A Time Duration Discrimination Task for the Study of Elapsed Time Processing in Rats

Abstract

Space and time are both essential features of episodic memory. However, while spatial tasks have been used effectively to study the behavioral relevance of place cells, the behavioral paradigms utilized for the study of time cells have not used time duration as a variable that animals need to be aware of to solve the task. In order to evaluate how time flow is coded into memory, time duration needs to be a variable that animals use to solve the behavioral task. This protocol describes a novel behavioral paradigm, the time duration discrimination (TDD) task, which is designed to directly investigate the neurological mechanisms that underlie temporal processing. During the TDD task, rats navigate around a Figure-8 Maze, which contains a rectangular track with a central arm and a delay box at the end of the central arm. While confined to the delay box, rats experience a 10-or 20-second time delay, during which a tone will play for the duration of the 10-or 20-second delay. When the delay box opens, the rat will choose whether to turn left or right out of the delay box and receive a reward for the correct choice (e.g., 10 seconds = left turn; 20 seconds = right turn). By directly manipulating elapsed time, we can better explore the behavioral relevance of hippocampal time cells and whether the time-dependent activity seen in physiological recordings of hippocampal neurons reflects a neuronal representation of time flow that can be used by the animal for learning and storing memories.

Memory deficits and hippocampal cytokine expression in a rat model of ADHD

“…Deficits in memory for elapsed time are another important characteristic of ADHD yet inconclusively measured in SHR ( Smith et al, 2002 ; Toplak and Tannock, 2005 ; Lee and Yang, 2019 ). While previous research by Ferguson et al (2007) found comparable temporal processing performances between SHR and WKY rats, our study employed the TDD task ( Sabariego et al, 2021 ; Tenney et al, 2021 ) to assess time discrimination of longer delay periods in male and female SHR and WKY rats. Our findings showed that female SHR struggled to differentiate between delay lengths, particularly in longer, 20-s delay trials, aligning with time processing deficits observed in individuals with ADHD ( Lee and Yang, 2019 ; Smith et al, 2002 ; Toplak and Tannock, 2005 ).…”

“…The TDD task is a hippocampal-dependent task designed to assess a rat's ability to discriminate between different lengths of elapsed time ( Sabariego et al, 2021 ; Tenney et al, 2021 ). For detailed methods on the procedure used for this task, see Tenney et al (2021) .…”

“…The TDD task is a hippocampal-dependent task designed to assess a rat's ability to discriminate between different lengths of elapsed time ( Sabariego et al, 2021 ; Tenney et al, 2021 ). For detailed methods on the procedure used for this task, see Tenney et al (2021) . In short, rats were trained to turn to one side of a figure-8-maze (e.g., left) after a 10-s delay and to the other side (e.g., right) after a 20-s delay, as depicted in Fig.…”