Neutral stimuli associated with unconditioned stimuli (USs) acquire the ability to act as conditioned stimuli (CSs), which can elicit behaviors similar to the US with which they are associated. The neural mechanisms by which this occurs are not fully known. We have previously proposed a model stipulating CSs function as such because they acquire the capacity to activate dopamine (DA) neurons at the level of the ventral tegmental area (VTA). In the present experiments we hypothesized that a food-associated CS (light), which demonstrably functions as such by eliciting conditioned responses (CRs), comes to acquire the capacity to activate VTA DA neurons. In Experiment 1, rats were allowed to eat or not eat food (food being the US). In Experiment 2, rats were trained to retrieve food pellets after light presentations (the CS) and then tested for the expression of the food checking response (the CR) with only CS presentations. In Experiment 1, eating food (exposure to the US) caused a significantly greater number of VTA DA (TH-labeled) cells to express c-Fos than not eating. In Experiment 2, CS (light) presentations caused a significant amount of conditioned approach and a significantly greater number of VTA TH-labeled (DA) cells to express c-Fos. These findings support our model stipulating that conditioned approach learning occurs when CSs acquire the capacity to cause conditioned activation of VTA DA neurons.
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http://dx.doi.org/10.1016/j.bbr.2012.07.044 | DOI Listing |
Transl Psychiatry
January 2025
School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
Recreational use of nitrous oxide (NO) has risen dramatically over the past decades. This study aimed to examine its rewarding effect and the underlying mechanisms. The exposure of mice to a subanesthetic concentration (20%) of NO for 30 min for 4 consecutive days paired with NO in the morning and paired with the air in the afternoon produced apparent rewarding behavior in the conditioned place preference (CPP) paradigm.
View Article and Find Full Text PDFPhysiol Behav
January 2025
Department of Biomedical Sciences, Joan C Edwards School of Medicine at Marshall University, 1700 3(rd) Avenue, Huntington, WV 25703, USA. Electronic address:
With the rise in fast-food culture and the continued high numbers of tobacco-related deaths, there has been a great deal of interest in understanding the relationship between high-fat diet (HFD) and nicotine use behaviors. Using adult mice and a patch-clamp electrophysiology assay, we investigated the influence of HFD on the excitability of ventral tegmental area (VTA) dopamine neurons and pyramidal neurons in the medial prefrontal cortex (mPFC) given their role in modulating the reinforcing effects of nicotine and natural rewards. We then examined whether HFD-induced changes in peripheral markers were associated with nicotine use behaviors.
View Article and Find Full Text PDFJ Neurosci
January 2025
Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, 9 Gronostajowa street, 30-387 Kraków, Poland.
Dopaminergic (DA) neurons of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) play a crucial role in controlling animals' orienting and approach behaviors toward relevant environmental stimuli. The ventral midbrain receives sensory input from the superior colliculus (SC), a tectal region processing information from contralateral receptive fields of various modalities. Given the significant influence of dopamine release imbalance in the left and right striatum on animals' movement direction, our study aimed to investigate the lateralization of the connection between the lateral SC and the midbrain DA system in male rats.
View Article and Find Full Text PDFJ Neurochem
January 2025
Department of Pathology, School of Veterinary Medicine, University of São Paulo, Sao Paulo, Brazil.
Autism spectrum disorder (ASD) is a complex developmental disorder characterized by several behavioral impairments, especially in socialization, communication, and the occurrence of stereotyped behaviors. In rats, prenatal exposure to valproic acid (VPA) induces autistic-like behaviors. Previous studies by our group have suggested that the autistic-like phenotype is possibly related to dopaminergic system modulation because tyrosine hydroxylase (TH) expression was affected.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Animal and Human Physiology, Faculty of Biology, University of Gdansk, 59 Wita Stwosza Str., 80-308 Gdansk, Poland.
Amphetamine abuse is a global health epidemic that is difficult to treat due to individual differences in response to environmental factors, including stress reactivity and anxiety levels, as well as individual neuronal differences, which may result in increased/decreased vulnerability to addiction. In the present study, we investigated whether the Wistar rats behavioral traits of high (HR) and low (LR) locomotor activity to novelty influence motivational behavior (induced feeding model; iFR by electrical stimulation of the ventral tegmental area; Es-VTA) supported by amphetamine injection into the nucleus accumbens shell (AcbSh) (HR, n = 5; LR, n = 5). A correlation was found between the novelty test's locomotor activity score and the frequency threshold percentage change ( < 0.
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