Modeling of DC-DC Converters

Non

Agenesis of Corpus Callosum and Emotional Information Processing in Schizophrenia

Corpus callosum (CC) is essential in providing the integration of information related to perception and action within a subcortico-cortical network, thus supporting the generation of a unified experience about and reaction to changes in the environment. Its role in schizophrenia is yet to be fully elucidated, but there is accumulating evidence that there could be differences between patients and healthy controls regarding the morphology and function of CC, especially when individuals face emotionally laden information. Here, we report a case study of a patient with partial agenesis of corpus callosum (agCC patient with agenesis of the anterior aspect, above the genu) and we provide a direct comparison with a group of patients with no apparent callosal damage (CC group) regarding the brain activity during the processing of emotionally laden information. We found that although the visual cortex activation in response to visual stimuli regardless of their emotional content was comparable in agCC patient and CC group both in terms of localization and intensity of activation, we observed a very large, non-specific and non-lateralized cerebral activation in the agCC patient, in contrast with the CC group, which showed a more lateralized and spatially localized activation, when the emotional content of the stimuli was considered. Further analysis of brain activity in the regions obtained in the CC group revealed that the agCC patient actually had an opposite activation pattern relative to most participants with no CC agenesis, indicating a dysfunctional response to these kind of stimuli, consistent with the clinical presentation of this particular patient. Our results seem to give support to the disconnection hypothesis which posits that the core symptoms of schizophrenia are related to aberrant connectivity between distinct brain areas, especially when faced with emotional stimuli, a fact consistent with the clinical tableau of this particular patient

Essential Tremor, the Cerebellum, and Motor Timing: Towards Integrating Them into One Complex Entity

Essential tremor (ET) is the most common movement disorder in humans. It is characterized by a postural and kinetic tremor most commonly affecting the forearms and hands. Isolated head tremor has been found in 1–10% of patients, suggesting that ET may be a composite of several phenotypes. The exact pathophysiology of ET is still unknown. ET has been repeatedly shown as a disorder of mild cerebellar degeneration, particularly in postmortem studies. Clinical observations, electrophysiological, volumetric and functional imaging studies all reinforce the fact that the cerebellum is involved in the generation of ET. However, crucial debate exists as to whether ET is a neurodegenerative disease. Data suggesting that it is neurodegenerative include postmortem findings of pathological abnormalities in the brainstem and cerebellum, white matter changes on diffusion tensor imaging, and clinical studies demonstrating an association with cognitive and gait changes. There is also conflicting evidence against ET as a neurodegenerative disease: the improvement of gait abnormalities with ethanol administration, lack of gray matter volume loss on voxel-based morphometry, failure to confirm the prominent presence of Lewy bodies in the locus ceruleus, and other pathological findings. To clarify this issue, future research is needed to describe the mechanism of cellular changes in the ET brain and to understand the order in which they occur. The cerebellum has been shown to be involved in the timing of movement and sensation, acting as an internal timing system that provides the temporal representation of salient events spanning hundreds of milliseconds. It has been reported that cerebellar timing function is altered in patients with ET, showing an increased variability of rhythmic hand movements as well as diminished performance during predictive motor timing task. Based on current knowledge and observations, we argue that ET is essentially linked with cerebellar degeneration, or at least cerebellar dysfunction, together with disturbance of motor timing. We explain the context of our current understanding on this topic, highlighting possible clinical consequences for patients suffering from ET and future research directions

The mechanisms of movement control and time estimation in cervical dystonia patients

