Steve M Potter

• PhD
• Professor (Associate, adjunct) at Georgia Institute of Technology

We have developed a closed-loop, high-throughput system that applies electrical stimulation and optical recording to facilitate the rapid characterization of extracellular, stimulus-evoked neuronal activity. In our system, a microelectrode array delivers current pulses to a dissociated neuronal culture treated with a calcium-sensitive fluorescent d...

Electrical stimulation is ubiquitous as a method for activating neuronal tissue, but there is still significant room for advancement in the ability of these electrical devices to implement smart stimulus waveform design to more selectively target populations of neurons. The capability of a device to encode more complicated and precise messages to a...

Distributed microelectrode array (MEA) recordings from consistent, viable, ≥500 μm thick tissue preparations over time periods from days to weeks may aid in studying a wide range of problems in neurobiology that require in vivo-like organotypic morphology. Existing tools for electrically interfacing with organotypic slices do not address necrosis t...

Significance Characterizing the dynamic encoding of body orientation and eye movements in the brain is central to understanding spatial representation. Studies in rodents have revealed an allocentric heading representation system known as the head-direction network. Visual information is presumed to be critical to rodent head-direction encoding; ho...

Background: Electrical brain stimulation has shown promise for reducing seizures in drug-resistant epilepsy, but the electrical stimulation parameter space remains largely unexplored. New stimulation parameters, electrode types, and stimulation targets may be more effective in controlling seizures compared to currently available options. Hypothes...

Optogenetic techniques enable precise excitation and inhibition of firing in specified neuronal populations and artifact-free recording of firing activity. Several studies have suggested that optical stimulation provides the precision and dynamic range requisite for closed-loop neuronal control, but no approach yet permits feedback control of neuro...

Homeostatic plasticity encompasses a set of mechanisms that are thought to stabilize firing rates in neural circuits. The most widely studied form of homeostatic plasticity is upward synaptic scaling (upscaling), characterized by a multiplicative increase in the strength of excitatory synaptic inputs to a neuron as a compensatory response to chroni...

Feedback and closed-loop circuits exist in just about every part of the nervous system. It is curious, therefore, that for decades neuroscientists have been probing the nervous system in an open-loop manner to understand it. Instead of the linear, reduction-istic "stimulate → record response" approach, a more modern approach is taking hold: closed-...

Microelectrode arrays (wire diameter <50 μm) were compared to traditional macroelectrodes for deep brain stimulation (DBS). Understanding the neuronal activation volume may help solve some of the mysteries associated with DBS, e.g., its mechanisms of action. We used c-fos immunohistochemistry to investigate neuronal activation in the rat hippocampu...

To study sensory processing, stimuli are delivered to the sensory organs of animals and evoked neural activity is recorded downstream. However, noise and uncontrolled modulatory input can interfere with repeatable delivery of sensory stimuli to higher brain regions. Here we show how channelrhodopsin-2 (ChR2) can be used to deliver continuous, subth...

To understand sensory processing in neuronal populations, it is necessary to deliver stimuli to the sensory organs of animals and record evoked population activity downstream. However, the pathways from sensory input to synaptic currents in cells that are several synapses removed from sensory organs are complex. Intrinsic noise and uncontrolled mod...

I discuss the ways in which neuroengineering may enhance us, and why we may want to do it.

This presentation reports on an undergraduate research experience (URE) designed to bridge interdisciplinary neuro-related research labs. While there are many labs on university campuses that are exploring research focused on the nervous system, they tend to work in isolation, unaware of their colleagues across campus who are also engaged with rela...

http://www.frontiersin.org/neural circuits/10.3389/fncir.2012.00098/abstract Single neuron feedback control techniques, such as voltage clamp and dynamic clamp, have enabled numerous advances in our understanding of ion channels, electrochemical signaling, and neural dynamics. Although commercially available multichannel recording and stimulation...

Deep Brain Stimulation (DBS) has provided remarkable relief to patients with brain disorders. Traditionally, DBS is performed through a single macroelectrode implanted at a specific deep brain structure (like the subthalamic nucleus for Parkinson's disease). Despite its great success, little is known about its mechanisms of action. We propose that...

Inspired by living neuron networks (LNNs) in the brain, artificial neural networks (ANNs) have been broadly used in various applications as a computational intelligence tool. However, due to many fundamental differences between ANNs and LNNs, despite the mature training mechanisms for ANNs, it is often challenging to use LNNs as a computational int...

Pathological high frequency oscillations (250-600 Hz) are present in the brains of epileptic animals and humans. The etiology of these oscillations and how they contribute to the diseased state remains unclear. This work identifies the presence of microstimulation-evoked high frequency oscillations (250-400 Hz) in dissociated neuronal networks cult...

