Figure 1.

The apparatus, two-step probabilistic learning task, recording sites, and LFPs analysis. (A) Schematic diagram of the pigeon training apparatus. (B) The two-step task for pigeons is as follows: A 5 s gray screen illuminates to indicate the trial is ready. Step 1 (transition structure) is initiated by the simultaneous presentation of two differently colored markers (S1⁺ and S1⁻) on both sides of the screen. The pigeons indicate their choice by pecking the key below the corresponding target option. A probabilistic transition takes place, with probability depending on the choice of the pigeons. Following this, a blue triangle (S2⁺) or a circle (S2⁻) marker appears in the middle of the screen, indicating the outcome of the transition and initiating Step 2 (reward structure). The pigeons then peck the key below the S2 target within 2 s. A 3 s reward is delivered with an appropriate probability. (C) The histological verification of the implantation site. (D) The schematic of the acquired 16-electrode LFP signals, represented in different colors. (E) Time-frequency patterns (1–100 Hz) were extracted from all electrodes. For every temporal epoch during the S1 and S2 presentation, the $\mathrm{z}$-scored power from every electrode $l$ and every frequency $f$ band was combined to create a single feature vector $Z_{l,f}$ for that epoch. Numbers 1–16 represent the electrode’s ID (F) Distributed oscillatory power of S1 (top panel) or S2 (bottom panel). Two feature vectors ${\overrightarrow{\mathrm{S}1}}_{\mathrm{i}}$ and ${\overrightarrow{\mathrm{S}2}}_{\mathrm{j}}$ composed of all vectors $Z_{l,f}$, for each S1 presentation temporal epoch $i$, and each S2 presentation temporal epoch $j$, were constructed. (G) Neural similarity (cosine similarity rho) for all temporal context-dependent state pairs was shown for a single trial.