Constructing and Analyzing Neural Network Dynamics for Information Objectives and Working Memory

Creation of quantitative models of neural functions and discovery of underlying principles of how neural circuits learn and compute are long-standing challenges in the field of neuroscience. In this work, we blend ideas from computational neuroscience, information and control theories with machine learning to shed light on how certain key functions are encoded through the dynamics of neural circuits. In this regard, we pursue the ‘top-down’ modeling approach of engineering neuroscience to relate brain functions to basic generative dynamical mechanisms. Our approach encapsulates two distinct paradigms in which ‘function’ is understood. In the first part of this research, we explore the synthesis of neural dynamics for task-independent, well-defined objective function: the information processing capacity of neural circuits/networks. We contribute our efforts to devise a strategy to optimize the dynamics of the network at hand using information maximization as an objective function. In this vein, our principle contributions are in terms of mathematical formulation of the optimization problem and proposing a simplification method to reduce the computational burden associated with mutual information optimization. Then, we illustrate the novelty of our ideas for well-understood dynamical systems. Our methodology results in dynamics that generically perform as encoder of afferent inputs distribution and facilitate information propagation. However, determining a well-defined mathematical objective function may not be straightforward in all cases, e.g. complex cognitive functions. To address this issue, in the second part of this research we consider top-down synthesis on the basis of a surrogate task. In particular, we optimize ‘artificial’ recurrent networks in order to perform a computational task that embodies the function we are interested in studying, i.e. working memory. We contribute our efforts to propose a realistic training paradigm for recurrent neural networks and elucidate how dynamics of the optimized artificial networks can support computations implemented in memory functions. We will discuss the theoretical and technical steps involved in our interpretations, as well as remaining open questions and future directions

Biochemical properties of digestive carbohydrases from the sugar beet weevil, Lixus incanescens (Coleoptera: Curculionidae)

The sugar beet weevil, Lixus incanescens B., is one of the most important pests of sugar beet plant in Iran. The petioles and leaves of sugar beet are attacked by larvae and adults of the sugar beet weevil. Chemical application is currently used for controlling the pest. Digestion in the alimentary canal of the sugar beet weevil is facilitated by some carbohydrases. Results of the in vitro studies indicated the presence of alpha-amylase, beta-glucosidase and beta-galactosidase in the digestive tract of the pest. Highest activities of alpha-amylase, beta-glucosidase and beta-galactosidase were at pH 5, pH 5 and pH 4, respectively. No significant alpha-glucosidase and alpha-galactosidase activity was detected in the pest's digestive system. Optimum temperatures for alpha-amylase, beta-glucosidase and beta-galactosidase activity were determined at 45, 50 and 40 oC, respectively. alpha-amylase was more stable under acidic condition (pH 4 to pH 6) than under highly acidic and alkaline condition. Na+ and K+ increased alpha-amylase activity, but sodium dodecyl sulfate significantly decreased amylase activity. Also, the activity of alpha-amylase was inhibited by the other compounds such as MgCl2, CaCl2 and EDTA. Zymogram analysis using native-PAGE revealed one band of alpha-amylase activity in Lixus incanescens. High activity of carbohydrases in the digestive system of adults was determined and further researches are needed to be applied to design new strategies for controlling the sugar beet weevil based on natural carbohydrase inhibitors

Evaluation of acute respiratory failure after cervical spinal cord injury in Mashhad Shahid Kamyab Hospital

Introduction:Acuterespiratory  complications are common in patients with cervical spinal cord injury. These complications can increase mortality and morbidity rates. The aim of this study is to specify the complications after traumatic cervical spinal cord injury, management of these patients and to select the appropriate remedial and preventive measures. Materials and Methods: This study has been performed retrospectively in Shahid Kamyab ICU wards for 2.5 years in patient group with cervical cord injury. The severity of injury had been scored based on Frankel scoring. We completed the charts for clinical and neurological findings, the remedial ways and the results. Finally, statistical analysis has been accomplished. Results: From 592 patients being admitted with spinal trauma, 61 cases had cervical spine injury. 27 patients (44.3%) had been hospitalized in ICU for respiratory problems. Methyl prednisolon succinate has been used only for 4 patients. There was not any difference in this group versus control group. 23 patients (85.18%) had been scored in Frankel A. Mortality rate was 11 cases (40.7%). Tracheostomy had been used for patients with prolonged intubation and respiratory infection. Conclusion: Respiratory complications after cervical spinal cord injury are common and are accompanied by numerous complications and even mortality. We can reduce the mortality and morbidity rates in these patients by paying attention to these complications and using the immediate and appropriate ways of treating

