Name: assessing the influence of personality on sensitivity to magnetic fields in zebrafish
Uploaded: 2019-03-18T14:45:00
Description: Watch this Scientific Journal Video about Assessing the Influence of Personality on Sensitivity to Magnetic Fields in Zebrafish at JoVE.com

The study was supported by the Basic Research Founding of the Physics Department and the Biology Department of the Naples University Federico II. The authors thank Dr. Claudia Angelini (Institute of Applied Calculus, Consiglio Nazionale delle Ricerche [CNR], Italy) for the statistical support. The authors thank Martina Scanu and Silvia Frassinet for their technical help with collecting the data, and the departmental technicians F. Cassese, G. Passeggio, and R. Rocco for their skillful assistance in the design and realization of the experimental setup. We thank Laura Gentile for helping conducting the experiment during the video shooting. We thank Diana Rose Udel from the University of Miami for shooting the interview statements of Alessandro Cresci.

The following protocol has been approved by the Institutional Animal Care and Use Committee of the University of Naples Federico II, Naples, Italy (2015).
1. Animal Maintenance
<ol>
	<li>Use tanks of at least 200 L to host a shoal of at least 50 individuals of both sexes in each tank. 
	NOTE: The density of the fish in the tank has to be one animal per 2 L or lower. Under these conditions, zebrafish will display normal shoaling behavior.</li>
	<li>Set the maintenance co...

<ol>
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The protocol described in this study allows scientists to quantify complex orientation responses of aquatic species resulting from the integration between two external cues (water current and geomagnetic field) and one internal factor of the animal, such as personality. The overall concept is to create an experimental design that allows scientists to separate individuals of different personality and investigate their orientation behavior while controlling separately or simultaneously the external environmental cues.
...

In the present study, we describe a lab-based behavioral protocol which has the scope of investigating the role of fish personality on the orientation response of shoaling fish to external orientation cues, such as water currents and magnetic fields.
The orienting decisions of animals result from weighing various sensory information. The decision process is influenced by the ability of the animal to navigate (e.g., the capacity to select and keep a direction), its internal state (e.g., feeding or reproductive needs), its ability to move (e.g., locomotion biomechanics), and several additional external factors (e.g., time of day, interaction with conspecifics)1.
The role of the internal state or animal personality in the orientation behavior is often poorly understood or not explored2. Additional challenges arise in the study of the orientation of social aquatic species, which often perform coordinated and polarized group movement behavior3.
Water currents play a key role in the orientation process of fish. Fish orient to water currents through an unconditioned response called rheotaxis4, which can be positive (i.e., upstream oriented) or negative (i.e. downstream oriented) and is used for several activities, ranging from foraging to the minimization of energetic expenditure5,6. Moreover, a growing body of literature reports that many fish species use the geomagnetic field for orientation and navigation7,8,9.
The study of rheotaxis and swimming performance in the fish is usually conducted in flow chambers (flume), where fish are exposed to the stepwise increase of the flow speed, from low to high speeds, often until exhaustion (called critical speed)10,11. On the other hand, previous studies investigated the role of the magnetic field in the orientation through the observation of the swimming behavior of the animals in arenas with still water12,13. Here, we describe a laboratory technique that allows researchers to study the behavior of fish while manipulating both the water currents and the magnetic field. This method was utilized for the first time on shoaling zebrafish (Danio rerio) in our previous study, leading to the conclusion that the manipulation of the surrounding magnetic field determines the rheotactic threshold (i.e., the minimal water speed at which shoaling fish orient upstream)14. This method is based on the use of a flume chamber with slow flows combined with a setup designed to control the magnetic field in the flume, within the range of the earth&#8217;s magnetic field intensity.
The swimming tunnel utilized to observe the behavior of zebrafish is outlined in Figure 1. The tunnel (made of a nonre&#64258;ecting acrylic cylinder with a 7 cm diameter and 15 cm in length) is connected to a setup for the control of the flow rate14. With this setup, the range of flow rates in the tunnel varies between 0 and 9 cm/s.
To manipulate the magnetic field in the swimming tunnel, we use two methodological approaches: the first is one-dimensional and the second is three-dimensional. For any application, these methods manipulate the geomagnetic field to obtain specific magnetic conditions in a defined volume of water&#8212;thus, all the values of magnetic field intensity reported in this study include the geomagnetic field.
Concerning the one-dimensional approach15, the magnetic field is manipulated along the water flow direction (defined as the x-axis) using a solenoid wrapped around the swimming tunnel. This is connected to a power unit, and it generates uniform static magnetic fields (Figure 2A). Similarly, in the case of the three-dimensional approach, the geomagnetic field in the volume containing the swimming tunnel is modified using coils of electric wires. However, to control the magnetic field in three dimensions, the coils have the design of three orthogonal Helmholtz pairs (Figure 2B). Each Helmholtz pair is composed of two circular coils oriented along the three orthogonal space directions (x, y, and z) and equipped with a three-axial magnetometer working in closed-loop conditions. The magnetometer works with field intensities comparable with the earth&#8217;s natural field, and it is located close to the geometrical center of the coils set (where the swimming tunnel is located).
We implement the techniques described above to test the hypothesis that the personality traits of the fish composing a shoal influence the way they respond to magnetic fields16. We test the hypothesis that individuals with proactive and reactive personality17,18 respond differently when exposed to water flows and magnetic fields. To test this, we first sort zebrafish using an established methodology to assign and group individuals that are proactive or reactive17,19,20,21. Then, we evaluate the rheotactic behavior of zebrafish swimming in shoals composed of only reactive individuals or composed of only proactive individuals in the magnetic flume tank, which we present as sample data.
The sorting method is based on the different tendency of the proactive and reactive individuals to explore novel environments21. Specifically, we use a tank divided into a bright and a dark side17,19,20,21 (Figure 3). Animals are acclimated to the dark side. When access to the bright side is open, proactive individuals tend to quickly exit the dark half of the tank to explore the new environment, while the reactive fish do not leave the dark tank.

