Biology subjects

Lampl, I.

Publications and source records attributed to Lampl, I..

4 recordsLinked to original sources

bioRxiv2018

The correlated state in balanced neuronal networks

Understanding the magnitude and structure of inter-neuronal correlations and their relationship to synaptic connectivity structure is an important and difficult problem in computational neuroscience. Early studies show that neuronal network models with excitatory-inhibitory balance naturally create very weak spike train correlations. Later work showed that, under some connectivity structures, balanced networks can produce larger correlations between some neuron pairs, even when the average correlation is very small. All of these previous studies assume that the local neuronal network receives feedforward synaptic input from a population of uncorrelated spike trains. We show that when spike trains providing feedforward input are correlated, the downstream recurrent neuronal network produces much larger correlations. We provide an in-depth analysis of the resulting \"correlated state\" in balanced networks and show that, unlike the asynchronous state of previous work, it produces a tight excitatory-inhibitory balance consistent with in vivo cortical recordings.

neuroscience↗

bioRxiv2017

Membrane potential correlates of network decorrelation and improved SNR by cholinergic activation in the somatosensory cortex.

The nucleus basalis (NB) projects cholinergic axons to the cortex where they play a major role in arousal, attention and learning. Cholinergic inputs shift cortical dynamics from synchronous to asynchronous and improves the signal to noise ratio (SNR) of sensory response. Yet, the underlying mechanisms of these changes remain unclear. Using simultaneous extracellular and whole cell patch recordings in layer 4 barrel cortex we show that activation of the cholinergic system has a differential effect on ongoing and sensory evoked activities. Cholinergic activation eliminated the large and correlated spontaneous synaptic fluctuations in membrane potential while sparing the synaptic response to whisker stimulation. This differential effect of cholinergic activation provides a unified explanation for the increased SNR of sensory response and for the reduction in both trial to trial variability and noise correlations as well as explaining the shift into desynchronized cortical state which are the hallmarks of arousal and attention.

neuroscience↗

bioRxiv2017

High-efficiency optogenetic silencing with soma-targeted anion-conducting channelrhodopsins

Optogenetic silencing allows time-resolved functional interrogation of defined neuronal populations. However, the limitations of inhibitory optogenetic tools impose stringent constraints on experimental paradigms. The high light power requirement of light-driven ion pumps and their effects on intracellular ion homeostasis pose unique challenges, particularly in experiments that demand inhibition of a widespread neuronal population in vivo. Guillardia theta anion-conducting channelrhodopsins (GtACRs) are promising in this regard, due to their high single-channel conductance and favorable photon-ion stoichiometry. However, GtACRs show poor membrane targeting in mammalian cells, and the activity of such channels can cause transient excitation in the axon due to an excitatory chloride reversal potential in this compartment. Here we address both problems by enhancing membrane targeting and subcellular compartmentalization of GtACRs. The resulting GtACR-based optogenetic tools show improved photocurrents, greatly reduced axonal excitation, high light sensitivity and rapid kinetics, allowing highly efficient inhibition of neuronal activity in the mammalian brain.

neuroscience↗

bioRxiv2017

Coupling Of Tactile LFP Signals Between Mouse Cortex And Olfactory Bulb

Local field potentials are an important measure of brain activity and have been used to address various mechanistic and behavioral questions. We revealed a prominent whisker evoked local field potential signal in the olfactory bulb and investigated its physiology. This signal, dependent on barrel cortex activation and highly correlated with its local activity, represented a pure volume conductance signal that was sourced back to the activity in the ventro-lateral orbitofrontal cortex, located a few millimeters away. Thus, we suggest that special care should be taken when acquiring and interpreting LFP data.

neuroscience↗