Avoidance Performance Research Articles

Collision Avoidance System for Motorcycles (Automated Steering Control Using Model Predictive Control)

This study examines a collision avoidance system for motorcycles by automated steering control. The Model Predictive Control (MPC) is applied to the automated steering control with constraints on the motorcycle rolling motion by considering the rider's body movement in emergency avoidance. Two types of MPC controllers are designed and evaluated by the simple computer simulation of obstacle avoidance. One is a controller with a constraint on the rolling angle. The other is a controller with a constraint on the roll rate. Both controllers improve obstacle avoidance performance in comparison with the Liner Quadratic (LQ) controllers as conventional control theory. The MPC controller with the constraint on the roll rate decreases the roll rate under the permissible rolling angle. The controller with constraints on not only the roll rate but also the steering torque suppresses the large steering torque input. The improved avoidance performance by the MPC controller is observed at other vehicle velocities.

1119 自動車用可変特性操舵系による障害物回避性能の改善(OS1O-4機械の動的解析と設計問)

1119 自動車用可変特性操舵系による障害物回避性能の改善(OS1O-4機械の動的解析と設計問)

Nasal instillation of nanoparticle-rich diesel exhaust particles slightly affects emotional behavior and learning capability in rats

In the present study, in order to reveal novel adverse effects of ultrafine particles (UFP) on the central nervous system, the effects of nanoparticle-rich diesel exhaust particles (NRDEP; count mode diameter, 21.45 nm) on emotional behavior, learning capability and brain neurotransmitter levels were studied in rats by intranasal instillation (iNI). NRDEP (10 and 50 µg/rat) was instilled into 2-week old infant, male rats once a week for 4 weeks. Spontaneous motor activity measured was observed to be inverse to the dose level. In active avoidance tests using a shuttle box, NRDEP-treated animals showed a lower avoidance performance than control animals given air-instillation. The levels of dopamine and its metabolite (DOPAC) in the medial mammillary nucleus of the brain tended to be lower in the NRDEP-treated animals. From these results, although the effects of NRDEP by iNI on the emotionality and the brain neurotransmitter levels were not fully clear, the results obtained by avoidance testing suggested involvement of UFP in learning capability.

Two-way avoidance acquisition is negatively related to conditioned freezing and positively associated with startle reactions: A dissection of anxiety and fear in genetically heterogeneous rats

The double, fear-driven "passive avoidance/active avoidance" conflict appearing during acquisition of two-way active avoidance, involves high levels of anxiety and a dominant tendency for freezing responses, which in turn run against the appearance of active escape/avoidance behavior. In the present study, by using a large sample genetically heterogeneous (N/Nih-HS) rats, we have tested the hypothesis that rats showing relatively higher levels of context-conditioned freezing (during the initial trials of that task) should show lower efficiency to acquire two-way avoidance behavior, i.e. the prediction that the initial context-conditioned freezing in the shuttle box would be negatively related to avoidance acquisition efficiency. In agreement with such a hypothesis, the results from the three rat subsamples used show that context-conditioned freezing (during the first 5 inter-trial intervals of the 40-trial two-way avoidance session) is negatively correlated (r=-0.34 to r=-0.64, p<0.001) with two-way avoidance acquisition, in a way that subgroups of rats with extremely high or low levels of freezing markedly differ in their avoidance performance: "high freezer" rats show much worse avoidance acquisition than "low freezers". Moreover, the relationships of conditioned freezing and avoidance acquisition with baseline and fear-potentiated startle, as well as with unconditioned anxiety (in the elevated zero-maze test), have also been studied. Taken collectively, the results indicate that: (i) context conditioned freezing is a reliable (and negative) predictor of two-way avoidance acquisition; (ii) baseline and fear-potentiated startle responses show positive associations with avoidance responding, and (iii) unconditioned anxiety in the elevated zero-maze is also negatively associated with two-way avoidance acquisition. Such patterns of associations are considered to be very informative in regard to the search for (common or differential) neural and genetic mechanisms of different forms of (unlearned or learned) anxious or fear responses.

