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Protein Degradation during Reconsolidation as a Mechanism for Memory Reorganization
Kaang, Bong-Kiun,Choi, Jun-Hyeok Frontiers Research Foundation 2011 Frontiers in Behavioral Neuroscience Vol.5 No.-
<P>Memory is a reference formed from a past experience that is used to respond to present situations. However, the world is dynamic and situations change, so it is important to update the memory with new information each time it is reactivated in order to adjust the response in the future. Recent researches indicate that memory may undergo a dynamic process that could work as an updating mechanism. This process which is called reconsolidation involves destabilization of the memory after it is reactivated, followed by restabilization. Recently, it has been demonstrated that the initial destabilization process of reconsolidation requires protein degradation. Using protein degradation inhibition as a method to block reconsolidation, recent researches suggest that reconsolidation, especially the protein degradation-dependent destabilization process is necessary for memory reorganization.</P>
Echtermeyer, Christoph,Han, Cheol E.,Rotarska-Jagiela, Anna,Mohr, Harald,Uhlhaas, Peter J.,Kaiser, Marcus Frontiers Research Foundation 2011 Frontiers in neuroinformatics Vol.5 No.-
<P>Human brain networks can be characterized at different temporal or spatial scales given by the age of the subject or the spatial resolution of the neuroimaging method. Integration of data across scales can only be successful if the combined networks show a similar architecture. One way to compare networks is to look at spatial features, based on fiber length, and topological features of individual nodes where outlier nodes form single node motifs whose frequency yields a fingerprint of the network. Here, we observe how characteristic single node motifs change over age (12–23 years) and network size (414, 813, and 1615 nodes) for diffusion tensor imaging structural connectivity in healthy human subjects. First, we find the number and diversity of motifs in a network to be strongly correlated. Second, comparing different scales, the number and diversity of motifs varied across the temporal (subject age) and spatial (network resolution) scale: certain motifs might only occur at one spatial scale or for a certain age range. Third, regions of interest which show one motif at a lower resolution may show a range of motifs at a higher resolution which may or may not include the original motif at the lower resolution. Therefore, both the type and localization of motifs differ for different spatial resolutions. Our results also indicate that spatial resolution has a higher effect on topological measures whereas spatial measures, based on fiber lengths, remain more comparable between resolutions. Therefore, spatial resolution is crucial when comparing characteristic node fingerprints given by topological and spatial network features. As node motifs are based on topological and spatial properties of brain connectivity networks, these conclusions are also relevant to other studies using connectome analysis.</P>
Kim, Dong-Kyu,Cho, Eun Bee,Moon, Mi Jin,Park, Sumi,Hwang, Jong-Ik,Do Rego, Jean-Luc,Vaudry, Hubert,Seong, Jae Young Frontiers Research Foundation 2012 Frontiers in neuroscience Vol.6 No.-
<P>The neuropeptides gonadotropin-releasing hormone (GnRH) and kisspeptin (KiSS), and their receptors gonadotropin-releasing hormone receptor (GnRHR) and kisspeptin receptor (KiSSR) play key roles in vertebrate reproduction. Multiple paralogous isoforms of these genes have been identified in various vertebrate species. Two rounds of genome duplication in early vertebrates likely contributed to the generation of these paralogous genes. Genome synteny and phylogenetic analyses in a variety of vertebrate species have provided insights into the evolutionary origin of and relationship between paralogous genes. The paralogous forms of these neuropeptides and their receptors have coevolved to retain high selectivity of the ligand–receptor interaction. These paralogous forms have become subfunctionalized, neofunctionalized, or dysfunctionalized during evolution. This article reviews the evolutionary mechanism of GnRH/GnRHR and KiSS/KiSSR, and the fate of the duplicated paralogs in vertebrates.</P>
Inactivation of Medial Prefrontal Cortex Impairs Time Interval Discrimination in Rats
Kim, Jieun,Jung, Amy Hyeyun,Byun, Jayoung,Jo, Suhyun,Jung, Min Whan Frontiers Research Foundation 2009 Frontiers in Behavioral Neuroscience Vol.3 No.-
<P>Several lines of evidence suggest the involvement of prefrontal cortex in time interval estimation. The underlying neural processes are poorly understood, however, in part because of the paucity of physiological studies. The goal of this study was to establish an interval timing task for physiological recordings in rats, and test the requirement of intact medial prefrontal cortex (mPFC) for performing the task. We established a temporal bisection procedure using six different time intervals ranging from 3018 to 4784 ms that needed to be discriminated as either long or short. Bilateral infusions of muscimol (GABA<SUB>A</SUB> receptor agonist) into the mPFC significantly impaired animal's performance in this task, even when the animals were required to discriminate between only the longest and shortest time intervals. These results show the requirement of intact mPFC in rats for time interval discrimination in the range of a few seconds.</P>