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			<td style="width:389px;">Gaussmeter, DC-10 kHz; probe resolution:&#160; 0.01 &#956;T&#160;</td>
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			<td height="46" style="height:47px;width:216px;">ALR3003D</td>
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			<td style="width:196px;">Home made</td>
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			<td height="46" style="height:47px;width:216px;">HMC588L</td>
			<td style="width:196px;">Honeywell</td>
			<td style="width:141px;">900405 Rev E</td>
			<td style="width:389px;">Digital three-axis magnetometer</td>
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			<td height="46" style="height:47px;width:216px;">MO99-2506</td>
			<td style="width:196px;">FWBell</td>
			<td style="width:141px;">129966</td>
			<td style="width:389px;">Single axis magnetic probe</td>
		</tr>
		<tr height="46">
			<td height="46" style="height:47px;width:216px;">Swimming apparatus</td>
			<td style="width:196px;">M2M Engineering Custom Scientific Equipment</td>
			<td style="width:141px;">N/A</td>
			<td style="width:389px;">Swimming apparatus composed by peristaltic pump and SMC Flow switch flowmeter with digital feedback</td>
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		<tr height="46">
			<td height="46" style="height:47px;width:216px;">TECO 278</td>
			<td style="width:196px;">TECO</td>
			<td style="width:141px;">N/A</td>
			<td style="width:389px;">Thermo-cryostat&#160;</td>
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assessing the influence of personality on sensitivity to magnetic fields in zebrafish

