Simultaneous recording of evoked potentials and T2-Weighted MR images during somatosensory stimulation of rat

• Published in: Magnetic resonance in medicine Vol. 41; no. 3; pp. 469 - 473
• Main Authors: BRINKER, G, BOCK, C, BUSCH, E, KREP, H, HOSSMANN, K.-A, HOEHN-BERLAGE, M
• Format: Journal Article
• Language: English
• Published: Baltimore, MD Williams & Wilkins 01.03.1999
• Subjects: Animals; Biological and medical sciences; Brain - anatomy & histology; Brain - physiology; Cerebrovascular Circulation - physiology; Electric Stimulation; Electrophysiology; Evoked Potentials, Somatosensory; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging; Male; Medical sciences; Nervous system; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Rats; Rats, Wistar; Reproducibility of Results; Sensitivity and Specificity; Rat; Rodentia; Central nervous system; Electrophysiology; Stimulation; Functional analysis; Nuclear magnetic resonance imaging; Electrodiagnosis; Vertebrata; Mammalia; Spin spin relaxation; Animal; Simultaneous measurement; Medical imagery; Somatosensory evoked potential; Brain (vertebrata)
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/(sici)1522-2594(199903)41:3<469::aid-mrm7>3.0.co;2-9

Somatosensory evoked potentials (SEP) and T2*-weighted nuclear magnetic resonance (NMR) images were recorded simultaneously during somatosensory stimulation of rat to investigate the relationship between electrical activation of the brain tissue and the signal intensity change in functional NMR imaging. Electrical forepaw stimulation was performed in Wistar rats anesthetized with alpha-chloralose. SEPs were recorded with calomel electrodes at stimulation frequencies of 1.5, 3, 4.5, and 6 Hz. At the same time, T2*-weighted imaging was performed, and the signal intensity increase during stimulation was correlated with the mean amplitude of the SEP. Both the stimulation-evoked signal intensity increase in T2*-weighted images and the amplitude of SEPs were dependent on the stimulation frequency, with the largest signals at a stimulation frequency of 1.5 Hz and decreasing activations with increasing frequencies. The feasibility of simultaneous, artifact-free recordings of T2*-weighted NMR images and of evoked potentials is proved. Furthermore, the study demonstrates-in the intact brain-the validity of functional magnetic resonance imaging for estimating the intensity of electrocortical activation.