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. Author manuscript; available in PMC: 2017 Aug 20.
Published in final edited form as: Nat Neurosci. 2017 Feb 20;20(4):590–601. doi: 10.1038/nn.4509

Figure 6. Probe neurons reflect WM-retrieval related evoked activity in MFC.

Figure 6

(a) Firing rate of an example probe neuron recorded from the pre-SMA, shown separately for trials where the probe was held in (IN,cyan) or not (OUT,magenta) in memory. Upper panel shows the PSTH (binsize 200 bins, stepsize 2 ms, shaded areas represent ±s.e.m). Middle panel marks points of time with a significant difference between IN and OUT trials, corrected for multiple comparisons using a cluster-size approach. Bottom panel shows raster with re-ordered trials. Gray vertical bars mark image presentation. (b) Same neuron as in (a), but aligned the response (button press was at 1.2 sec after image presentation) to button press. Note the much reduced peak response (1.44 Hz vs 0.45 Hz, permuted t-test: P=0.005). (c) Percentage of probe neurons in each area. Probe neurons were most prominent in pre-SMA, followed by dACC. (d) Probe neurons elevated their firing rate only during retrieval, but not encoding (P=0.0002, permuted t-test). (e–f) Percentage of probe neurons in each area whose firing rate during probe (−800-0 ms relative to button press) differed as a function of IN vs. OUT (e) or as a function of button press (f). Most cells showed no difference, i.e. they responded equally strongly (but selectively) to the probe stimulus. (c,e,f) Significance was assessed based on a null distribution estimated based on permuted labels. * denotes p< 0.05, ** p< 0.01 and *** p< 0.001.