A flexible multi-electrode-array (MEA) with parylene-C (PA-C) cages on PA-C substrate for neural network study in vitro is presented here. 8×8 cage arrays were fabricated on a 10-μm-thick PA-C film. For our use, the array was glued on a 100μm-thick glass substrate for ease of handling. Each cage is to trap an individual neuron to force a close proximity of the neuron to an embedded electrode inside the cage for stimulation and recording. In addition, each neurocage has six tunnels emanating from the cage to allow axons and dendrites to grow outward and form synapses with other trapped neurons. The Electrode inside each neurocage can then be used to stimulate and/or record electrical activity from the trapped cell at any given time. Why thin and flexible? From our previous work, it is learned that manually loading neuron one-by-one into the cage is time-consuming. We then propose to use laser tweezer to do the cell loading from the backside of the array. To facilitate laser tweezer neuron loading, the neurocage array must be transparent and thin. On the other hand, device flexibility facilitates a high-yield fabrication, easy singulation and attachment to almost any substrate for use.

An electricity laboratory course has been created at Caltech that is based on students doing experiments in their rooms, using parts and tools from a kit they receive at the start, for work during 20 weeks of the school year. The first laboratories are at a very basic level and the complexity increases over time. In the final experiment the students make a microwave transmitter and receiver and study radiation and detection by dipole antennas. During the course the physics of all the Maxwell equations is studied as well as circuit design and basic transistor electronics. Most of the students have little or no electronics knowledge at the start and they exhibit solid long-lasting learning.

The use of an optical tweezer for moving dissociated neurons was studied. The main features of the tweezers are outlined as well as the general principles of its operation. Infrared beams at 980 and 1064 nm were used, focused so as to make a trap for holding neurons and moving them. Absorption by cells at those wavelengths is very small. Experiments were done to evaluate nonsticky substrate coatings, from which neurons could be easily lifted with the tweezers. The maximum speed of cell movement as a function of laser power was determined. Detailed studies of the damage to cells as a function of beam intensity and time of exposure were made. The 980 nm beam was much less destructive, for reasons that are not understood, and could be used to safely move cells through distances of millimeters in times of seconds. An illustrative application of the use of the tweezers to load neurons without damage into plastic cages on a glass substrate was presented. The conclusion is that optical tweezers are an accessible and practical tool for helping to establish neuron cultures of cells placed in specific locations.

Traditional techniques for investigating cultured neural networks, such as the patch clamp and multi-electrode array, are limited by: (1) the number of identified cells which can be simultaneously electrically contacted, (2) the length of time for which cells can be studied, and (3) the lack of one-to-one neuron-to-electrode specificity. Here, we present a new device - the caged neuron multi-electrode array - which overcomes these limitations. This micro-machined device consists of an array of neurocages which mechanically trap a neuron near an extracellular electrode. While the cell body is trapped, the axon and dendrites can freely grow into the surrounding area to form a network. The electrode is bi-directional, capable of both stimulating and recording action potentials. This system is non-invasive, so that all constituent neurons of a network can be studied over its lifetime with stable one-to-one neuron-to-electrode correspondence. Proof-of-concept experiments are described to illustrate that functional networks form in a neurochip system of 16 cages in a 4 x 4 array, and that suprathreshold connectivity can be fully mapped over several weeks. The neurochip opens a new domain in neurobiology for studying small cultured neural networks.

A large number of American elementary school students are now studying science using the hands-on inquiry curricula developed in the 1990s: Insights; Full Option Science System (FOSS); and Science and Technology for Children (STC). A goal of these programs, echoed in the National Science Education Standards, is that children should gain “abilities to do scientific inquiry” and “understanding about scientific inquiry.” We have studied the degree to which students can do inquiries by using four hands-on performance assessments, which required one or three class periods. To be fair, the assessments avoided content that is studied in depth in the hands-on programs. For a sample of about 1000 fifth grade students, we compared the performance of students in hands-on curricula with an equal number of students with textbook curricula. The students were from 41 classrooms in nine school districts. The results show little or no curricular effect. There was a strong dependence on students' cognitive ability, as measured with a standard multiple-choice instrument. There was no significant difference between boys and girls. Also, there was no difference on a multiple-choice test, which used items released from the Trends in International Mathematics and Science Study (TIMSS). It is not completely clear whether the lack of difference on the performance assessments was a consequence of the assessments, the curricula, and/or the teaching. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 467–484, 2006

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, following several induction protocols related to those used in the literature, as well as some novel ones. Experiments were performed with spontaneous culture-wide bursting suppressed by either distributed electrical stimulation or by elevated extracellular magnesium concentrations as well as with spontaneous bursting untreated. Changes concomitant with induction were no larger in magnitude than changes that occurred spontaneously, except in one novel protocol in which spontaneous bursts were quieted using distributed electrical stimulation.