II. Cognitive performance of middle-aged female rats is influenced by capacity to metabolize progesterone in the prefrontal cortex and hippocampus

Cognitive decline can occur with aging; however, some individuals experience less cognitive decline than do others. Secretion of ovarian hormones is reduced post-menopause and may contribute to cognitive function. The extent to which hormonal effects may be parsed out from other age-related factors to influence cognition is of interest. Middle-aged (12-month-old) female rats that were retired breeders were categorized as maintaining or declining reproductive function based upon their estrous cyclicity (regular 4–5 day cycles), fertility (> 60 % successful pregnancy), and fecundity (> 10 pups/litter). Performance in object recognition, Y-maze, water maze, inhibitory avoidance, and contextual–cued fear conditioning was evaluated. Estradiol, progesterone (P 4), dihydroprogesterone, and 5α-pregnan-3α-ol-20-one (3α,5α-THP) were assessed in medial prefrontal cortex (mPFC) and hippocampus; corticosterone was assessed in plasma. Rats maintaining reproductive function performed significantly better on the object recognition, Y-maze, water maze, inhibitory avoidance, and cued fear conditioning tasks than did rats with declining reproductive function. Steroid concentrations varied greatly within groups. Higher levels of P 4 in mPFC and hippocampus were associated with better Y-maze performance. In mPFC, higher levels of P 4 were associated with poorer inhibitory avoidance performance; greater levels of 3α,5α-THP were associated with better object memory. Neither estradiol nor corticosterone levels significantly contributed to cognitive performance. Thus, the capacity for cortico-limbic P 4 utilization may influence cognitive performance in aging.

The effect of sodium metabisulphite on active avoidance performance in hypercholesterolemic rats

The purpose of this study was to investigate the effects of hypercholesterolemia and sulphite on active avoidance learning. Male Wistar rats were divided into eight groups as follows: Control (C), Sulphite (S), Vitamin E (E), Sulphite + Vitamin E (SE), Hypercholesterolemia (H), Hypercholesterolemia + Sulphite (HS), Hypercholesterolemia + Vitamin E (HE), and Hypercholesterolemia + Sulphite + Vitamin E (HSE). At the end of the experimental period, the serum cholesterol level (mean ± SD) was significantly higher in H group (111.5 ± 11.11 mg dL(-1) ) as compared to C group (63.5 ± 4.9 mg dL(-1) ). Levels of thiobarbituric acid reactive substances (TBARS) were increased in HS group as compared to C, H, and S groups. Vitamin E reduced TBARS levels in HSE group compared with HS group. Active avoidance results indicated that hypercholesterolemia was associated with learning impairment. Our data clearly revealed that the combination of hypercholesterolemia and sulphite results in exaggerated impairment of active avoidance. Vitamin E improved active avoidance in HSE group compared with HS group. Therefore, the synergistic effect of hypercholesterolemia and sulphite may be associated with a considerable health risk.

Earthworms, as ecosystem engineers, influence multiple aspects of a salamander’s ecology

Ecosystem engineers create habitat that can be used by other species in multiple ways, such as refugees from predators, places to breed, or areas with increased prey resources. I conducted a series of enclosure experiments to: (1) determine if salamanders use earthworm burrows, and (2) examine the potential influence of earthworm burrow use and indirect effects on salamander intra- and interspecific competition, predator avoidance, and seasonal performance. I found that one species of woodland salamander, Plethodon cinereus, used earthworm burrows 50% of the time when burrows were present. Neither adults nor juveniles of the congeneric P. glutinosus used earthworm burrows. Intraspecific, but not interspecific, competition by P. cinereus affected salamander behavior when earthworms were absent, with P. cinereus found under cover objects >70% of the time when alone or with a P. glutinosus, but only 40% of the time when with another P. cinereus. When earthworms were present, the behavior of P. cinereus was similar across salamander treatments. Earthworms decreased the amount of leaf litter and microinvertebrates, although this did not affect salamander mass. In subsequent experiments using only P. cinereus, the refuge provided by earthworm burrows increased the survival of P. cinereus over the winter and allowed P. cinereus to avoid being consumed by the common garter snake (Thamnophis sirtalis). Because earthworm burrows provide a refuge for P. cinereus during intraspecific encounters, in the presence of a predator and over the winter, they may serve as an important belowground-aboveground linkage in eastern forests where salamanders are common.

