Quantification and reduction of unobserved mortality rates for snow, southern Tanner, and red king crabs (Chionoecetes opilio, C. bairdi, and Paralithodes camtschaticus) after encounters with trawls on the seafloor

Unobserved mortalities of nontarget species are among the most troubling and difficult issues associated with fishing, especially when those species are targeted by other fisheries. Of such concern are mortalities of crab species of the Bering Sea, which are exposed to bottom trawling from groundfish fisheries. Uncertainty in the management of these fisheries has been exacerbated by unknown mortality rates for crabs struck by trawls. In this study, the mortality rates for 3 species of commercially important crabs—red king crab, (Paralithodes camtschaticus), snow crab (Chionoecetes opilio) and southern Tanner crab (C. bairdi)—that encounter different components of bottom trawls were estimated through capture of crabs behind the bottom trawl and by evaluation of immediate and delayed mortalities. We used a reflex action mortality predictor to predict delayed mortalities. Estimated mortality rates varied by species and by the part of the trawl gear encountered. Red king crab were more vulnerable than snow or southern Tanner crabs. Crabs were more likely to die after encountering the footrope than the sweeps of the trawl, and higher death rates were noted for the side sections of the footrope than for the center footrope section. Mortality rates were ≤16%, except for red king crab that passed under the trawl wings (32%). Herding devices (sweeps) can expand greatly the area of seafloor from which flatfishes are captured, and they subject crabs in that additional area to lower (4–9%) mortality rates. Raising sweep cables off of the seafloor reduced red king crab mortality rates from 10% to 4%.

Effect of chloral hydrate on metabolic rate of Labeo rohita (Ham) and Poecilia reticulata (Peters)

Comparative impact of chloral hydrate anaesthesia on the metabolic rate of Indian major carp Labeo rohita and larvivorous fish Poecilia reticulata was assessed. Observation on the Oxygen Consumption Rate (OCR) revealed that in common guppies OCR was substantially low (1.105 and 1.097 mg/g/hr) at 0.1 and 0.25 g/l concentrations of chloral hydrate as against OCR of 1.487 mg/g/hr in the control. Fry of L. rohita in group showed lower metabolic rates in the control as well as treated conditions as compared to the individuals of this fish. This may be due to sympathetic psychophysiological reflex of grouped fish. Higher dose of chloral hydrate (0.25 g/l) also caused higher OCR probably due to distress. Application of chloral hydrate also favoured lesser release of metabolic wastes (ammonia and carbon dioxide). There was significant positive correlation between time and oxygen consumption, whereas, for time and OCR this relationship was negative. Regression of chloral hydrate doses for OCR and time has also been calculated.

How is somatosensory information used to adapt to changes in the mechanical environment?

Recent studies examining adaptation to unexpected changes in the mechanical environment highlight the use of position error in the adaptation process. However, force information is also available. In this chapter, we examine adaptation processes in three separate studies where the mechanical environment was changed intermittently. We compare the expected consequences of using position error and force information in the changes to motor commands following a change in the mechanical environment. In general, our results support the use of position error over force information and are consistent with current computational models of motor learning. However, in situations where the change in the mechanical environment eliminates position error the central nervous system does not necessarily respond as would be predicted by these models. We suggest that it is necessary to take into account the statistics of prior experience to account for our observations. Another deficiency in these models is the absence of a mechanism for modulating limb mechanical impedance during adaptation. We propose a relatively simple computational model based on reflex responses to perturbations which is capable of accounting for iterative changes in temporal patterns of muscle co-activation.

Learning feedforward commands to muscles using time-shifted sensory feedback

In adapting to changing forces in the mechanical environment, humans change the force being applied by the limb by reciprocal changes in the activation of antagonistic muscles. However, they also cocontract these muscles when interaction with the environment is mechanically unstable to increase the mechanical impedance of the limb. We have postulated that appropriate patterns of muscle activation could be learned using a simple scheme in which the naturally occurring stretch reflex is used as a template to adjust feedforward commands to muscles. Feedforward commands are modified iteratively by shifting a scaled version of the reflex response forward in time and adding it to the previous feedforward command. We show that such an algorithm can account for the principal features of changes in muscle activation observed when human subjects adapt to instabilities in the mechanical environment. © 2006.

How are internal models of unstable tasks formed?

The results of recent studies suggest that humans can form internal models that they use in a feedforward manner to compensate for both stable and unstable dynamics. To examine how internal models are formed, we performed adaptation experiments in novel dynamics, and measured the endpoint force, trajectory and EMG during learning. Analysis of reflex feedback and change of feedforward commands between consecutive trials suggested a unified model of motor learning, which can coherently unify the learning processes observed in stable and unstable dynamics and reproduce available data on motor learning. To our knowledge, this algorithm, based on the concurrent minimization of (reflex) feedback and muscle activation, is also the first nonlinear adaptive controller able to stabilize unstable dynamics.

