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Melior Discovery neurophysiology

Cortical EEG Frequency
Cortical EEG activity can be recorded from chronically implanted rats and mice and evaluated as a function of frequency to characterize or compare effects of psychoactive drugs such as benzodiazepines, NMDA antagonists, etc.  EEG activity (0.03 - 100 Hz) is recorded for 24 hours or more, and evaluated over discrete frequency ranges and time periods depending on the observed drug effects.

Figure A- Baseline EEG:

Raw EEG data is analyzed by Fourier analysis to derive EEG power as a function of frequency.  Raw data (left) shows typical reduction in power with frequency (average over 90 minutes prior to dosing).  Middle graph shows the same data subdivided into 7 discrete frequency ranges and normalized across animals.  Right graph is normalized data with Vehicle group subtracted showing no pre-dosing difference between groups. 

 

Figure B- EEG power after treatment with Diazepam:

          

Graphs above are vehicle-subtracted curves of EEG power at indicated times after treatment with diazepam (5mg/kg IV) in rats.  Note the initial increase in low frequency power at 5 minutes, reversal at 60 minutes and reversal again at 540 minutes.  Also note the general reciprocity of effects below 30 Hz (where increased power is associated with sleep or sedation) versus above 30 Hz, which is associated with wake or cognition.

 

Video- 3-D View of EEG Power Following Administration of Zolpidem as a Function of Frequency and Time:

                                                          

This video shows a 3-D graph of average EEG power from 0.3 - 96 Hz following dosing with Zolpidem (30mg/kg IP at 3pm = ZT-8, time 0) in mice. The EEG power shown is vehicle-subtracted as in the graphs above, thus the Z-axis (power) represents change relative to the vehicle group up to 8.5 hours post dosing.  Note that power is relatively increased between 0.3 - 2 Hz and 8 - 30 Hz; all other frequencies are decreased.  The peak EEG power at 20 Hz is maximum at 5 minutes post dosing, and then EEG power across all frequencies approaches the vehicle values over the next 2.5 hours.  Drug effects can be compared using 3-factor ANOVA. 

 

If you are interested in learning more about Cortical EEG Frequency testing, please contact models@meliordiscovery.com to start the conversation today.