To orient themselves in their environment, animals integrate a wide array of external cues, which interact with several internal factors, such as personality. Here, we describe a behavioral protocol designed for the study of the influence of zebrafish personality on their orientation response to multiple external environmental cues, specifically water currents and magnetic fields. This protocol aims to understand whether proactive or reactive zebrafish display different rheotactic thresholds (i.e., the flow speed at which the fish start swimming upstream) when the surrounding magnetic field changes its direction. To identify zebrafish with the same personality, fish are introduced in the dark half of a tank connected with a narrow opening to a bright half. Only proactive fish explore the novel, bright environment. Reactive fish do not exit the dark half of the tank. A swimming tunnel with low flow rates is used to determine the rheotactic threshold. We describe two setups to control the magnetic field in the tunnel, in the range of the earth&#8217;s magnetic field intensity: one that controls the magnetic field along the flow direction (one dimension) and one that allows a three-axial control of the magnetic field. Fish are filmed while experiencing a stepwise increase of the flow speed in the tunnel under different magnetic fields. Data on the orientation behavior are collected through a video-tracking procedure and applied to a logistic model to allow the determination of the rheotactic threshold. We report representative results collected from shoaling zebrafish. Specifically, these demonstrate that only reactive, prudent fish show variations of the rheotactic threshold when the magnetic field varies in its direction, while proactive fish do not respond to magnetic field changes. This methodology can be applied to the study of magnetic sensitivity and rheotactic behavior of many aquatic species, both displaying solitary or shoaling swimming strategies.

As sample data we present results obtained controlling the magnetic field along the water flow direction on proactive and reactive shoaling zebrafish16 using the setup shown in Figure 2A (see section 3 of the protocol). These results show how the described protocol can highlight differences in responses to the magnetic field in fish with different personalities. The overall concept of these trials relies on the finding that the directi...

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Assessing the Influence of Personality on Sensitivity to Magnetic Fields in Zebrafish

We describe a behavioral protocol designed to assess how zebrafish&#8217;s personalities influence their response to water currents and weak magnetic fields. Fishes with the same personalities are separated based on their explorative behavior. Then, their rheotactic orientation behavior in a swimming tunnel with a low flow rate and under different magnetic conditions is observed.

To orient themselves in their environment, animals integrate a wide array of external cues, which interact with several internal factors, such as ...

