Genesis of MEG signals in a mammalian CNS structure

Yoshio C. Okada, Jie Wu, Shinichi Kyuhou

Research output: Contribution to journalArticlepeer-review

142 Scopus citations

Abstract

Neuromagnetic signals of guinea pig hippocampal slices were characterized and compared with the extracellular field potential to elucidate the genesis of magnetoencephalographic signals in a mammalian CNS structure. The spatial distribution of magnetic evoked field (MEF) directed normal to bath surface was similar for transverse CA1, longitudinal CA1 and longitudinal CA3 slices in the presence of 0.1 mM picrotoxin (PTX) which blocks inhibitory synaptic transmission. Their MEFs were produced by currents along the longitudinal axis of the pyramidal cells. Comparisons of the MEF with the laminar potential profile revealed that the MEF was generated by intracellular longitudinal currents. The dipolar component of the intracellular currents was the dominant factor generating the MEF even at a distance of 2 mm from the slice. The MEF from a slice in Ringer's solution without PTX became similar in temporal waveform with time to the MEF in the presence of PTX, indicating the predominance of excitatory connections in generating the MEF and the existence of highly synchronous population activities across the slice even in PTX-free Ringer's solution. The presence of such highly synchronous population activities underlying the MEFs was verified directly with field potentials recorded across the slice. A systematic variation of the stimulation site revealed a characteristic waveform for each site. The variation of the waveform with stimulation site suggested the contribution of many factors, both synaptic and voltage- sensitive conductances, to the overall waveform of the MEF.

Original languageEnglish (US)
Pages (from-to)474-485
Number of pages12
JournalElectroencephalography and Clinical Neurophysiology
Volume103
Issue number4
DOIs
StatePublished - Oct 1997
Externally publishedYes

Keywords

  • Biomagnetism
  • CA1
  • CA3
  • Electroencephalography (EEG)
  • Hippocampus
  • Magnetoencephalography (MEG)

ASJC Scopus subject areas

  • General Neuroscience
  • Clinical Neurology

Fingerprint

Dive into the research topics of 'Genesis of MEG signals in a mammalian CNS structure'. Together they form a unique fingerprint.

Cite this