Effect of adrenalectomy and corticosterone replacement on prepulse inhibition and locomotor activity in mice

1 Stress is a risk factor in psychiatric illnesses such as schizophrenia. The aim of the present study was to investigate the effect of different circulating levels of the adrenal steroid corticosterone (CORT) on locomotor hyperactivity and prepulse inhibition of acoustic startle, two behavioural animal models of aspects of schizophrenia. 2 Male C57BL/6J mice (n = 10 per group) were anaesthetised with isoflurane and sham-operated or adrenalectomised (ADX). ADX mice were implanted with 50 mg pellets consisting of 100% cholesterol, or 2, 10 or 50 mg of CORT mixed with cholesterol. CORT pellet implantation dose dependently increased plasma CORT levels 3 weeks after surgery. Starting 1 week after surgery, mice were tested for prepulse inhibition after injection of saline or 5 mg kg(-1) of haloperidol. 3 In intact mice and in mice implanted with 10 mg of CORT, haloperidol treatment significantly increased prepulse inhibition (average values from 38 - 42 to 52%). Similar results were observed when testing the mice for amphetamine-induced locomotor hyperactivity (5 mg kg(-1)). In contrast, there was no significant effect of haloperidol in mice implanted either with cholesterol or 2 or 50 mg of CORT. 4 These results in behavioural animal models of schizophrenia suggest an important role of the stress hormone CORT in modulating dopaminergic activity in this illness.

Interaction of corticosterone and nicotine in regulation of prepulse inhibition in mice

The aim of the present Study was to investigate if different levels of circulating corticosterone (CORT) modulate the effect of nicotine on prepulse inhibition (PPI), a measure of sensorimotor gating that is disrupted in schizophrenia and other mental illnesses. Four groups of mice were investigated: sham-operated, adrenalectomized (ADX) and implanted with a cholesterol pellet, ADX and implanted with a 10 mg CORT pellet, or ADX and 50 mg, of CORT. Different CORT levels or doses of nicotine did not significantly affect startle responses. Baseline PPI was significantly reduced in mice implanted with the highest dose of CORT. In ADX mice implanted with cholesterol, nicotine treatment influenced PPI depending on the prepulse intensity. In ADX mice implanted with 50 mg of CORT, treatment with 10 mg/kg of nicotine caused a significant increase in PPI at all prepulse intensities. Binding studies showed that corticosterone treatment had significantly affected nicotinic acetylcholine receptor (nAChR) density in the mouse brain. Treatment with 50 mg CORT decreased I-125-epibatidine binding in the globus pallidus and I-125-alpha-bungarotoxin binding in the claustrum. These results suggest a possible interaction of corticosterone and nicotine at the level of the alpha4- and alpha7-type nAChR in the regulation of PPI. In situations of high circulating levels of corticosterone, nicotine may be beneficial to restore disruption of PPI. (C) 2004 Elsevier Ltd. All rights reserved.

Task-dependent coordination of rapid bimanual motor responses.

Optimal feedback control postulates that feedback responses depend on the task relevance of any perturbations. We test this prediction in a bimanual task, conceptually similar to balancing a laden tray, in which each hand could be perturbed up or down. Single-limb mechanical perturbations produced long-latency reflex responses ("rapid motor responses") in the contralateral limb of appropriate direction and magnitude to maintain the tray horizontal. During bimanual perturbations, rapid motor responses modulated appropriately depending on the extent to which perturbations affected tray orientation. Specifically, despite receiving the same mechanical perturbation causing muscle stretch, the strongest responses were produced when the contralateral arm was perturbed in the opposite direction (large tray tilt) rather than in the same direction or not perturbed at all. Rapid responses from shortening extensors depended on a nonlinear summation of the sensory information from the arms, with the response to a bimanual same-direction perturbation (orientation maintained) being less than the sum of the component unimanual perturbations (task relevant). We conclude that task-dependent tuning of reflexes can be modulated online within a single trial based on a complex interaction across the arms.

