Neuroscience
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Anxiety disorders are more likely to occur in women than in men, usually emerge during adolescence and exhibit high comorbidity with alcohol use disorders (AUD). Adolescents with high levels of anxiety or heightened reactivity to stress may be at-risk for developing AUD. An approach to analyze if high levels of inborn anxiety predict greater ethanol drinking is to assess the latter variable in subjects classified as high- or low-anxiety responders. ⋯ Stress induced a significant increase in FOS immunoreactivity at the paraventricular nucleus, yet this effect was unaffected by level of anxiety response. Female adolescents with high levels of basal anxiety may be at-risk for exhibiting increased predisposition for ethanol intake and preference. The study also indicates that stress may exert differential effects on adolescent ethanol intake as a function of the level of anxiety response.
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Numerous intrinsic currents are known to collectively shape neuronal membrane potential dynamics, or neuronal signatures. Although how sets of currents shape specific signatures such as spiking characteristics or oscillations has been studied individually, it is less clear how a neuron's suite of currents jointly shape its entire set of signatures. Biophysical conductance-based models of neurons represent a viable tool to address this important question. ⋯ We illustrate the methodology using two example case rodent pyramidal neurons, from the lateral amygdala and the hippocampus. The methodology also helped reveal that a single-core compartment model could capture multiple neuronal properties. Such biophysical single-compartment models have potential to improve the fidelity of large network models.
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The dorsal diencephalic conduction system (DDC) is an important pathway of the brain reward circuitry, linking together forebrain and midbrain structures. The present work was aimed at describing the effect of a DDC lesion on the distribution of Fos-like immunoreactivity (FLIR) following intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH). Rats were implanted with monopolar electrodes and divided into three groups; the first two groups were trained to self-stimulate at the LH, whereas the third group received no stimulation and served as a control. ⋯ As previously shown, a lesion at the DDC resulted in significant attenuations of the rewarding effectiveness of LH stimulation. Results also show a higher FLIR in several reward-related areas following LH stimulation, especially in the hemisphere ipsilateral to the stimulation electrode. Compared to non-lesioned rats, lesioned animals had lower FLIR in certain brain regions, suggesting that those regions that were activated by the rewarding stimulation may be functionally interconnected with the DDC.
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Brain neurons of the deep-diving hooded seal (Cystophora cristata) are known to be inherently hypoxia tolerant. Here, we have used in vitro field potential recordings in hippocampal slices to compare effects of severe hypoxia on synaptic transmission in hooded seals vs. non-diving mammals. Synaptic responses of mice (Mus musculus) to hypoxia were in accordance with previously published data. ⋯ Paired pulse facilitation (PPF), typically associated with increased presynaptic calcium (Ca(2+)) levels, was significantly reduced in the seal slices. We propose that the build-up of Ca(2+) concentration is limited in seal presynaptic terminals, possibly due to a high Ca(2+) buffering capacity, which could explain both the attenuated PPF and the remarkable neural hypoxia tolerance of this species. Although we found no significant hypoxia-induced upregulation of mRNA for the Ca(2+) binding proteins calbindin d28k or parvalbumin in hooded seal hippocampal slices, a recent study reports very high transcript levels of the Ca(2+) binding protein S100B in this species, which is in support of the hypothesis.
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The unilaterally-lesioned 6-hydroxydopamine (6-OHDA) rat is one of the most commonly used experimental models of Parkinson's disease (PD). Here we investigated whether magnetic resonance imaging (MRI) that is widely used in human PD research, has the potential to non-invasively detect macroscopic structural brain changes in the 6-OHDA rat in ways translatable to humans. ⋯ Unilateral nigrostriatal 6-OHDA lesioning leads to widespread GMV changes, which extend beyond the nigrostriatal system and resemble advanced Parkinsonism. This study highlights the potential of structural MRI, and VBM in particular, for the system-level phenotyping of rodent models of Parkinsonism and provides a methodological framework for future studies in novel rodent models as they become available to the research community.