Jena Hales
  • Faculty, University of San Diego
Research fields
  • Neuroscience
A Time Duration Discrimination Task for the Study of Elapsed Time Processing in Rats

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.


Graphic abstract:



Elapsed time duration discrimination in rats

Displaced Object Recognition Memory in Rats
Authors:  Ali N. Mclagan and Jena B. Hales, date: 04/20/2019, view: 5188, Q&A: 0
The Displaced Object Recognition (DOR) task, sometimes called the Novel Object Location task, assesses spatial recognition memory without navigational demands, explicit instruction, or the need for multiple days of training. This memory task has two phases. First, the subject is familiarized to an open arena with two objects and is allowed to explore the objects. Following a delay period, the subject returns to the arena, but one of the previous objects has been moved to a new location. Greater exploration of the displaced object is used as the index of memory for the previous object location. An advantage of the DOR task is that subjects can be tested without explicit training, since this task exploits the natural tendency to be more interested in something novel. The spontaneous aspect of this task allows for the testing of animals as well as human populations that are unable to follow verbal instructions, such as babies. Therefore, this powerful test of recognition memory can be administered similarly for many species, including rats and humans, allowing for better translatability.
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