Richárd Fiáth

Richárd Fiáth
Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest · Institute of Cognitive Neuroscience and Psychology

PhD

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65
Publications
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809
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Publications

Publications (65)
Article
Full-text available
Episodic learning and memory retrieval are dependent on hippocampal theta oscillation, thought to rely on the GABAergic network of the medial septum (MS). To test how this network achieves theta synchrony, we recorded MS neurons and hippocampal local field potential simultaneously in anesthetized and awake mice and rats. We show that MS pacemakers...
Article
Full-text available
The meaning behind neural single unit activity has constantly been a challenge, so it will persist in the foreseeable future. As one of the most sourced strategies, detecting neural activity in high-resolution neural sensor recordings and then attributing them to their corresponding source neurons correctly, namely the process of spike sorting, has...
Article
Despite advantage of neuroimaging measures in translational research frameworks, less is known about the psychometric properties thereof, especially in middle-late adolescents. Earlier, we examined evidence of convergent and incremental validity of reward anticipation and response event-related potentials (ERPs) and here we examined, in the same sa...
Article
Objective: Local cooling of the brain as a therapeutic intervention is a promising alternative for patients with epilepsy who do not respond to medication. In vitro and in vivo studies have demonstrated the seizure-suppressing effect of local cooling in various animal models. In our work, focal brain cooling in a bicuculline induced epilepsy model...
Article
Full-text available
Publicly available neural recordings obtained with high spatial resolution are scarce. Here, we present an electrophysiological dataset recorded from the neocortex of twenty rats anesthetized with ketamine/xylazine. The wideband, spontaneous recordings were acquired with a single-shank silicon-based probe having 128 densely-packed recording sites a...
Article
Objective: The growing number of recording sites of silicon-based probes means that an increasing amount of neural cell activities can be recorded simultaneously, facilitating the investigation of underlying complex neural dynamics. In order to overcome the challenges generated by the increasing number of channels, highly automated signal processi...
Article
Full-text available
A Correction to this paper has been published: https://doi.org/10.1038/s41593-020-00779-0.
Preprint
Full-text available
Episodic learning and memory retrieval are critically dependent on a hippocampal 4-12 Hz oscillatory 'clock' signal, the theta oscillation. This clock is largely externally paced, by a network of GABAergic neurons in the medial septum (MS). Theoretical studies suggested a range of hypotheses how this network may achieve theta synchrony; however, ex...
Article
Full-text available
Multisite, silicon-based probes are widely used tools to record the electrical activity of neuronal populations. Several physical features of these devices are designed to improve their recording performance. Here, our goal was to investigate whether the position of recording sites on the silicon shank might affect the quality of the recorded neura...
Article
Adolescence is a developmental period characterized by heightened reward sensitivity which, in turn, confers risk for pertinent negative outcomes, underscoring the need to better understand biological bases and behavioral correlates of reward responsiveness during this developmental phase. Our goals in the current study were to examine, in a sample...
Article
Full-text available
To understand the function of cortical circuits, it is necessary to catalog their cellular diversity. Past attempts to do so using anatomical, physiological or molecular features of cortical cells have not resulted in a unified taxonomy of neuronal or glial cell types, partly due to limited data. Single-cell transcriptomics is enabling, for the fir...
Article
Full-text available
A community-based transcriptomics classification and nomenclature of neocortical cell types To understand the function of cortical circuits, it is necessary to catalog their cellular diversity. Past attempts to do so using anatomical, physiological or molecular features of cortical cells have not resulted in a unified taxonomy of neuronal or glial...
Preprint
Full-text available
Objective: Multisite, silicon-based probes are widely used tools to record the electrical activity of neuronal populations. Several physical features of these devices (e.g. shank thickness, tip geometry) are designed to improve their recording performance. Here, our goal was to investigate whether the position of recording sites on the silicon shan...
Article
Full-text available