A path-following driver-vehicle model with neuromuscular dynamics, including measured and simulated responses to a step in steering angle overlay

An existing driver-vehicle model with neuromuscular dynamics is improved in the areas of cognitive delay, intrinsic muscle dynamics and alpha-gamma co-activation. The model is used to investigate the influence of steering torque feedback and neuromuscular dynamics on the vehicle response to lateral force disturbances. When steering torque feedback is present, it is found that the longitudinal position of the lateral disturbance has a significant influence on whether the drivers reflex response reinforces or attenuates the effect of the disturbance. The response to angle and torque overlay inputs to the steering system is also investigated. The presence of the steering torque feedback reduced the disturbing effect of torque overlay and angle overlay inputs. Reflex action reduced the disturbing effect of a torque overlay input, but increased the disturbing effect of an angle overlay input. Experiments on a driving simulator showed that measured handwheel angle response to an angle overlay input was consistent with the response predicted by the model with reflex action. However, there was significant intra-and inter-subject variability. The results highlight the significance of a drivers neuromuscular dynamics in determining the vehicle response to disturbances. © 2012 Copyright Taylor and Francis Group, LLC.

Changes in plasma thyroid hormones and cortisol levels in crucian carp (Carassius auratus) exposed to the extracted microcystins

The endocrine response of crucian carp injected intraperitoneally with extracted microcystins (MC) was investigated in this study. Fish were injected intraperitoneally either with 0.75% NaCl (control) and Microcystis extract corresponding to 150 and 600 mu g microcystins per kg body weight. The plasma levels of triiodothyronine (T-3), thyroxine (T-4), free triiodothyronine (FT3), free thyroxine (FT4), and cortisol were determined at 0, 1, 3, 12, 24. and 48 h post-administration of MC-containing extract. Treated fish displayed abnormal behaviors, Such as a startle response and disoriented swimming, as well as changes in ventilation rates. Plasma cortisol concentrations of fish in both dose groups significantly increased after administration of extracted MC and remained high throughout the experiment, which suggested that MC elicited a stress response in treated fish. The profiles of cortisol changes in treated fish appeared to be dose dependent, indicating that fish in the high dose group experienced greater MC-incluced disturbance. Mortality occurred after 12 h in the high dose group. Plasma levels of T-4, T-3, FT4, and FT3 did not vary significantly between the control fish. In contrast to this, fish exposed to MC-containing extract showed significant declines in T-3, FT4, and FT3 levels in a dose-depenclent manner throughout the experiment. Plasma T4 levels, however, did not vary significantly in the low dose group, whereas they decreased significantly it 48 h post injection in the high dose group. This study demonstrates that administration of microcystins-containing extract causes a stress response and reduces the plasma levels of thyroid hormones in crucian carp. These results illustrate that microcystins exerted potent effects on the endocrine system of crucian carp, through activating their hypothalamus-pituitary- interrenal axis and disturbing thyroid function. (c) 2008 Elsevier Ltd. All rights reserved.

Self-organization of reflexive behavior from spontaneous motor activity.

In mammals, the development of reflexes is often regarded as an innate process. However, recent findings show that fetuses are endowed with favorable conditions for ontogenetic development. In this article, we hypothesize that the circuitry of at least some mammalian reflexes can be self-organized from the sensory and motor interactions brought forth in a musculoskeletal system. We focus mainly on three reflexes: the myotatic reflex, the reciprocal inhibition reflex, and the reverse myotatic reflex. To test our hypothesis, we conducted a set of experiments on a simulated musculoskeletal system using pairs of agonist and antagonist muscles. The reflex connectivity is obtained by producing spontaneous motor activity in each muscle and by correlating the resulting sensor and motor signals. Our results show that, under biologically plausible conditions, the reflex circuitry thus obtained is consistent with that identified in relation to the analogous mammalian reflexes. In addition, they show that the reflex connectivity obtained depends on the morphology of the musculoskeletal system as well as on the environment that it is embedded in.

Self-organization of spinal reflexes involving homonymous, antagonist and synergistic interactions

Recent results in spinal research are challenging the historical view that the spinal reflexes are mostly hardwired and fixed behaviours. In previous work we have shown that three of the simplest spinal reflexes could be self-organised in an agonist-antagonist pair of muscles. The simplicity of these reflexes is given from the fact that they entail at most one interneuron mediating the connectivity between afferent inputs and efferent outputs. These reflexes are: the Myotatic, the Reciprocal Inibition and the Reverse Myotatic reflexes. In this paper we apply our framework to a simulated 2D leg model actuated by six muscles (mono- and bi-articular). Our results show that the framework is successful in learning most of the spinal reflex circuitry as well as the corresponding behaviour in the more complicated muscle arrangement. © 2012 Springer-Verlag.

