Design of a 1×4 micro-magnetic stimulation device and its targeted,
coordinated regulation on LTP of Schaffer-CA1 in the hippocampus of rats
Abstract
Micro-magnetic technology has a small size and high spatial resolution,
efficiently realizing the targeted stimulation of deep nuclei inside the
brain. Studying the precise magnetic stimulation of the hippocampal
trisynaptic nerve loop in the brain is essential. Within this work we
designed a 1×4-array micro-magnetic stimulation (μMS) device with four
submillimeter sized commercial inductance. A 3 cm circular coil was
utilized to determine that the 70 kHz/2 mT/1 min stimulation parameters
could elevate the LTP within the CA1 region. Then, using a
micromanipulator, the μMS device was shifted to the CA1, CA3, and DG
areas, after successful induction of LTP using HFS with a 1-s train of
pulses delivered at 100 Hz, the fEPSPs was continuously recorded for 15
min. Based on this procedure, two magnetic stimulation schemes were
utilized. Scheme a (magnetic stimulation of a single region). The 70
kHz/2 mT/1 min magnetic stimulation was introduced to CA1/CA3 and DG
target regions. The experimental results revealed that the LTP enhanced
the most in a single CA1 area, followed by the CA3 area, and not
significantly within the DG area. Scheme b (magnetic stimulation of the
multiple regions). First, the CA1 region was magnetically stimulated and
fEPSPs were recorded. Then, further magnetic stimulation of various
areas was performed. Experimental results revealed that the increased
LTP in the CA1 region was the most effective after magnetic stimulation
among the three CA1/CA3/DG regions. Magnetic stimulation of multiple
areas performed better than stimulation of a single region.