Much shorter pulses are achievable with greater modulation depth [22] with the theoretical limit of Ytterbium well under 20 fs and the practical record currently at 47 fs [32].
Thus, the greater modulation depth of RR units at replay events compared to nonreplay events did not derive from differences in the intensity of hippocampal spiking.
In addition, the large modulation depth indicated coupling to at least two neighbors.
The majority of VTA units that were significantly modulated at SPW-R events were RR (17/20 compared to 47/84 recorded, p=0.03, chi = 4.6, Chi-square test), and SPW-R modulation depth was greater for RR units than nonRR units (RR units 0.21 ± 0.04, n = 45; nonRR units 0.11± 0.02; p=0.017, n = 23, rank-sum test).
Moreover, the modulator showed a maximum modulation depth of 99%.
Psychometric functions (percent correct discrimination of modulated from unmodulated stimuli versus modulation depth) were obtained.
(C ) PETH modulation depth of RR units (blue) is greater for replay than nonreplay events; p=4.5 × 10-4, signed-rank test).
All target tones were either 1007 Hz pure tones or 1007 Hz amplitude-modulated tones (modulation frequency 40 Hz; modulation depth 0.9).
The advantage of greater Q factor is that the energy requirements are reduced for the same modulation depth.
Moreover, since the modulation depth of the spatial overlap in the focal region is much greater than those in out-of-focus regions, out-of-focus background signals, which limit the obtainable imaging depth, are well suppressed.
This modulator features ease of fabrication, low cost, and a controllable modulation depth.
