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The effect of retrosplenial cortex lesions in rats on incidental and active spatial learning.

Nelson AJ, Hindley EL, Pearce JM, Vann SD, Aggleton JP - Front Behav Neurosci (2015)

Bottom Line: The study examined the importance of the retrosplenial cortex for the incidental learning of the spatial arrangement of distinctive features within a scene.In a modified Morris water-maze, rats spontaneously learnt the location of an escape platform prior to swimming to that location.A reduced preference for the correct corner was also found in Experiment 2, when platform location was determined by the juxtaposition of highly salient visual cues (black vs. white walls).

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, Cardiff University Cardiff, UK.

ABSTRACT
The study examined the importance of the retrosplenial cortex for the incidental learning of the spatial arrangement of distinctive features within a scene. In a modified Morris water-maze, rats spontaneously learnt the location of an escape platform prior to swimming to that location. For this, rats were repeatedly placed on a submerged platform in one corner of either a rectangular (Experiment 1) or square (Experiments 2, 3) pool with walls of different appearance. The rats were then released in the center of the pool for their first test trial. In Experiment 1, the correct corner and its diagonally opposite partner (also correct) were specified by the geometric properties of the pool. Rats with retrosplenial lesions took longer to first reach a correct corner, subsequently showing an attenuated preference for the correct corners. A reduced preference for the correct corner was also found in Experiment 2, when platform location was determined by the juxtaposition of highly salient visual cues (black vs. white walls). In Experiment 3, less salient visual cues (striped vs. white walls) led to a robust lesion impairment, as the retrosplenial lesioned rats showed no preference for the correct corner. When subsequently trained actively to swim to the correct corner over successive trials, retrosplenial lesions spared performance on all three discriminations. The findings not only reveal the importance of the retrosplenial cortex for processing various classes of visuospatial information but also highlight a broader role in the incidental learning of the features of a spatial array, consistent with the translation of scene information.

No MeSH data available.


Schematic diagram of the water-mazes used in Experiments 1–3. The top row depicts the gray rectangular pool (incidental and active learning) and the kite-shaped pool (for probe trials) used in Experiment 1. Experiment 2 used a square pool with white walls and either one black wall (initial incidental training) or two black walls (active training and probe). Experiment 3 used a square white pool with one wall having vertical black stripes. The small circle represents the location of the platform where the rat was placed during passive training. The small dotted circle represents the other identical (correct) corner (where applicable).
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Figure 1: Schematic diagram of the water-mazes used in Experiments 1–3. The top row depicts the gray rectangular pool (incidental and active learning) and the kite-shaped pool (for probe trials) used in Experiment 1. Experiment 2 used a square pool with white walls and either one black wall (initial incidental training) or two black walls (active training and probe). Experiment 3 used a square white pool with one wall having vertical black stripes. The small circle represents the location of the platform where the rat was placed during passive training. The small dotted circle represents the other identical (correct) corner (where applicable).

Mentions: In Experiment 1, rats were passively trained in a plain rectangular pool to assess the ability to learn geometric properties. The ability to detect geometric relationships, which may underpin the creation of accurate representations of the shape of the environment, is known to depend on the hippocampus and anterior thalamus (O’Keefe and Burgess, 1996; Pearce et al., 2004; Aggleton et al., 2009; Kosaki et al., 2014), both closely interconnected with the retrosplenial cortex. In the rectangular pool, each pair of opposite corners shares the same arrangement with respect to the adjacent long and short walls that form the corner, e.g., long wall to left of a short wall (see Figure 1; Horne et al., 2012; Dumont et al., 2014). The escape platform was located in one of these pairs of corners during passive acquisition. The rats’ ability to use this geometric information was then assessed in a probe trial in which the rat could swim, for the first time, in the rectangular pool. To assess whether the spatial memory used to identify the correct corner in the rectangle depended on local geometric cues, in a subsequent probe the rats were placed in a novel environment (a kite-shaped pool) that contained only some of the same local geometric cues as the rectangle. The rats were next trained “actively” in the rectangle, i.e., allowed to swim to the escape location on every trial. This comparison between the passive and active versions of the task helped test for any gross navigational impairments that could contribute to any observed deficits on the passive probe.


