Dynamics of decision‐related activity in hippocampus

Abstract

Place-selective activity in hippocampal neurons can be modulated by the trajectory that will be taken in the immediate future ("prospective coding"), information that could be useful in neural processes elaborating choices in route planning. To determine if and how hippocampal prospective neurons participate in decision making, we measured the time course of the evolution of prospective activity by recording place responses in rats performing a T-maze alternation task. After five or seven alternation trials, the routine was unpredictably interrupted by a photodetector-triggered visual cue as the rat crossed the middle of central arm, signaling it to suddenly change its intended choice. Comparison of the delays between light cue presentation and the onset of prospective activity for neurons with firing fields at various locations after the trigger point revealed a 420 ms processing delay. This surprisingly long delay indicates that prospective activity in the hippocampus appears much too late to generate planning or decision signals. This provides yet another example of a prominent brain activity that is unlikely to play a functional role in the cognitive function that it appears to represent (planning future trajectories). Nonetheless, the hippocampus may provide other contextual information to areas active at the earliest stages of selecting future paths, which would then return signals that help establish hippocampal prospective activity.

Is there a pilot in the brain? Contribution of the self-positioning system to spatial navigation

“…Overall, we think that there is a deep need for re-assessing the fine structure of the spatial behavior of the animal in register with the discharge properties of cells carrying spatial signals. A good illustration of the type of analysis that would be useful is provided by studies in which neuronal activity is analyzed in relation to specific behaviors at specific places, such as decision points (e.g., Johnson and Redish, 2007 ; Catanese et al, 2012 ), specific landmark objects (e.g., Save et al, 1998 ), goal locations (e.g., Hok et al, 2007 ), as well as during performance of well-designed spatial navigation tasks (e.g., Pfeiffer and Foster, 2013 ). In such a way, it becomes possible to draw functional relationships between cell firing and cognitive processes hypothesized to support self-localization and navigation.…”

Behavioral correlates of activity of optogenetically identified locus coeruleus noradrenergic neurons in rats performing T-maze tasks

“…The behavioral task (adapted from ref. 38 ) took place in an area closed off by black curtains forming a large cylinder. Within this was an automated T maze elevated 70 cm above the floor (see Fig.…”

Distributed cell assemblies spanning prefrontal cortex and striatum

“…The automated T-maze with return arms (See Figure 4A; cf. Wood et al 89 and Catanese et al 90 ). The experimental chamber was a 3 m diameter cylindrical space, enclosed by black curtains running from floor to ceiling and was lit by a ceiling mounted light bulb.…”