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PROJECTIONS OF DORSAL AND MEDIAN RAPHE NUCLEI TO DORSAL AND VENTRAL STRIATUM
G. R. Hassanzadeh G. Behzadi
Acta Medica Iranica , 2007,
Abstract: The ascending serotonergic projections are derived mainly from mesencephalic raphe nuclei. Topographical projections from mesencephalic raphe nuclei to the striatum were examined in the rat by the retrograde transport technique of HRP (horseradish peroxidase). In 29 rats stereotaxically injection of HRP enzyme were performed in dorsal and ventral parts of striatum separately. The extent of the injection sites and distribution of retrogradely labeled neuronal cell bodies were drawed on representative sections using a projection microscope. Following ipsilateral injection of HRP into the dorsal striatum, numerous labeled neurons were seen in rostral portion of dorsal raphe (DR) nucleus. In the same level the cluster of labeled neurons were hevier through caudal parts of DR. A few neurons were also located in lateral wing of DR. More caudally some labeled neurons were found in lateral, medial line of DR. In median raphe nucleus (MnR) the labeled neurons were scattered only in median portion of this nucleus. The ipsilateral injection of HRP into the ventral region of striatum resulted on labeling of numerous neurons in rostral, caudal and lateral portions of DR. Through the caudal extension of DR on 4th ventricle level, a large number of labeled neurons were distributed along the ventrocaudal parts of DR. In MnR, labeled neurons were observed only in median part of this nucleus. These findings suggest the mesencephalic raphe nuclei projections to caudo-putamen are topographically organized. In addition dorsal and median raphe nuclei have a stronger projection to the ventral striatum.
Cocaine exposure shifts the balance of associative encoding from ventral to dorsolateral striatum  [PDF]
Yuji Takahashi,Matthew R Roesch,Thomas A Stalnaker,Geoffrey Schoenbaum
Frontiers in Integrative Neuroscience , 2007, DOI: 10.3389/neuro.07.011.2007
Abstract: Both dorsal and ventral striatum are implicated in the “habitization” of behavior that occurs in addiction. Here we examined the effect of cocaine exposure on associative encoding in these two regions. Neural activity was recorded during go∕no-go discrimination learning and reversal. Activity in ventral striatum developed and reversed rapidly, tracking the valence of the predicted outcome, whereas activity in dorsolateral striatum developed and reversed more slowly, tracking discriminative responding. This difference is consistent with the putative roles of these two areas in promoting habit-like behavior. Dorsolateral striatum has been directly implicated in habit or stimulus–response learning, whereas ventral striatum appears to be involved indirectly by allowing cues associated with reward to exert a general motivational influence on responding. Interestingly cocaine exposure did not uniformly enhance processing across both regions. Instead cocaine reduced the degree and flexibility of cue-evoked firing in ventral striatum while marginally enhanced cue-selective firing in dorsolateral striatum. Thus cocaine exposure causes regionally specific effects on neural processing in striatum; these effects may promote the habitization of behavior by shifting control from ventral to dorsolateral regions.
Signatures of Value Comparison in Ventral Striatum Neurons  [PDF]
Caleb E. Strait?,Brianna J. Sleezer?,Benjamin Y. Hayden
PLOS Biology , 2015, DOI: 10.1371/journal.pbio.1002173
Abstract: The ventral striatum (VS), like its cortical afferents, is closely associated with processing of rewards, but the relative contributions of striatal and cortical reward systems remains unclear. Most theories posit distinct roles for these structures, despite their similarities. We compared responses of VS neurons to those of ventromedial prefrontal cortex (vmPFC) Area 14 neurons, recorded in a risky choice task. Five major response patterns observed in vmPFC were also observed in VS: (1) offer value encoding, (2) value difference encoding, (3) preferential encoding of chosen relative to unchosen value, (4) a correlation between residual variance in responses and choices, and (5) prominent encoding of outcomes. We did observe some differences as well; in particular, preferential encoding of the chosen option was stronger and started earlier in VS than in vmPFC. Nonetheless, the close match between vmPFC and VS suggests that cortex and its striatal targets make overlapping contributions to economic choice.
