We sincerely thank the Whitehall Foundation for their funding support and startup funds from The Scripps Research Institute for carrying out this work.

1. Preparation of Abdominal Ganglia, Electrophysiological Measurements, and Isolation of Single Identified Neurons from Abdominal Ganglion of Aplysia californica
<ol>
	<li>Maintain Aplysia in the laboratory aquarium with circulating artificial seawater (ASW) at 16 &#176;C under 12:12 light:dark conditions.</li>
	<li>Isolation of abdominal ganglion.
	<ol>
		<li>Anesthetize animals by injecting 380 mM MgCl2 solution for 5-10 min&#160;(equivalent to 30-35% of the animal&#39;s body weight).</li...

Authors do not have any competing financial interests.

The neuron R15 is involved in regulating cardiovascular, digestive, respiratory, and reproductive systems30. A regularly rhythmic bursting activity of the AP is a feature of R15. As shown in the results section, paired recording of R15 and L7 show that the ganglia preparation has preserved activity of R15 neurons. R15 and L7 neurons responded appropriately to Ach. This ganglia preparation could be maintained up to 8-10 hr&#160;and electrophysiological activity could be continuously monitored. Thus, one could s...

The human brain is extraordinarily complex with almost 100 billion neurons and trillions of synaptic connections. There are almost an equal number of nonneuronal cells that interact with neurons and regulate their function in the brain. Neurons are organized into circuits that regulate specific behaviors. Despite the advances in our understanding of brain functions and neural circuits, little is known about the identity of circuitry components that control a specific behavior. Knowledge of the identities of various components of a circuitry will greatly facilitate our understanding of both cellular and molecular basis of behavior and aid in developing novel therapeutic strategies for neuropsychiatric disorders.
The marine snail Aplysia californica has been a workhorse for determining neuronal circuits underlying specific behaviors1-14. The Aplysia nervous system contains approximately 20,000 neurons that are organized into 9 different ganglia. The neurons of Aplysia are large and can be easily identified based on their size, electrical properties, and position in the ganglia. Aplysia has a rich repertoire of behaviors that can be studied. One of the well-studied behaviors is the gill-withdrawal reflex (GWR). The central components of this reflex are situated in abdominal ganglia. Components of the GWR circuitry have been mapped and contributions of various components determined. Importantly, GWR circuitry undergoes associative and nonassociative learning5,6,15-19. Decades of study on this reflex have also identified several signaling pathways that have a key role in learning and memory20-24.
Several different preparations of Aplysia were used to study cellular and molecular basis of memory storage. These include the intact animal2,3, semi-intact preparation1,7,13,14,16 and reconstitution of major components of neural circuitry25-29. A reduced preparation for exploring Aplysia ganglia for the electrophysiological and molecular analyses of identified neuronal circuits is described here. The following four identified neurons were studied. R15, a bursting neuron, L7 and L11, two different motor neurons and R2, a cholinergic neuron were studied. R2 is the largest neuron described in the invertebrate nervous system. Briefly, this methodology involves protease treatment of ganglia, electrophysiological measurements before and after pharmacological treatments, and isolation of single neurons for quantitative analysis of gene expression. This methodology enables us to combine molecular analyses with simultaneous recording from multiple neurons. This methodology was successfully used to study responses of R15 and L7 neurons to acetylcholine (Ach) by paired intracellular recordings. Following electrophysiological measurements R15 and L7 and other identified neurons such as L11 and R2 were isolated for quantitative polymerase chain reaction (qPCR) analysis of expression of CREB1, a transcription factor important for memory storage.

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			<td height="101" style="height:101px;width:120px;">Aplysia</td>
			<td style="width:123px;">National Aplysia Resource Facility, University of Miami</td>
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aplysia ganglia preparation for electrophysiological and molecular analyses of single neurons

A major challenge in neurobiology is to understand the molecular underpinnings of neural circuitry that govern a specific behavior. Once the specific molecular mechanisms are identified, new therapeutic strategies can be developed to treat abnormalities in specific behaviors caused by degenerative diseases or aging of the nervous system. The marine snail Aplysia californica is well suited for the investigations of cellular and molecular basis of behavior because neural circuitry underlying a specific behavior could be easily determined and the individual components of the circuitry could be easily manipulated. These advantages of Aplysia have led to several fundamental discoveries of neurobiology of learning and memory. Here we describe a preparation of the Aplysia nervous system for the electrophysiological and molecular analyses of individual neurons. Briefly, ganglion dissected from the nervous system is exposed to protease to remove the ganglion sheath such that neurons are exposed but retain neuronal activity as in the intact animal. This preparation is used to carry out electrophysiological measurements of single or multiple neurons. Importantly, following the recording using a simple methodology, the neurons could be isolated directly from the ganglia for gene expression analysis. These protocols were used to carry out simultaneous electrophysiological recordings from L7 and R15 neurons, study their response to acetylcholine and quantitating expression of CREB1 gene in isolated single L7, L11, R15, and R2 neurons of Aplysia.

The weights of animals that were used in this study ranged from 100-200 g. Following the described protocols, we conducted electrophysiological measurements and molecular analysis of neurons of abdominal ganglia isolated from animals ranging from 2-5 g&#160;to 200-300 g.
Standardization of protease treatment is important for successful electrophysiological measurements of neurons in the ganglia. Initially, multiple protease (Dispase) concentrations and durations were used and bursting action p...

Watch this Scientific Journal Video about Aplysia Ganglia Preparation for Electrophysiological and Molecular Analyses of Single Neurons at JoVE.com

Aplysia Ganglia Preparation for Electrophysiological and Molecular Analyses of Single Neurons

Marine snail Aplysia californica has been widely used as a neurobiology model for the studies on cellular and molecular basis of behavior. Here a methodology is described for exploring the nervous system of Aplysia for the electrophysiological and molecular analyses of single neurons of identified neural circuitry.

Aplysia Ganglia Preparation for Electrophysiological and Molecular Analyses of Single Neurons

A major challenge in neurobiology is to understand the molecular underpinnings of neural circuitry that govern a specific behavior. Once the specific ...

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9.0K Views.  The Scripps Research Institute, Florida. Marine snail Aplysia californica has been widely used as a neurobiology model for the studies on cellular and molecular basis of behavior. Here a methodology is described for exploring the nervous system of Aplysia for the electrophysiological and molecular analyses of single neurons of identified neural circuitry.