Indeed, in some experiments (n = 5), we also employed sparse noise stimuli (similar to those used previously in the mouse [ 12]), and we found a good correlation to estimates of RF position and diameter obtained with bars.
EA was delivered using a stimulator for 15 min (HANS-200A, Nanjing Jisheng Medical Technology Co., Ltd., China) in alternating trains of dense-sparse rectangular stimuli (2/15 Hz, 0.8 ~ 1.3 mA).
Finally, because responses from the same cell could be compared across stimulus intensities, these data show that the absolute number of responding cells becomes more sparse as the stimulus strength decreases in control animals.
They developed a fast algorithmic version of their previously proposed neural model of motion perception [15], in which a sparse representation of stimulus motion (local velocities) is used and further refined.
The framework introduced in Sect. 3 can be extended to the sparse decoding of spatio-temporal stimuli and the sparse identification of spatio-temporal DSPs of complex cells.
Third, the spike trains observed are used to reconstruct the encoded novel stimuli by the sparse decoding algorithm, assuming that the circuit parameters take the identified values.
In this section, we provide examples that demonstrate the tractability of sparse decoding of spatio-temporal stimuli encoded with complex cells using a small number of spikes.
Although some studies with auditory stimuli have used "sparse" imaging (Hall et al. 1999; Gaab et al. 2002), the continuous nature of the rhythm presentation made it unfeasible to present all stimuli in intermittent silent periods.
For each participant, 1464 EPI volumes, each comprising 26 × 3 mm-thick slices, were acquired with a fast sparse protocol such that speech stimuli could be presented in the 800-ms silent gap between volume acquisitions (TR = 2500 ms, TA = 1700 ms, TE = 30 ms, FA = 78°, matrix size: 64 × 64, in-plane resolution: 3 × 3 mm, slice gap = 25%).
For each stimulus presentation, the spike times generated by the circuit were then utilized to recover the stimulus using the sparse reconstruction algorithm.