This protocol allows exploration on how the internal state or personality of a zebrafish influences the orientation response to cues coming from the environment such as water currents or magnetic fields. This technique is used to observe how both internal factors and environmental cues impact to the zebrafish orientation. However, it can also be applied to a broad variety of experimental designs.This method could provide insight into behavioral ecology of sensor biology research. And is species flexible so it's suitable for any aquatic animal that actively swims. We advise that, upon performing in the experiments, you become familiar with the behavior of the animal you intend to use and with how to minimize animal stress.For personality selection in zebrafish collect individual fish using a 250 milliliter beaker in a net to move them into a transfer tank and transfer the fish to the dark side of the personality selection tank. After one hour of acclimatization open the sliding door and allow the individuals you exit from the hole to explore the bright side of the tank for 10 minutes. At the end of the exploration period, gently collect the fish in two separated containers, collecting the proactive fish from the bright side and after additional five minutes the reactive fish from the dark box.To set up a magnetic field with one dimensional magnetic field manipulation, keep the tunnel open and switch on power unit and magnetometer. Place a magnetic probe connected to a gas Tesla meter inside the tunnel and verify the voltage necessary to obtain the chosen magnetic field value along the major axis of the tunnel. Then disconnect the probe and connect the flow tunnel to the swimming apparatus.To set up a magnetic field with three dimensional magnetic field manipulation, turn on the computer, digital to analog converter in coil drivers and set the chosen magnetic field on the x, y, z axes. Then place the tunnel in the center of the Helmholtz pairs set. When the magnetic field that choice has been set up, select one to five fish for the rheotactic test.Transfer the fish in the tunnel, set the flow rate in the tunnel to 4.5 liters per minute and turn on the pump. Be sure to close the outlet valve before feeling the tunnel with water and transfer the fish and open it before setting the floor right. After the animals have acclimated there in the swimming tunnel for an hour, start recording the behavior of the fish within the tunnel and begin the step wise increasing the flow rate according to the chosen experimental protocol.The same swimming tunnel with the coil removed, can be placed in the center of the Helmholtz pairs set. At the end of the rheotaxis experiment, take photos of individual fish in amorphous metric chamber and open the photos in image J.Note the sex of the animal. Male zebrafish are slender and tend to be yellowish, while females are more rounded and tend to have blue and white colorings.Next, click analyze and set scale. To set the scale of the image in centimeters, using the camera scale as reference and with the segmented line tool selected, draw a line from the snout tip to the coddled pentacle to measure standard length or to the tail tip for the total length. Then click Analyze and measure and record the linear length of the animal in centimeters.To track the zebrafish activity within the tunnel, open the appropriate video analysis and modeling software program. Click File, Import and video and open one of the videos and click coordinate system to set the length units to centimeters and the time units, to seconds. Click coordinate axes and set the reference system to track the position of the fish over time with the x axis along the tunnel, setting the origin at the low corner of the wall at the water outlet.Click track new in calibration to set the scale and track new in point to mass, to start tracking one fish at a time. Advanced the video manually at half second, five frame intervals and mark the time and position of the animal at each upstream downstream turn and at each downstream upstream turn. At the end of each tracking session select the X and time values from the table.Right click on the data and click copy data in full precision. Then save the time values and x values of all of the turning positions on a template spreadsheet file. To calculate the total upstream and downstream time, as well as the values of the rheotactic index and percentages for each full step.In this representative experiment, after a one hour acclimation period in the tunnel as demonstrated, one show at a time was video recorded while swimming in the tunnel in the water current was accelerated with a stepwise increase in the flow rate for seven steps. During these trials, the magnetic field was controlled in one dimension. During the tracked time, the terms of each fish at each flow rate were highlighted and used as reference points for calculating the rheotactic index of each fish at each full speed.When the rheotactic index is higher than 50%and indicates that the animal had a positive rheotactic response corresponding to a prevalence of upstream swimming, a rheotactic index not significantly different from 50%indicates an absence of a rheotactic response. Arc sign transformation of the average rheotactic index percent values of all five fish in this experiment demonstrated a sigmoidal increase in the rheotactic index value when the water speed increases, allowing quantification of the zebrafish rheotaxis using a simple mathematical method. From these curves, it is visible that under magnetic fields of different directions, the rheotactic responsive of proactive fish is not affected and the response of the two experimental groups is represented by the same curve.On the other hand, reactive fish change the rheotactic orientation according to the magnetic field and the response is represented by to significantly different curves. Remember that this is a behavioral experiment and the fish behavior can be affected by stress. Handling and transferring fish can be tricky.So, train yourself before the experiments. This rheotactic magnetic technique has allowed us to further explore the effects of personality on magnetal sensitivity in zebrafish and the other aquatic vertebrates and invertebrates.

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Research

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Behavior

A Procedure to Study the Effect of Prolonged Food Restriction on Heroin Seeking in Abstinent Rats

In human drug addicts, exposure to drug-associated cues or environments that were previously associated with drug taking can trigger relapse during abstinence. Moreover, various environmental challenges can exacerbate this effect, as well as increase ongoing drug intake.
The procedure we describe here highlights the impact of a common environmental challenge, food restriction, on drug craving that is expressed as an augmentation of drug seeking in abstinent rats.
Rats are implanted with chronic intravenous i.v. catheters, and then trained to press a lever for i.v. heroin over a period of 10-12 days. Following the heroin self-administration phase the rats are removed from the operant conditioning chambers and housed in the animal care facility for a period of at least 14 days. While one group is maintained under unrestricted access to food (sated group), a second group (FDR group) is exposed to a mild food restriction regimen that results in their body weights maintained at 90% of their nonrestricted body weight. On day 14 of food restriction the rats are transferred back to the drug-training environment, and a drug-seeking test is run under extinction conditions (i.e.&#160;lever presses do not result in heroin delivery).
The procedure presented here results in a highly robust augmentation of heroin seeking on test day in the food restricted rats. In addition, compared to the acute food deprivation manipulations we have used before, the current procedure is a more clinically relevant model for the impact of caloric restriction on drug seeking. Moreover, it might be closer to the human condition as the rats are not required to go through an extinction-training phase before the drug-seeking test, which is an integral component of the popular reinstatement procedure.

