Table 2 Statistical results for skewness of the target vs. foil distributions at retrieval by the pattern of firing at encoding.

From: Neuronal allocation and sparse coding of episodic memories in the human hippocampus

 

Skewness

Interaction

Region

Δ (H–A) Target–Foil

Hippocampus

Amygdala

p

Targets

Foils

p

Targets

Foils

p

Low–High

0.008**

6.79

3.05

0.004**

3.27

3.28

0.989

High–High

0.803

2.61

3.05

0.716

3.18

3.28

0.878

High–Low

0.891

2.21

3.05

0.527

2.64

3.28

0.388

Low–Low

0.473

3.10

3.05

0.965

2.42

3.28

0.173

  1. A significant interaction was defined as a greater difference in a given statistical moment between one subset of targets partitioned by the pattern of firing at encoding (spiking activity directly before and during stimulus onset) vs. the foil normalized spike count distributions in one region (e.g., the hippocampus), compared to the corresponding difference in the other region (e.g., the amygdala), according to bootstrap tests (Δ(H–A) Target–Foil, B = 10,000, Bonferroni corrected, p < 0.0125, two-tailed). The interaction was significant for the subset of targets with a relative increase in excitability at encoding (Low-High: p = 0.008) but not for any other categories of targets (High-High: p = 0.803, High-Low: p = 0.891, or Low-Low: p = 0.473). Within the hippocampus, a significant difference between the skewness values of the target vs. foil distributions at retrieval (theoretically indicative of the item-specific memory signal) was observed only for targets with a relative increase in excitability at encoding (Low-High: p = 0.004). Within the amygdala, no significant difference in skewness between the target and foil distributions was observed. Corresponding analyses for the other statistical moments are reported in Supplementary Table 1. **p < 0.01.
Back to article page