42 research outputs found
Impulsive rats are less maternal.
No full textEarly life environment and maternal care can have long-lasting effects on behavior and physiology. Previously, we found that compared to mother-reared (MR) female rats, rats reared without mothers, siblings, and nest, through artificially rearing (AR), show reduced levels of maternal behavior when they grow up. These effects can be reversed if AR pups are provided with extra “licking-like” tactile stimulation during the preweaning period [Gonzalez et al. [2001] Developmental Psychobiology, 38(1), 11–42]. We also found that AR rats are more action impulsive and have reduced attentional capacities in comparison to their MR siblings [Lovic, Fletcher, & Fleming, in preparation; Lovic & Fleming [2004] Behavioural Brain Research 148: 209–219]. However, it is unknown whether increased impulsivity contributes to reduced levels of maternal behaviors. The purpose of this study was to assess the relationship between impulsivity and maternal behavior in AR and MR rats. Female rats were reared with (MR) or without mothers (AR) and half of the AR rats received additional stroking stimulation. As adults, AR and MR rats were mated and maternal behavior towards their own pups was assessed. In addition, rats were assessed on impulsive action (differential reinforcement of low-rate schedule; DRL-20s). Consistent with previous findings, AR rats were both less maternal and more action impulsive than MR rats. Partial correlations revealed that impulsivity was inversely related to pup licking-impulsive rats were less maternal. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 53: 13–22, 2011.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78484/1/20481_ftp.pd
The Effects of Maternal Deprivation, Through Artificial Rearing, on Impulsiveness in Rats
No full textMammalian brain and behaviour are plastic, particularly early in development when offspring are under the care of their mothers. Adverse early life events, such as maternal and social deprivation, have short- and long-term consequences for neurobiology and consequently for behaviour. The purpose of this thesis was to investigate the effects of maternal and social deprivation, through artificial rearing (AR), on adult impulsive behaviour.
Rats were raised in isolation from mothers and siblings (AR) or with their mothers and siblings in the nest [maternal rearing (MR)]. In addition, half of the AR rats were provided with replacement somatosensory stimulation designed to simulate mothers’ licking (see Gonzalez et al., 2001).
As adults, rats were tested on impulsive action using the differential reinforcement of low rates (DRL) operant task and locomotor activity. Both male and female AR rats were more impulsive than MR rats; they made more responses and they were less efficient at earning rewards. In addition, they displayed greater levels of locomotor activity. These effects were partially reversed by replacement somatosensory stimulation. Furthermore, impulsivity was positively correlated with locomotor activity.
Impulsive choice was then assessed using a delay discounting operant schedule. On this task, AR rats were less likely to discount the value of large-delayed reward, suggesting that they were better able to tolerate delays to large reward and were less impulsive. However, performance on a modified version of delay discounting revealed that AR rats were less efficient at switching their responses; that is, they displayed reduced behavioural flexibility. To address this finding, impulsive choice was next assessed in fixed consecutive chain operant schedule of reinforcement, but there were no differences between AR and MR animals.
Finally, the relationship between impulsive action and a species-characteristic behaviour, maternal behaviour, was investigated. Consistent with the literature, AR rats were less maternal and more impulsive. Moreover, there was a negative correlation between impulsivity and maternal behaviour.
Overall, this set of studies demonstrates that maternal and social deprivation produces an increase in impulsive action without an effect on impulsive choice. Furthermore, increased action impulsiveness is a significant moderator of disrupted maternal behaviour observed in artificially reared rats.Ph
The Effects of Maternal Deprivation, Through Artificial Rearing, on Impulsiveness in Rats
No full textMammalian brain and behaviour are plastic, particularly early in development when offspring are under the care of their mothers. Adverse early life events, such as maternal and social deprivation, have short- and long-term consequences for neurobiology and consequently for behaviour. The purpose of this thesis was to investigate the effects of maternal and social deprivation, through artificial rearing (AR), on adult impulsive behaviour.
Rats were raised in isolation from mothers and siblings (AR) or with their mothers and siblings in the nest [maternal rearing (MR)]. In addition, half of the AR rats were provided with replacement somatosensory stimulation designed to simulate mothers’ licking (see Gonzalez et al., 2001).
As adults, rats were tested on impulsive action using the differential reinforcement of low rates (DRL) operant task and locomotor activity. Both male and female AR rats were more impulsive than MR rats; they made more responses and they were less efficient at earning rewards. In addition, they displayed greater levels of locomotor activity. These effects were partially reversed by replacement somatosensory stimulation. Furthermore, impulsivity was positively correlated with locomotor activity.
