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. Author manuscript; available in PMC: 2009 Jul 1.
Published in final edited form as: Neurobiol Learn Mem. 2008 Mar 17;90(1):125–137. doi: 10.1016/j.nlm.2008.02.001

Figure 3.

Figure 3

Effectiveness of NBstm and tone alone on the auditory cortex after completion of the place-preference test, and comparison with EEG activation during tone-NBstm pairing. Subjects received 200 presentations each of tone and NBstm randomly. (A) Example of EEG activation by NBstm (200 ms, 100 Hz, 60 µA bipolar stimulation) observed for “All Bands”, “Alpha” and “Gamma” bands, as described in Figure 2. As for EEG activation during tone-NBstm pairing, there is a shift from higher voltage, slower waves to lower voltage, faster waves (“All Bands”) with pronounced decrease in alpha activity and increase in gamma activity. Thick narrow bar indicates 200 ms period of NBstm. (B) Group mean spectral changes in EEG induced by NBstm alone. NB stimulation-induced spectral changes in the EEG relative to pre-stimulation period (first 2 s out of 4 s immediately preceding NBstm, computed as in Figure 2. (C) Comparison of EEG activation during training and after place-preference test. The graph shows the mean “EEG Activation Index” (EAI) for tone + NBstim during pairing, NBstm alone and also tone alone after place-preference test. Note that there was no significant difference between the peak magnitudes of the EAI values (p > 0.15 for designated data points), indicating that NBstm potency had not diminished after induction of specific memory during training. During tone-NBstm pairing, both stimuli contribute to the magnitude of EEG activation. However, the contributions of the tone preceding presentation of the NBstm can be observed in the first two data points following tone onset. This probably reflects conditioned EEG activation (McLin, Miasnikov and Weinberger, 2003). Tone alone after the place-preference test still elicits considerable EEG activation although obtained in the absence of pairing (i.e, potential extinction period). Its peak EAI is not significantly different from activation to tone during pairing with NBstm (p > 0.10), suggesting conditioned EEG activation is robust. (D) EEG spectral changes to tone alone after place-preference test. Although smaller in magnitude, note the similarity of the EEG effects of tone alone with the tone-NBstm pairing (Figure 2B) and NBstm alone (Figure 3B).

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