Guanxiao Qi

• Dr. rer. nat.
• Research Associate at Forschungszentrum Jülich

Genetic variation in the α5 nicotinic acetylcholine receptor (nAChR) subunit of mice results in behavioral deficits linked to the prefrontal cortex (PFC). rs16969968 is the primary Single Nucleotide Polymorphism (SNP) in CHRNA5 strongly associated with nicotine dependence and schizophrenia in humans. We performed single cell-electrophysiology combi...

The FOXP2/Foxp2 gene, linked to fine motor control in vertebrates, is a potential candidate gene thought to play a prominent role in human language production. It is expressed specifically in a subset of corticothalamic (CT) pyramidal cells (PCs) in layer 6 (L6) of the neocortex. These L6 FOXP2+ PCs project exclusively to the thalamus, with L6a PCs...

Transporting human brain tissue from the operating theater to an off-site laboratory may affect sample integrity for electrophysiological studies. This study investigated how a 30-40 minute transport influenced the intrinsic, synaptic, and morphological properties of human cortical neurons. Electrophysiological recordings were performed on Layer 2/...

Three major types of GABAergic interneurons, parvalbumin-, somatostatin-, and vasoactive intestinal peptide-expressing (PV, SOM, VIP) cells, play critical but distinct roles in the cortical microcircuitry. Their specific electrophysiology and connectivity shape their inhibitory functions. To study the network dynamics and signal processing specific...

Rhythmic brain activity is critical to many brain functions and is sensitive to neuromodulation, but so far very few studies have investigated this activity on the cellular level in vitro in human brain tissue samples. This study reveals and characterizes a novel rhythmic network activity in the human neocortex. Using intracellular patch-clamp reco...

The FOXP2/Foxp2 gene is involved in fine motor control in many vertebrate species; in humans, it is one of the candidate genes thought to play a prominent role in language production. Several studies suggest that in the neocortex, Foxp2 is exclusively expressed in a subset of corticothalamic (CT) pyramidal cells (PCs) in layer 6 (L6). However, the...

Background: Genetic variation in the alpha5 nicotinic acetylcholine receptor (nAChR) subunit of mice results in behavioral deficits linked to the prefrontal cortex (PFC). A Single Nucleotide Polymorphisms (SNP) in CHRNA5 imparts a partial loss of function to the alpha5 subunit-containing (alpha5*) nAChRs and have been demonstrated to be associated...

Three major types of GABAergic interneurons, the parvalbumin- (PV), somatostatin- (SOM) and vasoactive intestinal peptide-expressing (VIP) cells, play critical but distinct roles in the cortical microcircuitry. Their inhibitory functions are shaped by their specific electrophysiology and connectivity. To study how this diversity contributes to the...

Rhythmic brain activity is critical to many brain functions and is sensitive to neuromodulation, but so far very few studies have investigated this activity on the cellular level in vitro in human brain tissue samples. This study reveals and characterizes a novel rhythmic network activity in the human neocortex. Using intracellular patch-clamp reco...

Rhythmic brain activity has been implicated in many brain functions and it is sensible to neuromodulation, but so far very few studies have been carried out from in vitro experiments in humans. In this study we revealed and characterized a novel rhythmic network activity in layer 2/3 (L2/3) of human neocortex. Intracellular patch-clamp recordings s...

The neuromodulator acetylcholine (ACh) plays an important role in arousal, attention, vigilance, learning and memory. ACh is released during different behavioural states and affects the brain microcircuit by regulating neuronal and synaptic properties. Here, we investigated how a low concentration of ACh (30 μM) affects the intrinsic properties of...

The neuromodulator acetylcholine (ACh) plays an important role in arousal, attention, vigilance, learning and memory. ACh is released during different behavioural states and affects the brain microcircuit by regulating neuronal and synaptic properties. Here, we investigated how a low concentration of ACh (30 μM) affects the intrinsic properties of...

Neocortical layer 6 plays a crucial role in sensorimotor co-ordination and integration through functionally segregated circuits linking intracortical and subcortical areas. We performed whole-cell recordings combined with morphological reconstructions to identify morpho-electric types of layer 6A pyramidal cells (PCs) in rat barrel cortex. Cortico-...

Neocortical layer 6 plays a crucial role in sensorimotor coordination and integration through functionally segregated circuits linking intracortical and subcortical areas. However, because of the high neuronal heterogeneity and sparse intralaminar connectivity data on the cell-type specific synaptic microcircuits in layer 6 remain few and far betwe...

Neuron classification is an important component in analyzing network structure and quantifying the effect of neuron topology on signal processing. Current quantification and classification approaches rely on morphology projection onto lower-dimensional spaces. In this paper a 3D visualization and quantification tool is presented. The Density Visual...

