Name: a novel pavlovian fear conditioning paradigm to study freezing and flight behavior
Uploaded: 2021-01-05T12:30:00
Description: Watch this Scientific Journal Video about A Novel Pavlovian Fear Conditioning Paradigm to Study Freezing and Flight Behavior at JoVE.com

This work was supported by the Louisiana Board of Regents through the Board of Regents support fund (LEQSF(2018-21)-RD-A-17) and the National Institute of Mental Health of the National Institutes of Health under award number R01MH122561. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

The following steps/procedures were conducted in accordance with institutional guidelines after approval from the Institutional Animal Care &#38; Use Committee of Tulane University.
1. Preparation of mice
<ol>
	<li>Use male and/or female adult mice aged between 3-5 months. In the present study, we used male C57BL/6J mice obtained from Jackson Laboratory, but any mouse strain from a reputable supplier can be used.</li>
	<li>At least one week before the experiment, house all the mice individua...

<ol>
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The described sound and shock parameters are important elements of this protocol. It is critical, therefore, to test the shock amplitude and sound pressure level before starting the experiments. Fear conditioning studies typically use 70-80 dB sound pressure levels and 0.1-1 mA shock intensity18; thus, the described parameters are within the bounds of traditional fear conditioning paradigms. In a previous CS-only (no footshock) control experiment, we did not observe flight or freezing responses in...

Fear is an evolutionarily conserved adaptive response to an immediate threat1,2. While organisms possess innate defensive responses to a threat, learned associations are crucial to elicit appropriate defensive responses to stimuli predictive of danger3. Dysregulation in brain circuits controlling defensive responses is likely to contribute to maladaptive reactions associated with multiple debilitating anxiety disorders, such as post-traumatic stress disorder (PTSD), panic disorder4, and specific phobias5,6. The prevalence rate in the United States for anxiety disorders is 19.1% for adults and 31.9% in adolescents7,8. The burden of these illnesses is extremely high on the daily routine of individuals and negatively impacts their quality of life.
Over the last several decades, Pavlovian fear conditioning has served as a powerful model system to gain tremendous insight into the neural mechanisms underlying fear-related learning and memory9,10,11. Pavlovian fear conditioning entails pairing a conditioned stimulus (CS, such as an auditory stimulus) with an aversive unconditioned stimulus (US; for example, an electrical footshock)12. Because freezing is the dominant behavior evoked and measured in standard Pavlovian conditioning paradigms, the neural control mechanisms of active forms of defensive behavior such as escape/flight responses remain largely unexplored. Previous studies show that different forms of defensive behavior, such as flight, are evoked depending upon the threat intensity, proximity and context13,14. Studying how the brain controls different types of defensive behavior may significantly contribute to the understanding of the neuronal processes that are dysregulated in fear and anxiety disorders.
To address this critical need, we developed a modified Pavlovian conditioning paradigm that elicits flight and escape jumps, in addition to freezing15. In this paradigm, mice are conditioned with a serial compound stimulus (SCS) consisting of a pure tone followed by white noise. Following two days of pairing the SCS with a strong electrical footshock, mice exhibit freezing in response to the tone component and flight during the white noise. Behavioral switches between conditioned freezing and flight behavior are rapid and consistent. Interestingly, mice exhibit flight behavior only when the white noise CS is presented in the same context as a previously delivered footshock (the conditioning context) but not in a neutral context. Instead, freezing responses dominate in this the neutral context, with significantly greater levels of freezing in response to the white noise compared to the tone. This is consistent with the role of context in modulating defensive response intensity and with the regulatory role of contextual information in fear-related learning and memory found in traditional threat conditioning paradigms16,17. This model allows for direct, within-subject comparisons of multiple defensive behaviors in a context-specific manner.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	
	<tbody>
		<tr >
			<td >Neutral context</td>
			<td ></td>
			<td ></td>
			<td >Plexiglass cylinder 30 X 30 cm&#160;</td>
		</tr>
		<tr >
			<td >Fear conditioning box</td>
			<td >Med Associates, Inc.</td>
			<td >VFC-008</td>
			<td>25 X 30 X 35 cm dimentions</td>
		</tr>
		<tr >
			<td >Audio generator&#160;</td>
			<td >Med Associates, Inc.</td>
			<td >ANL-926&#160;</td>
			<td></td>
		</tr>
		<tr >
			<td >Shocker</td>
			<td >Med Associates Inc.</td>
			<td >ENV-414S</td>
			<td>Stainless steel grid</td>
		</tr>
		<tr >
			<td >Speaker</td>
			<td >Med Associates, Inc.</td>
			<td >ENV-224AM</td>
			<td>Suitable for pure tone and white noise&#160;</td>
		</tr>
		<tr >
			<td >C57/BL6J mice</td>
			<td >Jackson laboratory, USA</td>
			<td >664</td>
			<td>Aged 3-5 month</td>
		</tr>
		<tr >
			<td >Cineplex software (Editor/ studio)</td>
			<td >Plexon</td>
			<td>CinePlex Studio v3.8.0</td>
			<td>For video tracking and behavioral scoring analysis</td>
		</tr>
		<tr >
			<td >MedPC software V</td>
			<td >Med Associates, Inc.</td>
			<td >SOF-736</td>
			<td></td>
		</tr>
		<tr >
			<td >Neuroexplorer</td>
			<td >Plexon</td>
			<td ></td>
			<td>Used to extract the freezing data scored in PlexonEditor</td>
		</tr>
		<tr >
			<td >GraphPad Prism 8</td>
			<td >GraphPad Software, Inc.</td>
			<td >Version 8</td>
			<td>Statistical analysis software</td>
		</tr>
	</tbody>
</table>

