| Caenorhabditis elegans (C. elegans) are studied due to its useful systems. It offersvarious neurobiological processes at the molecular and cellular level cellular for studying.C. elegans has a very simple nervous system (302neurons). It explores its environment byinterrupting its forward movement with occasional turns and reversals turns. Its reversalsturns occur at stable frequencies but in irregular intervals, producing probabilisticexploratory behaviors. In this thesis, we discuss how the neurons circuit controls are usedfor seeking food behaviors in C. elegans.By stimulating long reversals and omega turns upon removal from food, AWC andASK play a major role in the local search state. npr-9is responsible of search/pivoting. Itdisplays an increased local search/pivoting that impairs their ability to travel long distancesand roam on for food. Role head motor neurons were manipulated and tested. Thefrequency of short reversals increased when RIM was killed. On the other hand when bothRIM and AVA neurons were killed, the effect of eliminating RIM was suppressed. RIMmakes synapses and gap junctions onto the command interneurons, which mean that it mayinhibit short reversals through these connections. SMB motor neurons also make synapsesonto the command neurons, and it inhibits short reversals. Neither RMD nor SMD synapseonto the command neurons directly. Killing either cell increases the frequency of reversals.Omega turns were stimulated by SMD and RIV motor neurons. Killing SMD and RIVneurons leads to a decrease in the frequency of omega turns.RMG inter/motor neuron is a hub of a gap-junction network connecting sevenclasses of neurons. RMG neurons stimulate aggregation-related behaviors in npr-1mutants,and indicate that NPR-1inhibits RMG activity in solitary strains. When RMG was killed,it resulted in the elimination of aggregation, bordering and rapid movement. AVECommand interneurons along with AVA, AVD and A-type motor neurons drive backwardmovement of the animal. |
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