In this review we will discuss the effect of two neuromodulatory transmitters, acetylcholine (ACh) and adenosine, on the synaptic release probability and short-term synaptic plasticity. ACh and adenosine differ fundamentally in the way they are released into the extracellular space. ACh is released mostly from synaptic terminals and axonal bouton o...

Synaptic transmission between neurons is the basic mechanism for information processing in cortical microcircuits. To date, paired recording from synaptically coupled neurons is the most widely used method which allows a detailed functional characterization of unitary synaptic transmission at the cellular and synaptic level in combination with a st...

Acetylcholine (ACh) is known to regulate cortical activity during different behavioral states, for example, wakefulness and attention. Here we show a differential expression of muscarinic ACh receptors (mAChRs) and nicotinic ACh receptors (nAChRs) in different layer 6A (L6A) pyramidal cell (PC) types of somatosensory cortex. At low concentrations,...

Acetylcholine (ACh) is known to regulate cortical activity during different behavioral states, e.g. wakefulness and attention. Here we show a differential expression of muscarinic ACh receptors (mAChRs) and nicotinic AChRs (nAChRs) in different layer 6A (L6A) pyramidal cell (PC) types of somatosensory cortex. At low concentrations, ACh induced a pe...

Rhythmic patterns in the neuronal motifs are studied. For nonequal time-delays without noises, two situations are considered, where the conditions for synchronization, winnerless competition (WLC) and “two plus one” (TPO) are studied. In the first situation, if the coupling strengths are the same, then the time-delays are set the same. WLC and sync...

GABAergic interneurons are notorious for their heterogeneity, despite constituting a small fraction of the neuronal population in the neocortex. Classification of interneurons is crucial for understanding their widespread cortical functions as they provide a complex and dynamic network, balancing excitation and inhibition. Here, we investigated dif...

Recent years have seen substantial progress in studying the structural and function properties of GABAergic interneurons and their roles in the neuronal networks of barrel cortex. Although GABAergic interneurons represent only about 12% of the total number of neocortical neurons, they are extremely diverse with respect to their structural and funct...

Adenosine is considered to be a key regulator of sleep homeostasis by promoting slow-wave sleep through inhibition of the brain's arousal centers. However, little is known about the effect of adenosine on neuronal network activity at the cellular level in the neocortex. Here, we show that adenosine differentially modulates synaptic transmission bet...

The fate of the subplate (SP) is still a matter of debate. The SP and layer 6 (which is ontogenetically the oldest and innermost neocortical lamina) develop coincidentally. Yet, the function of sublamina 6B is largely unknown. It has been suggested that it consists partly of neurons from the transient SP, however, experimental evidence for this hyp...

An elementary feature of sensory cortices is thought to be their organisation into functional signal-processing units called ‘cortical columns’. These elementary units process sensory information arriving from peripheral receptors; they are vertically oriented throughout all cortical layers and contain several thousands of excitatory and inhibitory...

Excitatory connections between neocortical layer 4 (L4) and L6 are part of the corticothalamic feedback microcircuitry. Here we studied the intracortical element of this feedback loop, the L4 spiny neuron-to-L6 pyramidal cell connection. We found that the distribution of synapses onto both putative corticothalamic (CT) and corticocortical (CC) L6 p...

The combination of patch clamp recordings from two (or more) synaptically coupled neurons (paired recordings) in acute brain slice preparations with simultaneous intracellular biocytin filling allows a correlated analysis of their structural and functional properties. With this method it is possible to identify and characterize both pre- and postsy...

Excitatory layer 4 (L4) neurons in the 'barrel field' of the rat somatosensory cortex represent an important component in thalamocortical information processing. However, no detailed information exists concerning the quantitative geometry of synaptic boutons terminating on these neurons. Thus, L4 synaptic boutons were investigated using serial ultr...

Synchronization of two time-delayed chemically coupled neurons with burst-spiking states is studied. Different from the previous study by N. Buric et al. (Phys. Rev. E 78, 036211 (2008)), it is found that exactly synchronous burst-spiking dynamics can occur for small coupling strengths and time delays. The results are confirmed by common time delay...

The neuromodulator adenosine is widely considered to be a key regulator of sleep homeostasis and an indicator of sleep need. Although the effect of adenosine on subcortical areas has been previously described, the effects on cortical neurons have not been addressed systematically to date. To that purpose, we performed in vitro whole-cell patch-clam...

We show that delayed coupling could induce or enhance stable chaotic synchronization in complex networks, where no or weak synchrony would exist for the usual instantaneous coupling. The mechanism behind this phenomenon reveals that the phase structure of the coupled chaotic oscillator plays the main role. Numerical results for Rössler and Lorenz o...

The dynamics of brain functional motifs are studied. It is shown that different rhythms can occur in the motifs when time delay is taken into account. These rhythms include synchronization, winnerless competition (WLC) and “two plus one” (TPO). The main discovery is that the transition from WLC to synchronization can be induced simply by time delay...

