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X-APPLE-TRAVEL-ADVISORY-BEHAVIOR:AUTOMATIC
234836
20260417T081356Z
DTSTART;TZID=America/New_York:20260422T154500
DTEND;TZID=America/New_York:2
 0260422T170000
URL;TYPE=URI:https://www.wpi.edu/news/calendar/events/ece-m
 s-thesis-presentation-isabelle-benson-clarke
ECE MS Thesis Presentation by: Isabelle Benson-Clarke
\n\n\nImage\n  \n\n\n\nTitle:\nExperimental Investigation of Magnetic and E
 lectrical Stimulation in the Crayfish Giant Axon\n\nAbstract:\nThis resear
 ch tests whether a single-pulse magnetic or electrical stimulation can evo
 ke an action potential (AP) in an isolated crayfish (Procambarus clarkii) 
 axon. There are two working hypotheses:\n\n\nElectrical (extracellular) St
 imulation- The induced electric field (E) produced by an electrical pulse 
 would depolarize the axonal membrane sufficiently to trigger an AP. The sp
 ecific objective was to determine the parameters necessary (electrical cur
 rent, probe placement, axon position) and under which an electrically evok
 ed AP can be detected, establishing practical threshold bounds for an unmy
 elinated invertebrate axon.\nMagnetic (intracellular) Stimulation- The ind
 uced electric field (E) produced by a rapidly changing coil current (dI/dt
 ) would depolarize the axonal membrane sufficiently to trigger an action p
 otential. The specific objective was to determine the parameter ranges (co
 il position, intensity, pulse width, axon position) under which a magnetic
 ally evoked AP can be detected, establishing practical threshold bounds fo
 r an unmyelinated invertebrate axon.\n\nFor both experiments, adult crayfi
 sh were prepared using established dissection protocols, with abdominal ga
 nglia left in continuity and immersed in saline. For intracellular experim
 ents, the ganglia were additionally desheathed. In the electrical stimulat
 ion experiments, electrical stimuli were applied at the ganglia, while act
 ion potentials were monitored using suction electrodes. In the magnetic st
 imulation experiments, the desheathed axon was probed with microelectrodes
  to record membrane potentials, and the single-pulse magnetic stimulation 
 was delivered via a coil, while the axon was positioned in a chamber desig
 ned to maximize field gradients.\nDespite systematic variation of coil pos
 ition and stimulation intensity, no reproducible action potential was reco
 rded in response to magnetic pulses. Similarly, no reproducible action pot
 ential was recorded in response to electrical pulses. These results demons
 trate that under the tested conditions, the stimulation was insufficient t
 o reach the activation threshold. The crayfish axon is unmyelinated across
  the recording region. The absence of myelin means that capacitive charge 
 leaks continuously along the membrane. This reduces the effectiveness of a
 ny transient field. Consequently, the unmyelinated crayfish axon represent
 s a challenging target for excitation as it requires a higher activation t
 hreshold. The necessary magnetic and electrical stimuli were not possible 
 within the scope of these experiments.\n\nResearch Advisor:\nProf. Sergey 
 Makaroff\nECE Department, WPI\n\nResearch Committee:\nProf. Reinhold Ludwi
 g\nECE Department, WPI\nProf. Greg Noetscher\nECE Department, WPI\nDr. Wil
 liam Wartman\nECE Department, WPI\n\n
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