Publications by authors named "Ron Sullivan"

The indusium griseum (IG) and anterior hippocampal continuation (AHC) are longitudinal and continuous structures that consist of two narrow strips of gray matter overlying the rostrocaudal length of the corpus callosum, extending rostrally to the genu of the corpus callosum and ventrally to the rostrum. The present study aimed to characterize the phenotype of neuronal innervations to the IG-AHC and their intra-structural topographic organization. Using immunohistochemistry, we found nerve fibers expressing choline acetyltransferase, tyrosine hydroxylase, dopamine-β-hydroxylase, the serotonin reuptake transporter as well as glutamic acid decarboxylase-67 and parvalbumin.

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Depletion of cholinergic interneurons in the ventral striatum (nucleus accumbens or N.Acc.) in adult rats increases the locomotor activating effects of amphetamine.

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In rats, selective depletion of the cholinergic interneurons in the ventral striatum (nucleus accumbens or N.Acc.) results in heightened behavioural sensitivity to amphetamine and impaired sensorimotor gating processes, suggesting a hyper-responsiveness to dopamine (DA) activity in the N.

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Birth complications involving reduced oxygen to the fetus pose risks for neurodevelopmental disorders like schizophrenia and ADHD, which involve central dopamine (DA) dysfunction and also show gender differences in incidence or severity. Here, we examine possible sex differences in the long-term consequences of perinatal anoxia in the rat, on central DA systems and DA-mediated behaviour. As adults, sensorimotor gating (prepulse inhibition, PPI) was differentially affected by anoxia in males and females, tending to be impaired only in males.

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A delicate balance between dopaminergic and cholinergic activity in the ventral striatum or nucleus accumbens (N.Acc) appears to be important for optimal performance of a wide range of behaviours. While functional interactions between these systems are complex, some data suggest that acetylcholine in the N.

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Study Objectives: Acute myocardial infarction (MI) is followed, within a few hours, by neuronal loss in the central nervous system (CNS), including the limbic system, the hypothalamus, and the brainstem. Sleep before and after MI was investigated in the first experiment. In a parallel experiment, 2 weeks after MI, we quantified brainstem cholinergic neurons known to control paradoxical sleep (PS).

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This study examined the possibility that hemispheric differences in stress-induced brain activation vary as a function of sex. Using in-vivo voltammetry, increases in extracellular dopamine release in response to predator odour and tail pinch stress were recorded bilaterally and simultaneously in either the infralimbic cortex or basolateral amygdala. In both stress-sensitive brain regions, significant sex x hemisphere interactions were observed, with males and females showing greater dopamine activation in right-brain and left-brain structures, respectively.

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Stress-related psychopathology is particularly prevalent in women, although the neurobiological reason(s) for this are unclear. Dopamine (DA) and serotonin (5-HT) systems however, are known to play important adaptive roles in stress and emotion regulation. The aims of the present study included examination of sex differences in stress-related behaviour and neuroendocrine function as well as post mortem neurochemistry, with the main hypothesis that corticolimbic DA and 5-HT systems would show greater functional activity in males than females.

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The infralimbic (IL) cortex is importantly involved in regulating behavioral and physiological responses to stress, including those of the hypothalamic-pituitary-adrenal (HPA) axis. The mesocortical dopamine (DA) system is an important afferent modulator of this region, is highly stress sensitive and frequently shows functional hemispheric asymmetry. Postnatal handling stimulation facilitates development of cortical asymmetry and is also associated with optimal HPA axis regulation.

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The present review surveys a broad range of findings on the functions of the rodent prefrontal cortex (PFC) in the context of the known pathophysiology of attention-deficit/hyperactivity disorder (ADHD). An overview of clinical findings concludes that dysfunction of the right PFC plays a critical role in ADHD and that a number of early developmental factors conspire to increase the risk of the disorder. Rodent studies are described which go far in explaining how the core processes which are deficient in ADHD are mediated by the PFC and that the mesocortical dopamine (DA) system plays a central role in modulating these functions.

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The ventral region of the medial prefrontal cortex (mPFC) is highly sensitive to stressful inputs and implicated in a variety of behaviors. Studies have also demonstrated numerous functional hemispheric asymmetries within this brain area of the rat. The present study examines the effects of ibotenic acid or sham lesions targeting the left, right or bilateral infralimbic cortex, on a variety of behaviors.

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In recent years, dysfunction of hypothalamic-pituitary-adrenal (HPA) axis function has been implicated in a wide variety of psychiatric conditions. The importance of this system in responding to and coping with stress is well documented, and the integrity of such systems is of obvious significance to good mental health. The prefrontal cortex (PFC) is also heavily implicated in numerous psychopathological conditions.

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