Contribution of the medial entorhinal cortex to performance on the Traveling Salesperson Problem in rats.

In order to successfully navigate through space, animals must rely on multiple cognitive processes, including orientation in space, memory of object locations, and navigational decisions based on that information. Although highly-controlled behavioral tasks are valuable for isolating and targeting specific processes, they risk producing a narrow understanding of complex behavior in natural contexts. The Traveling Salesperson Problem (TSP) is an optimization problem that can be used to study naturalistic foraging behaviors, in which subjects select routes between multiple baited targets. Foraging is a spontaneous, yet complex, behavior, involving decision-making, attention, course planning, and memory. Previous research found that hippocampal lesions in rats impaired TSP task performance, particularly on measures of spatial memory. Although traditional laboratory tests have shown the medial entorhinal cortex (MEC) to play an important role in spatial memory, if and how the MEC is involved in finding efficient solutions to the TSP remains unknown. In the current study, rats were trained on the TSP, learning to retrieve bait from targets in a variety of spatial configurations. After recovering from either an MEC lesion or control sham surgery, the rats were tested on eight new configurations. Our results showed that, similar to rats with hippocampal lesions, MEC-lesioned rats were impaired on measures of spatial memory, but not spatial decision-making, with greatest impairments on configurations requiring a global navigational strategy for selecting the optimal route. These findings suggest that the MEC is important for effective spatial navigation, especially when global cue processing is required.

Target number influences strategy use by rats (Rattus norvegicus) in the traveling salesperson problem.

The traveling salesman problem (TSP) is an optimization problem in which the goal is to find the shortest possible route that passes through each of a set of points in space. The TSP is of interest not only in the fields of mathematics, computer science, and engineering, but also in cognitive and behavioral research to study problem-solving and spatial navigation. Humans are able to complete even complex TSPs with a high degree of efficiency, and distance minimization in TSP analogs has been observed in a variety of nonhuman species as well. Tasks based on the TSP also have the potential for translational research on cognitive and neurological disorders such as Alzheimer's disease. The current experiment was designed to examine the effects of target number on TSP performance in rats. After pretraining, rats were tested once on each of several target configurations, and their travel routes were recorded. We examined the routes for general efficiency, as well as evidence for strategy use including the nearest neighbor (NN) strategy and crossing avoidance. Our results indicate that latency and route length increase in proportion to the number of targets. Rats also showed a strong tendency to avoid path crossing, and to select NN targets, which strengthened with increasing target numbers. Taken together, our results indicate that travel efficiency decreases linearly in relation to the target number rather than the number of possible routes, which grows factorially with a target number. Additionally, spatial memory and route selection strategy are also affected by an increasing number of targets. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Investigating the Compatibility of TTMSP and FEC Electrolyte Additives for LiNi0.5Mn0.3Co0.2O2 (NMC)-Silicon Lithium-Ion Batteries.

This study examines the compatibility of multielectrolyte additives for NMC-silicon lithium-ion batteries. Research studies with Si-based anodes have shown stable reversible cycling using electrolytes containing fluoroethylene carbonate (FEC). At the same time, the electrolyte additive, tris(trimethylsilyl) phosphite (TTMSP), has shown to improve the electrochemical performance of nickel-rich layered cathodes, such as LiNi0.5Mn0.3Co0.2O2 (NMC). However, the combination of these electrolyte additives for the realization of a full-cell NMC-Si lithium-ion battery has not been previously explored. Changes in the electrochemical performance (capacity retention, internal cell resistance, and electrochemical impedance) in half-cells are studied as the ratio of TTMSP and FEC is tuned. At the optimal TTMSP/FEC ratio of 0.33 (T1F3), the NMC-Si full-cells achieve a 2× longer cycle life when compared to the FEC-rich (T0F4) electrolyte. Moreover, T1F3 full-cells demonstrate 1.5 mAh/cm2 areal capacities and high-capacity retention (25% more than T0F4). A detailed investigation of the electrode-electrolyte interfaces is conducted by using time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The chemical species depth profiles and elemental analysis illustrate adequate hydrogen fluoride (HF) scavenging. These results demonstrate the synergistic effects of electrolyte additives in minimizing the capacity degradation in NMC-Si full-cells by effectively stabilizing the electrode-electrolyte interfaces.