We study the synchronisation dynamics in complex modular networks. Through theoretical analysis, three types of synchronisation, i.e. uniform, modular and pattern synchronisation, are identified and necessary conditions for their stabilities are given. Numerical simulations with identical chaotic logistic maps and Lorenz oscillators are given to su...

We dissect Rössler equation and give a linear core, which can capture the essence of Rössler oscillator. The maximal transversal Lyapunov exponents calculated from the core are in good agreement with those obtained from Rössler equation. The idea is also tested for coupled Chua's circuit systems. Numerical experiments are given.

We investigate the coevolution dynamics of node activities and coupling strengths in coupled chaotic oscillators via a simple threshold adaptive scheme. The coupling strength is synchronous activity regulated, which in turn is able to boost the synchronization remarkably. In the case of weak coupling, the globally coupled oscillators present a high...

Synchronization stability in complex networks is a topic of theoretical interest and practical importance. Increasing effort has been devoted to the enhancement of synchronizability of networks, or more specifically, the design of synchronizable networks. However, most previous attempts turn the coupling weight/gradient or change the topological in...

In searching the indicators of synchronizability of complex networks, the maximal betweenness centrality is usually proposed as a good indicator. However, we find that a better indicator for synchronizability in heterogeneous networks is the maximal degree from both the average results and the individual realization of a network, which usually make...

An analytical expression for the synchronization time in coupled-map networks is given. By means of the expression, the synchronization time for any given network can be predicted accurately. Furthermore, for networks in which the distributions of nontrivial eigenvalues of coupling matrices have some unique characteristics, analytical results for t...

We study the fast synchronization in complex networks of coupled Hindmarsh-Rose neurons. The relation between the maximal Lyapunov exponent corresponding to the least stable transverse mode and the speed of synchronization is given, based on which we can obtain an optimal value of global coupling strength, with which the network synchronizes with t...

The effects of dynamical symmetry on the chaotic pattern synchronization in modular networks have been studied. It is found that the topological and the coupling symmetries between modules (subnetworks) can both enhance and speed up the chaotic pattern synchronization between modules. The calculation of Lyapunov exponent shows that this dynamical s...

We investigate the dynamical stabilities of ring and linear arrays of chaotic oscillators with asymmetric nearest-neighbor and long-range couplings. It is shown that the instabilities of complete chaotic synchronization occur as the numbers of oscillators are increased beyond critical values which depend on the coupling schemes and coupling paramet...

We show that if the dynamical flow, i.e., the non-vanishing coupling term, exists between nodes in synchronized networks, a wide variety of stable synchronous states of complex networks may occur, which may differ substantially from the dynamics of an individual isolated node. Stability analysis of the dynamics of Hindmarsh-Rose and foodweb network...

The synchronous dynamics of complex networks of pulse-coupled bursting neurons with heterogeneous coupling is studied. The results reveal that the generation and the stability of the completely synchronous state in such networks only depends on the input weight of each neuron, which is independent of the network structure. If the input weight is he...

We study the dynamic stabilities of unidirectionally coupled linear arrays of chaotic oscillators with time-delay feedbacks in star configuration, and find that if all oscillators in the network are identical, then the oscillators in the linear arrays can anticipate the driving oscillators, and simultaneously the oscillators in the linear arrays wi...

Stable propagation of noise-induced synchronous spiking in uncoupled linear neuron arrays is studied numerically. The chaotic neurons in the unidirectionally coupled linear array are modeled by Hindmarsh-Rose neurons. Stability analysis shows that the synchronous chaotic spiking can be successfully transmitted to cortical areas through layered sync...

Based on the spatial periodic chaos synchronization in coupled ring and linear arrays, we proposed a random high-dimensional chaotic encryption scheme. The transmitter can choose hyperchaotic signals randomly from the ring at any different time and simultaneously transmit the information of chaotic oscillators in the ring to receiver through public...

We study the time-delay and unidirectionally coupled ring and linear arrays of chaotic systems, and find that under certain conditions, the linear array can spatial periodically "copy" the chaotic dynamics of the ring with very long anticipation times. Numerical calculations of the Lyapunov exponents show that the delay times can result in unsynchr...

We study the dynamical localization in the system of a two-level Rydberg atom interacting exactly with a pulsed standing microwave. This system approaches an atom optics realization of usual delta-kicked rotor under the rotating-wave approximation (RWA). We find that the non-energy-conserving processes neglected in the RWA have a strong effect on t...

We study the dynamics of unidirectionally coupled linear arrays of chaotic oscillators in star configuration, and find that if the central driving oscillator is different from the oscillators come off from it in the linear arrays, then the oscillators in different linear arrays with the same position with respect to the central one are synchronized...