@article {2810, title = {Local field potentials primarily reflect inhibitory neuron activity in human and monkey cortex}, journal = {Nature Scientific Reports}, year = {2017}, abstract = {

The local field potential (LFP) is generated by large populations of neurons, but unitary contribution of spiking neurons to LFP is not well characterized. We investigated this contribution in multi-electrode array recordings from the cerebral cortex of human and monkey by calculating the spike-triggered LFP average (st-LFP). The resulting st-LFPs were dominated by broad spatio-temporal components due to on-going activity, synaptic inputs and recurrent connectivity. To observe the local field of a single spike we applied spatial filtering. The filtered st-LFPs were limited to an area of 800 μm from the neuron, and propagated at axonal speed, which is consistent with their unitary nature. In addition, we discriminated between putative inhibitory and excitatory neurons and found that the former dominated this unitary LFP contribution, consistently with previous findings in hippocampal slices. Thus, in human and monkey cortex, the LFP may primarily reflect inhibitory neuron activity.

}, doi = {10.1038/srep40211}, url = {http://www.nature.com/articles/srep40211}, author = {Bartosz Telenczuk and Nima Dehghani and Michel Le Van Quyen and Sydney Cash and Eric Halgren and Nicholas Hatsopoulos and Alain Destexhe} } @article {2811, title = {High-frequency oscillations in human and monkey neocortex during the wake{\textendash}sleep cycle}, journal = {Proceedings of the National Academy of Sciences}, year = {2016}, doi = {10.1073/pnas.1523583113}, url = {http://www.pnas.org/content/113/33/9363}, author = {Michel Le Van Quyen and Lyle Muller and Bartosz Telenczuk and Eric Halgren and Sydney Cash and Nicholas Hatsopoulos and Nima Dehghani and Alain Destexhe} } @article {2813, title = {Avalanche analysis from multielectrode ensemble recordings in cat, monkey, and human cerebral cortex during wakefulness and sleep}, journal = {Frontiers in Physiology}, year = {2012}, abstract = {

Self-organized critical states are found in many natural systems, from earthquakes to forest fires, they have also been observed in neural systems, particularly, in neuronal cultures. However, the presence of critical states in the awake brain remains controversial. Here, we compared avalanche analyses performed on different\ in vivo\ preparations during wakefulness, slow-wave sleep, and REM sleep, using high density electrode arrays in cat motor cortex (96 electrodes), monkey motor cortex and premotor cortex and human temporal cortex (96 electrodes) in epileptic patients. In neuronal avalanches defined from units (up to 160 single units), the size of avalanches never clearly scaled as power-law, but rather scaled exponentially or displayed intermediate scaling. We also analyzed the dynamics of local field potentials (LFPs) and in particular LFP negative peaks (nLFPs) among the different electrodes (up to 96 sites in temporal cortex or up to 128 sites in adjacent motor and premotor cortices). In this case, the avalanches defined from nLFPs displayed power-law scaling in double logarithmic representations, as reported previously in monkey. However, avalanche defined as positive LFP (pLFP) peaks, which are less directly related to neuronal firing, also displayed apparent power-law scaling. Closer examination of this scaling using the more reliable cumulative distribution function (CDF) and other rigorous statistical measures, did not confirm power-law scaling. The same pattern was seen for cats, monkey, and human, as well as for different brain states of wakefulness and sleep. We also tested other alternative distributions. Multiple exponential fitting yielded optimal fits of the avalanche dynamics with bi-exponential distributions. Collectively, these results show no clear evidence for power-law scaling or self-organized critical states in the awake and sleeping brain of mammals, from cat to man.

}, doi = {10.3389/fphys.2012.00302}, url = {http://journal.frontiersin.org/article/10.3389/fphys.2012.00302}, author = {Nima Dehghani and Nicholas Hatsopoulos and Zach Haga and Rebecca Parker and Bradley Greger and Eric Halgren and Sydney Cash and Alain Destexhe} } @article {2812, title = {Spatiotemporal dynamics of neocortical excitation and inhibition during human sleep}, journal = {Proceedings of the National Academy of Sciences}, year = {2012}, abstract = {

Intracranial recording is an important diagnostic method routinely used in a number of neurological monitoring scenarios. In recent years, advancements in such recordings have been extended to include unit activity of an ensemble of neurons. However, a detailed functional characterization of excitatory and inhibitory cells has not been attempted in human neocortex, particularly during the sleep state. Here, we report that such feature discrimination is possible from high-density recordings in the neocortex by using 2D multielectrode arrays. Successful separation of regular-spiking neurons (or bursting cells) from fast-spiking cells resulted in well-defined clusters that each showed unique intrinsic firing properties. The high density of the array, which allowed recording from a large number of cells (up to 90), helped us to identify apparent monosynaptic connections, confirming the excitatory and inhibitory nature of regular-spiking and fast-spiking cells, thus categorized as putative pyramidal cells and interneurons, respectively. Finally, we investigated the dynamics of correlations within each class. A marked exponential decay with distance was observed in the case of excitatory but not for inhibitory cells. Although the amplitude of that decline depended on the timescale at which the correlations were computed, the spatial constant did not. Furthermore, this spatial constant is compatible with the typical size of human columnar organization. These findings provide a detailed characterization of neuronal activity, functional connectivity at the microcircuit level, and the interplay of excitation and inhibition in the human neocortex.

}, doi = {10.1073/pnas.1109895109}, url = {http://www.pnas.org/content/109/5/1731}, author = {Adrien Peyrache and Nima Dehghani and Emad Eskandar and Joseph Madsen and WS Anderson and Jacob Donoghue and Leigh Hochberg and Eric Halgren and Sydney Cash and Alain Destexhe} }