ones that reported implant duration, the total number of SGBIs explanted, and the number of SGBIs for which shell rupture or failure ("not intact") was confirmed upon surgical removal. An exponential regression plot of data indicated a direct correlation of implant duration with percent shell failure (r2 = 0. 63 and r = 0.79 ). SGBI failure was found to be 30% at 5 years, 50% at 10 years, and 70% at 17 years. The failure rate was 6% per year during the first 5 years following primary implant surgery. ANOVA comparison of three implant age groups (mean implant durations of 3. 9, 10.2, and 18.9 years) indicated a highly significant statistical correlation of percent failure with implant duration (p < 0.001). Complications necessitating at least one additional surgery occurred for 33% of implants within 6 years following primary implant surgery. Shell failure was found to be an order of magnitude greater than the 4 to 6% rupture prevalence suggested by the AMA Council on Scientific Affairs in 1993, the 0.2 to 1.1% cited by manufacturers at that time, and the 5% rupture that was stated to be "not a safety standard that the FDA can accept."

The role of learned pictorial cues in the programming and control of grasping.

Binocular information has been shown to be important for the programming and control of reaching and grasping. Even without binocular vision, people are still able to reach out and pick up objects accurately - albeit less efficiently. It remains unclear, which of the many available monocular depth cues humans use to calibrate manual prehension when binocular information is not available. In the present experiment, we examined whether or not subjects could use a learned relationship between the elevation of a goal object in the visual scene and its distance to help program and control the required grasp. The elevation of the goal object was systematically varied with distance in some blocks of trials by presenting the object at different positions along a horizontal plane 35 cm below eye level. In other blocks of trials, elevation did not vary with distance because the objects were always presented along the subject's line of sight. When subjects viewed these two displays monocularly, they showed fewer on-line adjustments in the trajectory of the limb and the aperture of the fingers when the elevation of the target object in the visual scene could be used to help program the required movements. No such difference between performance on the two arrays was seen when subjects were allowed a full binocular view. This study confirms that subjects are indeed able to use a learned relationship between the elevation of an object and its distance as a cue for programming grasping movements when binocular information is not available. Together with evidence from work with neurological patients who have difficulty perceiving pictorial cues, these findings suggest that the visuomotor system might normally "prefer" to use binocular cues, but can fall back on learned pictorial information when binocular vision is denied.

Does a monocularly presented size-contrast illusion influence grip aperture?

The present study tested the idea that if subjects rely more on scene-based pictorial cues when binocular cues are not available, then both their perceptual judgements and their grasp might be influenced by pictorial illusions such as the Ebbinghaus (Titchener) Circles Illusion under monocular viewing conditions. Under binocular viewing conditions, subjects were always able to scale their grip accurately to the true size of the target disc and were unaffected by the illusion. Under monocular viewing, however, subjects appeared to be influenced by the illusion. Thus, when confronted with physically different target discs displayed on backgrounds that made them appear equivalent in size, subjects treated the two discs as equivalent--even when picking them up. These results, combined with earlier work from our laboratory suggests that binocular information plays a critical role in normal human prehension but when this information is not available the visuomotor system is able to "fall back" on the remaining monocular cues, which can cause the visuomotor system to be more susceptible to pictorial illusions.

[Rare testicular tumors]. / Tumeurs testiculaires rares.

We report one case of "sex-cord stromal tumor" composed by Leydig and Sertoli cells. An epidermoid cyst of the testicle will be described. Finally, a case of scrotal leiomyoma is reported.