Spiking activity of individual neurons can be separated from the acquired multi-unit activity with spike sorting methods. Processing the recorded high-dimensional neural data can take a large amount of time when performed on general-purpose computers. Methods: In this paper, an FPGA- based real-time spike sorting system is presented which takes i...
Article
Full-text available
The use of SU-8 material in the production of neural sensors has grown recently. Despite its widespread application, a detailed systematic quantitative analysis concerning its biocompatibility in the central nervous system is lacking. In this immunohistochemical study, we quantified the neuronal preservation and the severity of astrogliosis around...
Article
Objective: The extraction and identification of single-unit activities in intracortically recorded electric signals have a key role in basic neuroscience, but also in applied fields, like in the development of high-accuracy brain-computer interfaces. The purpose of this paper is to present our current results on the detection, classification and p...
Preprint
Full-text available
To understand the function of cortical circuits it is necessary to classify their underlying cellular diversity. Traditional attempts based on comparing anatomical or physiological features of neurons and glia, while productive, have not resulted in a unified taxonomy of neural cell types. The recent development of single-cell transcriptomics has e...
Article
Aims In this study, we introduce an edge-type laminar silicon probe suitable for improved cell accessibility during in vitro brain slice recordings. With protruding contact sites, the spiky probe provides high signal yield and quality while approaching cells located deeper in the tissue. Methods. The spiky probe comprises an angled shank carrying 3...
Article
Full-text available
Neural probes designed for extracellular recording of brain electrical activity are traditionally implanted with an insertion speed between 1 µm/s and 1 mm/s into the brain tissue. Although the physical effects of insertion speed on the tissue are well studied, there is a lack of research investigating how the quality of the acquired electrophysiol...
Article
Background The cortical slow (~1 Hz) oscillation (SO), which is thought to play an active role in the consolidation of memories, is a brain rhythm characteristic of slow-wave sleep, with alternating periods of neuronal activity and silence. Although the laminar distribution of cortical activity during SO is well-studied by using linear neural probe...
Preprint
Full-text available
It is an uninformative truism to state that the brain operates at multiple spatial and temporal scales, each with each own set of emergent phenomena. More worthy of attention is the point that our current understanding of it cannot clearly indicate which of these phenomenological scales are the significant contributors to the brain’s function and p...
Article
Full-text available
Stereo-electroencephalography depth electrodes, regularly implanted into drug-resistant patients with focal epilepsy to localize the epileptic focus, have a low channel count (6-12 macro- or microelectrodes), limited spatial resolution (0.5-1 cm) and large contact area of the recording sites (~mm2). Thus, they are not suited for high-density local...
Article
In this study, we developed and validated a single-shank silicon-based neural probe with 128 closely-packed microelectrodes suitable for high-resolution extracellular recordings. The 8-mm-long, 100-µm-wide and 50-µm-thick implantable shank of the probe fabricated using a 0.13-µm complementary metal-oxide-semiconductor (CMOS) metallization technolog...
Article
Full-text available
We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor) active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm) and 12 reference pixels (20 µm × 80 µm), densely packed on a 50 µm thick, 100 µm wide, and 8 mm long shank. The active electrodes or pixels consist of dedicated i...
Article
Full-text available
This article reports on the development, i.e., the design, fabrication, and validation of an implantable optical neural probes designed for in vivo experiments relying on optogenetics. The probes comprise an array of ten bare light-emitting diode (LED) chips emitting at a wavelength of 460 nm and integrated along a flexible polyimide-based substrat...
Conference Paper
Full-text available
Electro-physiological recording of neural bioelectrical activity contains local field potentials and unit activities. Unit activity is a mixture of action potentials generated by the neurons. Spike sorting is a method to determine which individual neurons produce the recorded unit activity. High-channel-count neural probes can measure more than a h...
Article
Full-text available
Recording simultaneous activity of a large number of neurons in distributed neuronal networks is crucial to understand higher order brain functions. Here, we demonstrate the in vivo performance of a recently developed electrophysiological recording system comprising a two-dimensional, multi-shank, high-density silicon probe with integrated CMOS ele...
Article