a novel pavlovian fear conditioning paradigm to study freezing and flight behavior

Fear- and anxiety-related behaviors significantly contribute to an organism&#8217;s survival. However, exaggerated defensive responses to perceived threat are characteristic of various anxiety disorders, which are the most prevalent form of mental illness in the United States. Discovering the neurobiological mechanisms responsible for defensive behaviors will aid in the development of novel therapeutic interventions. Pavlovian fear conditioning is a widely used laboratory paradigm to study fear-related learning and memory. A major limitation of traditional Pavlovian fear conditioning paradigms is that freezing is the only defensive behavior monitored. We recently developed a modified Pavlovian fear conditioning paradigm that allows us to study both conditioned freezing and flight (also known as escape) behavior within individual subjects. This model employs higher intensity footshocks and a greater number of pairings between the conditioned stimulus and unconditioned stimulus. Additionally, this conditioned flight paradigm utilizes serial presentation of pure tone and white noise auditory stimuli as the conditioned stimulus. Following conditioning in this paradigm, mice exhibit freezing behavior in response to the tone stimulus, and flight responses during the white noise. This conditioning model can be applied to the study of rapid and flexible transitions between behavioral responses necessary for survival.

As described in the diagram (Figure 1A), the session starts with pre-exposure (Day 1), followed by fear conditioning (Days 2 and 3), and then either extinction or retrieval (Day 4).
Presentations of the SCS in the pre-exposure (Day 1) session did not elicit flight or freezing response in the mice (Figure 2A-2B). Behavioral analysis during conditioning (Days 2 and 3) revealed that the tone component of the SCS signific...

Watch this Scientific Journal Video about A Novel Pavlovian Fear Conditioning Paradigm to Study Freezing and Flight Behavior at JoVE.com

A Novel Pavlovian Fear Conditioning Paradigm to Study Freezing and Flight Behavior

Defensive behavioral responses are contingent upon threat intensity, proximity, and context of exposure. Based on these factors, we developed a classical conditioning paradigm that elicits clear transitions between conditioned freezing and flight behavior within individual subjects. This model is crucial for the understanding the pathologies involved in anxiety, panic, and post-traumatic stress disorders.

Fear- and anxiety-related behaviors significantly contribute to an organism&#8217;s survival. However, exaggerated defensive responses to perceived threat ...