Modulatory action of taurine on ethanol-induced aggressive behavior in zebrafish.

Alcohol is a potent agent for eliciting aggression in vertebrates. Taurine (TAU) is an amino sulfonic acid with pleiotropic actions on brain function. It is one of the most abundant molecules present in energy drinks frequently used as mixers for alcoholic beverages. However, the combined effects of TAU and ethanol (EtOH) on behavioral parameters such as aggression are poorly understood. Considering that zebrafish is a suitable vertebrate to assess agonistic behaviors using noninvasive protocols, we investigate whether TAU modulates EtOH-induced aggression in zebrafish using the mirror-induced aggression (MIA) test. Since body color can be altered by pharmacological agents and may be indicative of emotional state, we also evaluated the actions of EtOH and TAU on pigment response. Fish were acutely exposed to TAU (42, 150, and 400mg/L), EtOH (0.25%), or cotreated with both molecules for 1h and then placed in the test apparatus for 6min. EtOH, TAU 42, TAU 400, TAU 42/EtOH and TAU 400/EtOH showed increased aggression, while 150mg/L TAU only increased the latency to attack the mirror. This same concentration also prevented EtOH-induced aggression, suggesting that it antagonizes the effects of acute alcohol exposure. Representative ethograms revealed the existence of different aggressive patterns and our results were confirmed by an index used to estimate aggression in the MIA test. TAU did not alter pigment intensity, while EtOH and all cotreated groups presented a substantial increase in body color. Overall, these data show a biphasic effect of TAU on EtOH-induced aggression of zebrafish, which is not necessarily associated with changes in body color.

Spontaneous object recognition: a promising approach to the comparative study of memory.

Spontaneous recognition of a novel object is a popular measure of exploratory behavior, perception and recognition memory in rodent models. Because of its relative simplicity and speed of testing, the variety of stimuli that can be used, and its ecological validity across species, it is also an attractive task for comparative research. To date, variants of this test have been used with vertebrate and invertebrate species, but the methods have seldom been sufficiently standardized to allow cross-species comparison. Here, we review the methods necessary for the study of novel object recognition in mammalian and non-mammalian models, as well as the results of these experiments. Critical to the use of this test is an understanding of the organism's initial response to a novel object, the modulation of exploration by context, and species differences in object perception and exploratory behaviors. We argue that with appropriate consideration of species differences in perception, object affordances, and natural exploratory behaviors, the spontaneous object recognition test can be a valid and versatile tool for translational research with non-mammalian models.

Behavioral and proteomic analysis of stress response in zebrafish (Danio rerio).

The purpose of this study is to determine the behavioral and proteomic consequences of shock-induced stress in zebrafish (Danio rerio) as a vertebrate model. Here we describe the behavioral effects of exposure to predictable and unpredictable electric shock, together with quantitative tandem mass tag isobaric labeling workflow to detect altered protein candidates in response to shock exposure. Behavioral results demonstrate a hyperactivity response to electric shock and a suppression of activity to a stimulus predicting shock. On the basis of the quantitative changes in protein abundance following shock exposure, eight proteins were significantly up-regulated (HADHB, hspa8, hspa5, actb1, mych4, atp2a1, zgc:86709, and zgc:86725). These proteins contribute crucially in catalytic activities, stress response, cation transport, and motor activities. This behavioral proteomic driven study clearly showed that besides the rapid induction of heat shock proteins, other catalytic enzymes and cation transporters were rapidly elevated as a mechanism to counteract oxidative stress conditions resulting from elevated fear/anxiety levels.

Subchronic atrazine exposure changes defensive behaviour profile and disrupts brain acetylcholinesterase activity of zebrafish.

