We acknowledge the audiovisual technician and video producer Rebeca De las Heras Ponce as well as the head veterinarian Gonzalo Moreno del Val, for the supervision of good practice during mouse experimentation.&#160;Work was funded by grants from the GVA Excellence Program (2022/8) and the Spanish Research Agency (PID2022143237OB-I00) to Isabel P&#233;rez-Ota&#241;o.

In the current study, adult (2-3 months old) C57BL/6J mice of both sexes were used. Animals were housed two to five per cage with ad libitum access to food and water in an animal unit under observation and maintained in a temperature-controlled environment on a 12 h dark/light cycle. All procedures were conducted in accordance with the European and Spanish regulations (2010/63/UE; RD 53/2013) and were approved by the Ethical Committee of the Generalitat Valenciana and the animal welfare committee of the Universi...

Automated Assessment of Fine Motor Performance in Mice Using the Erasmus Ladder

<ol>
	<li>Brooks, S. P., Dunnett, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tests+to+assess+motor+phenotype+in+mice:+a+user's+guide.">Tests to assess motor phenotype in mice: a user's guide.</a> Nat. Rev. Neurosci. 10 (7), 519-529 (2009).</li><li>. Available from: <a target="_blank" href="https://www.noldus.com/erasmusladder">https://www.noldus.com/erasmusladder</a> (2023)</li><li>Cupido, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Detecting cerebellar phenotypes with the Erasmus ladder[dissertation]. , (2009).</li><li>Van Der Giessen, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+olivary+electrical+coupling+in+cerebellar+motor+learning.">Role of olivary electrical coupling in cerebellar motor learning.</a> Neuron. 58 (4), 599-612 (2008).</li><li>Vinueza Veloz, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+an+mGluR5+inhibitor+on+procedural+memory+and+avoidance+discrimination+impairments+in+Fmr1+KO+mice.">The effect of an mGluR5 inhibitor on procedural memory and avoidance discrimination impairments in Fmr1 KO mice.</a> Genes Brain Behav. 11 (3), 325-331 (2012).</li><li>Vinueza Veloz, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebellar+control+of+gait+and+interlimb+coordination.">Cerebellar control of gait and interlimb coordination.</a> Brain Struct. Funct. 220 (6), 3513-3536 (2015).</li><li>Sathyanesan, A., Kundu, S., Abbah, J., Gallo, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neonatal+brain+injury+causes+cerebellar+learning+deficits+and+Purkinje+cell+dysfunction.">Neonatal brain injury causes cerebellar learning deficits and Purkinje cell dysfunction.</a> Nat. Commun. 9 (1), 3235 (2018).</li><li>Sathyanesan, A., Gallo, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebellar+contribution+to+locomotor+behavior:+A+neurodevelopmental+perspective.">Cerebellar contribution to locomotor behavior: A neurodevelopmental perspective.</a> Neurobiol. Learn Mem. 165, 106861 (2019).</li><li>McKenzie, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motor+skill+learning+requires+active+central+myelination.">Motor skill learning requires active central myelination.</a> Science. 346 (6207), 318-322 (2014).</li><li>Xiao, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+production+of+new+oligodendrocytes+is+required+in+the+earliest+stages+of+motor-skill+learning.">Rapid production of new oligodendrocytes is required in the earliest stages of motor-skill learning.</a> Nat. Neurosci. 19 (9), 1210-1217 (2016).</li></ol>

The authors have no conflicts of interest to disclose.

The Erasmus Ladder presents major advantages for motor phenotype assessment beyond current approaches. Testing is easy to conduct, automated, reproducible, and allows researchers to assess various aspects of motor behavior separately using a single mouse cohort. In the current study, reproducibility allowed the generation of robust data with a small number of WT mice taking advantage of the features of the device, experimental design, and analysis methods. For instance, when compared to traditional beam-walk assays, the ...