The overall aim of this paradigm is to assess complex defensive behavior in rodents. This protocol is significant because it facilitates investigations into the transitions between defensive behaviors, making it ideal for researchers interested in studying complex adaptive responses to threat. This protocol uses temporarily precise condition stimuli to elicit transition between defensive responses, allowing us to study both, conditioned freezing and flight behaviors within individual subject.Using this model to uncover the mechanisms of defensive behavior can provide insight into PTSD-related dysfunction and panic disorders and could aid in the development of novel therapeutics. To set up the behavioral protocols, in the program, define the SCS, setting the stimuli to be delivered as either a ten-second pure Tone, or a ten-second White Noise, and defining the inter-trial intervals to be presented pseudo-randomly following each trial. To set up the software tracking, place a test mouse in each relevant context, define the center of gravity, and adjust the contour size.Use the size of the chambers and the pixel dimensions of the camera to determine the calibration coefficient. Then, generate the TTL pulse code for synchronizing the event markers of the central computer to their real-time occurrences. Before beginning an experiment, turn on the fear-conditioning box controller, shocker, and video recording software.Mount an overhead speaker above the contexts for delivery of the auditory stimuli at 75 decibels, and set a programmable audio generator to generate auditory stimuli on a predefined schedule. After confirming that the Tone and White Noise are functional, set the system for data acquisition and transport three to five month old male or female mice to the conditioning room. Before beginning the preconditioning trial, clean a 30 centimeter diameter, 30 centimeter high clear cylindrical plexiglass chamber with 1%acetic acid to be used as the Context A chamber.For preconditioning, place the mouse in Context A and allow it to acclimate for three minutes before exposing the mouse to four 20-second SCS trails with a 90-second average pseudo-random inter-trial interval. After 10 minutes of acclimation, transfer one mouse into the Context A chamber and immediately activate the fear-conditioning system and data collection programs. Before beginning a fear-conditioning experiment, clean an at least 35 centimeter high, 25 by 30 centimeter rectangular enclosure with an electrical grid floor with 70%ethanol to be used as the Context B chamber.Then, connect the shocker with the electrical grid floor of the Context B chamber, and define the frequency, onset, and duration of the shocks in the appropriate computer program. When all of the parameters have been set, check that the shock intensity is delivered properly from both shocker and grid floor. On days two and three, place the mouse into the Context B chamber for three minutes before exposing the animal to five pairings of the SCS co-terminating with a one-second, 0.9 milliamp AC foot shock and a 120-second average inter-trial interval.At the end of the session, put the mouse back in the home cage. Depending on the goal of the experiment, to subject the animals to a Recall session, on day four, place the mouse in the Context A chamber for three minutes before presenting the animal with four SCS trials without foot shock with a 90-second average pseudo-random inter-trial interval over 590 seconds to test the animal's Fear Recall response. Or, to test for Fear Extinction, on day four, place the mouse into the Context B chamber for three minutes before subjecting the animal to 16 trials of SCS without foot shock with a 90-second average pseudo-random inter-trial interval over a period of 1, 910 seconds.To quantify the mouse's behavior, at the end of the experiment, have an observer blind to the analysis score the recorded videos for freezing behavior using automatic freezing detector thresholding followed by a frame-by-frame analysis of the pixel changes. Define freezing as a complete cessation of bodily movements, except for those required for respiration for a minimum of one second. Score a jump as an instance when all four paws leave the floor, resulting in a vertical and/or horizontal movement.When the entire segment has been analyzed, export the marked file with freezing, jump and event markers and extract the relevant events from the defined time periods of interest into a spreadsheet. To calculate the duration of freezing, subtract the start time from the end time for each respective trial period. Sum the total number of jumps from a particular trial duration.To calculate the speed of the mouse, track the coordinates from the frame-by-frame XY axis movement of the center of gravity of the mouse. To calculate the flight scores, divide the average speed during each SCS by the average speed during the ten-second pre-SCS, and add one point for each escape jump. A flight score of one indicates no change in flight behavior from the pre-SCS period.Then, analyze the data for statistical significance using an appropriate statistical analysis software program. SCS presentations in the pre-exposure session do not elicit flight or freezing responses in mice. Behavioral analysis during conditioning reveals that the Tone component of the SCS significantly enhances freezing compared to freezing during the pre-SCS.Flight scores changed significantly across sessions, and mice exhibit higher speeds and more jumps to the White Noise cue compared to the Tone cue. Mice show a clear defensive behavior transition, exhibiting lower flight scores during the Tone and higher flight scores during the White Noise, with the opposite observed for freezing responses. Mice subjected to 16 trials of extinction training demonstrate a rapid extinction of conditioned flight, with fight scores during the first block of four trials measuring higher during White Noise compared to the Tone cue.At the end of the extinction session, flight behavior is no longer elicited by either cue. Freezing to the Tone is significantly higher than freezing to the White Noise for the first block of four trials during extinction. Tone-induced freezing decreases over the 16 trials of extinction, while an increase in White Noise-mediated freezing is observed.In the Recall session, exposure to White Noise in a neutral context does not elicit flight, as the flight scores are below one. Rather, White Noise presentations in the neutral context elicit freezing responses that are higher than those elicited by the Tone. It is important to clean the context throughoutly, and it is critical to test the shock amplitude and sound pressure level before starting an experiment.This paradigm is currently being used by groups who are interested in understanding the complexities of defensive behavior, and can be used to further our understanding of defensive action selection.

