This work was funded by grants of the Swiss National Science Foundation (Grant 31003A-149315-1 to M.E.S. and Grant IZK0Z3-150809 to A.Z.), to A.Z. the Heidi Demetriades Foundation, to M.E.S. the European Research Council (&#8216;Nogorise&#8217;) and the Christopher and Dana Reeve Foundation (CDRF).

All experiments were performed in accordance with the guidelines of the Veterinary Office of the Canton Zurich, Switzerland.
1. Animal Handling and Habituation
<ol>
	<li>Animal Handling 
	Note: 5 days prior to the start of the experiment, perform step 1.1.1 daily.
	<ol>
		<li>For behavioral experiments, accustom the animals to the experimenter. Have daily handling sessions lasting 10-15 min per animal. Clean the box after each animal&#8217;s session.
		<ol>
			<li>Initi...

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The paradigm shown in this study is adapted from Buitrago et al.18 and differs from the classical single pellet reaching paradigm17 mainly in two aspects:
First, studying within-session improvement allows analysis of the learned task within a single day, which can provide a different level of information such as investigation of the fast learning component compared to the slow learning component represented by the average daily values (see Figures 3</stro...

Movement control is a core function of the central nervous system (CNS). Motricity is the main measurable output of CNS function and the main possibility for individuals to interact with the external world. Understanding the principles of motor function and the mechanisms that underlie the learning of a motor task is currently one of the big challenges in neuroscience. Morphological, physiological and molecular changes were found upon acquisition of a new motor task. For example, the shape and number of synapses change in response to skilled motor training1-5, and functional changes of the synaptic machinery were observed after motor learning. Synaptic responses were higher in the connections of the forelimb-representing region of the trained motor cortex compared to the untrained hemisphere of the same animal or to responses from untrained animals6,7. Electrophysiological observations also suggest that long-term potentiation (LTP) and long-term depression (LTD) like mechanisms take place during the learning of a new motor skill, and that the range of synaptic operation, which is defined between the limiting borders of LTP and LTD saturation, is modified8. Furthermore, it has been shown that activity markers and plasticity promoting molecules such as c-fos, GAP-43, or BDNF but also plasticity inhibiting molecules such as Nogo-A display regulatory roles for learning-related neuronal plasticity9-16.
These advances towards a better understanding of the mechanisms underlying motor learning could only be achieved with the use of behavioral paradigms that allow precise control of the acquisition of a new motor skill, e.g., skilled forelimb-reaching. Only a well-structured behavioral task allows to monitor and capture correlative changes that occur upon learning and execution of the respective task. Here we visually demonstrate a modified version of the skilled forelimb single-pellet reaching task in rats adapted from Buitrago et al.17 The presented paradigm allows the analysis of movement acquisition within a daily training session (within-session) representing the fast learning component and primary acquisition as well as skilled motor learning over several sessions (between-session) representing the slow learning component and maintenance of the learned task18. Importantly, this behavioral paradigm increases the degree of difficulty and complexity of the motor skill task due to two features: First, the rats are trained to turn around their axis after each grasp and thus to realign their body prior to the next pellet reach and renew the body orientation, preventing constant movement execution from the same angle. Second, pellets are retrieved from a vertical post placed in front of the cage. Due to the small diameter of the post, pellets can easily be kicked off requiring a precise grasp for successful retrieval and preventing simple pulling of the pellet towards the animal.
Such complex behavioral testing allows deeper insights into the mechanisms underlying motor learning. Compared to mice, rats are superior in their performance of complex behavioral tasks and thus better suited for complex paradigms as presented in this study. Considering the increasing genetic possibilities available for rats19,20, the combination of precise and well controlled behavioral testing methods with genetic manipulations, imaging and physiological techniques represents a powerful toolbox to better understand the neurobiological basis of motor learning and memory.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>1</td>
			<td>Training Box</td>
			<td>Self Made</td>
			<td></td>
		</tr>
		<tr>
			<td>2</td>
			<td>Pedestal</td>
			<td>Self Made</td>
			<td></td>
		</tr>
		<tr>
			<td>3</td>
			<td>Sugar Pellets</td>
			<td colspan="2">45-mg dustless precision pellets, TSE Systems Intl. Group</td>
		</tr>
		<tr>
			<td>4</td>
			<td>Animals</td>
			<td>5-6 week old Sprague Dawley Male Rats</td>
			<td></td>
		</tr>
		<tr>
			<td>5</td>
			<td>Laptop</td>
			<td>Hewlett Packard</td>
			<td></td>
		</tr>
		<tr>
			<td>6</td>
			<td>Stop Watch</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>7</td>
			<td>Forceps</td>
			<td>Fine Science Tools (FST)</td>
			<td></td>
		</tr>
		<tr>
			<td>8</td>
			<td>Software</td>
			<td>Excel (Microsoft), GraphPad Prism (GraphPad)</td>
			<td></td>
		</tr>
		<tr>
			<td>9</td>
			<td>Weighing scale</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>10</td>
			<td>Counter</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

acquisition of a high-precision skilled forelimb reaching task in rats

Movements are the main measurable output of central nervous system function. Developing behavioral paradigms that allow detailed analysis of motor learning and execution is of critical importance in order to understand the principles and processes that underlie motor function. Here we present a paradigm to study movement acquisition within a daily session of training (within-session) representing the fast learning component and primary acquisition as well as skilled motor learning over several training sessions (between-session) representing the slow learning component and consolidation of the learned task. This behavioral paradigm increases the degree of difficulty and complexity of the motor skill task due to two features: First, the animal realigns its body prior to each pellet retrieval forcing renewed orientation and preventing movement execution from the same angle. Second, pellets are grasped from a vertical post that matches the diameter of the pellet and is placed in front of the cage. This requires a precise grasp for successful pellet retrieval and thus prevents simple pulling of the pellet towards the animal. In combination with novel genetics, imaging and electrophysiological technologies, this behavioral method will aid to understand the morphological, anatomical and molecular underpinnings of motor learning and memory.

Successful motor skill acquisition is only achieved through consistent practice. Despite careful consideration of all aspects, some rats fail to learn the task (Figure 2). These &#39;non-learners&#39; either lack motivation resulting in few or absent attempts of pellet retrieval from the start of the experiment or generally lose interest in reaching for the pellets leading to continuously failed attempts. By contrast, some animals show aggressive and over-motivated behavior resulting in overhasty and rus...

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Acquisition of a High-precision Skilled Forelimb Reaching Task in Rats

A paradigm is presented to analyze the acquisition of a high-precision skilled forelimb reaching task in rats.

Movements are the main measurable output of central nervous system function. Developing behavioral paradigms that allow detailed analysis of motor ...

acquisition-of-a-high-precision-skilled-forelimb-reaching-task-in-rats

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10.1K 조회수.  University of Zurich. A paradigm is presented to analyze the acquisition of a high-precision skilled forelimb reaching task in rats.