Multiple spine boutons are formed after long-lasting LTP in the awake rat

The formation of multiple spine boutons (MSBs) has been associated with cognitive abilities including hippocampal-dependent associative learning and memory. Data obtained from cultured hippocampal slices suggest that the long-term maintenance of synaptic plasticity requires the formation of new synaptic contacts on pre-existing synapses. This postulate however, has never been tested in the awake, freely moving animals. In the current study, we induced long-term potentiation (LTP) in the dentate gyrus (DG) of awake adult rats and performed 3-D reconstructions of electron micrographs from thin sections of both axonal boutons and dendritic spines, 24 h post-induction. The specificity of the observed changes was demonstrated by comparison with animals in which long-term depression (LTD) had been induced, or with animals in which LTP was blocked by an N-methyl-D-aspartate (NMDA) antagonist. Our data demonstrate that whilst the number of boutons remains unchanged, there is a marked increase in the number of synapses per bouton 24 h after the induction of LTP. Further, we demonstrate that this increase is specific to mushroom spines and not attributable to their division. The present investigation thus fills the gap existing between behavioural and in vitro studies on the role of MSB formation in synaptic plasticity and cognitive abilities

A novel synthesis route for brookite rich titanium dioxide photocatalyst involving organic intermediate

© 2014, Springer Science+Business Media New York.High temperature stable brookite rich titanium dioxide of average crystallite size 20 nm has been prepared by a novel aqueous sol–gel method involving hydroxyethyl cellulose polymer (HEC) as an organic intermediate, wherein titania powder with brookite phase content as high as 44 wt% was obtained. The existence of brookite phase has been evident even after calcination of the samples at 900 °C, which also helped to maintain a specific surface area value of 5.5 m2g-1 compared to the surface area of 2.2 m2g-1 measured on pure titania sample with only rutile phase. The brookite rich titania exhibited superior photocatalytic activity under UV irradiation with a rate constant value of 0.011 min-1 compared to the value of 0.003 min-1 measured for pure rutile phase rich titania samples under similar conditions. The present study indicates that HEC assisted thermal decomposition can be an effective route to produce efficient photoactive brookite rich titania powders