Neuroscience
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Comparative Study
Impact of anesthetic regimen on the respiratory pattern, EEG microstructure and sleep in the rat model of cholinergic Parkinson's disease neuropathology.
We hypothesized that the impact of distinct anesthetic regimens could be differently expressed during anesthesia and on post-anesthesia sleep in the neurodegenerative diseases. Therefore, we followed the impact of ketamine/diazepam and pentobarbital anesthesia in a rat model of the severe Parkinson's disease cholinergic neuropathology on the electroencephalographic (EEG) microstructure and respiratory pattern during anesthesia, and on the post-anesthesia sleep. ⋯ Our data show that the ketamine/diazepam anesthetic regimen in the PPT-lesioned rats induces more alterations in the EEG microstructure and respiratory pattern than does the pentobarbital anesthesia. In addition, the equal time required to establish an anesthetized state, and the long-term effect on post-anesthesia sleep in the PPT-lesioned vs. control rats suggest this anesthetic regimen as potentially more beneficial both for anesthesia induction and for post-anesthesia sleep in the surgical procedures of the elderly, and Parkinson's, and Alzheimer's patients.
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Acetylcholine (ACh) acts through nicotinic and muscarinic ACh receptors in the ventral midbrain and striatal areas to influence dopamine (DA) transmission. This cholinergic control of DA transmission is important for processes such as attention and motivated behavior, and is manipulated by nicotine in tobacco products. Identifying and characterizing the key ACh receptors involved in cholinergic control of DA transmission could lead to small molecule therapeutics for treating disorders involving attention, addiction, Parkinson's disease, and schizophrenia. α6-Containing nicotinic acetylcholine receptors (nAChRs) are highly and specifically expressed in midbrain DA neurons, making them an attractive drug target. ⋯ To complement these behavioral studies, we studied the ability of in vivo α6(∗) nAChR activation to support plasticity changes in midbrain DA neurons that are relevant to behavioral sensitization and addiction. By coupling local infusion of drugs and brain slice patch-clamp electrophysiology, we show that activating α6(∗) nAChRs in midbrain DA areas is sufficient to enhance glutamatergic transmission in ventral tegmental area (VTA) DA neurons. Together, these results from in vivo studies strongly suggest that α6(∗) nAChRs expressed by VTA DA neurons are positioned to strongly influence both DA-mediated behaviors and the induction of synaptic plasticity by nicotine.
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Comparative Study
Functional differences in face processing between the amygdala and ventrolateral prefrontal cortex in monkeys.
The ability to categorize social information is essential to survive in a primate's social group. In the monkey brain, there are neural systems to categorize social information. Among these, the relationship between the amygdala and the ventrolateral prefrontal cortex (vlPFC) has recently gained focus with regard to emotion regulation. ⋯ Information analyses revealed that the amount of information conveyed by the amygdala neurons about the type of emotion transiently increased immediately after stimulus presentation. In contrast, the information conveyed by the vlPFC neurons showed sustained elevation during stimulus presentation. Therefore, our results suggest that the amygdala processes strong emotion roughly but rapidly, whereas the vlPFC spends a great deal of time processing ambiguous facial information in communication, and make an accurate decision from multiple possibilities based on memory.
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Comparative Study
Electron tomographic structure and protein composition of isolated rat cerebellar, hippocampal and cortical postsynaptic densities.
Electron tomography and immunogold labeling were used to analyze similarities and differences in the morphology and protein composition of postsynaptic densities (PSDs) isolated from adult rat cerebella, hippocampi, and cortices. There were similarities in physical dimensions and gross morphology between cortical, hippocampal and most cerebellar PSDs, although the morphology among cerebellar PSDs could be categorized into three distinct groups. The majority of cerebellar PSDs were composed of dense regions of protein, similar to cortical and hippocampal PSDs, while others were either composed of granular or lattice-like protein regions. ⋯ The scaffold molecule PSD-95, a major component of cortical PSDs, was found absent in a fraction of cerebellar PSDs and when present was clustered in its distribution. In contrast, immunogold labeling for the proteasome was significantly more abundant in cerebellar and hippocampal PSDs than cortical PSDs. Together, these results indicate that PSDs exhibit remarkable diversity in their composition and morphology, presumably as a reflection of the unique functional demands placed on different synapses.
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Studies on sound perception show a tendency to overestimate the distance of an approaching sound source, leading to a faster reaction time compared to a receding sound source. Nevertheless, it is unclear whether motor preparation and execution change according to the perceived sound direction and distance, particularly when the sound falls inside the individual's peripersonal space. In this study we developed several auditory stimuli by means of two speakers, generating sounds moving toward the perceiver but stopping at different distances from her/him. ⋯ Results showed that action initiation was anticipated as a function of sound distance: the closer the sound, the earlier the movement onset, when the sound entered the subject's peripersonal space. Less error for distance estimation was present when the sound was inside the peripersonal space with a modulation in the order of a few centimeters. Overall, our results reveal a link between perceptual bias in sound distance evaluation and peripersonal space, suggesting the presence of motor plan specificity.