A variety of tests have been developed to assess motor phenotypes in mice. Each test gives information on a specific aspect of motor behavior1. For example, the open field test informs on general locomotion and anxiety state; the rotarod and walking beam tests on coordination and balance; footprint analysis is about gait; the treadmill or running wheel on forced or voluntary physical exercise; and the complex wheel is about motor skill learning. To analyze mouse motor phenotypes, investigators must perform these tests sequentially, which involves a lot of time and effort and often several animal cohorts. If there is information at the cellular or circuitry level, the investigator normally opts for a test that monitors a related aspect and follows from there. However, paradigms that discriminate different aspects of motor behavior in an automated way are lacking.
This article describes a protocol to use the Erasmus Ladder2,3, a system that allows comprehensive assessment of a variety of motor learning features in mice. The main advantages are the reproducibility and sensitivity of the method, along with the ability to titrate motor difficulty and to separate deficits in motor performance from impaired associative motor learning. The main component consists of a horizontal ladder with alternate high (H) and low (L) rungs equipped with touch-sensitive sensors that detect the position of the mouse on the ladder. The ladder is made of 2 x 37 rungs (L, 6 mm; H, 12 mm) spaced 15 mm apart from each other and positioned in a left-right alternating pattern with 30 mm gaps (Figure 1A). Rungs can be moved individually to generate various levels of difficulty, that is, creating an obstacle (raising the high rungs by 18 mm). Coupled with an automated recording system and associating modifications of the rung pattern with sensory stimuli, the Erasmus ladder tests for fine motor learning and adaptation of motor performance in response to environmental challenges (appearance of a higher rung to simulate an obstacle, an unconditioned stimulus [US]) or association with sensory stimuli (a tone, a conditioned stimulus [CS]). Testing involves two distinct phases, each assessing improvement in motor performance over 4 days, during which mice undergo a session of 42 consecutive trials per day. In the initial phase, mice are trained to navigate the ladder to assess &#34;fine&#34; or &#34;skilled&#34; motor learning. The second phase consists of interleaved trials where an obstacle in the form of a higher rung is presented in the path of the moving animal. The perturbation can be unexpected to assess &#34;challenged&#34; motor learning (US-only trials) or announced by an auditory tone to assess &#34;associative&#34; motor learning (Paired trials).
The Erasmus ladder has been developed relatively recently2,3. It has not been extensively used because setting up and optimizing the protocol required focused effort and was specifically designed to assess cerebellar-dependent associative learning without exploring in detail its potential to reveal other motor deficits. To date, it has been validated for its ability to unveil subtle motor impairments linked to cerebellar dysfunction in mice3,4,5,6,7,8. For instance, connexin36 (Cx36) knockout mice, where gap junctions are impaired in olivary neurons, display firing deficits due to lack of electrotonic coupling but the motor phenotype had been hard to pinpoint. Testing using the Erasmus ladder suggested that the role of inferior olivary neurons in a cerebellar motor learning task is to encode precise temporal coding of stimuli and facilitate learning-dependent responses to unexpected events3,4. Fragile X Messenger Ribonucleoprotein 1 (Fmr1) knockout mouse, a model for Fragile-X-Syndrome (FXS), exhibits a well-known cognitive impairment along with milder defects in procedural memory formation. Fmr1 knockouts showed no significant differences in step times, missteps per trial, or motor performance improvement over sessions in the Erasmus Ladder but failed to adjust their walking pattern to the suddenly appearing obstacle compared to their wild-type (WT) littermates, confirming specific procedural and associative memory deficits3,5. Furthermore, cell-specific mouse mutant lines with defects in cerebellar function, including impaired Purkinje cell output, potentiation, and molecular layer interneuron or granule cell outputs, exhibited problems in motor coordination with altered acquisition of efficient step patterns and in the number of steps taken to cross the ladder6. Neonatal brain injury causes cerebellar learning deficits and Purkinje cell dysfunction that could also be detected with the Erasmus Ladder7,8.
In this video, we present a comprehensive step-by-step guide, which details the setup of the behavioral room, the behavioral test protocol, and subsequent data analysis. This report is crafted to be accessible and user-friendly and is designed specifically to assist newcomers. This protocol provides insight into different phases of motor training and expected motor patterns that mice adopt. Finally, the article proposes a systematic workflow for data analysis using a powerful non-linear regression approach, complete with valuable recommendations and suggestions for adapting and applying the protocol in other research contexts.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>C57BL/6J mice (Mus musculus)</td>
			<td>Charles Rivers</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Erasmus Ladder device</td>
			<td>Noldus, Wageningen, Netherlands</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Erasmus Ladder 2.0 software</td>
			<td>Noldus, Wageningen, Netherlands</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Excel software</td>
			<td>Microsoft&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sigmaplot software</td>
			<td>Systat Software, Inc.</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