P.4.b.006 Interpreting the social scene: threat detection and cost attribution in social anxiety

A wealth of evidence indicates that the dorsal raphe nucleus (DR) is not a homogenous structure, but an aggregate of distinctive populations of neurons that may differ anatomically, neurochemically and functionally. Other findings suggest that serotonergic neurons within the mid-caudal and caudal part of the DR are involved in anxiety processing while those within the lateral wings (lwDR) and ventrolateral periaqueductal gray (vlPAG) are responsive to panic-evoking stimuli/situations. However, no study to date has directly compared the activity of 5-HT and non-5HT neurons within different subnuclei of the DR following the expression of anxiety- and panic-related defensive responses. In the present investigation, the number of doubly immunostained cells for Fos protein and tryptophan hydroxylase, a marker of serotonergic neurons, was assessed within the rat DR, median raphe nucleus (MRN) and PAG following inhibitory avoidance and escape performance in the elevated T-maze, behaviors associated with anxiety and panic, respectively. Inhibitory avoidance, but not escape, significantly increased the number of Fos-expressing serotonergic neurons within the mid-caudal part of the dorsal subnucleus, caudal and interfascicular subnuclei of the DR and in the MRN. Escape, on the other hand, caused a marked increase in the activity of non-5HT cells within the lwDR, vlPAG, dorsolateral and dorsomedial columns of the PAG. These results strongly corroborate the view that different subsets of neurons in the DR are activated by anxiety- and panic-relevant stimuli/situations, with important implications for the understanding of the pathophysiology of generalized anxiety and panic disorders.

Amygdala Activity, Fear, and Anxiety: Modulation by Stress

Amygdala Activity, Fear, and Anxiety: Modulation by Stress

컴프레시브 수신기가 내장된 RFID 리더의 채널 충돌 회피 성능 분석

In this paper, the interference avoidance performance of the RFID reader with the compressive receiver was analyzed. In the environment of the multiple dense readers operating, the recognition rates of the conventional RFID reader and the proposed RFID reader with the compressive receiver were measured and compared. The recognition rate of the proposed reader was improved more than 2.7 times compared to the conventional reader. Especially, in the environment of two proposed RFID readers operating simultaneously, little degradation of the recognition rate was observed.

A highly interpretable fuzzy rule base using ordinal structure for obstacle avoidance of mobile robot

Conventional fuzzy logic controller is applicable when there are only two fuzzy inputs with usually one output. Complexity increases when there are more than one inputs and outputs making the system unrealizable. The ordinal structure model of fuzzy reasoning has an advantage of managing high-dimensional problem with multiple input and output variables ensuring the interpretability of the rule set. This is achieved by giving an associated weight to each rule in the defuzzification process. In this work, a methodology to design an ordinal fuzzy logic controller with application for obstacle avoidance of Khepera mobile robot is presented. The implementation will show that ordinal structure fuzzy is easier to design with highly interpretable rules compared to conventional fuzzy controller. In order to achieve high accuracy, a specially tailored Genetic Algorithm (GA) approach for reinforcement learning has been proposed to optimize the ordinal structure fuzzy controller. Simulation results demonstrated improved obstacle avoidance performance in comparison with conventional fuzzy controllers. Comparison of direct and incremental GA for optimization of the controller is also presented.

Differential Neuromodulation of Acquisition and Retrieval of Avoidance Learning by the Lateral Habenula and Ventral Tegmental Area

