Neuroscience
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The temporal lobe plays a major role in anxiety and depression disorders and is also of importance for trait anxiety in the non-pathological range. The present study investigates self-report data of personality dimensions linked to trait anxiety in the context of white matter tract integrity in the temporal lobes of the human brain in a large sample of N=110 healthy participants. The results show that especially in men values for fractional anisotropy of several white matter tracts in the temporal lobe of the left hemisphere correlate substantially with individual differences in trait anxiety (depending on the tract investigated between .40 and .49). The present study shows that not only data from functional magnetic resonance imaging (fMRI), but also from structural diffusion tensor imaging (DTI) provide interesting insights into the biological foundation of human personality traits.
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Deep brain stimulation (DBS) is an emerging treatment of epilepsy. Anterior nucleus of the thalamus (ANT) is considered to be an attractive target due to its close connection to the limbic structures and wide regions of neocortex. The present study aimed to investigate the effects of high frequency stimulation (HFS) targeting the ANT on amygdala-kindled seizures in Wistar rats in two different stimulation modes i.e. pre-treatment and post-treatment stimulations, mimicking the scheduled and responsive stimulations in clinical use respectively. ⋯ However, Δ(GST-ADT) increased by at least 20 μA in bilateral post-treatment group, while less in bilateral pre-treatment group. Additionally, unilateral post-treatment with HFS failed to inhibit seizures. Our data show that anti-epileptic effect of bilateral post-treatment with HFS of ANT is much stronger than that of bilateral pre-treatment HFS, indicating bilateral responsive stimulation might be more appropriate for clinical anti-epileptic treatment of ANT HFS.
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The cortical cholinergic innervation, which is important for memory and cognition, has been implicated in schizophrenia. To experimentally analyze such a possible role of the cholinergic system, we have used the dissociative drug phencyclidine (PCP), known to produce schizophrenia-like psychosis in humans, to model aspects of schizophrenia in rats. We previously showed that induced cortical cholinergic hypofunction leads to enhanced PCP-induced locomotor activity and attenuated social interaction. ⋯ Specific unilateral lesioning of the uncrossed cholinergic projections to the cortical mantle by 192-IgG-saporin immunotoxin delivery to nc basalis (NBM) caused a striking ipsilateral decrease of the PCP-induced cortical c-fos mRNA induction, restricted to areas which had become effectively denervated. Because PCP at low doses is unlikely to directly influence cortical neurons, we suggest that it acts by activation of the cholinergic input, which in turn leads to cortical c-fos mRNA increases. Our results are compatible with a role for the cholinergic system in symptoms of schizophrenia, by showing that the basalo-cortical cholinergic projections are needed in order for PCP to have full activating effects on cortical neurons.
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The angiotensin II receptor subtype 2 (AT2-R) has been proposed to mediate protective vascular actions after brain injury. In this study we investigated the participation of this peptide in the tolerance to cellular damage induced by preconditioning in a rat model of neonatal hypoxia-ischemia (HI). We found that injured animals present a decreased number of microvessels in the ipsilateral (IPLT) side of the brain while in the contralateral (CNLT) side the microvessel number is increased. ⋯ However these vessels show a remarkable increase of the fluorescent signal when they are labeled with antiFlk-1 (VEGFR2), while the Flt-1 (VEGFR1) signal faded in both the injured and the preconditioned animals. The pharmacological blockade of the AT2-R by the drug PD123319 (1.69 mM in the lateral ventricle) diminished the resilience of the microvasculature to HI injury provided by preconditioning and also the Flk-1 increase that occurred in these animals. In conclusion these results suggest an interaction of the AT2-R with VEGFR2 in the neonatal brain microvasculature that produces protective effects which are associated with injury tolerance.
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Sensory-evoked propagating waves are frequently observed in sensory cortex. However, it is largely unknown how an evoked propagating wave affects the activity evoked by subsequent sensory inputs, or how two propagating waves interact when evoked by simultaneous sensory inputs. Using voltage-sensitive dye imaging, we investigated the interactions between two evoked waves in rat visual cortex, and the spatiotemporal patterns of depolarization in the neuronal population due to wave-to-wave interactions. ⋯ Fusion significantly shortens the latency and half-width of the response, leading to changes in the spatial profile of evoked population activity. The visually-evoked propagating wave may also be suppressed by a preceding spontaneous wave. The refractory period following a propagating wave and the fusion between two waves may contribute to visual sensory processing by modifying the spatiotemporal profile of population neuronal activity evoked by sensory events.