monitoring fine and associative motor learning in mice using the erasmus ladder

Behavior is shaped by actions, and actions necessitate motor skills such as strength, coordination, and learning. None of the behaviors essential for sustaining life would be possible without the ability to transition from one position to another. Unfortunately, motor skills can be compromised in a wide array of diseases. Therefore, investigating the mechanisms of motor functions at the cellular, molecular, and circuit levels, as well as understanding the symptoms, causes, and progression of motor disorders, is crucial for developing effective treatments. Mouse models are frequently employed for this purpose.
This article describes a protocol that allows the monitoring of various aspects of motor performance and learning in mice using an automated tool called the Erasmus Ladder. The assay involves two phases: an initial phase where mice are trained to navigate a horizontal ladder built of irregular rungs (&#34;fine motor learning&#34;), and a second phase where an obstacle is presented in the path of the moving animal. The perturbation can be unexpected (&#34;challenged motor learning&#34;) or preceded by an auditory tone (&#34;associative motor learning&#34;). The task is easy to conduct and is fully supported by automated software.
This report shows how different readouts from the test, when analyzed with sensitive statistical methods, allow fine monitoring of mouse motor skills using a small cohort of mice. We propose that the method will be highly sensitive to evaluate motor adaptations driven by environmental modifications as well as early-stage subtle motor deficits in mutant mice with compromised motor functions.

Author Spotlight: Unveiling Neural Mechanisms Through Automated Evaluation of Motor Learning and Myelin Plasticity Studies Using the Erasmus Ladder 

Monitoring Fine and Associative Motor Learning in Mice Using the Erasmus Ladder

In the lab, we study brain plasticity. One of our goals is to identify the neural circuits and mechanisms that are engaged and understand what's wrong in disease, so we can find suitable targets for interventions that are lacking. One of our critical needs is to have robust training protocols to evaluate, to induce plasticity, and evaluate the impact of genetic manipulations in healthy mice and in disease models.Current research needs sensitive, versatile, and automatic techniques to assess mice behavior. We are mainly interested in motor behavioral learning, and traditional tests requires sequential implementation, which consumes significant time and resources. Also, traditional tests don't always have enough accuracy.However, Erasmus Ladder allows motor learning future explanation and analysis in a single automated setup. While existing paradigms often focus on specific aspects of motor behavior, our approach aims to discriminate between fine motor learning, challenge motor learning, and associative motor learning in an automated and non invasive way, filling a gap in current methodologies. Testing is easy to conduct, automated, reproducible, and allow researchers to study different aspects of motor behavior separately using a single mouse cohort.The automatic software and adjustable parameters announce the precision of data collection and analysis, and also the versatility and customization of the protocol according to the scientific question. Our lab will focus on further refining the Erasmus Ladder protocols, combining cellular and molecular techniques to investigate motor adaptation and the underlying neuronal mechanisms. In particular, one of our projects focuses on myelin plasticity, a phenomenon triggered during complex motor skill learning that could help finding cures for patients with dysmyelinating disease.

The Erasmus Ladder device, setup, and protocol applied are presented in Figure 1. The protocol consists of four undisturbed and four challenge sessions (42 trials each). Each trial is one run on the ladder between the starting and ending goal boxes. At the beginning of the session, a mouse is placed in one of the starting boxes. After a set time of 15 &#177; 5 s (&#34;resting&#34; state), the light is turned on (cue 1, for a maximum of 3 s). A light air cue (cue 2, 45 s maximum) is then appl...

Watch this Scientific Journal Video about Unveiling Neural Mechanisms Through Automated Evaluation of Motor Learning and Myelin Plasticity Studies Using the Erasmus Ladder at JoVE.com

This article presents a protocol that allows a non-invasive and automated assessment of fine motor performance, as well as adaptive and associative motor learning upon challenges, using a device called the Erasmus Ladder. Task difficulty can be titrated to detect motor impairment ranging from major to subtle degrees.

Behavior is shaped by actions, and actions necessitate motor skills such as strength, coordination, and learning. None of the behaviors essential for ...

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Research

JoVE Journal

Neuroscience

872 vistas.  Spain - Consejo Superior de Investigaciones Científicas and Universidad Miguel Hernández. En el laboratorio, estudiamos la plasticidad cerebral. Uno de nuestros objetivos es identificar los circuitos y mecanismos neuronales que están comprometidos y comprender qué es lo que está mal en la enfermedad, de modo que podamos encontrar objetivos adecuados para las intervenciones que faltan. Una de nuestras necesidades críticas es contar con protocolos de entrenamiento robustos para evaluar, inducir plasticidad y evaluar el impacto de las manipulaciones genéticas en ratones sanos y ...

Video: Autor destacado: Desvelando los mecanismos neuronales a través de la evaluación automatizada del aprendizaje motor y los estudios de plasticidad de la mielina utilizando la escalera Erasmus 