Hippocampus Leads Ventral Striatum in Replay of Place-Reward Information  [PDF]
Carien S. Lansink,Pieter M. Goltstein,Jan V. Lankelma,Bruce L. McNaughton,Cyriel M. A. Pennartz
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000173
Abstract: Associating spatial locations with rewards is fundamental to survival in natural environments and requires the integrity of the hippocampus and ventral striatum. In joint multineuron recordings from these areas, hippocampal–striatal ensembles reactivated together during sleep. This process was especially strong in pairs in which the hippocampal cell processed spatial information and ventral striatal firing correlated to reward. Replay was dominated by cell pairs in which the hippocampal “place” cell fired preferentially before the striatal reward-related neuron. Our results suggest a plausible mechanism for consolidating place-reward associations and are consistent with a central tenet of consolidation theory, showing that the hippocampus leads reactivation in a projection area.
Hippocampus Leads Ventral Striatum in Replay of Place-Reward Information  [PDF]
Carien S. Lansink,Pieter M. Goltstein,Jan V. Lankelma,Bruce L. McNaughton,Cyriel M. A. Pennartz
PLOS Biology , 2009, DOI: 10.1371/journal.pbio.1000173
Abstract: Associating spatial locations with rewards is fundamental to survival in natural environments and requires the integrity of the hippocampus and ventral striatum. In joint multineuron recordings from these areas, hippocampal–striatal ensembles reactivated together during sleep. This process was especially strong in pairs in which the hippocampal cell processed spatial information and ventral striatal firing correlated to reward. Replay was dominated by cell pairs in which the hippocampal “place” cell fired preferentially before the striatal reward-related neuron. Our results suggest a plausible mechanism for consolidating place-reward associations and are consistent with a central tenet of consolidation theory, showing that the hippocampus leads reactivation in a projection area.
Separate Populations of Neurons in Ventral Striatum Encode Value and Motivation  [PDF]
Gregory B. Bissonette, Amanda C. Burton, Ronny N. Gentry, Brandon L. Goldstein, Taylor N. Hearn, Brian R. Barnett, Vadim Kashtelyan, Matthew R. Roesch
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064673
Abstract: Neurons in the ventral striatum (VS) fire to cues that predict differently valued rewards. It is unclear whether this activity represents the value associated with the expected reward or the level of motivation induced by reward anticipation. To distinguish between the two, we trained rats on a task in which we varied value independently from motivation by manipulating the size of the reward expected on correct trials and the threat of punishment expected upon errors. We found that separate populations of neurons in VS encode expected value and motivation.
Expectancies in decision making, reinforcement learning, and ventral striatum  [PDF]
Matthijs A. A. van der Meer,A. David Redish
Frontiers in Neuroscience , 2010, DOI: 10.3389/neuro.01.006.2010
Abstract: Decisions can arise in different ways, such as from a gut feeling, doing what worked last time, or planful deliberation. Different decision-making systems are dissociable behaviorally, map onto distinct brain systems, and have different computational demands. For instance, “model-free” decision strategies use prediction errors to estimate scalar action values from previous experience, while “model-based” strategies leverage internal forward models to generate and evaluate potentially rich outcome expectancies. Animal learning studies indicate that expectancies may arise from different sources, including not only forward models but also Pavlovian associations, and the flexibility with which such representations impact behavior may depend on how they are generated. In the light of these considerations, we review the results of van der Meer and Redish (2009a) , who found that ventral striatal neurons that respond to reward delivery can also be activated at other points, notably at a decision point where hippocampal forward representations were also observed. These data suggest the possibility that ventral striatal reward representations contribute to model-based expectancies used in deliberative decision making.