Animal behaviour is the interaction between environment and an individual organism, which also can be influenced by its neighbours. Variations in environmental conditions, as those caused by contaminants, may lead to neurochemical impairments altering the pattern of the behavioural repertoire of the species. Atrazine (ATZ) is an herbicide widely used in agriculture that is frequently detected in surface water, affecting non-target species. The zebrafish is a valuable model organism to assess behavioural and neurochemical effects of different contaminants since it presents a robust behavioural repertoire and also all major neurotransmitter systems described for mammalian species. The goal of this study was to evaluate the effects of subchronic ATZ exposure in defensive behaviours of zebrafish (shoaling, thigmotaxis, and depth preference) using the split depth tank. Furthermore, to investigate a putative role of cholinergic signalling on ATZ-mediated effects, we tested whether this herbicide alters acetylcholinesterase (AChE) activity in brain and muscle preparations. Fish were exposed to ATZ for 14days and the following groups were tested: control (0.2% acetone) and ATZ (10 and 1000µg/L). The behaviour of four animals in the same tank was recorded for 6min and biological samples were prepared. Our results showed that 1000µg/L ATZ significantly increased the inter-fish distance, as well as the nearest and farthest neighbour distances. This group also presented an increase in the shoal area with decreased social interaction. No significant differences were detected for the number of animals in the shallow area, latency to enter the shallow and time spent in shallow and deep areas of the apparatus, but the ATZ 1000 group spent significantly more time near the walls. Although ATZ did not affect muscular AChE, it significantly reduced AChE activity in brain. Exposure to 10µg/L ATZ did not affect behaviour or AChE activity. These data suggest that ATZ impairs defensive behaviours of zebrafish, which could be related to its action on brain cholinergic neurotransmission. Moreover, the use of the split depth tank could be an alternative strategy to assess group behaviour and depth preference after exposure to chemical compounds.

Evaluation of spontaneous recovery of behavioral and brain injury profiles in zebrafish after hypoxia.

Cerebral hypoxia-ischemia can lead to motor and sensory impairments which can be dependent on the extent of infarcted regions. Since a better understanding of the neurochemical mechanisms involved in this injury is needed, the use of zebrafish as a cerebral hypoxia model has become quite promising because it could improve the knowledge about hypoxia-ischemia. In the current study, we aimed to investigate the spontaneous recovery of brain and behavioral impairments induced by hypoxia in adult zebrafish. Brain injury levels were analyzed by spectrophotometric measurement of mitochondrial dehydrogenase activity by staining with 2,3,5-triphenyltetrazolium chloride, and behavioral profiles were assessed by the open tank test. The induction of hypoxia substantially decreased mitochondrial activity in the brain and impaired behavior. The spontaneous recovery of fish subjected to hypoxia was assessed after 1, 3, 6, 24, and 48h under normoxia. The quantification of brain injury levels showed a significant increase until 24h after hypoxia, but after 48h this effect was completely reversed. Regarding behavioral parameters, we verified that locomotor activity and vertical exploration were impaired by hypoxia and these effects were reversed after 3h under normoxia. Taken together, these results show that zebrafish exhibited transient cerebral and behavioral impairments when submitted to hypoxia, and 1h under normoxic conditions was insufficient to reverse both effects. Therefore, our data help to elucidate the time window of spontaneous recovery in zebrafish after hypoxia and also the behavioral phenotypes involved in this phenomenon.

Measures of anxiety in zebrafish (Danio rerio): dissociation of black/white preference and novel tank test.

The effects of wall color stimuli on diving, and the effects of depth stimuli on scototaxis, were assessed in zebrafish. Three groups of fish were confined to a black, a white, or a transparent tank, and tested for depth preference. Two groups of fish were confined to a deep or a shallow tank, and tested for black-white preference. As predicted, fish preferred the deep half of a split-tank over the shallow half, and preferred the black half of a black/white tank over the white half. Results indicated that the tank wall color significantly affected depth preference, with the transparent tank producing the strongest depth preference and the black tank producing the weakest preference. Tank depth, however, did not significantly affect color preference. Additionally, wall color significantly affected shuttling and immobility, while depth significantly affected shuttling and thigmotaxis. These results are consistent with previous indications that the diving response and scototaxis may reflect dissociable mechanisms of behavior. We conclude that the two tests are complementary rather than interchangeable, and that further research on the motivational systems underlying behavior in each of the two tests is needed.

