Hippocampal Cytochrome Oxidase Activity of Rats in Easy and Difficult Visual Discrimination Learning

Hu, Dan; Xu, Xiaojuan; González-Lima, Francisco

doi:10.1080/00207450590523440

Cited by 10 publications

(3 citation statements)

References 24 publications

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“…Previous experiments in our laboratory examined the behavior of rats given regular alternation or visual discrimination of rewarded and non-rewarded trials in order to determine reward related expectancies in appetitive memory tasks and associated brain cytochrome oxidase activity, but no prior study has examined the effect of MB on discrimination learning (Hu et al 2005(Hu et al ,2006Lilliquist et al 1999;Nair and Gonzalez-Lima, 1999). We used a more difficult discrimination design than a simple discrimination based on a balanced alternation between reward and non-reward trials because the purpose of this study was to test the efficacy of MB on a more difficult learning task as opposed to a simpler learning task.…”

Section: Introductionmentioning

confidence: 99%

The brain metabolic enhancer methylene blue improves discrimination learning in rats

Wrubel

Riha

Maldonado

et al. 2007

Pharmacology Biochemistry and Behavior

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Methylene blue (MB) is a metabolic enhancer that has been demonstrated to improve memory retention when given post-training in low doses in a variety of tasks in rats, including inhibitory avoidance, spatial memory (in both normal and metabolically-impaired subjects), object recognition, and habituation to a familiar environment. MB has been also shown to improve memory retention of extinction of fear conditioning in the rat. No experiments have been conducted to determine the effects of MB on more complex learning such as in discrimination tasks that require repeated days of training. This study examined the effects of daily MB on spatial discrimination memory in a baited holeboard maze. Following three days of discrimination training, subjects treated daily with posttraining MB (1 mg/kg) reliably discriminated between rewarded (baited) and non-rewarded (unbaited) trials as indicated by a greater number of correct responses on rewarded trials than nonrewarded trials during the last three days of discrimination training. No such discrimination effects were observed in the saline-treated control group during the same training period. To determine whether the memory-enhancing effects of MB are associated with an increase in metabolic energy capacity in the brain, cytochrome c oxidation was measured in brains from rats treated with 1 mg/ kg MB or saline for three days. The number of daily injections was chosen based on the behavioral data which revealed group differences three days after the beginning of MB treatment. Brain cytochrome oxidase activity in the MB-treated group was approximately 70% higher than in salinetreated rats. The findings suggest that repeated post-training MB may improve memory consolidation between days of learning by an induction in the enzyme cytochrome oxidase, leading to increased metabolic capacity in brain regions requiring more energy during discrimination learning.

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Section: Introductionmentioning

confidence: 99%

The brain metabolic enhancer methylene blue improves discrimination learning in rats

Wrubel

Riha

Maldonado

et al. 2007

Pharmacology Biochemistry and Behavior

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“…In particular, the CA1 area and the dentate gyrus showed increased CO activity in the visual discrimination group compared with the control group. These hippocampal regions seem to be relevant for difficult visual discrimination learning (Hu et al,2005). In this regard, it has been reported that the CA1 hippocampal area is required for visual discrimination learning in a water maze task in which extramaze visual cues were hidden using black curtains, similar to our experimental conditions (Carli et al,1999).…”

Section: Discussionmentioning

confidence: 99%

“…Conversely, it has been demonstrated that lesions of the hippocampus can cause retrograde amnesia for simple visual discrimination tasks (Epp et al,2008). In addition, visual discrimination learning in a Y‐maze is correlated with CO activity in the CA subfields and the dentate gyrus of the hippocampus, especially in difficult visual discrimination tasks (Hu et al,2005, 2006).…”

Section: Discussionmentioning

confidence: 99%

Functional interaction between the dorsal hippocampus and the striatum in visual discrimination learning

Fidalgo

Conejo

González-Pardo

et al. 2011

J of Neuroscience Research

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The hippocampus and the striatum have traditionally been considered as part of different and independent memory systems. However, there is evidence that supports a functional interaction between the hippocampus and the dorsal striatum at least in particular learning tasks. Here, we evaluated the functional contribution of both brain regions in a visual discrimination learning task using cytochrome c oxidase (CO) quantitative histochemistry. Compared with other brain metabolic mapping techniques, CO activity reflects steady-state neuronal energy demand. Rats were trained for 6 days in a water T-maze to find a hidden escape platform associated with an intramaze visual cue. A control group of animals swam for an equivalent amount of time compared as the trained group but without any escape platform available. After finishing the behavioral task, CO activity was measured in subdivisions of the dorsal hippocampus and the dorsal striatum in both groups. Results show significantly higher CO activity in the CA1 area and the dentate gyrus of the dorsal hippocampus in the trained rats compared with the control group. In addition, a significant negative functional cross-correlation between area CA1 of the dorsal hippocampus and the anterodorsal striatum was found. Our results support current theories on competitive interaction of different memory systems during visual discrimination learning.

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Conditional self-discrimination enhances dendritic spine number and dendritic length at prefrontal cortex and hippocampal neurons of rats

Penagos-Corzo

Bonilla

Rodríguez‐Moreno

et al. 2015

Synapse

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We studied conditional self-discrimination (CSD) in rats and compared the neuronal cytoarchitecture of untrained animals and rats that were trained in self-discrimination. For this purpose, we used thirty 10-week-old male rats were randomized into three groups: one control group and two conditioning groups: a comparison group (associative learning) and an experimental group (self-discrimination). At the end of the conditioning process, the experimental group managed to discriminate their own state of thirst. After the conditioning process, dendritic morphological changes in the pyramidal neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus were evaluated using Golgi-Cox stain method and then analyzed by the Sholl method. Differences were found in total dendritic length and spine density. Animals trained in self-discrimination showed an increase in the dendritic length and the number of dendritic spines of neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus. Our data suggest that conditional self-discrimination improves the connectivity of the prefrontal cortex and dorsal CA1, which has implications for memory and learning processes.

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Hippocampal Cytochrome Oxidase Activity of Rats in Easy and Difficult Visual Discrimination Learning

Cited by 10 publications

References 24 publications

The brain metabolic enhancer methylene blue improves discrimination learning in rats

The brain metabolic enhancer methylene blue improves discrimination learning in rats

Functional interaction between the dorsal hippocampus and the striatum in visual discrimination learning

Conditional self-discrimination enhances dendritic spine number and dendritic length at prefrontal cortex and hippocampal neurons of rats

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