Several studies suggest an opponent functional relationship between the lateral habenula (LHb) and the ventral tegmental area (VTA). Previous work has linked LHb activation to the inhibition of dopaminergic neurons during loss of reward, as well as to deficits in escape and avoidance learning. We hypothesized that a dopamine signal might underlie the negative reinforcement of avoidance responses and that LHb activation could block this signal and thereby cause avoidance deficits. To test this idea, we implanted stimulating electrodes in either the VTA or LHb of gerbils engaged in two-way active avoidance learning, a task that shows learning-associated dopamine changes and that is acquired faster following LHb lesions. We delivered brief electrical brain stimulation whenever the animal performed a correct response, i.e., when the successful avoidance of foot shock was hypothesized to trigger an intrinsic reward signal. During the acquisition phase, VTA stimulation improved avoidance performance, while LHb stimulation impaired it. VTA stimulation appeared to improve both acquisition and asymptotic performance of the avoidance response, as VTA-stimulated animals reached above-normal performance but reverted to normal responding when stimulation was discontinued. The effects of LHb stimulation during avoidance acquisition were long lasting and persisted even after stimulation was discontinued. However, when given after successful acquisition of avoidance behavior, LHb stimulation had no effect, indicating that LHb stimulation specifically impaired avoidance acquisition without affecting memory retrieval or motivation or ability to perform the avoidance response. These results demonstrate opponent roles of LHb and VTA during acquisition but not during retrieval of avoidance learning.

Clinical audit: virological and immunological response to combination antiretroviral therapy in HIV patients at a Sydney sexual health clinic

Bigge Park Centre (BPC) is a sexual health clinic located in a socially disadvantaged area in Southwest Sydney. This served as a retrospective clinical audit, documenting patient demographics, identifying factors associated with virological, immunological and discordant responses, evaluating the centre's ability in HIV control and investigating changes in practice from 1996 to 2007. Data including age, gender, ethnicity, mode of transmission, hepatitis co-infection, prior acquired immune deficiency syndrome (AIDS)-defining-illness, HIV-1 RNA and CD4+cell counts of patients on combination antiretroviral therapy (CART) for treatment of HIV with at least 1-year follow up at the BPC were analysed. Results were compared with other cohorts in medical literature. BPC manages HIV patients from diverse backgrounds. Sequential monotherapy was associated with poor virological control, lower CD4+cell recovery and discordant response. When patients who had sequential monotherapy were excluded, Caucasian race, high viral load at 1 month and triple-NRTI (nucleoside reverse transcriptase inhibitor) regimen were associated with lack of virological control. Lower baseline viral load and triple-NRTI regimen were associated with lower CD4+cell recovery. Lower baseline CD4+cell count and prior diagnosis of AIDS were associated with discordant response. Virological control and CD4+cell recovery achieved were comparable to that documented in medical literature. There was no significant change over time in terms of timing of CART initiation, attainment of immunological response or virological control since the late 1990 s. HIV control achieved at the BPC was comparable to that reported in medical literature. Enhancement of strategies to promote screening and improve adherence as well as performance of HIV resistance assessment and avoidance of triple-NRTI therapy will likely improve patient care.

Proteomic analysis reveals changes in the hippocampus protein pattern of rats exposed to dietary zinc deficiency

An experiment was performed to observe protein changes in the hippocampus of zinc-deficient (ZD) rats. Twenty-four male weanling Wistar rats were randomly assigned to ZD (n=12) and control groups (n=12). After 4-wk treatment, we used 2-DE and MALDI-TOF-MS to analyze the proteomes of hippocampus in the two groups. One of the important differential proteins, ubiquitin C-terminal hydrolase L1 (Uch-L1), was confirmed by Western blot assays. The results demonstrated that compared with the controls, ZD rats had significantly reduced plasma zinc concentration and alkaline phosphatase activity. The latency period in passive avoidance performance was also significantly shorter for the ZD rats. Nine proteins were differentially expressed between the two groups. Eight of them were identified. Tubulin beta chain and voltage-dependent anion channel 1 were upregulated, while mitochondrial aldehyde dehydrogenase, alpha-enolase, dimethylarginine dimethylaminohydrolase 1, F-actin capping protein alpha-2 subunit, pyruvate dehydrogenase beta and Uch-L1 were downregulated, respectively. Importantly, some of the identified proteins (e.g. Uch-L1) are known to be involved in cognitive impairment. Western blot analysis of hippocampus Uch-L1 expression confirmed the proteomic findings. The data indicated that there may be common mechanisms or pathways in cognitive dysfunction between neurodegenerative diseases and zinc deficiency.

