The Journal of Neuroscience, June 7, 2006, ():
Hippocampal Slow Oscillation: A Novel EEG State and Its Coordination with Ongoing Neocortical Activity
J. Neurosci. Wolansky et al.
26: 6213
Supplemental data
Files in this Data Supplement:
- supplemental material
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Supplemental Figure 1: Neocortical indifferent electrode versus stereotaxic ground reference during urethane anesthesia.
(A) Raw signals recorded from the HPC and fCTX referenced to stereotaxic ground (left panel) and the neocortical indifferent electrode (right panel) appear very similar and are comparable to traces shown in the other figures of the manuscript. Spectral analysis of the signals reveals that (B) the peak frequency was the same in both the HPC and fCTX (0.83Hz) and the maximum power was not significantly (t-test: p>0.01) different in either the fCTX (versus ground 10.4 ± 1.9; versus indifferent electrode 16.8 ± 3.3mV2) or the HPC (versus ground 24.9 ± 4.6; versus indifferent electrode 19.1 ± 4.0mV2) across the two referencing conditions. (C) The coherence at the peak frequency across the HPC and fCTX was comparable to our other measurements (versus ground 0.75 ± 0.05; versus indifferent electrode 0.69 ± 0.06), and was not significantly (t-test: p>0.01) different across the two conditions. (D) Finally, there was no difference (t-test: p>0.01) in the phase angle of the two signals (versus ground -2.7 ± 0.1; versus indifferent electrode -2.6 ± 0.2rad) across the two conditions.
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Supplemental Figure 2: Spectral analysis of digitally filtered signals during urethane anesthesia.
(A) Overlaid samples of raw (grey) and digitally filtered (black) theta (left panel) and SO (right panel) activity and (E) crosscorrelation analysis demonstrate that filtering did not phase-distort the signals. Theta traces were bandpass filtered from 3 to 6Hz (3rd order) and SO traces were lowpass filtered at 2.5Hz (3rd order) (red lines represent filter bandwidths). Spectral analysis of the signals reveals identical power peak frequencies (B), perfect coherence (C), and zero phase shift (D) within filter frequency ranges.
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Supplemental Figure 3: Sin wave input/output analysis of Plexon amplifier system during urethane anesthesia.
A frequency-dependent phase shift was observed in the output of the amplifier system in response to stationary sin wave input (0.1 to 30Hz). The values of the phase shifts in radians are shown plotted against input frequency. Though the phase shift at 1Hz is significant (1.26 ± 0.06rad; 72.19 ± 3.44deg), we mathematically incorporated this shift into our phase values prior to subsequent analysis.
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Supplemental Figure 4: The slow oscillation is unrelated to the respiratory rhythm during urethane anesthesia.
(A) Simultaneously recorded field signal from the HPC, nCTX and respiration. Vertical lines aligned with the positive phase of the respiratory rhythm demonstrate that there is no phase relationship to hippocampal or neocortical slow oscillatory activity. Peak spectral frequencies of hippocampal (1.5Hz; 1.33 ± 0.08Hz) and neocortical (1Hz; 1.33 ± 0.08Hz) field are completely different from respiration (1.83Hz; 2.17 ± 0.15Hz; grey shaded area represents 95% confidence interval) (B). (C) No significant coherence was observed between respiration and SO field activity in the HPC (0.06; 0.19 ± 0.03) or nCTX (0.12; 0.14 ± 0.02), although hippocampal-neocortical coherence remained intact (0.74; 0.57 ± 0.03).