Insecticidal activity of spray dried microencapsulated essential oils of Rosmarinus officinalis and Zataria multiflora against Tribolium confusum

Rosmarinus officinalis and Zataria multiflora (Lamiaceae) essential oils (EOs) contain components with insecticidal properties that can be used as pesticides for stored product pests. In the present study, they were encapsulated in octenyl succinic anhydride (OSA) - starch in order to test their insecticidal activity against Tribolium confusum. First an oil-in-water emulsion was prepared and afterwards, it was dried by spray-drying technique. The emulsions were characterized regarding particle size (461–854 nm), stability and encapsulated oil efficiency (68–88%). Also, solid formulations were characterized by particle size (8.29–11.35 μm), encapsulation efficiency (5–52%) and water activity (0.19–0.26). Further, the release rate at storage conditions (at 27 ± 3 °C and 70–75% relative humidity in the dark) was measured over a period of 40 days. The insecticidal activity against T. confusum was determined by specific bioassays performed at 27 ± 3 °C temperature and 70–75% relative humidity in the dark. Five concentrations were used for estimation of fumigant toxicity of rosemary and Zataria oils after 72 h exposure in adult beetles. Fumigant toxicity results revealed that microencapsulated oils were more effective than non-formulated oils against beetles in long time. Similarly, it was demonstrated that microencapsulation of the essential oils increases their persistence: non-formulated oils have not insecticidal activity after 15 days of the storage period, whereas at the same period, the mortality rate against T. confusum of rosemary and Zataria microencapsulated oils was 46.6 and 35.5%, respectively.The authors acknowledge Junta de Castilla y León (Spain) with Project VA040U16 and University of Teheran (Iran) for funding. Seyed Mohammad Ahsaei thanks the Ministry of Science, Research and Technology of the Islamic Republic of Iran and Iran Nanotechnology Innovation Council (Project 97699) for his mobility scholarship. Soraya Rodríguez Rojo acknowledges Junta de Castilla y León and FEDER 2014–2020 for her postdoctoral contract under Project VA040U16

Changes in energy content of Podisus maculiventris (Say) (Hemiptera: Pentatomidae) in response to different diets

Nymphal instars and adults of the spined soldier bug, Podisus maculiventris, preferably feed on lepidopteran and colopteran larvae. Different prey diets can change fitness including energy reservoirs of the predator. In the present study, effects of different artificial and natural diets as well as starvation was studied on energy contents of the third and fourth nymphal instars of P. maculiventris. Total available energy calculated as the sum of the energy contents of lipids, carbohydrates, glycogen, and proteins did not significantly differ in the third and fourth nymphal instars fed on natural and artificial diets. Among the energy reservoirs, only total lipid storage of the starved nymphal instars was significantly different from that in the bugs fed on the natural diet. In conclusion, total energy reserves cannot be changed in response to artificial diet. A better understanding of the impact of artificial diets on the energy reserves of natural enemies can be considered as a biomarker for more appropriate mass rearing approaches of natural enemies

Energy budget changes in response to desiccation stress in Tribolium castaneum (Coleoptera: Tenebrionidae)

Humidity is probably the most important abiotic factor influencing life cycles, distribution, survival, and population dynamics of stored product pests. Although most of these pests can complete their life cycles in any given relative humidity, their prolonged development time, as well as decreased emergence rate and fecundity, have been well documented in several previous studies. In the present study, we evaluated the changes in energetic substances (lipids, soluble carbohydrates, glycogen, and proteins) accumulated in different life stages of larvae and adults of Tribolium castaneum in response to different relative humidity levels (5, 12, 22, 30, 45, and 65%). The results showed that young larvae were more susceptible to low relative humidity levels and desiccation stress. Larvae tended to accumulate higher proportions of lipids during earlier stages while their energy content shifted towards proteins with an increase in their age. Adult beetles experienced a significant decrease in their protein content immediately after they initiated reproduction. The importance of these fluctuations in the biology of the red flour beetles was discussed in detail