One-way avoidance learning in female inbred Roman high- and low-avoidance rats: Effects of bilateral electrolytic central amygdala lesions

Female inbred Roman high- (RHA-I) and low- (RLA-I) avoidance rats show differences in one-way avoidance learning only when the task implies a highly aversive situation (1 s in the “non-shock”-associated safe compartment, as opposed to 30 s). These between-strain differences seem to depend on strain differences in emotionality, given that: (i) they are abolished by IP administration of the GABAergic anxiolytic diazepam (Torres et al. [32]) and (ii) avoidance responding appears to correlate with cellular density in the basolateral amygdala (Gómez et al. [9]). In the present study we further analyzed whether the implication of the amygdala in one-way avoidance depends on the experimental situation aversiveness (30 s vs. 1 s in safety). After bilateral electrolytic lesions (1 mA; 20 s) of the central amygdala (CeA), RHA-I and RLA-I rats were exposed to a danger compartment (where they received a warning signal – 88 dB tone – followed by a 1 mA electric foot-shock), and a safe compartment, where these stimuli were not presented. The number of trials needed to reach 5 consecutive avoidance responses was used as dependent variable. Sham lesioned RLA-I rats showed poorer performance than sham lesioned RHA-I rats only under the 1 s condition. The CeA lesion disrupted the avoidance response only in 1 s groups, abolishing the between-strain performance differences observed under this condition. These results indicate the implication of CeA in one-way avoidance performance, and suggest a reciprocal modulation of fear and reinforcement (i.e. fear relief) in this form of aversive learning.

The role of amygdala nuclei in the expression of auditory signaled two-way active avoidance in rats

Using a two-way signaled active avoidance (2-AA) learning procedure, where rats were trained in a shuttle box to avoid a footshock signaled by an auditory stimulus, we tested the contributions of the lateral (LA), basal (B), and central (CE) nuclei of the amygdala to the expression of instrumental active avoidance conditioned responses (CRs). Discrete or combined lesions of the LA and B, performed after the rats had reached an asymptotic level of avoidance performance, produced deficits in the CR, whereas CE lesions had minimal effect. Fiber-sparing excitotoxic lesions of the LA/B produced by infusions of N-methyl-d-aspartate (NMDA) also impaired avoidance performance, confirming that neurons in the LA/B are involved in mediating avoidance CRs. In a final series of experiments, bilateral electrolytic lesions of the CE were performed on a subgroup of animals that failed to acquire the avoidance CR after 3 d of training. CE lesions led to an immediate rescue of avoidance learning, suggesting that activity in CE was inhibiting the instrumental CR. Taken together, these results indicate that the LA and B are essential for the performance of a 2-AA response. The CE is not required, and may in fact constrain the instrumental avoidance response by mediating the generation of competing Pavlovian responses, such as freezing.

The effect of parental modeling of anxious behaviors and cognitions in school-aged children: An experimental pilot study

The current study tested: (1) the impact of parental modeling of anxious behaviors and cognitions on child anxiety level, anxious cognitions, desired avoidance, and objective performance using an experimental paradigm; and (2) whether the impact of parental modeling of anxious behaviors and cognitions differed by parent gender. Twenty-five parents (a random selection of 12 male and 13 female parents) participated with one of their children (ages 8–12 years; 56.0% male; 76.0% Caucasian). All children experienced two test conditions: an anxious condition in which their parent was trained to act anxiously before a planned spelling test and a non-anxious condition in which their parent was trained to act in a relaxed and confident manner before a planned spelling test. Results showed that, regardless of parent gender, children endorsed higher anxiety levels, anxious cognitions, and desired avoidance of the spelling test in the anxious relative to the non-anxious condition. Parental modeling of anxiety did not affect child spelling performance. Significant interaction effects indicated that fathers had a stronger impact on child anxiety level and cognitions than did mothers. Results highlight the importance of parental modeling and the potential role of both mothers and fathers in prevention and treatment for child anxiety.

Effects of Uncaria tomentosa total alkaloid and its components on experimental amnesia in mice: elucidation using the passive avoidance test.