Homeostatic plasticity is a set of mechanisms for maintaining appropriate levels of spiking activity in developing neural circuits. When spiking in a cultured cortical network was blocked for 2 days using tetrodotoxin (TTX), there was a compensatory increase in excitatory synaptic strength (scaling). Upward scaling of synaptic strength also occured...

Temporal lobe epilepsy (TLE) is the most drug resistant form of epilepsy. Many patients with TLE are not candidates for surgical resection because of risk to memory and other vital functions. Electrical stimulation therapy is a potential alternative that has shown some promise, but more research needs to be devoted to this area to find better stimu...

Proper neuronal and synaptic maturation is dependent on electrical activity patterns that occur during the development of neuronal circuits . Because many forms of neural activation are causally tied to somatic spiking, deducing the independent role of spiking and other forms of neural activation on network development has been difficult. Multichan...

The emergence of synchronous bursts of action potentials is a hallmark of cultured neuronal networks during the first few weeks in-vitro. While it has often been assumed that pharmacological blockade of AMPAergic transmission using CNQX eliminates population bursts, we have shown that this effect is transient, and when CNQX is applied chronically,...

Here we present Silent Barrage, a closed loop system in which a culture of rat brain cells is given a new body in the form of a small 'forest' of robotic poles located within an art space. This system allows us to study the relationship between brain and body in both scientific and artistic contexts.

To further understand computation in living neuronal networks (LNNs) and improve artificial neural networks (NNs), we seek to create ahybrid liquid state machine (LSM) that relies on an LNN for the reservoir.This study embarks on a crucial first step, establishing effective methods for findinglarge numbers of separable input stimulation patternsin...

High-frequency oscillations (HFOs) are an emerging biomarker for epileptic tissue. Yet the mechanism by which HFOs are produced is unknown, and their rarity makes them difficult to study. Our objective was to examine the occurrence of HFOs in relation to action potentials (APs) and the effect of microstimulation in the tetanus toxin (TT) model of e...

Multiple extracellular microelectrodes (multi-electrode arrays, or MEAs) effectively record rapidly varying neural signals, and can also be used for electrical stimulation. Multi-electrode recording can serve as artificial output (efferents) from a neural system, while complex spatially and temporally targeted stimulation can serve as artificial in...

For the last century, many neuroscientists around the world have dedicated their lives to understanding how neuronal networks work and why they stop working in various diseases. Studies have included neuropathological observation, fluorescent microscopy with genetic labeling, and intracellular recording in both dissociated neurons and slice prepara...

Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide...

This paper presents a method for improved automatic delineation of dendrites and spines from three-dimensional (3-D) images of neurons acquired by confocal or multi-photon fluorescence microscopy. The core advance presented here is a direct grayscale skeletonization algorithm that is constrained by a structural complexity penalty using the minimum...

Referencing is frequently used to remove common-mode signals from multielectrode data, in both freely moving animals and in vitro preparations. For action potential (AP) detection, referencing by subtracting the common average signal has been shown to increase AP signal-to-noise ratio (SNR). This method fails, however, when large transients occur o...

Closed-loop systems, where neural signals are used to control electrical stimulation, show promise as powerful experimental platforms and nuanced clinical therapies. To increase the availability, affordability, and usability of these devices, we have created a flexible open source system capable of simultaneous stimulation and recording from multip...

The study of nonlinear long-term correlations in neuronal signals is a central topic for advanced neural signal processing. In particular, the existence of long-term correlations in neural signals recorded via multielectrode array (MEA) could provide interesting information about changes in interneuron communications. In this study we propose a new...

Brain slice preparations are well-established models for a wide spectrum of in vitro investigations in the neuroscience discipline. However, these investigations are limited to acute preparations or thin organotypic culture preparations due to the lack of a successful method that allows culturing of thick organotypic brain slices. Thick brain slice...

Neurons modify their activity through synaptic and intrinsic plasticity mechanisms induced by afferent input and temper these changes through homeostatic mechanisms. Consequently, most cortical neurons tend to fire within a frequency range of a few Hertz. While comparisons of firing rates have been used to show plasticity in intracellular recording...

Commercially available data acquisition systems for multielectrode recording from freely moving animals are expensive, often rely on proprietary software, and do not provide detailed, modifiable circuit schematics. When used in conjunction with electrical stimulation, they are prone to prolonged, saturating stimulation artifacts that prevent the re...

High-frequency oscillations in the 250-500 Hz range are believed to be associated with aberrant neural activity, indicative of epilepsy. Additionally, oscillations at 100-250 Hz, while found in many normal brain states, have also been linked to epileptiform activity in several studies. However, the causes and effects of such oscillations remain unc...