The improvement of thick oxidized porous silicon layer growth process - art. no. 60290S

Oxidizing thick porous silicon layer into silicon dioxide is a timesaving and low-cost process for producing thick silicon dioxide layer used in silicon-based optical waveguide devices. The solution of H2O2 is proposed to post-treat thick porous silicon (PS) films. The prepared PS layer as the cathode is applied about 10 mA/cm(2) current in mixture of ethanol, HF, and H2O2 solutions, in order to improve the stability and the smoothness of the surface. With the low-temperature dry-O-2 pre-oxidizations and high-temperature wet O-2 oxidizations process, a high-quality SiO2 30 mu m thickness layer that fit for the optical waveguide device was prepared. The SEM images show significant improved smoothness on the surface of oxidized PS thick films, the SiO2 film has a stable and uniformity reflex index that measured by the prism coupler, the uniformity of the reflex index in different place of the wafer is about 0.0003.

阿片类药物成瘾者瞳孔光反射的检测和特征提取

建立了一种基于图像处理的快速瞳孔直径检测算法,运用此算法提取了反映阿片类药物成瘾人员与正常人对瞳孔光反射变化差异的3个特征值:绝对收缩幅度(absolute amplitude of contraction,AAC)、相对收缩幅度(relative amplitude of contraction,RAC)和收缩斜率(SCV,slope of contraction velocity);分别研究了成瘾、性别、近视、年龄、睡眠剥夺等因素对于这3个特征值的影响。不同性别、近视人员、睡眠剥夺人员与正常人之间的3个特征值均无显著差异,成瘾人员与之对比均显著减小。老年人相对于正常青年人,3个特征值都明显减小;与成瘾人员相比,仅在RAC值上有显著差异。结果表明,阿片类药物成瘾人员除了与正常人外,也与其他具有潜在影响瞳孔变化因素的非阿片成瘾人员在瞳孔对光反射的特征值上具有显著差异。该研究的实验数据为进一步建立基于检测瞳孔对光反射其直径发生变化的方法来快速、非接触地鉴别出阿片类药物成瘾人员提供了可靠的依据。

1. 快速扫视系统对瞳孔对光反射系统的调制作用2. 麻醉状态下纳洛酮对吗啡依赖大鼠的岛叶神经元的自发放的影响

一. 快速扫视系统对瞳孔对光反射系统的调制作用快速扫视系统是研究运动神经控制的一个很好的模型。瞳孔对光反射是由进入视网膜的光亮度的增加而引起的瞳孔的收缩。之前的实验研究表明这两个系统都是开放的系统。但是对快速扫视系统是否对瞳孔对光反射系统有调制作用并没有研究过。本实验研究了注视状态和快速扫视状态下的瞳孔对光反射的潜伏期和瞳孔直径的变化。结果显示在注视状态下的和出现快速扫视时瞳孔对光反射的潜伏期表现出显著不同。外展和内收会引起瞳孔对光反射的潜伏期和瞳孔相对收缩率不同变化。在出现外展运动时，瞳孔对光反射的潜伏期显著下降，而出现内收运动时，瞳孔对光反射的潜伏期表现出显著增加。而瞳孔相对收缩率在出现两种运动时与注视状态下相比也发生不同的变化：外展运动引起瞳孔对光反射的瞳孔相对收缩率的增加，而内收运动引起瞳孔相对收缩率的减少。尽管快速扫视本身会引起瞳孔的收缩，但是引起的瞳孔收缩的变化不等于在出现快速扫视时的瞳孔对光反射的瞳孔直径的变化，这个结果说明在出现快速扫视时的瞳孔对光反射的变化并不是来源于光效应和快速扫视效应的简单叠加。基于快速扫视出现时间的进一步分析说明在瞳孔对光反射周期内不同时间出现两种快速扫视引起的瞳孔对光反射的潜伏期和瞳孔相对收缩率的变化不同。这些结果说明两个系统是有相互作用的，快速扫视系统可以调节瞳孔对光反射系统。关键词：快速扫视 瞳孔对光反射 调制二. 麻醉状态下纳洛酮对吗啡依赖大鼠的岛叶神经元的自发放的影响药物成瘾是药物长期作用于脑而产生的一种慢性复吸性脑疾病。之前有研究表明岛叶参与成瘾的过程。本实验以CPP为检测手段，检测实验大鼠是否产生吗啡依赖(吗啡给药方式为隔天给药，腹腔注射(10mg/kg)，共三次。然后采用四合一电极对纳洛酮诱发戒断的麻醉大鼠的岛叶和体感皮层进行细胞外电生理记录。与对照组相比，在记录的神经元中，被激活的神经元的所占比例（71.43%）远远大于对照组。将对照组和实验组的发放显著增加的神经元在给药前后的相对平均发放进行比较，两组神经元发放增加并没有显著差异。采用卡方检验比较了对照组和实验组的发放模式，结果显示两组发放模式存在显著差异。说明岛叶参与的方式可能是有更多数目的神经元参与，而不是通过改变单个神经元的发放参与。这也在神经元水平上为岛叶参与成瘾过程提供了一个证据。