Temporal encoding: Relative and absolute representations of time guide behavior

Abstract

Temporal information-processing is critical for adaptive behavior and goal-directed action. It is thus crucial to understand how the temporal distance between behaviorally relevant events is encoded to guide behavior. However, research on temporal representations has yielded mixed findings as to whether organisms utilize relative versus absolute judgments of time intervals. To address this fundamental question about the timing mechanism, we tested mice in a duration discrimination procedure in which they learned to correctly categorize tones of different durations as short or long. After being trained on a pair of target intervals, the mice were transferred to conditions in which cue durations and corresponding response locations were systematically manipulated so that either the relative or absolute mapping remained constant. The findings indicate that transfer occurred most readily when relative relationships of durations and response locations were preserved. In contrast, when subjects had to re-map these relative relations, even when positive transfer initially occurred based on absolute mappings, their temporal discrimination performance was impaired, and they required extensive training to re-establish temporal control. These results demonstrate that mice can represent experienced durations both as having a certain magnitude (absolute representation) and as being shorter or longer of the two durations (an ordinal relation to other cue durations), with relational control having a more enduring influence in temporal discriminations. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Figure 1.

Proportion of correct responses on short and long trials after transfer shown separately for each experimental group in Phase 2 of Experiment 1. The insets show the average proportion of correct responses for all trials. Error bars show SEM. Note that we only included the first 12 post-transfer sessions in this graph, as some animals completed Phase 2 in 12 sessions, whereas others required more prolonged training.

Figure 2.

Number of sessions required to perform at ≥ 75% accuracy for two consecutive sessions shown separately for short and long cue durations in Phase 2 transfer test. Lines (solid: short duration, dotted: long duration) show the mean session numbers and symbols (square: short duration, cross: long duration) illustrate individual subjects’ data.

Figure 3.

Proportion of correct responses on short and long trials after transfer shown separately for each experimental group in Phase 2 of Experiment 2. The insets show the average proportion of correct responses for all trials. Error bars show SEM. Note that we only included the first 12 post-transfer sessions in this graph, as some animals completed Phase 2 in 12 sessions, whereas others required more prolonged training.

Figure 4.

Number of sessions required to perform at ≥ 75% accuracy shown separately for short and long cue durations in Phase 2 transfer test. Lines (solid: short duration, dotted: long duration) show the mean session numbers and symbols (square: short duration, cross: long duration) illustrate individual subjects’ data.

Figure 5.

Proportion of correct responses on short and long trials after transfer shown separately for both experimental groups in Phase 3 of Experiment 2. Group_MeanLong (A) consisted of the control and reversal groups of Phase 2, Group_MeanShort (B) consisted of the relative and absolute groups of Phase 2 (refer to the inset plots for each sub-groups’ discrimination accuracy in the first post-shift session). Note that we only included the first 7 post-transfer sessions in this graph, as some animals completed Phase 3 in 7 sessions, whereas others required more prolonged training. Error bars show SEM.