Deliberative decision making

A recent direction in our laboratory work is the understanding of the neural substrates of decision making. This work is funded by a grant from the Human Frontiers Science Program. At the moment, three projects are underway:

The hippocampus and vicarious trial-and-error behaviour

When an animal faces a decision point - say, a T junction on a maze - they often make a back-and-forth head movements before choosing which way to go. This is termed vicarious trial-and-error (VTE), and was characterised by experimental psychologist in the early 20th century. The purpose of this experiment is to determine whether the hippocampus is necessary for VTE behaviour, and whether this differs in a spatial task (below left) and a visual discrimation task (below right).

Double Y-maze Vicarious trial and error

The role of the hippocampus in delay-discounting behaviour

A second experiment, in collaboration with David Redish, is testing whether the hippocampus is necessary for the weighing of spatial alternatives. Rats are trained on a task in which they have to choose between an immediate, small reward or a delayed, larger reward. The twist here is that the rats can change the longer delay by selecting the immediate reward repeatedly, and they tend to show more vicarious trial-and-error behaviours prior to achieving a stable delay.

Uncertainty and vicarious trial-and-error

A third experiment, designed by Anthony Cruickshank, a Neuroinformatics MSc student, is testing the effects of uncertainty on decision making in a continuous T-maze. Rats are trained to associate one tone with each of the maze arms, e.g., tone A indicates that the left arm is rewarded, and tone B indicates that the right arm is rewarded. The tone is played when the animal is on the centre stem of the T, before it has made its choice. In the experiment, the discriminability of the tones will be altered to make the decision more difficult.