Behavioral effects of taurine pretreatment in zebrafish acutely exposed to ethanol.

Taurine (TAU) is an amino sulfonic acid that plays protective roles against neurochemical impairments induced by ethanol (EtOH). Mounting evidence shows the applicability of zebrafish for evaluating locomotor parameters and anxiety-like behavioral phenotypes after EtOH exposure in a large scale manner. In this study, we assess the effects of TAU pretreatment on the behavior of zebrafish in the open tank after acute 1% EtOH (v/v) exposure (20 and 60 min of duration) and on brain alcohol contents. The exposure for 20 min exerted significant anxiolytic effects, which were prevented by 42, 150, and 400 mg/L TAU. Conversely, the 60-min condition induced depressant/sedative effects, in which the changes on vertical activity were associated to modifications on the exploratory profile. Although all TAU concentrations kept locomotor parameters at basal levels, 150 mg/L TAU, did not prevent the impairment on vertical activity of EtOH[60]. Despite the higher brain EtOH content detected in the 60-min exposure, 42, 150, and 400 mg/L TAU attenuated the increase of alcohol content in EtOH[60] group. In conclusion, our data suggest that both protocols of acute EtOH exposure induce significant changes in the spatio-temporal behavior of zebrafish and that TAU may exert a preventive role by antagonizing the effects induced by EtOH possibly due to its neuromodulatory role and also by decreasing brain EtOH levels. The hormetic dose-response of TAU on vertical exploration suggests a complex interaction between TAU and EtOH in the central nervous system.

Route selection by rats and humans in a navigational traveling salesman problem.

Spatial cognition is typically examined in non-human animals from the perspective of learning and memory. For this reason, spatial tasks are often constrained by the time necessary for training or the capacity of the animal's short-term memory. A spatial task with limited learning and memory demands could allow for more efficient study of some aspects of spatial cognition. The traveling salesman problem (TSP), used to study human visuospatial problem solving, is a simple task with modifiable learning and memory requirements. In the current study, humans and rats were characterized in a navigational version of the TSP. Subjects visited each of 10 baited targets in any sequence from a set starting location. Unlike similar experiments, the roles of learning and memory were purposely minimized; all targets were perceptually available, no distracters were used, and each configuration was tested only once. The task yielded a variety of behavioral measures, including target revisits and omissions, route length, and frequency of transitions between each pair of targets. Both humans and rats consistently chose routes that were more efficient than chance, but less efficient than optimal, and generally less efficient than routes produced by the nearest-neighbor strategy. We conclude that the TSP is a useful and flexible task for the study of spatial cognition in human and non-human animals.

Differences in spatio-temporal behavior of zebrafish in the open tank paradigm after a short-period confinement into dark and bright environments.

The open tank paradigm, also known as novel tank diving test, is a protocol used to evaluate the zebrafish behavior. Several characteristics have been described for this species, including scototaxis, which is the natural preference for dark environments in detriment of bright ones. However, there is no evidence regarding the influence of "natural stimuli" in zebrafish subjected to novelty-based paradigms. In this report, we evaluated the spatio-temporal exploratory activity of the short-fin zebrafish phenotype in the open tank after a short-period confinement into dark/bright environments. A total of 44 animals were individually confined during a 10-min single session into one of three environments: black-painted, white-painted, and transparent cylinders (dark, bright, and transparent groups). Fish were further subjected to the novel tank test and their exploratory profile was recorded during a 15-min trial. The results demonstrated that zebrafish increased their vertical exploratory activity during the first 6-min, where the bright group spent more time and travelled a higher distance in the top area. Interestingly, all behavioral parameters measured for the dark group were similar to the transparent one. These data were confirmed by automated analysis of track and occupancy plots and also demonstrated that zebrafish display a classical homebase formation in the bottom area of the tank. A detailed spatio-temporal study of zebrafish exploratory behavior and the construction of representative ethograms showed that the experimental groups presented significant differences in the first 3-min vs. last 3-min of test. Although the main factors involved in these behavioral responses still remain ambiguous and require further investigation, the current report describes an alternative methodological approach for assessing the zebrafish behavior after a forced exposure to different environments. Additionally, the analysis of ethologically-relevant patterns across time could be a potential phenotyping tool to evaluate the zebrafish exploratory profile in the open tank task.