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Behavior

The Resident-intruder Paradigm: A Standardized Test for Aggression, Violence and Social Stress

This video publication explains in detail the experimental protocol of the resident-intruder paradigm in rats. This test is a standardized method to measure offensive aggression and defensive behavior in a semi natural setting. The most important behavioral elements performed by the resident and the intruder are demonstrated in the video and illustrated using artistic drawings. The use of the resident intruder paradigm for acute and chronic social stress experiments is explained as well. Finally, some brief tests and criteria are presented to distinguish aggression from its more violent and pathological forms.

This video shows the resident-intruder paradigm in rats. This test is a standardized method to measure offensive aggression, defensive behavior and violence in a semi-natural setting. The use of the paradigm for social stress experiments is explained as well.

This video publication explains in detail the experimental protocol of the resident-intruder paradigm in rats. This test is a standardized method to ...

Contextual and Cued Fear Conditioning Test Using a Video Analyzing System in Mice

The contextual and cued fear conditioning test is one of the behavioral tests that assesses the ability of mice to learn and remember an association between environmental cues and aversive experiences. In this test, mice are placed into a conditioning chamber and are given parings of a conditioned stimulus (an auditory cue) and an aversive unconditioned stimulus (an electric footshock). After a delay time, the mice are exposed to the same conditioning chamber and a differently shaped chamber with presentation of the auditory cue. Freezing behavior during the test is measured as an index of fear memory. To analyze the behavior automatically, we have developed a video analyzing system using the ImageFZ application software program, which is available as a free download at http://www.mouse-phenotype.org/. Here, to show the details of our protocol, we demonstrate our procedure for the contextual and cued fear conditioning test in C57BL/6J mice using the ImageFZ system. In addition, we validated our protocol and the video analyzing system performance by comparing freezing time measured by the ImageFZ system or a photobeam-based computer measurement system with that scored by a human observer. As shown in our representative results, the data obtained by ImageFZ were similar to those analyzed by a human observer, indicating that the behavioral analysis using the ImageFZ system is highly reliable. The present movie article provides detailed information regarding the test procedures and will promote understanding of the experimental situation.

This article presents a protocol for a contextual and cued fear conditioning test using a video analyzing system to assess fear learning and memory in mice.

The contextual and cued fear conditioning test is one of the behavioral tests that assesses the ability of mice to learn and remember an association ...