The effect of retrosplenial cortex lesions in rats on incidental and active spatial learning.

Nelson AJ, Hindley EL, Pearce JM, Vann SD, Aggleton JP - Front Behav Neurosci (2015)

Schematic diagram of the water-mazes used in Experiments 1–3. The top row depicts the gray rectangular pool (incidental and active learning) and the kite-shaped pool (for probe trials) used in Experiment 1. Experiment 2 used a square pool with white walls and either one black wall (initial incidental training) or two black walls (active training and probe). Experiment 3 used a square white pool with one wall having vertical black stripes. The small circle represents the location of the platform where the rat was placed during passive training. The small dotted circle represents the other identical (correct) corner (where applicable).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4319482&req=5

Figure 1: Schematic diagram of the water-mazes used in Experiments 1–3. The top row depicts the gray rectangular pool (incidental and active learning) and the kite-shaped pool (for probe trials) used in Experiment 1. Experiment 2 used a square pool with white walls and either one black wall (initial incidental training) or two black walls (active training and probe). Experiment 3 used a square white pool with one wall having vertical black stripes. The small circle represents the location of the platform where the rat was placed during passive training. The small dotted circle represents the other identical (correct) corner (where applicable).
Mentions: In Experiment 1, rats were passively trained in a plain rectangular pool to assess the ability to learn geometric properties. The ability to detect geometric relationships, which may underpin the creation of accurate representations of the shape of the environment, is known to depend on the hippocampus and anterior thalamus (O’Keefe and Burgess, 1996; Pearce et al., 2004; Aggleton et al., 2009; Kosaki et al., 2014), both closely interconnected with the retrosplenial cortex. In the rectangular pool, each pair of opposite corners shares the same arrangement with respect to the adjacent long and short walls that form the corner, e.g., long wall to left of a short wall (see Figure 1; Horne et al., 2012; Dumont et al., 2014). The escape platform was located in one of these pairs of corners during passive acquisition. The rats’ ability to use this geometric information was then assessed in a probe trial in which the rat could swim, for the first time, in the rectangular pool. To assess whether the spatial memory used to identify the correct corner in the rectangle depended on local geometric cues, in a subsequent probe the rats were placed in a novel environment (a kite-shaped pool) that contained only some of the same local geometric cues as the rectangle. The rats were next trained “actively” in the rectangle, i.e., allowed to swim to the escape location on every trial. This comparison between the passive and active versions of the task helped test for any gross navigational impairments that could contribute to any observed deficits on the passive probe.

Bottom Line: The study examined the importance of the retrosplenial cortex for the incidental learning of the spatial arrangement of distinctive features within a scene.In a modified Morris water-maze, rats spontaneously learnt the location of an escape platform prior to swimming to that location.A reduced preference for the correct corner was also found in Experiment 2, when platform location was determined by the juxtaposition of highly salient visual cues (black vs. white walls).

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, Cardiff University Cardiff, UK.

ABSTRACT
The study examined the importance of the retrosplenial cortex for the incidental learning of the spatial arrangement of distinctive features within a scene. In a modified Morris water-maze, rats spontaneously learnt the location of an escape platform prior to swimming to that location. For this, rats were repeatedly placed on a submerged platform in one corner of either a rectangular (Experiment 1) or square (Experiments 2, 3) pool with walls of different appearance. The rats were then released in the center of the pool for their first test trial. In Experiment 1, the correct corner and its diagonally opposite partner (also correct) were specified by the geometric properties of the pool. Rats with retrosplenial lesions took longer to first reach a correct corner, subsequently showing an attenuated preference for the correct corners. A reduced preference for the correct corner was also found in Experiment 2, when platform location was determined by the juxtaposition of highly salient visual cues (black vs. white walls). In Experiment 3, less salient visual cues (striped vs. white walls) led to a robust lesion impairment, as the retrosplenial lesioned rats showed no preference for the correct corner. When subsequently trained actively to swim to the correct corner over successive trials, retrosplenial lesions spared performance on all three discriminations. The findings not only reveal the importance of the retrosplenial cortex for processing various classes of visuospatial information but also highlight a broader role in the incidental learning of the features of a spatial array, consistent with the translation of scene information.

No MeSH data available.