When
it comes to mechanisms of brain functions such as learning
and memory mediated by neural networks, existing multichannel electrophysiological
detection and regulation technology at the cellular level does not
suffice. To address this challenge, a 128-channel microelectrode array
(MEA) was fabricated for electrical stimulation (ES) training and
electrophysiological recording of the hippocampal neurons in vitro.
The PEDOT:PSS/PtNPs-coated microelectrodes dramatically promote the
recording and electrical stimulation performance. The MEA exhibited
low impedance (10.94 ± 0.49 kohm), small phase delay (−12.54
± 0.51°), high charge storage capacity (14.84 ± 2.72
mC/cm2), and high maximum safe injection charge density
(4.37 ± 0.22 mC/cm2), meeting the specific requirements
for training neural networks in vitro. A series of ESs at various
frequencies was applied to the neuronal cultures in vitro, seeking
the optimum training mode that enables the neuron to display the most
obvious plasticity, and 1 Hz ES was determined. The network learning
process, including three consecutive trainings, affected the original
random spontaneous activity. Along with that, the firing pattern gradually
changed to burst and the correlation and synchrony of the neuronal
activity in the network have progressively improved, increasing by
314% and 240%, respectively. The neurons remembered these changes
for at least 4 h. Collectively, ES activates the learning and memory
functions of neurons, which is manifested in transformations in the
discharge pattern and the improvement of network correlation and synchrony.
This study offers a high-performance MEA revealing the underlying
learning and memory functions of the brain and therefore serves as
a useful tool for the development of brain functions in the future.
Most of the world’s mountain glaciers have been retreating for more than a century in response to climate change. Glacier retreat is evident on all continents, and the rate of retreat has accelerated during recent decades. Accurate, spatially explicit information on the position of glacier margins over time is useful for analyzing patterns of glacier retreat and measuring reductions in glacier surface area. This information is also essential for evaluating how mountain ecosystems are evolving due to climate warming and the attendant glacier retreat. Here, we present a non-comprehensive spatially explicit dataset showing multiple positions of glacier fronts since the Little Ice Age (LIA) maxima, including many data from the pre-satellite era. The dataset is based on multiple historical archival records including topographical maps; repeated photographs, paintings, and aerial or satellite images with a supplement of geochronology; and own field data. We provide ESRI shapefiles showing 728 past positions of 94 glacier fronts from all continents, except Antarctica, covering the period between the Little Ice Age maxima and the present. On average, the time series span the past 190 years. From 2 to 46 past positions per glacier are depicted (on average: 7.8).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.