Trace Fear Conditioning in Mice

In this experiment we present a technique to measure learning and memory. In the trace fear conditioning protocol presented here there are five pairings between a neutral stimulus and an unconditioned stimulus. There is a 20 sec trace period that separates each conditioning trial. On the following day freezing is measured during presentation of the conditioned stimulus (CS) and trace period. On the third day there is an 8 min test to measure contextual memory. The representative results are from mice that were presented with the aversive unconditioned stimulus (shock) compared to mice that received the tone presentations without the unconditioned stimulus. Trace fear conditioning has been successfully used to detect subtle learning and memory deficits and enhancements in mice that are not found with other fear conditioning methods. This type of fear conditioning is believed to be dependent upon connections between the medial prefrontal cortex and the hippocampus. One current controversy is whether this method is believed to be amygdala-independent. Therefore, other fear conditioning testing is needed to examine amygdala-dependent learning and memory effects, such as through the delay fear conditioning.

In the following experiment we describe a protocol for trace fear conditioning in mice. This type of associative memory includes a trace period that separates the neutral stimulus and the unconditioned stimulus.

In this experiment we present a technique to measure learning and memory. In the trace fear conditioning protocol presented here there are five pairings ...

A Procedure to Observe Context-induced Renewal of Pavlovian-conditioned Alcohol-seeking Behavior in Rats

Environmental contexts in which drugs of abuse are consumed can trigger craving, a subjective Pavlovian-conditioned response that can facilitate drug-seeking behavior and prompt relapse in abstinent drug users. We have developed a procedure to study the behavioral and neural processes that mediate the impact of context on alcohol-seeking behavior in rats. Following acclimation to the taste and pharmacological effects of 15% ethanol in the home cage, male Long-Evans rats receive Pavlovian discrimination training (PDT) in conditioning chambers. In each daily (Mon-Fri) PDT session, 16 trials each of two different 10 sec auditory conditioned stimuli occur. During one stimulus, the CS+, 0.2 ml of 15% ethanol is delivered into a fluid port for oral consumption. The second stimulus, the CS-, is not paired with ethanol. Across sessions, entries into the fluid port during the CS+ increase, whereas entries during the CS- stabilize at a lower level, indicating that a predictive association between the CS+ and ethanol is acquired. During PDT each chamber is equipped with a specific configuration of visual, olfactory and tactile contextual stimuli. Following PDT, extinction training is conducted in the same chamber that is now equipped with a different configuration of contextual stimuli. The CS+ and CS- are presented as before, but ethanol is withheld, which causes a gradual decline in port entries during the CS+. At test, rats are placed back into the PDT context and presented with the CS+ and CS- as before, but without ethanol. This manipulation triggers a robust and selective increase in the number of port entries made during the alcohol predictive CS+, with no change in responding during the CS-. This effect, referred to as context-induced renewal, illustrates the powerful capacity of contexts associated with alcohol consumption to stimulate alcohol-seeking behavior in response to Pavlovian alcohol cues.

A procedure to study the capacity of an alcohol associated environmental context to trigger the renewal of alcohol-seeking behavior in rats is described.

Environmental contexts in which drugs of abuse are consumed can trigger craving, a subjective Pavlovian-conditioned response that can facilitate ...

Using the Threat Probability Task to Assess Anxiety and Fear During Uncertain and Certain Threat

Fear of certain threat and anxiety about uncertain threat are distinct emotions with unique behavioral, cognitive-attentional, and neuroanatomical components. Both anxiety and fear can be studied in the laboratory by measuring the potentiation of the startle reflex. The startle reflex is a defensive reflex that is potentiated when an organism is threatened and the need for defense is high. The startle reflex is assessed via electromyography (EMG) in the orbicularis oculi muscle elicited by brief, intense, bursts of acoustic white noise (i.e., &#8220;startle probes&#8221;). Startle potentiation is calculated as the increase in startle response magnitude during presentation of sets of visual threat cues that signal delivery of mild electric shock relative to sets of matched cues that signal the absence of shock (no-threat cues). In the Threat Probability Task, fear is measured via startle potentiation to high probability (100% cue-contingent shock; certain) threat cues whereas anxiety is measured via startle potentiation to low probability (20% cue-contingent shock; uncertain) threat cues. Measurement of startle potentiation during the Threat Probability Task provides an objective and easily implemented alternative to assessment of negative affect via self-report or other methods (e.g., neuroimaging) that may be inappropriate or impractical for some researchers. Startle potentiation has been studied rigorously in both animals (e.g., rodents, non-human primates) and humans which facilitates animal-to-human translational research. Startle potentiation during certain and uncertain threat provides an objective measure of negative affective and distinct emotional states (fear, anxiety) to use in research on psychopathology, substance use/abuse and broadly in affective science. As such, it has been used extensively by clinical scientists interested in psychopathology etiology and by affective scientists interested in individual differences in emotion.

