Neuroscience
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Knowledge of how the head moves during locomotion is essential for understanding how locomotion is controlled by sensory systems of the head. We have analyzed head movements of the cat walking along a straight flat pathway in the darkness and light. We found that cats' head left-right translations, and roll and yaw rotations oscillated once per stride, while fore-aft and vertical translations, and pitch rotations oscillated twice. ⋯ Forward acceleration was 25-100% higher and peak-to-peak amplitude of head pitch oscillations was ∼20°/s larger. We concluded that, during walking, the head of the cat is held actively. Reflexes appear to play only a partial role in determining head movement, and vision might further diminish their role.
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Previous work on Parkinson's disease (PD) has indicated a predominantly afferent coupling between affected arm muscle activity and electrophysiological activity within the subthalamic nucleus (STN). So far, no information is available indicating which frequency components drive the afferent information flow in PD patients. Non-directional coupling e.g. by measuring coherence is primarily established in the beta band as well as at tremor frequency. ⋯ For the AR patients, no significant difference in afferent and efferent connections within the STN was found for the different frequency bands. Still, for the AR patients dorsal of the STN significantly more afferent than efferent connections were associated with coherence in the frequency range from 12 to 16Hz. These results provide further evidence for the differential pathological oscillations and pathways present in AR and TD Parkinson patients.
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Leptin is an important hormone that regulates food intake and energy homeostasis by acting on central and peripheral targets. In the gustatory system, leptin is known to selectively suppress sweet responses by inhibiting the activation of sweet sensitive taste cells. Sweet taste receptor (T1R2+T1R3) is also expressed in gut enteroendocrine cells and contributes to nutrient sensing, hormone release and glucose absorption. ⋯ This effect was inhibited by a leptin antagonist (mutant L39A/D40A/F41A) and by ATP gated K(+) (KATP) channel closer glibenclamide, suggesting that leptin affects sweet taste responses of enteroendocrine cells via activation of leptin receptor and KATP channel expressed in these cells. Moreover, leptin selectively inhibited sweet-induced but not bitter-induced glucagon-like peptide-1 (GLP-1) secretion from STC-1 cells. These results suggest that leptin modulates sweet taste responses of enteroendocrine cells to regulate nutrient sensing, hormone release and glucose absorption in the gut.
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The rat has long been considered an important model system for studying neural mechanisms of auditory perception and learning, and particularly mechanisms involving auditory thalamo-cortical processing. However, the functional topography of the auditory thalamus, or medial geniculate body (MGB) has not yet been fully characterized in the rat, and the anatomically-defined features of field-specific, layer-specific and tonotopic thalamo-cortical projections have never been confirmed electrophysiologically. ⋯ We also demonstrated that microstimulation in the MGv elicited cortical activation in layer-specific, region-specific and tonotopically organized manners. To our knowledge, the present study has provided the first and most compelling electrophysiological confirmation of the anatomical organization of the primary thalamo-cortical pathway in the rat, setting the groundwork for further investigation.
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Gender Differences of Peripheral Plasma and Liver Metabolic Profiling in APP/PS1 Transgenic AD mice.
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive impairment. Currently, there is less knowledge of the involvement of the peripheral biofluid/organ in AD, compared with the central nervous system. In addition, with reported high morbidity in women in particular, it has become very important to explore whether gender difference in the peripheral metabolome is associated with AD. ⋯ Disturbances in AD male mice were milder with depletion of monounsaturated fatty acids. We also observed a higher activity of delta-6-desaturate and suppressed activity of delta-5-desaturate in female mice, whereas inhibited stearoyl-CoA-desaturase in male mice suggested that AD induced by the double mutant genes results in different fatty acids catabolism depending on gender. Our results provide metabolic clues into the peripheral biofluid/organs involved in AD, and we propose that a gender-specific scheme for AD treatment in men and women may be required.