Impulsive choice was then assessed using a delay discounting operant schedule. On this task, AR rats were less likely to discount the value of large-delayed reward, suggesting that they were better able to tolerate delays to large reward and were less impulsive. However, performance on a modified version of delay discounting revealed that AR rats were less efficient at switching their responses; that is, they displayed reduced behavioural flexibility. To address this finding, impulsive choice was next assessed in fixed consecutive chain operant schedule of reinforcement, but there were no differences between AR and MR animals.
Finally, the relationship between impulsive action and a species-characteristic behaviour, maternal behaviour, was investigated. Consistent with the literature, AR rats were less maternal and more impulsive. Moreover, there was a negative correlation between impulsivity and maternal behaviour.
Overall, this set of studies demonstrates that maternal and social deprivation produces an increase in impulsive action without an effect on impulsive choice. Furthermore, increased action impulsiveness is a significant moderator of disrupted maternal behaviour observed in artificially reared rats.Ph
Localization of Zinc in the Circadian System and its Role in the Modulation of Circadian Responses to Light
No full textZinc is found in multiple brain areas where it can act as a neuromodulator of postsynaptic receptors. There is evidence for the existence of zinc in the SCN as well as its vesicle transporter (ZnT3) in the retina. However, its presence in other circadian areas has not been examined. This study observed the anatomical distribution of zinc in the SCN and IGL as well as ZnT3 in the retinal ganglion cells that project to these areas. The role of zinc in photic entrainment was also examined. The IGL contained considerable amounts of zinc while ZnT3 was present in retinal cells that are able to project to the IGL. Nevertheless zinc in the IGL was not implicated in the photic entrainment pathway and the retina was shown not to be a necessary zinc input source. Together, these results present the first report of zinc in the IGL and circadian retinal projections
Contributions of early life adversity, sex, and traits towards compulsive opioid self-administration
No full textMany people try addictive drugs, but only a small percentage transition from situational/recreational use to the escalating, compulsive, and relapsing disorder of addiction. It is therefore important to characterize the individual differences that render individuals vulnerable to addiction. Substantial evidence suggests that individual differences in early life experience, biological sex, personality traits, and neurobiology of the reward system are all associated with the development of addiction. A dimensional model of how all these factors relate to addiction is necessary, but simultaneously and experimentally probing all these processes in humans is impossible. I therefore conducted a large-scale study to explore these phenomena in rats.
Throughout ‘adolescence’ (PND 21-35), I exposed a group of rats to a variety of stressors [i.e., forced-swim, restraint, predator odour, food-restriction, and social isolation; termed ‘early life adversity’ (ELA)]. As adults (PND 60-140), I assessed them on numerous addiction-relevant behavioural traits (i.e., impulsivity, anxiety, novelty-preference, and attraction to reward cues). After trait assessment, I observed the rats’ propensity to self-administer the opiate remifentanil. I then killed a subset of rats and quantified DA receptor mRNA in the mPFC.
ELA decreased impulsivity and decreased the rate of acquisition of opiate self-administration in male rats only. Compared to males, female rats exhibited greater anxiety-like behaviour and potentiated opioid self-administration. Anxiety-like behaviour and attraction to reward cues predicted several addiction-relevant behaviours
Early-life maternal separation and social isolation produce an increase in impulsive action but not impulsive choice.
No full text
Functionally Distinct Dopamine Signals in Nucleus Accumbens Core and Shell in the Freely Moving Rat
No full textDynamic signaling of mesolimbic dopamine (DA) neurons has been implicated in reward learning, drug abuse, and motivation. However, this system is complex because firing patterns of these neurons are heterogeneous; subpopulations receive distinct synaptic inputs, and project to anatomically and functionally distinct downstream targets, including the nucleus accumbens (NAc) shell and core. The functional roles of these cell populations and their real-time signaling properties in freely moving animals are unknown. Resolving the real-time DA signal requires simultaneous knowledge of the synchronized activity of DA cell subpopulations and assessment of the down-stream functional effect of DA release. Because this is not yet possible solely by experimentation in vivo, we combine computational modeling and fast-scan cyclic voltammetry data to reconstruct the functionally relevant DA signal in DA neuron subpopulations projecting to the NAc core and shell in freely moving rats. The approach provides a novel perspective on real-time DA neuron firing and concurrent activation of presynaptic autoreceptors and postsynaptic targets. We first show that individual differences in DA release arise from differences in autoreceptor feedback. The model predicts that extracellular DA concentrations in NAc core result from constant baseline DA firing, whereas DA concentrations in NAc shell reflect highly dynamic firing patters, including synchronized burst firing and pauses. Our models also predict that this anatomical difference in DA signaling is exaggerated by intravenous infusion of cocaine.Lundbeck FoundationUniversity of Copenhagen (2016 Excellence Programme for Interdisciplinary Research (DSIN))National Institute on Drug Abuse (P01 DA031656
