title: Design and demonstration in vitro of a mouse-specific Transcranial Magnetic Stimulation coil

authors: Khokhar, Farah Adeebah

abstract: Background. Transcranial Magnetic Stimulation (TMS) is a technique used to treat different neurological disorders non-invasively. A pulsed current to a coil generates a magnetic field (B-field) which induces an electric field (E-field). Underlying biophysical effects of TMS are unclear. Therefore, animal experiments are needed; however, making small TMS coils suitable for mice is difficult and their field strengths are typically much lower than for human sized coils. Objectives/Hypothesis. We aimed to design and demonstrate a mouse-specific coil that can generate high and focused E-field. Methods. We designed a tapered TMS coil of 50 turns of 0.2 mm diameter copper wire around a 5 mm diameter tapered powdered iron core and discharged a 220 μF capacitor at 50 V through it. We measured B-field with a Hall probe and induced E-field with a wire loop. We measured temperature rise with a thermocouple. We applied 1200 pulses of continuous theta burst stimulation (cTBS) and intermittent theta burst stimulation (iTBS) to mouse brain slices and analysed how spontaneous electrical activity changed. Results. The coil gave maximum B-field of 685 mT at the base of the coil and 340 mT at 2 mm below the coil, and maximum E-field 2 mm below the coil of approximately 10 V/m, at 50 V power supply, with a temperature increase of 20 degrees after 1200 pulses of cTBS. We observed no changes in B-field with heating. cTBS reduced frequency of spontaneous population events in mouse brain slices up to 20 minutes after stimulation and iTBS increased frequency up to 20 minutes after stimulation. No frequency changes occurred after 20 minutes. No changes in amplitude of spontaneous events were found. Conclusion. The design generated fields strong enough to modulate brain activity in vitro.

text: Design and demonstration in vitro of a mouse-specific Transcranial Magnetic Stimulation coil Background. Transcranial Magnetic Stimulation (TMS) is a technique used to treat different neurological disorders non-invasively. A pulsed current to a coil generates a magnetic field (B-field) which induces an electric field (E-field). Underlying biophysical effects of TMS are unclear. Therefore, animal experiments are needed; however, making small TMS coils suitable for mice is difficult and their field strengths are typically much lower than for human sized coils. Objectives/Hypothesis. We aimed to design and demonstrate a mouse-specific coil that can generate high and focused E-field. Methods. We designed a tapered TMS coil of 50 turns of 0.2 mm diameter copper wire around a 5 mm diameter tapered powdered iron core and discharged a 220 μF capacitor at 50 V through it. We measured B-field with a Hall probe and induced E-field with a wire loop. We measured temperature rise with a thermocouple. We applied 1200 pulses of continuous theta burst stimulation (cTBS) and intermittent theta burst stimulation (iTBS) to mouse brain slices and analysed how spontaneous electrical activity changed. Results. The coil gave maximum B-field of 685 mT at the base of the coil and 340 mT at 2 mm below the coil, and maximum E-field 2 mm below the coil of approximately 10 V/m, at 50 V power supply, with a temperature increase of 20 degrees after 1200 pulses of cTBS. We observed no changes in B-field with heating. cTBS reduced frequency of spontaneous population events in mouse brain slices up to 20 minutes after stimulation and iTBS increased frequency up to 20 minutes after stimulation. No frequency changes occurred after 20 minutes. No changes in amplitude of spontaneous events were found. Conclusion. The design generated fields strong enough to modulate brain activity in vitro.

year: 2021

title: Marlborough, Nelson and Tasman Regions–A Socio-Demographic Profile 1986-2061

authors: Jackson, Natalie

abstract: A Socio-Demographic Profile for Marlborough, Nelson and Tasman Regions.

text: Marlborough, Nelson and Tasman Regions–A Socio-Demographic Profile 1986-2061 A Socio-Demographic Profile for Marlborough, Nelson and Tasman Regions.

year: 2012

title: Frozen rights?: The right to develop Maori treaty and aboriginal rights

authors: Joseph, Robert

subjects: Maori

abstract: Bishop Manuhuia Bennett often asked the question: "What did Maori call New Zealand before the arrival of the Pakeha [Europeans]?" After a deliberate pause, he would then simply utter: "Ours".

text: Frozen rights?: The right to develop Maori treaty and aboriginal rights Bishop Manuhuia Bennett often asked the question: "What did Maori call New Zealand before the arrival of the Pakeha [Europeans]?" After a deliberate pause, he would then simply utter: "Ours".

year: 2011