A procedure that allows a demonstration of robust augmentation of drug seeking in food-restricted rats is described. Following heroin self-administration training, rats go through an abstinence period, in a drug-free environment, during which they are mildly food restricted. Drug seeking is then tested in the drug-associated environment.

In human drug addicts, exposure to drug-associated cues or environments that were previously associated with drug taking can trigger relapse during ...

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.

It is unclear how top-down signals from the ventral visual stream affect movement. We developed a paradigm to test motor behavior towards a target on a 3D depth inversion illusion. Significant differences are reported in both deliberate, goal-directed movements and automatic actions under illusory and veridical viewing conditions.

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are ...

Assessing the Effects of Music Listening on Psychobiological Stress in Daily Life

Music listening is associated with stress-reducing effects. However, most of the results on music listening and stress were gathered in experimental settings. As music listening is a popular activity of daily life, it is of utmost importance to study the effects of music listening on psychobiological stress in an everyday, daily-life setting. Here, a study protocol is presented that allows the assessment of associations between music listening and psychobiological stress in daily life by noninvasively measuring salivary cortisol (as a marker of the Hypothalamic-Pituitary-Adrenal (HPA) axis) and salivary alpha-amylase (as a marker of the Autonomic Nervous System (ANS)). The protocol includes advice on the study design (e.g., sampling protocol), the materials and methods (e.g., the assessment of psychobiological stress in daily life, the assessment of music listening, and the manual), the selection of participants (e.g., the approval of the institutional review board and inclusion criteria), and the statistical analyses (e.g., the multilevel approach). The representative results provide evidence for a stress-reducing effect of music listening in daily life. Particularly, specific reasons for listening to music (especially relaxation), as well as the presence of others while doing so, increase this stress-reducing effect. At the same time, music listening in daily life differentially affects the HPA axis and ANS functioning, thus emphasizing the need for a multi-dimensional assessment of stress in daily life.

A study protocol is presented on how to assess associations between music listening and psychobiological stress (as measured by subjective stress levels, salivary cortisol, and salivary alpha-amylase) in daily life. Advice on study design, materials, methods, selection of participants, and statistical handling is provided. Representative results are presented and discussed.

Music listening is associated with stress-reducing effects. However, most of the results on music listening and stress were gathered in experimental ...

Use of a Psychophysiological Script-driven Imagery Experiment to Study Trauma-related Dissociation in Borderline Personality Disorder

This protocol offers a detailed description of a psychophysiological experiment using script-driven trauma-related imagery and standardized clinical instruments within a comparative design assessing physiological and psychopathological features of individuals with BPD. This method aims at studying the psychological and physiological effects of trauma-related dissociation. Since the psychodiagnostic classification of trauma-related disorders relies on the observation of evolutionarily determined responses to life-threat, an integrated assessment paradigm for the study of reactions to traumatic memories proposes a very appropriate methodological approach.
The employed script-driven imagery paradigm uses individual recall instructions to activate trauma-related memory networks and prompt associated emotional and physiological responses. These responses are measured by means of self-rating scales and physiological assessments. During the individual recall, participants are asked to vividly imagine traumatic and everyday experiences and other situations triggered by short personalized verbal scripts they authored beforehand together with the experimenters. A wide range of affective reactions and different physiological parameters can be measured. We used this paradigm to investigate dissociative states in BPD and to find physiological and affective correlates of dissociative states. Some of the participants were having severe traumatic antecedents.
To investigate different reaction patterns within the same diagnostic group, participants with different levels of traumatic histories, symptom severities, and co-morbidities should be included. By using short verbal scripts, the level of stress induced to participants is held as low as possible without affecting the validity of the object of investigation.

We present a protocol of personalized script-driven trauma-related imagery and clinical assessments within a comparison design for investigating peritraumatic dissociation (PD), psychophysiological reactions, i.e. heart rate (HR) and skin conductance (SC), and psychological features of often severely traumatized individuals with borderline personality disorder (BPD).

This protocol offers a detailed description of a psychophysiological experiment using script-driven trauma-related imagery and standardized clinical ...

