Neural control of fast-regular saccades and antisaccades: an investigation using positron emission tomography

 Regional cerebral blood flow changes related to the performance of two oculomotor tasks and a central fixation task were compared in ten healthy human subjects. The tasks were: (a) performance of fast-regular saccades; (b) performance of voluntary antisaccades away from a peripheral cue; (c) passive maintenance of central visual fixation in the presence of irrelevant peripheral stimulation. The saccadic task was associated with a relative increase in activity in a number of occipitotemporal areas. Compared with both the fixation and the saccadic task, the performance of antisaccades activated a set of areas including: the superior and inferior parietal lobules, the precentral and prefrontal cortex, the cingulate cortex, and the supplementary motor area. The results of the present study suggest that: (a) compared with self-determined saccadic responses the performance of fast regular, reflexive saccades produces a limited activation of the frontal eye fields; (b) in the antisaccadic task the inferior parietal lobes subserve operations of sensory-motor integration dealing with attentional disengagement from the initial peripheral cue (appearing at an invalid spatial location) and with the recomputation of the antisaccadic vector on the basis of the wrong (e.g., spatially opposite) information provided by the same cue. Received: 20 May 1996 / Accepted: 28 January 1997     

Septate uterus: nosographic overview and endoscopic treatment

To comment on the prevalence, diagnosis, and treatment of the septate uterus, with special reference to hysteroscopic metroplasty and its effect on reproductive outcome, we searched publications in PubMed and Embase. Original articles, meta-analysis, reviews, and opinion articles were selected. The studies suggest that the prevalence of the septate uterus is increased in women with repeated pregnancy loss and infertility. Reliable diagnosis depends on accurate assessment of the uterine fundal contour and uterine cavity by means of magnetic resonance and three-dimensional ultrasound. Pertinent published data comparing pregnancy outcome before and after hysteroscopic metroplasty indicated a marked improvement after surgery. Magnetic resonance and three-dimensional ultrasound represent the gold standard for diagnosis of septate uterus. Hysteroscopic metroplasty with its simplicity, minimal postoperative sequelae, and improved reproductive outcome is the gold standard for treatment, not only in patients with recurrent pregnancy loss and premature labor but also in patients with infertility, especially if in vitro fertilization is being contemplated.     

Ex vivo histological analysis of the thermal effects created by a 445-nm diode laser in oral soft tissue biopsy

The aim of this study was to evaluate, ex vivo, the histological effects of 445-nm diode laser (Eltech K-Laser srl, Treviso, Italy), during an oral soft ti     

Influence of Figure-Ground Contrast on the Implicit and Explicit Processing of Line Drawings in Patients with Left Unilateral Neglect

The implicit and explicit processing of pairs of line drawings segregated from a ground by low luminance contrast or by high isoluminant colour contrast was assessed in a group of 13 consecutive patients with left unilateral neglect. Left-side differences between the two figures were recognised far less frequently than were right-side differences. Low luminance contrast worsened the explicit recognition of left-side differences. However, when left-side differences were not explicitly recognised, statistically significant implicit processing was found for high colour contrast trials both in the group of patients and in four individual cases. With low luminance contrast trials, implicit processing was found in only one individual case and was not found in the group of patients. A control experiment showed that normal subjects can discriminate the left or the right side of low luminance contrast stimuli with 90 accuracy, while fixating the opposite extremity of stimuli. The results of the present study show that, in patients with left unilateral neglect, implicit processing can be compromised by difficult preattentive discriminability of stimuli and are in keeping with: 1 Farah's 1994a proposal that visual awareness may be related to the quality of visual inputrepresentation in the brain; 2 Spinelli and co-workers' Spinelli, Angelelli, De Luca, & Burr, 1996; Spinelli, Burr, & Morrone, 1994 proposal that patients with left unilateral neglect may suffer from unilateral impaired functioning of the magnocellular pathway, which has high sensitivity to low luminance contrast.     