Rhythmic slow waves characterize brain electrical activity during natural deep sleep and under anesthesia, reflecting the synchronous membrane potential fluctuations of neurons in the thalamocortical network. Strong evidence indicates that the neocortex plays an important role in the generation of slow wave activity (SWA), however, contributions of...
Article
Full-text available
Utilization of polymers as insulator and bulk materials of microelectrode arrays (MEAs) makes the realization of flexible, biocompatible sensors possible, which are suitable for various neurophysiological experiments such as in vivo detection of local field potential changes on the surface of the neocortex or unit activities within the brain tissue...
Data
The file is a zipped folder, containing data of the spikes presented in Fig 8B. Matlab can be used in order to open the.fig files and to extract the data. E.g. the file Rat1_ClusterAvg02.fig represents the average single unit waveforms of the 2nd cluster of Rat-1. Piled single unit waveforms of Rat-2 measured on channel 7 are stored in Rat2_ch07.fi...
Data
The file is a Microsoft Excel document. Its first page contains the data obtained by depth electrodes (Fig 8B). Its second page contains data obtained by surface electrodes (Fig 8A). (XLSX)
Data
A Matalab .m file, containing an avg matrix (which is the average of 10 periods of slow waves). The CSD can be calculated from the avg matrix and can be visualized using the CSDplotter toolbox with the following electrode positions: 0.0:0.2:3.0. (MAT)
Data
The results of electrochemical impedance spectroscopy measurements on a probe. (XLSX)
Data
Polyimide microelectrode arrays on a 4-inch silicon wafer (JPG)
Article
This paper presents a low power neural signal amplifier with tunable cut-off frequencies. The presented compact amplifier, which is used for sensing various types of neural signals, reduces the size and the power consumption of the whole circuit. The distinguishing features of this solution are the large time constant, linearity, and small achievab...
Article
Abstract In this article, we evaluated the electrophysiological performance of a novel, high-complexity silicon probe array. This brain-implantable probe implements a dynamically reconfigurable voltage-recording device, coordinating large numbers of electronically switchable recording sites, referred to as electronic depth control (EDC). Our result...
Article
Full-text available
In this paper, manufacturing and in vivo testing of extreme-long Si-based neural microelectrode arrays are presented. Probes with different shaft lengths (15-70 mm) are formed by deep reactive ion etching and have been equipped with platinum electrodes of various configurations. In vivo measurements on rats indicate good mechanical stability, robus...
Article
Full-text available
Silicon micromachined deep brain multielectrodes (up to 70 mm) with monolithically integrated microfluidic channels have been realized to perform simultaneous electrical recording and drug delivery in deep brain regions. Fabrication process of the drug delivery channels and the Pt recording sites is demonstrated. Electrical characterization, impeda...
Article
Full-text available
Glutamate and γ-aminobutyric acid (GABA) transporters play important roles in balancing excitatory and inhibitory signals in the brain. Increasing evidence suggest that they may act concertedly to regulate extracellular levels of the neurotransmitters. Here we present evidence that glutamate uptake-induced release of GABA from astrocytes has a dire...
Article
Full-text available
A novel silicon-based microelectrode array with one- and two-dimensional variants was developed in the framework of the EU-funded research project NeuroProbes. The electrode array comprises complementary-metal-oxide-semiconductor based integrated circuitry to implement the concept of electronic depth control which is used to select up to 32 recordi...
Article
This paper presents multi-electrode arrays for in vivo neural recording applications incorporating the principle of electronic depth control (EDC), i.e., the electronic selection of recording sites along slender probe shafts independently for multiple channels. Two-dimensional (2D) arrays were realized using a commercial 0.5- μm complementary-metal...
Article
Full-text available
A novel wet chemical etching process has been developed for the construction of multisite silicon-based neural interfaces. The fabricated probe shaft is 280μm wide, 80μm thick and 7mm long. The current probe is equipped with 24 square-shaped platinum recording sites of 30μm×30μm. The applied combination of wet chemical etching steps for the formati...
Article
Multi-electrode arrays for in vivo neural recording are presented incorporating the principle of electronic depth control, i.e. an electronic selection of electrode locations along the probe shaft independently for multiple channels. Two-dimensional (2D) arrays are realized using a commercial CMOS process for the electronic circuits combined with p...

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