Driving Under the Influence: How Music Listening Affects Driving Behaviors

Car driving is a daily activity for many individuals in modern societies. Drivers often listen to music while driving. The method presented here investigates how listening to music influences driving behaviors. A driving simulation was selected because it offers both a well-controlled environment and a good level of ecological validity. Driving behaviors were assessed through a car-following task. In practice, participants were instructed to follow a lead vehicle as they would do in real life. The lead vehicle speed changed over time requiring constant speed adjustments for the participants. The inter-vehicular time was used to assess driving behaviors. To complement the driving behaviors, the subjective mood and physiological level of arousal were also collected. As such, the results collected using this method offer insights on both the human internal state (i.e., subjective mood and physiological arousal) and driving behaviors in the car following task.

Here, we present a protocol to assess driving behaviors while following a vehicle in a simulated driving environment. The presented protocol is used to compare the impact of different auditory backgrounds on driving behaviors.

Car driving is a daily activity for many individuals in modern societies. Drivers often listen to music while driving. The method presented here ...

Exploring Infant Sensitivity to Visual Language using Eye Tracking and the Preferential Looking Paradigm

We discuss the use of the preferential looking paradigm in eye tracking studies in order to study how infants develop, understand, and attend to the world around them. Eye tracking is a safe and non-invasive way to collect gaze data from infants, and the preferential looking paradigm is simple to design and only requires the infant to be attending to the screen. By simultaneously showing two visual stimuli that differ in one dimension, we can assess whether infants show different looking behavior for either stimulus, thus demonstrating sensitivity to that difference. The challenges in such experimental approaches are that experiments must be kept brief (no more than 10 min) and be carefully controlled such that the two stimuli differ in only one way. The interpretation of null results must also be carefully considered. In this paper, we illustrate a successful example of an infant eye tracking study with a preferential looking paradigm to discover that 6-month-olds are sensitive to linguistic cues in a signed language despite having no prior exposure to signed language, suggesting that infants possess intrinsic or innate sensitivities to these cues.

Eye tracking studies using a preferential looking paradigm can be used to study infants&#39;&#160;emerging understanding of, and attention to, their external visual world.

We discuss the use of the preferential looking paradigm in eye tracking studies in order to study how infants develop, understand, and attend to the world ...

Assessing the Coherence of Parents' Short Narratives Regarding their Child Using the Five-Minute Speech Sample Procedure

Valid and efficient measures for assessing the quality of parent-child relationships are needed to facilitate research and evidence-based practice with parents. This paper focuses on such a method, namely Five-Minute Speech Sample-Coherence (FMSS-Coherence). In this method, a parent is asked to speak for five uninterrupted minutes about her/his child and their relationship. The resulted narrative is coded for coherence, namely the extent to which the parent provides&#160;in the narrative&#160;a clear, consistent, multidimensional and well-supported portrayal of the child. FMSS-Coherence is based on attachment research that shows that the coherence of parents&#8217; narratives is indicative of the quality of the parent-child relationship and child adjustment. It overcomes the limitations of attachment narrative measures which are typically labor intensive. FMSS-Coherence is less nuanced than extant attachment narrative measures. Yet, studies of families from different cultural backgrounds, across different child ages and in the context of typically developing children as well as children with special needs suggest that coherence can be reliably evaluated using the FMSS procedure. Furthermore, parents&#8217; FMSS-Coherence is associated with parenting quality and children&#8217;s socio-emotional adjustment. Thus, it holds promise for researchers and practitioners who seek a relatively time- and cost-effective method for assessing the coherence of parents&#8217; narratives regarding their child.

Assessing the Coherence of Parents&#039; Short Narratives Regarding their Child Using the Five-Minute Speech Sample Procedure

This paper introduces a method for assessing the coherence of parents' short narratives regarding their child and their relationship using the five-minute speech sample procedure.

Valid and efficient measures for assessing the quality of parent-child relationships are needed to facilitate research and evidence-based practice with ...