Objective : Our lab has previously shown that microstimulation distributed over multiple microelectrodes can eliminate epileptiform bursting in dissociated cultures of neocortical rat neurons (Wagenaar et al., 2005). This stimulation is carried out at lower frequencies and voltages than contemporary deep brain stimulation (DBS), making it a potenti...

We developed an adaptive training algorithm, whereby an in vitro neocortical network learned to modulate its dynamics and achieve pre-determined activity states within tens of minutes through the application of patterned training stimuli using a multi-electrode array. A priori knowledge of functional connectivity was not necessary. Instead, effecti...

The acts of learning and memory are thought to emerge from the modifications of synaptic connections between neurons, as guided by sensory feedback during behavior. However, much is unknown about how such synaptic processes can sculpt and are sculpted by neuronal population dynamics and an interaction with the environment. Here, we embodied a simul...

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Movie of a successful-learning simulation. The trajectory, the trajectory around the inner circle (zoom-in), and the animat's distance from the origin in a successful-learning simulation are shown. A switching of the sensory mappings in Q1 and Q3 was applied after 10 minutes into the simulation. The animat's position is indicated as a blue dot. The...

The precise temporal control of neuronal action potentials is essential for regulating many brain functions. From the viewpoint of a neuron, the specific timings of afferent input from the action potentials of its synaptic partners determines whether or not and when that neuron will fire its own action potential. Tuning such input would provide a p...

Spatiotemporal selectivity of extracellular stimuli is a significant challenge in the development of neural interfacing devices. Although models have been previously presented to investigate various stimulus waveforms, it would have great utility if we could experimentally validate the stimulus-evoked cellular response and use that information to o...

Population bursts of action potentials are the most prominent feature of activity recorded from mammalian neuronal networks grown on MEAs. In the intact brain or spinal cord, they are considered variously as motor patterns, sensory gates, sleep spindles, UP-states, developmental signals, epileptiform activity, or memories. I prefer to remain agnost...

How do neurons encode and store information for long periods of time? Recurring patterns of activity have been reported in various cortical structures and were suggested to play a role in information processing and memory. To study the potential role of bursts of action potentials in memory mechanisms, we investigated patterns of spontaneous multi-...

Electrically interfaced cortical networks cultured in vitro can be used as a model for studying the network mechanisms of learning and memory. Lasting changes in functional connectivity have been difficult to detect with extracellular multi-electrode arrays using standard firing rate statistics. We used both simulated and living networks to compare...

The human brain is the best example of intelligence known, with unsurpassed ability for complex, real-time interaction with a dynamic world. AI researchers trying to imitate its remarkable functionality will benefit by learning more about neuroscience, and the differences between Natural and Artificial Intelligence. Steps that will allow AI researc...

Recurring patterns of neural activity, a potential substrate of both information transfer and transformation in cortical networks, have been observed in the intact brain and in brain slices. Do these patterns require the inherent cortical microcircuitry of such preparations or are they a general property of self-organizing neuronal networks? In net...

The advanced and robust computational power of the brain is shown by the complex behaviors it produces. By embodying living cultured neuronal networks with a simulated animal (animat) and situating them within a simulated environment, we study how the basic principles of neuronal network communication can culminate into one of these behaviors: adap...

An alien power plant was unearthed in a remote South American jungle. After exca-vating and dusting it off, the archeologists flip the switch, and it still works! It gener-ates electricity continuously without needing fuel. Wouldn't we want to make more of these power plants? Wouldn't we want to know how this one works? The sci-entists and engineer...

Here, we and others describe an unusual neurorobotic project, a merging of art and science called MEART, the semi-living artist. We built a pneumatically actuated robotic arm to create drawings, as controlled by a living network of neurons from rat cortex grown on a multi-electrode array (MEA). Such embodied cultured networks formed a real-time clo...

The advanced and robust computational power of the brain is shown by the complex behaviors it produces. By embodying living cultured neuronal networks with a robotic or simulated animal (animat) and situating them within an environment, we study how the basic principles of neuronal network communication can culminate into adaptive goal-directed beh...

Willfully controlling the focus of an extracellular stimulus remains a significant challenge in the development of neural prosthetics and therapeutic devices. In part, this is due to the fact that experimental validation of the evoked response to stimuli is an arduous and time-consuming task. The development of a high-throughput data acquisition an...

Three remarkable features of the nervous system--complex spatiotemporal patterns, oscillations, and persistent activity--are fundamental to such diverse functions as stereotypical motor behavior, working memory, and awareness. Here we report that cultured cortical networks spontaneously generate a hierarchical structure of periodic activity with a...