The effects of Uncaria tomentosa total alkaloid and its oxindole alkaloid components, uncarine E, uncarine C, mitraphylline, rhynchophylline and isorhynchophylline, on the impairment of retention performance caused by amnesic drugs were investigated using a step-down-type passive avoidance test in mice. In this test, the retention performance of animals treated with the amnesic and test drugs before training was assessed 24 h after training. Uncaria tomentosa total alkaloid (10-20 mg kg(-1), i.p.) and the alkaloid components (10-40 mg kg(-1), i.p.), as well as the muscarinic receptor agonist oxotremorine (0.01 mg kg(-1), i.p.), significantly attenuated the deficit in retention performance induced by the muscarinic receptor antagonist scopolamine (3 mg kg(-1), i.p.). The effective doses of uncarine C and mitraphylline were larger than those of other alkaloid components. Uncarine E (20 mg kg(-1), i.p.) also blocked the impairment of passive avoidance performance caused by the nicotinic receptor antagonist mecamylamine (15 mg kg(-1), i.p.) and the N-methyl-D-aspartate (NMDA) receptor antagonist (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP; 7.5 mg kg(-1), i.p.), but it failed to affect the deficit caused by the benzodiazepine receptor agonist diazepam (2 mg kg(-1), i.p.). Rhynchophylline significantly reduced the mecamylamine-induced deficit in passive avoidance behaviour, but it failed to attenuate the effects of CPP and diazepam. These results suggest that Uncaria tomentosa total alkaloids exert a beneficial effect on memory impairment induced by the dysfunction of cholinergic systems in the brain and that the effect of the total alkaloids is partly attributed to the oxindole alkaloids tested. Moreover, these findings raised the possibility that the glutamatergic systems are implicated in the anti-amnesic effect of uncarine E.

Random Early Detection for Congestion Avoidance in Wired Networks: A Discretized Pursuit Learning-Automata-Like Solution

In this paper, we present a learning-automata-like The reason why the mechanism is not a pure LA, but rather why it yet mimics one, will be clarified in the body of this paper. (LAL) mechanism for congestion avoidance in wired networks. Our algorithm, named as LAL Random Early Detection (LALRED), is founded on the principles of the operations of existing RED congestion-avoidance mechanisms, augmented with a LAL philosophy. The primary objective of LALRED is to optimize the value of the average size of the queue used for congestion avoidance and to consequently reduce the total loss of packets at the queue. We attempt to achieve this by stationing a LAL algorithm at the gateways and by discretizing the probabilities of the corresponding actions of the congestion-avoidance algorithm. At every time instant, the LAL scheme, in turn, chooses the action that possesses the maximal ratio between the number of times the chosen action is rewarded and the number of times that it has been chosen. In LALRED, we simultaneously increase the likelihood of the scheme converging to the action, which minimizes the number of packet drops at the gateway. Our approach helps to improve the performance of congestion avoidance by adaptively minimizing the queue-loss rate and the average queue size. Simulation results obtained using NS2 establish the improved performance of LALRED over the traditional RED methods which were chosen as the benchmarks for performance comparison purposes.

Too much of a good thing? Elevated baseline sleep spindles predict poor avoidance performance in rats

Sleep spindles may be involved in synaptic plasticity. Learning-dependent increases in spindles have been observed in both humans and rats. In humans, the innate (i.e., baseline) number of spindles correlate with measures of academic potential such as Intelligence Quotient (IQ) tests. The present study investigated if spindles predict whether rats are able to learn to make avoidance responses in the two-way shuttle task. Baseline recordings were taken continuously for 24 h prior to training on the two-way shuttle task for 50 trials/day for two days followed by a 25 trial re-test on the third day. At re-test, rats were categorized into learners ( n = 16) or non-learners ( n = 21). Groups did not differ in baseline duration of rapid eye movement sleep, slow wave sleep, wake or spindle density. For combined groups, spindle density in the 21 to 24-hour period but not at any other period during baseline was negatively correlated with shuttle task performance at re-test. Conversely, the learning-related change in spindle density in the 21 to 24-hour period, but not at any other time after the first training session was positively correlated with shuttle task performance. Rats in the non-learning condition have a higher number of spindles at baseline, which is unaffected by training. On the other hand, learning rats have fewer spindles at baseline, but have a learning-related increase in spindles. Extreme spindle activity and high spindle density have been observed in humans with learning disabilities. Results suggest that while spindles may be involved in memory consolidation, in some cases, high levels of spindles prior to training may be maladaptive.