Right but not left angular gyrus modulates the metric component of the mental body representation: a tDCS study

The parietal lobes contribute to body-space representation. The present work aims at characterizing the functional role of the inferior parietal lobe in body-space representation and at studying the different roles of the angular gyrus in the right and left hemisphere. We conducted three separate transcranial direct current stimulation (tDCS) experiments using “tactile distance task” as an implicit measure of body representation. Whereas anodal tDCS on the right angular gyrus influences vocal reaction times (vRT) for stimuli delivered on the ipsilateral body parts without changes of accuracy, right tDCS improved both vRT and accuracy for tactile stimuli on the contralateral limbs. Sham or left parietal anodal tDCS had no effect. These evidences support the view that right parietal areas have a crucial role in the metric component of the body representation.     

Systemic venous atrium stimulation in transvenous pacing after mustard procedure

We present the case of a young woman corrected with a Mustard procedure undergoing successful transvenous double chamber pacemaker implantation with the atrial lead placed in the systemic venous channel. The case presented demonstrates that, when the systemic venous atrium is separate from the left atrial appendage, the lead can be easily and safely placed in the systemic venous left atrium gaining satisfactory sensing and pacing thresholds despite consisting partially of pericardial tissue.     

Iron-dependent erythropoiesis in women with excessive menstrual blood losses and women with normal menses

In women of fertile age, iron loss consequent to excessive menstrual discharge is by far the most frequent cause of iron-deficient anemia. However, the relationship between menstrual discharge and iron loss is poorly understood. In this prospective study, total menstrual and iron losses were assayed in a large cohort of non-anemic women and women with excessive menstrual blood losses (menorrhagia) in order to provide data useful for intervention. One hundred and five Caucasian women aged 20–45 years were recruited. Blood cell count and serum ferritin (SF) levels were determined in each case before menses. Menstrual fluid losses (MFL) were determined using a standardized pads’ weight method. Hematin concentration was assayed by a variant of the Alkaline Hematin Method from which iron concentration was calculated. Mean SF levels were 36.2 (range 8.6–100) ng/ml in healthy women and 6.4 (range 5–14) ng/ml in patients with menorrhagia. Median values of iron lost/cycle were 0.87 mg in healthy women and 5.2 mg in patients with menorrhagia (ranges 0.102–2.569 and 1.634–8.665 mg, respectively, p?<?0.001). In women with menorrhagia, iron lost/cycle strongly correlated (0.789, p?<?0.001) with MFL. In conclusion, healthy women with normal menses lose, on average, 1 mg iron/cycle. Average iron losses in patients with menorrhagia are, at least in our cohort, on average, five-to-six times higher than normal. Most women with menorrhagia had totally depleted iron stores. Indirect, quantitative evaluation of iron lost with menses may be useful to assess the risk of developing iron-deficient anemia in individual patients.     

Motor-evoked potentials in amyotrophic lateral sclerosis: potential implications in detecting subclinical UMN involvement in lower motor neuron phenotype

Journal of Neurology - In amyotrophic lateral sclerosis (ALS), the involvement of lower motor neuron is well defined by electromyography, whereas a reliable marker of upper motor neuron (UMN)...     

Multiple reference frames used by the human brain for spatial perception and memory

We review human functional neuroimaging studies that have explicitly investigated the reference frames used in different cortical regions for representing spatial locations of objects. Beyond the general distinction between “egocentric” and “allocentric” reference frames, we provide evidence for the selective involvement of the posterior parietal cortex and associated frontal regions in the specific process of egocentric localization of visual and somatosensory stimuli with respect to relevant body parts (“body referencing”). Similarly, parahippocampal and retrosplenial regions, together with specific parietal subregions such as the precuneus, are selectively involved in a specific form of allocentric representation in which object locations are encoded relative to enduring spatial features of a familiar environment (“environmental referencing”). We also present a novel functional magnetic resonance imaging study showing that these regions are selectively activated, whenever a purely perceptual spatial task involves an object which maintains a stable location in space during the whole experiment, irrespective of its perceptual features and its orienting value as a landmark. This effect can be dissociated from the consequences of an explicit memory recall of landmark locations, a process that further engages the retrosplenial cortex.