We culture high-density cortical cultures on multi-electrode arrays (MEAs), which allow us to stimulate and record from thousands of neurons. One of the modes of activity in these high-density cultures is dish-wide synchronized bursting. Unlike in vivo, these synchronized patterns persist for the lifetime of the culture. Such aberrant patterns of a...

We attempted to induce functional plasticity in dense cultures of cortical cells using stimulation through extracellular electrodes embedded in the culture dish substrate (multi-electrode arrays, or MEAs). We looked for plasticity expressed in changes in spontaneous burst patterns, and in array-wide response patterns to electrical stimuli, followin...

We have collected a comprehensive set of multi-unit data on dissociated cortical cultures. Previous studies of the development of the electrical activity of dissociated cultures of cortical neurons each focused on limited aspects of its dynamics, and were often based on small numbers of observed cultures. We followed 58 cultures of different densit...

By combining MEA electrophysiology with long-term time-lapse imaging, it is possible to make correlations between changes in network function and changes in neuronal morphology. By re-embodying dissociated cultured networks, network function can be mapped onto behavior, and in vitro research can now make use of a new kind of behavioral studies that...

We culture dissociated mouse cortical neurons in a dense monolayer on multi-electrode arrays, which allow us to stimulate and record from thousands of neurons. Tetanization has been widely used in the study of long-term plasticity. Stimulus-evoked responses constantly change (drift), which makes it difficult to observe the changes caused by the pla...

We present a software suite, MeaBench, for data acquisition and online analysis of multi-electrode recordings, especially from micro-electrode arrays. Besides controlling data acquisition hardware, MeaBench includes algorithms for real-time stimulation artifact suppression and spike detection, as well as programs for online display of voltage trace...

We use dissociated cultures of E-18 rat cortical neurons to study how they process the information. To correlate electrophysiological data with corresponding network structure, we observe effects of the stimuli on structural changes in this culture using multiphoton microscopy. To keep our 2D and 3D cultures alive for long-term studies, it is neces...

We constructed a simulated spiking neural network model to investigate the effects of random background stimulation on the dynamics of network activity patterns and tetanus induced network plasticity. The simulated model was a "leaky integrate-and-fire" (LIF) neural model with spike-timing-dependent plasticity (STDP) and frequency-dependent synapti...

One of the major modes of activity of high-density cultures of dissociated neurons is globally synchronized bursting. Unlike in vivo, neuronal ensembles in culture maintain activity patterns dominated by global bursts for the lifetime of the culture (up to 2 years). We hypothesize that persistence of bursting is caused by a lack of input from other...

Electrical stimulation through multi-electrode arrays is used to evoke activity in dissociated cultures of cortical neurons. We study the efficacies of a variety of pulse shapes under voltage control as well as current control, and determine useful parameter ranges that optimize efficacy while preventing damage through electrochemistry. For any pul...

of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Over the last few decades, technology to record through ever increasing numbers of electrodes has become available to electrophysiologists. For the study of distributed neural processing, however, the ability to stimulate through equal numbers of electrodes, and thus to attain bidirectional communication, is of paramount importance. Here, we presen...

We are developing new tools to study the computational properties of living neuronal networks. We are especially interested in the collective, emergent properties at the mesoscopic scale (Freeman 2000) of thousands of brain cells working together to learn, process information, and to control behavior. We grow dissociated monolayer mammalian cortica...

Studying neuronal networks in vitro has revealed much about the mechanisms of synaptic plasticity. However, because in vitro systems are disembodied, many aspects of neural information processing, motor control, learning, and memory are absent. To address this problem, we have developed a new paradigm for in vitro research, embodied cultured networ...

Studying the brain in vitro, either with brain slices or dissociated cultures, has revealed much about the mechanisms of synaptic plasticity. However, because in vitro systems are disembodied, many aspects of neural information processing, motor control, learning and memory are absent. To address this problem, we have developed a new paradigm for i...

There are two fundamentally different goals for neural interfacing. On the biology side, to interface living neurons to external electronics allows the observation and manipulation of neural circuits to elucidate their fundamental mechanisms. On the engineering side, neural interfaces in animals, people, or in cell culture have the potential to res...

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We embodied networks of cultured biological neurons in simulation and in robotics. This is a new research paradigm to study learning, memory, and infor- mation processing in real time: the Neurally-Controlled Animat. Neural activity was subject to detailed electrical and optical observation using multi-electrode arrays and microscopy in order to ac...

ABSTRACT A gas permeable cover for a cell culture or medium storing container which comprises a solid support sized to fit the opening of the container to be covered and has at least one hole which is covered with a permeable section. The permeable section is sufficiently permeable to oxygen and carbon dioxide that live cells can be sustained, and...