Optical phase-space-time-frequency tomography.

We present a new approach for constructing optical phase-space-time-frequency tomography (OPSTFT) of an optical wave field. This tomography can be measured by using a novel four-window optical imaging system based on two local oscillator fields balanced heterodyne detection. The OPSTFT is a Wigner distribution function of two independent Fourier Transform pairs, i.e., phase-space and time-frequency. From its theoretical and experimental aspects, it can provide information of position, momentum, time and frequency of a spatial light field with precision beyond the uncertainty principle. Besides the distributions of x-p and t-ω, the OPSTFT can provide four other distributions such as x-t, p-t, x-ω and p-ω. We simulate the OPSTFT for a light field obscured by a wire and a single-line absorption filter. We believe that the four-window system can provide spatial and temporal properties of a wave field for quantum image processing and biophotonics.

Context-dependent sensitization to ethanol in zebrafish (Danio rerio).

One of the most robust and readily measurable effects of moderate doses of ethanol on zebrafish behavior is locomotor hyperactivity. Two experiments were designed to examine the effects of repeated exposures to ethanol on ethanol-induced locomotor hyperactivity, and to determine whether these effects are context-dependent. Adult, wild-type zebrafish were given repeated exposure to ethanol in the presence of one contextual stimulus (A), while exposed to water in the presence of a second contextual stimulus (B). Exposure to ethanol consistently induced locomotor hyperactivity. After repeated exposures, animals tested with ethanol in the ethanol-paired context (A) showed sensitization of locomotor activity. When tested with ethanol in the unpaired context (B), however, sensitization was not observed. When tested in the absence of ethanol, there were no differences in responding to the paired and unpaired stimuli. This is the first demonstration of ethanol-induced locomotor sensitization in zebrafish. Moreover, this sensitization was context-specific, indicating that learning can modify drug-induced behaviors in zebrafish.

Behavioral phenotyping in zebrafish: comparison of three behavioral quantification methods.

The zebrafish has been popular in developmental biology and genetics, but its brain function has rarely been studied. High-throughput screening of mutation or drug-induced changes in brain function requires simple and automatable behavioral tests. This article compares three behavioral quantification methods in four simple behavioral paradigms that test a range of characteristics of adult zebrafish, including novelty-induced responses, social behavior, aggression, and predator-model-induced responses. Two quantification methods, manual recording and computerized videotracking of location and activity, yielded very similar results, suggesting that automated videotracking reliably measures activity parameters and will allow high-throughput screening. However, observation-based event recording of posture patterns was found generally not to correlate with videotracking measures, suggesting that further refinement of automated behavior quantification may be considered.

Effects of acute and chronic ethanol exposure on the behavior of adult zebrafish (Danio rerio).

The zebrafish has been a popular subject of embryology and genetic research for the past three decades. Recently, however, the interest in its neurobiology and behavior has also increased. Nevertheless, compared to other model organisms, e.g., rodents, zebrafish behavior is understudied and very few behavioral paradigms exist for mutation or drug screening purposes. Alcoholism is one of the biggest and costliest diseases whose mechanisms are not well understood. Model organisms such as the zebrafish may be utilized in this line of research. Previously, we investigated the effects of acute ethanol exposure on adult zebrafish using four behavioral paradigms and employing manual quantification methods. Here, we study the effects of chronic ethanol exposure and analyze how it modifies the effects of acute ethanol treatment. We employ a videotracking-based automated quantification method in a predator model paradigm and show that this method is capable of detecting an avoidance reaction that is ameliorated by higher doses of ethanol, a potential anxiolytic effect. Importantly, we also demonstrate that chronic, two week long, exposure to ethanol results in significant adaptation to this substance in adult zebrafish. Overall, our results suggest that zebrafish will be an appropriate subject for high throughput screening applications aimed at the analysis of the mechanisms and pharmacology of acute and chronic ethanol induced changes in the vertebrate brain.