Traditionally, the pathophysiology of cervical dystonia has been regarded mainly in relation to neurochemical abnormities in the basal ganglia. Recently, however, substantial evidence has emerged for cerebellar involvement. While the absence of neurological "cerebellar signs" in most dystonia patients may be considered at least provoking, there are more subtle indications of cerebellar dysfunction in complex, demanding tasks. Specifically, given the role of the cerebellum in the neural representation of time, in the millisecond range, dysfunction to this structure is considered to be of greater importance than dysfunction of the basal ganglia. In the current study, we investigated the performance of cervical dystonia patients on a computer task known to engage the cerebellum, namely, the interception of a moving target with changing parameters (speed, acceleration, and angle) with a simple response (pushing a button). The cervical dystonia patients achieved significantly worse results than a sample of healthy controls. Our results suggest that the cervical dystonia patients are impaired at integrating incoming visual information with motor responses during the prediction of upcoming actions, an impairment we interpret as evidence of cerebellar dysfunction

Daytime Sleep Enhances Consolidation of the Spatial but Not Motoric Representation of Motor Sequence Memory

Motor sequence learning is known to rely on more than a single process. As the skill develops with practice, two different representations of the sequence are formed: a goal representation built under spatial allocentric coordinates and a movement representation mediated through egocentric motor coordinates. This study aimed to explore the influence of daytime sleep (nap) on consolidation of these two representations. Through the manipulation of an explicit finger sequence learning task and a transfer protocol, we show that both allocentric (spatial) and egocentric (motor) representations of the sequence can be isolated after initial training. Our results also demonstrate that nap favors the emergence of offline gains in performance for the allocentric, but not the egocentric representation, even after accounting for fatigue effects. Furthermore, sleep-dependent gains in performance observed for the allocentric representation are correlated with spindle density during non-rapid eye movement (NREM) sleep of the post-training nap. In contrast, performance on the egocentric representation is only maintained, but not improved, regardless of the sleep/wake condition. These results suggest that motor sequence memory acquisition and consolidation involve distinct mechanisms that rely on sleep (and specifically, spindle) or simple passage of time, depending respectively on whether the sequence is performed under allocentric or egocentric coordinates

In vitro bovine embryos evaluation based on OCT4, SOX2, IGF1R and IGF2R expression level

In vitro production of bovine embryos comprises a lot of factors that can influence the successful of this technique, oxidative stress being one of them. These factors can influence the evolution of important development processes such as the maternal to zygotic transition and the embryonic genome activation. Adding antioxidants to in vitro culture media exerts the key role to reduce the effects of reactive oxidative species produced during assisted reproduction technique, influencing in a positive way also the early embryonic developement. The objective of this study was to determine the effect of antioxidant rosmarinic acid (105 μM), added to in vitro bovine oocytes maturation media, on the quality of embryo produced based on gene expression level of OCT4, SOX2, IGF1R and IGF2R. For this purpose, we used 35 bovine ovaries taken from slougtherhouse from which we obtain 202 cumulus-oocyte-complexes and 127 of them were maturated in vitro based on morphological aspects. The cumulus-oocyte-complexes were divided in two groups: control (M1, M2, M3) and with acid rozmarinic (AR1, AR2 and AR3). The levels of OCT4, SOX2, IGF1R and IGF2R were the highest in group AR1, embryos obtain from oocytes class I supplemented with rozmarinic acid, where OCT4 expression was 4.08, SOX2 was 27.66, IGF1R and IGF2R were 53.44 and 25.10

Collection of blastomeres in order to establish sex and isolate genetic material-review

Globally, limited access to food needs in relation to meat or milk production has required the establishment of the sex of offspring from the embryonic stage. While the meat industry uses males, the dairy industry relies on females. During the period of exploitation, the number of products obtained from a female bovine is 5-6 individuals, their sex being able to be influenced by means of sexed semen. Embryo sexing programs can result in a large number of conception products, in a shorter period of time taking into account the desired sex. The use of the desired sex embryo facilitates the improvement of the genetic value. Embryonic sexing procedures involve the collection by biopsy of a minimum amount of genetic material that can ensure the determination of sex. Both invasive and non-invasive biopsy and sexing procedures can influence the subsequent viability of embryos prepared for embryo transfer. This paper highlights the methods of embryonic sexing along with the advantages and disadvantages of each technique involved in determining sex