A Task for Assessing the Impact of a Partner on the Speed and Accuracy of Motor Performance in Rats

To our knowledge, no study has examined the effect of mere presence on accuracy of performance in animals. Therefore, we developed an experimental task to measure rats&#8217; motor performance (speed and accuracy) in a social condition. Rats were trained to run on a runway and pull down a lever at the end of the runway. In testing, rats performed the task solitarily (single) or in the presence of a confederate rat beyond the lever (pair or a social condition). As indices of the performance speed, we measured the time needed to start running, run through the runway, and pull down the lever. As the index of performance accuracy, we counted the number of trials in which rats could pull down the lever during their first attempt. One-way and two-way repeated-measure analyses of variance were used to analyze the data. This run-and-pull task enabled us to examine the effect of the presence of another conspecific on both speed and accuracy of motor performance in one experiment. The results showed that rats performed the task faster but less accurately in pair sessions than in single sessions. This protocol would be a valid animal model to examine the effect of mere presence on speed and accuracy of motor performance in rats.

A procedure to measure the speed and accuracy of rats&rsquo; motor performance in a social condition is described. The protocol enables us to investigate the effect of the mere presence of others on speed and accuracy of motor performance in one experiment.

To our knowledge, no study has examined the effect of mere presence on accuracy of performance in animals. Therefore, we developed an experimental task to ...

Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain

Low back pain is the leading cause of disability worldwide, with dramatic personal, economic, and social consequences. To develop novel therapeutics, animal models are needed to examine the mechanisms and effectiveness of novel therapies from a translational perspective. Several rodent models of back pain are used in current investigations. Surprisingly, however, no standardized behavioral test was validated to assess mechanical sensitivity in back pain models. This is critical to confirm that animals with presumed back pain present local hypersensitivity to nociceptive stimuli, and to monitor sensitivity during interventions designed to relieve back pain. The objective of this study is to lay down a simple and accessible test to assess mechanical sensitivity in the back of rats. A test cage was fabricated specifically for this method; length x width x height: 50 x 20 x 7 cm, having a stainless-steel mesh on the top. This test cage allows the application of mechanical stimuli to the back. To perform the test, the back of the animal is shaved in the region of interest, and the test area is marked to repeat the test on different days, as needed. The mechanical threshold is determined with Von Frey filaments applied to the paraspinal muscles, utilizing the up-down method described previously. The positive responses include (1) muscle twitching, (2) arching (back extension), (3) rotation of the neck (4) scratching or licking the back, and (5) escaping. This behavioral test (Back Mechanical Sensitivity (BMS) test) is useful for mechanistic research with rodent models of back pain for the development of therapeutic interventions for the prevention and management of back pain.

To develop novel therapeutic interventions for the prevention and management of back pain, animal models are required to examine the mechanisms and effectiveness of these therapies from a translational perspective. The present protocol describes the BMS test, a standardized method to assess back mechanical sensitivity in the rat.

Low back pain is the leading cause of disability worldwide, with dramatic personal, economic, and social consequences. To develop novel therapeutics, ...

Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social hierarchies that are often based on dominant-submissive relationships. The dominant-submissive relationship is a normal behavioral pattern among the individuals of a species. Traumatic brain injury is a frequent cause of social interaction impairment and the reorganization of dominant-submissive relationships in animal pairs. This protocol describes submissive behavior in adult male Sprague-Dawley rats after the induction of traumatic brain injury using a fluid-percussion model compared to naive rats through a series of dominant-submissive tests performed between 29 days and 33 days after induction. The dominant-submissive behavior test shows how brain injury can induce submissive behavior in animals competing for food. After traumatic brain injury, the rodents were more submissive, as indicated by them spending less time at the feeder and being less likely to arrive first at the trough compared to the control animals. According to this protocol, submissive behavior develops after traumatic brain injury in adult male rats.

The present protocol describes a rat model of fluid percussion-induced traumatic brain injury followed by a series of behavioral tests to understand the development of dominant and submissive behavior. Using this model of traumatic brain injury in conjunction with specific behavioral tests enables the study of social impairments following brain injury.

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social ...