Changes in goal selection induced by cue conflicts are in register with predictions from changes in place cell field locations.

In the cognitive mapping theory of hippocampal function, currently active place cells represent a rat's spatial location (J. O'Keefe & L. Nadel, 1978). A systematic shift of firing field locations should therefore produce a similar shift in a rat's judgment of its location. A. A. Fenton, G. Csizmadia, and R. U. Muller (2000a) recorded place cells in cylinders with 2 cue cards separated by 135°. When the separation was changed, firing fields moved systematically, as described by a vector-field equation (A. A. Fenton, G. Csizmadia, & R. U. Muller, 2000b). Given this cohesive movement of firing fields, the mapping theory predicts that a rat's decisions about the location of an unmarked goal should move after card separation changes, as described by the vector-field equation. The authors tested this reasoning with a task in which the rat earned a food reward by pausing in a small, unmarked goal zone. When cues were shifted in the absence of reward, goal choice shifts were accurately predicted by the vector-field equation, providing strong support for the notion that a rat's judgment of its spatial location is intimately related to the across-cell discharge pattern of simultaneously active place cells. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transient sex differences in the between-sessions but not in the within-session memory underlying an active place avoidance task in weanling rats.

Spatial abilities were tested in male and female rats by training them to avoid an area in which there was a mild footshock while the arena rotated at 1 revolution/minute. The to-be-avoided area was stable in the coordinates of the room, so extramaze landmarks had to be used for accurate navigation, as the rotation made intramaze cues and substrate-based path integration useless for the avoidance. From Postnatal Day (PD) 19, rats were trained for 22 consecutive days. When the shock area was the same across sessions male rats reached optimal performance on PDs 23–24, 10 days before female rats, but when the location of the shock changed daily there were no sex differences. The results indicate that there are separate memory components underlying spatial competence: a within-session component that develops similarly in male and female rats and a between-sessions component that lasts at least 24 hr and appears earlier in male than in female rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)