18 research outputs found
A new approach and first steps to strengthen trauma management and road safety in North Vietnam
Attention Enhances the Retrieval and Stability of Visuospatial and Olfactory Representations in the Dorsal Hippocampus
Attention enhances the encoding and retrieval of olfactory and visuospatial representations by modulating place field stability, firing rate, and neuronal synchronization of pyramidal cells in the hippocampus
Transcriptional and Epigenetic Substrates of Methamphetamine Addiction and Withdrawal: Evidence from a Long-Access Self-Administration Model in the Rat
The Boundary Vector Cell Model of Place Cell Firing and Spatial Memory
We review evidence for the boundary vector cell model of the environmental determinants of the firing of hippocampal place cells. Preliminary experimental results are presented concerning the effects of addition or removal of environmental boundaries on place cell firing and evidence that boundary vector cells may exist in the subiculum. We review and update computational simulations predicting the location of human search within a virtual environment of variable geometry, assuming that boundary vector cells provide one of the input representations of location used in mammalian spatial memory. Finally, we extend the model to include experience-dependent modification of connection strengths through a BCM-like learning rule, and compare the effects to experimental data on the firing of place cells under geometrical manipulations to their environment. The relationship between neurophysiological results in rats and spatial behaviour in humans is discussed
Optogenetically Blocking Sharp Wave Ripple Events in Sleep Does Not Interfere with the Formation of Stable Spatial Representation in the CA1 Area of the Hippocampus
Biogenic iron-silver nanoparticles inhibit bacterial biofilm formation due to Ag+ release as determined by a novel phycoerythrin-based assay
Silver nanoparticles (Ag-NPs) can be considered as a cost-effective alternative to antibiotics. In the presence of Fe(III)-citrate and Ag+, Klebsiella oxytoca DSM 29614 produces biogenic Ag-NPs embedded in its peculiar exopolysaccharide (EPS). K. oxytoca DSM 29614 was cultivated in a defined growth medium–containing citrate (as sole carbon source) and supplemented with Ag+ and either low or high Fe(III) concentration. As inferred from elemental analysis, transmission and scanning electron microscopy, Fourier transform infrared spectrometry and dynamic light scattering, Ag-EPS NPs were produced in both conditions and contained also Fe. The production yield of high-Fe/Ag-EPS NPs was 12 times higher than the production yield of low-Fe/Ag-EPS NPs, confirming the stimulatory effect of iron. However, relative Ag content and Ag+ ion release were higher in low-Fe/Ag-EPS NPs than in high-Fe/Ag-EPS NPs, as revealed by emission-excitation spectra by luminescent spectrometry using a novel ad hoc established phycoerythrin fluorescence–based assay. Interestingly, high and low-Fe/Ag-EPS NPs showed different and growth medium–dependent minimal inhibitory concentrations against Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa ATCC 15442. In addition, low-Fe/Ag-EPS NPs exert inhibition of staphylococcal and pseudomonal biofilm formation, while high-Fe/Ag-EPS NPs inhibits staphylococcal biofilm formation only. Altogether, these results, highlighting the different capability of Ag+ release, support the idea that Fe/Ag-EPS NPs produced by K. oxytoca DSM 29614 can be considered as promising candidates in the development of specific antibacterial and anti-biofilm agents
Plasticity of the Hippocampal Place Cell Representation
The roie of the hippocampus in the
representation of 'place' has been attributed to
the place cells, whose spatially localised firing
suggests their participation in forming a cognitive map of the environment. That this map
is necessary for spatial memory formation is
indicated by the propensity of almost all
navigational tasks to be disrupted by hippocampal damage. The hippocampus has also long
been implicated in the formation of episodic
memories, and the unusually plastic nature of
hippocampal synapses testifies to its probable
mnemonic role. Arguably, the place cell
representation should, if it is to support spatial
learning, be modifiable according to known
principles of synaptic reorganization. The
present article reviews evidence that the place
cell representation is indeed plastic, and that its
plasticity depends on the same neurobiological
mechanisms known to underlie experimentally
induced synaptic plasticity. Inferences are
drawn regarding the architecture of the spatial
representation and the principles by which it is
modified. Spatial learning is promising to be the
first kind of memory which is completely
understood at all levels, from molecular through
circuitry to behaviour and beyond