Genetic approach to variability of memory systems: Analysis of place vs. response learning and Fos-related expression in hippocampal and striatal areas of C57BL/6 and DBA/2 mice

Abstract

C57 and DBA mice were trained in a crossed maze to assess possible strain differences in place or response learning as a function of training duration (8 or 17 days) and extramaze cueing conditions. The first condition consisted of a diffuse visually cued environment (rich cueing). The second was the same plus an explicit visual cue marking the direction of the baited arm (rich cueing plus cue). The third was a featureless environment (poor cueing). During training, mice were released from the south arm and rewarded in the east arm. Probe trials on which mice were released from the north arm and allowed to choose either the east (place learning) or the west (response learning) arm were given either on the ninth (PT1) or the eighteenth (PT2) days. Strain x context differences in the activation of the dorsal hippocampus and the dorsolateral striatum were examined by analyzing Fos expression following each probe trial. Results first showed that C57 were essentially place-learners, whereas no learning modality was predominant in DBA, except on the PT2 run with the explicit cue available. Examination of Fos expression in C57 trained under "rich cueing" and "rich cueing plus cue" conditions revealed a strong and parallel increase of immunoreactivity in the hippocampus and dorsolateral striatum following PT1 that decreased under PT2. In that strain, the similar time-course variation of Fos expression in both areas suggests a simultaneous involvement of hippocampal- and striatal-based learning mechanisms, even if those controlled by the hippocampus were prevailing on those controlled by the dorsolateral striatum. In DBA mice, however, the absence of any preferential learning modality was associated with 1) a consistent hippocampal activation persistent across probe trials, and 2) a global superior activation of the dorsolateral striatum. Distinct patterns of Fos expression were therefore associated with every strain-specific learning modality. In each strain, however, each modality was found to be remarkably stable, whatever the training duration and the cueing conditions.

Humanized Foxp2 accelerates learning by enhancing transitions from declarative to procedural performance

“…1). This possibility is in accord with reports of less efficient learning in an environment in which the two learning strategies of declarative/place-based and procedural/response-based learning can interact competitively (25) and that WT C57BL/6 mice are "essentially place learners" (33)(34)(35). By this view, the abundance of spatial cues in the original maze task did not impair the performance of the Foxp2 hum/hum mice, which might have dealt more effectively with competition between the two available learning strategies.…”

“…Given this result, we turned to a cross-maze task often used to discriminate place-based from response-based learning (15,17,25). We chose a Tolman variation of the task (16,36), tailored for our purposes, because the cross-maze variation by Packard and McGaugh (15) has been reported to be difficult for mice (33)(34)(35). In this cross-maze paradigm, we were able to test declarative/place-based learning and procedural/response-based learning separately as well as to challenge the interaction between them by testing the ability to change between place-based and response-based learning.…”

Re-thinking the role of the dorsal striatum in egocentric/response strategy

“…It seems now rather well established that rats strongly favour response strategy after extended training in a dual-solution task tested on in a cross-maze (Ritchie et al, 1950;Restle, 1957;Hicks, 1964;Mitchell and Hall, 1988;Packard and McGaugh, 1996;Oliveira et al, 1997;Passino et al, 2002;Yin and Knowlton, 2004). The present results showing that 74% of the control rats exhibited a response strategy during the second probe trial, confi rmed these previous fi ndings.…”

“…A large number of studies have shown that the use of place and response strategies early in training depends largely on intra-and extra-maze cue arrangements and densities (Tolman et al, 1946(Tolman et al, , 1947Restle, 1957;Oliveira et al, 1997;Passino et al, 2002;Canal et al, 2005). The capacity to use environmental cues to drive the behaviour (i.e.…”

The temporal dynamics of intrahippocampal corticosterone in response to stress-related stimuli with different emotional and physical load: An in vivo microdialysis study in C57BL/6 and DBA/2 inbred mice

“…C57BL/6 and DBA/2 inbred mice have previously been used as a genetic animal model for anxiety-related and depression-like behavior (Crawley et al, 1997;Griebel et al, 1997;Ohl et al, 2003;Jacobson and Cryan, 2007) as well as a model of distinct hippocampal functioning regarding learning and memory (Ammassari-Teule et al, 2000;Passino et al, 2002). Moreover, it has been reported that mice of both strains show differences in glucocorticoid hormone responses towards stress but not under basal conditions (Cabib et al, 1990;Jones et al, 1998;McNamara et al, 2003;Shanks et al, 1990).…”