Abstract
Advances in computer technology have allowed quantification of the electroencephalogram (EEG) and expansion of quantitative EEG (qEEG) analysis in neurophysiology, as well as clinical neurology, with great success. Among the variety of techniques in this field, frequency (spectral) analysis using Fast Fourier Transforms (FFT) provides a sensitive tool for time-course studies of different compounds acting on particular neurotransmitter systems. Studies presented here include Electrocorticogram (ECoG) analysis following exposure to a glutamic acid analogue - domoic acid (DOM), psychoactive indole alkaloid - ibogaine, as well as cocaine and gamma-hydroxybutyrate (GHB). The ECoG was recorded in conscious rats via a tether and swivel system. The EEG signal frequency analysis revealed an association between slow-wave EEG activity delta and theta and the type of behavioral seizures following DOM administration. Analyses of power spectra obtained in rats exposed to cocaine alone or after pretreatment with ibogaine indicated the contribution of the serotonergic system in ibogaine mediated response to cocaine (increased power in alpha1 band). Ibogaine also lowered the threshold for cocaine-induced electrographic seizures (increased power in the low-frequency bands, delta and theta). Daily intraperitoneal administration of cocaine for two weeks was associated with a reduction in slow-wave ECoG activity 24 hrs following the last injection when compared with controls. Similar decreased cortical activity in low-frequency bands observed in chronic cocaine users has been associated with reduced metabolic activity in the frontal cortex. The FFT analyses of power spectra relative to baseline indicated a significant energy increase over all except beta2 frequency bands following exposure to 400 and 800 mg/kg GHB. The EEG alterations detected in rats following exposure to GHB resemble absence seizures observed in human petit mal epilepsy. Spectral analysis of the EEG signals combined with behavioral observations may prove to be a useful approach in studying chronic exposure to drugs of abuse and treatment of drug dependence.
Highlights
Electroencephalography and neuroimaging are major techniques in brain investigation
Among the variety of techniques in this field, the computer assisted frequency analysis (FFT) of the EEG signals provides a sensitive tool for time-course studies of different compounds acting on particular neurotransmitter systems
The Fast Fourier Transforms (FFT) mathematical conversion applied to EEG signals takes into account both frequency and amplitude of the signal within defined powers
Summary
Electrocerebral activity represents local action potentials and widespread excitatory and inhibitory postsynaptic potentials recorded as the EEG. Among the variety of techniques in this field, the computer assisted frequency (spectral) analysis (FFT) of the EEG signals provides a sensitive tool for time-course studies of different compounds acting on particular neurotransmitter systems. Bipolar stainless steel electrodes were implanted 3 mm laterally from the sagittal fissure, 1 and 4 mm posterior to the bregma. They were referenced to a ground electrode placed in the dorsal neck. The power spectra obtained by use of FFT were divided into 1.25-4.5 Hz (delta), 4.75—6.75 (theta), 7.00-9.50 Hz (alpha1), 9.75-12.50 Hz (alpha2), 12.7518.5 Hz (beta1), and 18.75-35.00 Hz (beta2) frequency bands [2]. All animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of the NCTR and conducted in full accordance with the PHS policy on humane care and use of laboratory animals and the NIH guide for the care and use of laboratory animals
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