Potentiation of the startle reflex is measured via electromyography of the orbicularis oculi muscle during low (uncertain) and high (certain) probability electric shock threat in the Threat Probability Task. This provides an objective measure of distinct negative emotional states (fear/anxiety) for research on psychopathology, substance use/abuse, and broad affective science.

Fear of certain threat and anxiety about uncertain threat are distinct emotions with unique behavioral, cognitive-attentional, and neuroanatomical ...

A Cognitive Paradigm to Investigate Interference in Working Memory by Distractions and Interruptions

Goal-directed behavior is often impaired by interference from the external environment, either in the form of distraction by irrelevant information that one attempts to ignore, or by interrupting information that demands attention as part of another (secondary) task goal. Both forms of external interference have been shown to detrimentally impact the ability to maintain information in working memory (WM). Emerging evidence suggests that these different types of external interference exert different effects on behavior and may be mediated by distinct neural mechanisms. Better characterizing the distinct neuro-behavioral impact of irrelevant distractions versus attended interruptions is essential for advancing an understanding of top-down attention, resolution of external interference, and how these abilities become degraded in healthy aging and in neuropsychiatric conditions. This manuscript describes a novel cognitive paradigm developed the Gazzaley lab that has now been modified into several distinct versions used to elucidate behavioral and neural correlates of interference, by to-be-ignored distractors versus to-be-attended interruptors. Details are provided on variants of this paradigm for investigating interference in visual and auditory modalities, at multiple levels of stimulus complexity, and with experimental timing optimized for electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) studies. In addition, data from younger and older adult participants obtained using this paradigm is reviewed and discussed in the context of its relationship with the broader literatures on external interference and age-related neuro-behavioral changes in resolving interference in working memory.

A novel cognitive paradigm is developed to elucidate behavioral and neural correlates of interference by to-be-ignored distractors versus interference by to-be-attended interruptors during a working memory task. In this manuscript, several variants of this paradigm are detailed, and data obtained with this paradigm in younger/older adult participants is reviewed.

Goal-directed behavior is often impaired by interference from the external environment, either in the form of distraction by irrelevant information that ...

How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants

Placebo responses occur in every medical intervention when patients or participants expect to receive an effective treatment to relieve symptoms. However, underlying mechanisms of placebo responses are not fully understood. It has repeatedly been shown that placebo responses are associated with changes in neural activity but for many conditions it is unclear whether they also affect the target organ, such as the stomach in motion sickness. Therefore, we present a methodology for the multivariate assessment of placebo responses by subjective, behavioral and objective measures in motion sickness with a rotation chair paradigm. The physiological correlate of motion sickness is a shift in gastric myoelectrical activity towards tachygastria that can be recorded with electrogastrography. The presented study applied the so-called balanced placebo design (BPD) to investigate the effects of ginger compared to placebo and the effects of expectations by verbal information. However, the study revealed no significant main or interactional effects of ginger (as a drug) or information on outcome measures but showed interactions when sex of participants and experimenters are taken into considerations. We discuss limitations of the presented study and report modifications that were used in subsequent studies demonstrating placebo responses when rotation speed was lowered. In general, future placebo studies have to identify the appropriate target organ for the studied placebo responses and to apply the specific methods to assess the physiological correlates.

An experimental rotation chair paradigm is used to investigate whether a placebo intervention on motion sickness affects subjective outcome measures only or also affects behavioral and objective measures in a balanced placebo design.

Placebo responses occur in every medical intervention when patients or participants expect to receive an effective treatment to relieve symptoms. However, ...