Dopamine Signaling in Dorsal Versus Ventral Striatum: The Dynamic Role of Cholinergic Interneurons  [PDF]
Sarah Threlfell,Stephanie Jane Cragg
Frontiers in Systems Neuroscience , 2011, DOI: 10.3389/fnsys.2011.00011
Abstract: Mesostriatal dopaminergic neurons and striatal cholinergic interneurons participate in signaling the motivational significance of environmental stimuli and regulate striatal plasticity. Dopamine (DA) and acetylcholine (ACh) have potent interactions within the striatum at multiple levels that include presynaptic regulation of neurotransmitter release and postsynaptic effects in target cells (including ACh neurons). These interactions may be highly variable given the dynamic changes in the firing activities of parent DA and ACh neurons. Here, we consider how striatal ACh released from cholinergic interneurons acting at both nicotinic and muscarinic ACh receptors powerfully modulates DA transmission. This ACh–DA interaction varies in a manner that depends on the frequency of presynaptic activation, and will thus strongly influence how DA synapses convey discrete changes in DA neuron activity that are known to signal events of motivational salience. Furthermore, this ACh modulation of DA transmission within striatum occurs via different profiles of nicotinic and muscarinic receptors in caudate–putamen compared to nucleus accumbens, which may ultimately enable region-specific targeting of striatal function.
Intracranial haemorrhage after transport of premature newborns  [PDF]
Spasojevi? Slobodan,Stojanovi? Vesna,Savi? Radojica,Doronjski Aleksandra
Medicinski Pregled , 2010, DOI: 10.2298/mpns1008454s
Abstract: Intracranial hemorrhage remains an important factor of premature newborns’ morbidity. Its incidence is significantly influenced by adequate perinatal care and safe neonatal transport. Risk factors for the development of intracranial hemorrhage in premature newborns after neonatal transport were analyzed in the retrospective transversal clinical study. Out of 150 study subjects, 60% (n=90/150) had intracranial hemorrhage with a statistically significant difference in relation to Apgar score, gestational age, birth weight, age at the moment of transport and the prophylactic use of surfactant. In this group, grades I/II intracranial hemorrhage were detected in 77% (n=69/90), while grades III/IV intracranial hemorrhage were diagnosed in 23% (n=21/90). A statistically significant difference was observed in relation to gestational age, birth weight, antenatal use of tocolytics and steroids, delivery mode and age in the time of transport between these groups. All patients were transferred to Intensive Care Unit, the duration of transport was less than 5 minutes in 71% 9n=107/150), whereas longer transport was recorded in 29% (n=43/150). In the group of longer transport, prophylactic surfactant was less frequently used with a higher incidence of grades III/IV intracranial hemorrhage. In order to prevent the development of intracranial hemorrhage in premature newborns, the most important measures are the antenatal use of steroids and postnatal prophylactic use of surfactant.
Aversive Event Anticipation Affects Connectivity between the Ventral Striatum and the Orbitofrontal Cortex in an fMRI Avoidance Task  [PDF]
Ingeborg Bolstad, Ole A. Andreassen, Greg E. Reckless, Niels P. Sigvartsen, Andres Server, Jimmy Jensen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068494
Abstract: Ability to anticipate aversive events is important for avoiding dangerous or unpleasant situations. The motivation to avoid an event is influenced by the incentive salience of an event-predicting cue. In an avoidance fMRI task we used tone intensities to manipulate salience in order to study the involvement of the orbitofrontal cortex in processing of incentive salience. In the task, cues predicting either aversive or neutral avoidable tones were presented. Ventral striatum, amygdala and anterior insula activations were significantly stronger during presentation of cues for aversive than neutral tones. A psychophysiological interaction analysis showed stronger connectivity between the ventral striatum and the orbitofrontal cortex during aversive than neutral conditions. The present study shows an interaction between the ventral striatum, a structure previously linked to negative incentive salience, and the orbitofrontal cortex supporting a role for this region in processing salience. In addition, this study replicates previous findings suggesting that the task is robust.
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