Saturday, August 24th, 2024

Time	Event
1:33a	Tactile Mechanisms and Afferents Underlying the Rat Pup Transport Response Juvenile rodents and other altricial mammals react with calming, immobility and folding up of feet to parental pickup, a set of behaviors referred to as transport response. Here we investigate sensory mechanisms underlying the rat transport response. Grasping rat pups in anterior neck positions evokes strong immobility and folding up of feet, whereas more posterior grasping positions have lesser effects on immobility and foot position. Transport responses are enhanced by slow (1Hz) and even more so by fast (4Hz) gentle shaking and translation of the pup, features consistent with parental transport. In response to lateral grasping, the forepaw below the grasping position points downwards and the forepaw lateral to the grasping position points upwards and medially. Such forepaw adjustments put the pups center of gravity below the grasping point, optimizing pup transportability along with folding up of feet and tail lifting. Tactile stimuli on the back, belly, tail, whisker, dorsal forepaws and dorsal hind-paws do not significantly affect the behaviour of anterior-neck-held pups. Instead, ground contact or paw stimulation consistent with ground contact disrupts transport responses. We identify afferents mediating the transport response by examining membrane labelling with FM1-43 following anterior neck grasping. We observe a dense innervation of the anterior neck skin region (~30 terminals/ mm2). We also observed an age-related decrease of cytochrome oxidase reactivity in the rat somatosensory cortical neck representation, a possible correlate to the developmental decrease in the pup transport response. We conclude anterior neck grasping and loss of ground contact trigger calming and postural adjustments for parental transport in rat pups, responses putatively driven from the densely innervated anterior neck skin. (Comment on this)
3:31a	Properties and predictive potential of the pre-ictal oscillatory dynamics in an ex vivo model of epileptiform activity in the different hippocampal subregions Neuronal oscillatory activity facilitates the transmission of information between neurons. However, abnormally synchronous neuronal activity results in the emergence of seizure-like activity (SLA). The hippocampus (HPC) is a brain area highly susceptible to SLA. The mechanisms leading to SLA are not yet well understood, although changes in neuronal oscillations have been suggested to exist in the time period before SLA onset. Anti-epileptic drugs, such as diazepam (DZP), a GABAA receptor agonist, and carbamazepine (CBZ), a sodium channel blocker, have significant anti-convulsant properties. However, their role in modulating the oscillatory activity within HPC subregions remains unclear. In our study, we used a high [K+] (HK+) artificial cerebrospinal fluid (aCSF) solution to induce SLA in mouse HPC slices, which was detected using spontaneous local field potential (LFP) recordings. SLA activity was recorded in the three HPC subregions, namely CA1, CA3 and the dentate gyrus (DG). LFP analysis in the pre-ictal period revealed significant changes in the oscillatory activity compared to the absence of SLA and to ictal events. A classification algorithm revealed that the oscillatory dynamics, particularly in the CA1 subregion, can predict the emergence of an ictal event with high accuracy. Furthermore, we detected differential DZP and CBZ-induced changes in the oscillatory activity in the CA1, CA3 and DG. Imaging of neuronal activation in the ex vivo model of SLA, using the Fos protein as an activity marker, also revealed a subregion-dependent differential modulation following DZP and CBZ perfusion, which resembled the pattern of oscillatory activity changes. Therefore, the oscillatory dynamics could serve a potential electrophysiological biomarker for predicting seizure activity and are differentially modulated by anti-epileptic drugs. (Comment on this)

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