An in vivo Assay for Simultaneous Monitoring of Neuronal Activity and Behavioral Output in the Stomatogastric Nervous System of Decapod Crustaceans

Central pattern generators (CPGs) generate rhythmic output patterns and drive vital behaviors such as breathing, swallowing, locomotion and chewing 1-10. While most insights into the rhythm generating mechanisms of CPGs have been derived from isolated nervous system preparations, the relationship between neural activity and corresponding behavioral expression is often unclear. The stomatogastric system of decapod crustaceans is one of the best characterized neural system for motor pattern generation 9-12 and many mechanisms of motor pattern generation and selection have been discovered in this system. Since most studies are limited to the isolated nervous system, little is known about the actual behavioral output of this system. For example, it is unknown whether the observed flexibility in the motor patterns is present in vivo and whether distinct motor activities drive corresponding behavioral patterns. We present a method which allows electrophysiological recordings of CPG neurons and the simultaneous monitoring of the behavioral output of the stomatogastric nervous system. For this, we use extracellular hook electrodes either for recording or stimulation of neurons in the gastric mill CPG that drive the chewing movements of three teeth in the foregut of the animal. Electrodes are applied in tethered, but otherwise fully intact crabs (Cancer pagurus) and an endoscope is used to monitor tooth movements. Nerve and video recordings of the endoscopic camera are synchronized and motion tracking techniques are used to analyze gastric mill movements. This approach thus allows testing the behavioral relevance of the neural activity patterns produced by central pattern generators

Requirements for Data Valuation Methods

Data is considered the most significant intangible asset for the 21st century enterprise. Serving as key asset for ever-increasing digital transformation and entrepreneurship, they ensure economic success through empowering new technologies, services and business models. Despite their high relevance, there exist neither consistent valuation methods nor specific requirements for developing such methods. Data valuation is crucial in order to better understand their value and, for example, incorporating them into financial statements. Existing literature indicates relationship between data value and quality. Thereupon, we conducted semi-structured expert interviews to gain insights on data valuation methods in connection with data quality. This results in 11 requirements for data valuation methods and seven value-driving quality criteria. Furthermore, several challenges for future data valuation are derived from the empirical results

Identifying Dopamine Receptor Genes and Transcription Marbled Crayfish

Modulatory transmitters are major contributors to nervous system plasticity and behavioral flexibility, they determine motivational states and are involved in psychiatric and neurological disorders. Neuromodulators act through a variety of distinct receptors and due to the diversity in receptor subtypes and distribution, a single neuromodulator can exert many different actions. A prerequisite to understand the ways modulators work is thus to identify which receptors are expressed in an animal. I studied which Dopamine receptors are present in the Procambarus virginalis, a highly invasive species of all female genetic clones with high quality genome and transcriptomes. Their broad behavioral repertoire makes them ideal for studying the actions of neuromodulator receptors. We focused on Dopamine receptors as they play a role in Parkinson’s disease and the reward system of vertebrates and invertebrates. Using bioinformatics on the genome and transcriptome, we identified which dopamine receptors exist in marbled crayfish. Two receptors previously identified in lobsters, D1Alpha and D1beta, were considered. Like crayfish, lobsters are decapod crustaceans, and the evolutionary closest species with identified dopamine receptors. We identified homologs of both receptor genes in the genome and the transcriptome. However, a conserved domains search revealed no direct functional Dopamine receptor domain for these putative D1alpha and D1beta receptors. PCR with D1alpha primers on ventral nerve cord mRNA revealed that this putative receptor is expressed in the marbled crayfish nervous system. We are currently testing the expression of D1beta in in the ventral nerve cord

The Stomatogastric Nervous System as a Model for Studying Sensorimotor Interactions in Real-Time Closed-Loop Conditions

The perception of proprioceptive signals that report the internal state of the body is one of the essential tasks of the nervous system and helps to continuously adapt body movements to changing circumstances. Despite the impact of proprioceptive feedback on motor activity it has rarely been studied in conditions in which motor output and sensory activity interact as they do in behaving animals, i.e., in closed-loop conditions. The interaction of motor and sensory activities, however, can create emergent properties that may govern the functional characteristics of the system. We here demonstrate a method to use a well-characterized model system for central pattern generation, the stomatogastric nervous system, for studying these properties in vitro. We created a real-time computer model of a single-cell muscle tendon organ in the gastric mill of the crab foregut that uses intracellular current injections to control the activity of the biological proprioceptor. The resulting motor output of a gastric mill motor neuron is then recorded intracellularly and fed into a simple muscle model consisting of a series of low-pass filters. The muscle output is used to activate a one-dimensional Hodgkin–Huxley type model of the muscle tendon organ in real-time, allowing closed-loop conditions. Model properties were either hand tuned to achieve the best match with data from semi-intact muscle preparations, or an exhaustive search was performed to determine the best set of parameters. We report the real-time capabilities of our models, its performance and its interaction with the biological motor system

Long-Distance Modulation of Sensory Encoding via Axonal Neuromodulation

The neuromodulatory system plays a critical role in sensorimotor system function and animal behavior. Its influence on axons, however, remains enigmatic although axons possess receptors for a plethora of modulators, and pathologies of the neuromodulatory system impair neuronal communication. The most dramatic neuromodulatory effect on axons is ectopic spiking, a process common to many systems and neurons during which action potentials are elicited in the axon trunk and travel antidromically towards the site of sensory transduction. We argue that ectopic action potentials modify sensory encoding by invading the primary spike initiation zone in the periphery. This is a particularly intriguing concept, since it allows the modulatory system to alter sensory information processing. We demonstrate that aminergic modulation of a proprioceptive axon that elicits spontaneous ectopic action potentials changes spike frequency, which determines the burst behavior of the proprioceptor. Increasing ectopic spike frequency delayed the peripheral burst, caused reductions in spike number and burst duration, and changes in sensory firing frequency. Computational models show these effects depend on slow ionic conductances to modulate membrane excitability. Thus, axonal neuromodulation provides a means to rapidly influence sensory encoding without directly or locally affecting the sites of stimulus reception and spike initiation