Visual Classical Conditioning in Wood Ants

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, studies implementing classical conditioning paradigms with harnessed insects have been important for investigating the exact cues that individuals learn and the neural mechanisms underlying learning and memory formation. Here we present a protocol for evoking visual associative learning in wood ants through classical conditioning. In this paradigm, ants are harnessed and presented with a visual cue (a blue cardboard), the conditional stimulus (CS), paired with an appetitive sugar reward, the unconditional stimulus (US). Ants perform a Maxilla-Labium Extension Reflex (MaLER), the unconditional response (UR), which can be used as a readout for learning. Training consists of 10 trials, separated by a 5-minute intertrial interval (ITI). Ants are also tested for memory retention 10 minutes or 1 hour after training. This protocol has the potential to allow researchers to analyze, in a precise and controlled manner, the details of visual memory formation and the neural basis of learning and memory formation in wood ants.

We present a protocol for the classical conditioning of harnessed ants that permits researchers to study visual learning and memory formation at a level of analysis not possible with freely moving individuals.

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, ...

Using the Visual World Paradigm to Study Sentence Comprehension in Mandarin-Speaking Children with Autism

Sentence comprehension relies on the ability to rapidly integrate different types of linguistic and non-linguistic information. However, there is currently a paucity of research exploring how preschool children with autism understand sentences using different types of cues. The mechanisms underlying sentence comprehension remains largely unclear. The present study presents a protocol to examine the sentence comprehension abilities of preschool children with autism. More specifically, a visual world paradigm of eye-tracking is used to explore the moment-to-moment sentence comprehension in the children. The paradigm has multiple advantages. First, it is sensitive to the time course of sentence comprehension and thus can provide rich information about how sentence comprehension unfolds over time. Second, it requires minimal task and communication demands, so it is ideal for testing children with autism. To further minimize the computational burden of children, the present study measures eye movements that arise as automatic responses to linguistic input rather than measuring eye movements that accompany conscious responses to spoken instructions.

We present a protocol to examine the use of morphological cues during real-time sentence comprehension by children with autism.

Sentence comprehension relies on the ability to rapidly integrate different types of linguistic and non-linguistic information. However, there is ...

Fear Incubation Using an Extended Fear-Conditioning Protocol for Rats

Emotional memory has been primarily studied with fear-conditioning paradigms. Fear conditioning is a form of learning through which individuals learn the relationships between aversive events and otherwise neutral stimuli. The most-widely utilized procedures for studying emotional memories entail fear conditioning in rats. In these tasks, the unconditioned stimulus (US) is a footshock presented once or several times across single or several sessions, and the conditioned response (CR) is freezing. In a version of these procedures, called cued fear conditioning, a tone (conditioned stimulus, CS) is paired with footshocks (US) during the training phase. During the first test, animals are exposed to the same context in which training took place, and freezing responses are tested in the absence of footshocks and tones (i.e., a context test). During the second test, freezing is measured when the context is changed (e.g., by manipulating the smell and walls of the experimental chamber) and the tone is presented in the absence of footshocks (i.e., a cue test). Most cued fear conditioning procedures entail few tone-shock pairings (e.g., 1-3 trials in a single session). There is a growing interest in less common versions involving an extensive number of pairings (i.e., overtraining) related to the long-lasting effect called fear incubation (i.e., fear responses increase over time without further exposure to aversive events or conditioned stimuli). Extended fear-conditioning tasks have been key to the understanding of fear incubation&#8217;s behavioral and neurobiological aspects, including its relationship with other psychological phenomena (e.g., post-traumatic stress disorder). Here, we describe an extended fear-conditioning protocol that produces overtraining and fear incubation in rats. This protocol entails a single training session with 25 tone-shock pairings (i.e., overtraining) and a comparison of conditioned freezing responses during context and cue tests 48 h (short-term) and 6 weeks (long-term) after training.

We describe an extended fear-conditioning protocol that produces overtraining and fear incubation in rats. This protocol entails a single training session with 25 tone-shock pairings (i.e., overtraining) and a comparison of conditioned freezing responses during context and cue tests 48 h (short-term) and 6 weeks (long-term) after training.

Emotional memory has been primarily studied with fear-conditioning paradigms. Fear conditioning is a form of learning through which individuals learn the ...