The ability to conduct seems basic to an understanding of science. But how well are elementary students being taught to develop their skills? Mr. Pine and Ms. Aschbacher assessed the ability of students to pursue inquiry, and they conclude that educators need help to move beyond superficial teaching. ********** WHETHER YOU see the primary purpose of education as preparing tomorrow's work force, as helping individuals lead personally fulfilling and responsible lives, or as ensuring that we will have the collective wisdom and inclination to use and technology to solve the myriad problems facing the world, we're sure you'll agree that an understanding of scientific and the critical thinking skills that go with it have become invaluable in the modern world. For each of these purposes, we need to educate students to question, explore, reason, collaborate, and communicate with others rather than just follow directions and memorize a body of existing knowledge. Thus has become as basic a part of education as numeracy and literacy and has value both for its methodologies and for its ideas. is important to introduce early in children's education because, the longer nonscientific ideas are held, the more difficult they are to change, and attitudes toward seem to crystallize by the end of the elementary grades. Thus good elementary education can do much to provide a sound foundation for later learning, as well as helping students become comfortable with using and scientific thinking skills in their daily lives, whether in a career or as consumers and citizens. After a long lead time, inquiry-based education has finally become a major option in American schools. Many elementary students in hundreds of school districts are using the hands-on inquiry science curricula developed in the 1990s with support from the National Science Foundation. But are these curricula having the impact on student learning that reformers expected? In this article we discuss some basic research on the abilities of elementary students and draw implications for curriculum policy and teacher professional development. What are these curricula, and what was their genesis? Beginning at least in the 17th century, when Galileo rolled balls down ramps, scientific research has been based on inquiry--experimental investigations that attempt to answer questions about the natural world. However, the idea that teaching should have students conduct investigations rather than absorb facts from textbooks was slow to gain support. In the latter part of the 19th century, some eminent scientists, such as Herbert Spencer and T. H. Huxley, urged that be taught through students' experiences, as did Charles Eliot in 1869 in his inaugural address as president of Harvard University. (1) However, teachers of the day mainly lectured and conducted demonstrations. Looking back from the vantage of 1920 on his education in the late 1800s in Switzerland, Einstein said, It is in fact nothing short of a miracle that the modern methods of instruction have not entirely strangled the holy curiosity of inquiry. In 1902, John Dewey added his considerable weight in support of inquiry-based education: The map does not take the place of the actual journey. The logically formulated material of a is no substitute for the having of individual experiences. The mathematical formula for a falling body does not take the place of personal contact and immediate individual experience with the falling thing. (2) However, in spite of a few powerful supporters, inquiry-based education remained rare through the first half of the 20th century. That changed beginning in October 1957, when at the height of the Cold War Russia's Sputnik I became the first successful manmade satellite. …

Background 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 densities – 3000 to 50,000 neurons on areas of 30 to 75 mm 2 – growing on multi-electrode arrays (MEAs) during the first five weeks of their development. Results Plating density had a profound effect on development. While the aggregate spike detection rate scaled linearly with density, as expected from the number of cells in proximity to electrodes, dense cultures started to exhibit bursting behavior earlier in development than sparser cultures. Analysis of responses to electrical stimulation suggests that axonal outgrowth likewise occurred faster in dense cultures. After two weeks, the network activity was dominated by population bursts in most cultures. In contrast to previous reports, development continued with changing burst patterns throughout the observation period. Burst patterns were extremely varied, with inter-burst intervals between 1 and 300 s, different amounts of temporal clustering of bursts, and different firing rate profiles during bursts. During certain stages of development bursts were organized into tight clusters with highly conserved internal structure. Conclusion Dissociated cultures of cortical cells exhibited a much richer repertoire of activity patterns than previously reported. Except for the very sparsest cultures, all cultures exhibited globally synchronized bursts, but bursting patterns changed over the course of development, and varied considerably between preparations. This emphasizes the importance of using multiple preparations – not just multiple cultures from one preparation – in any study involving neuronal cultures. These results are based on 963 half-hour-long recordings. To encourage further investigation of the rich range of behaviors exhibited by cortical cells in vitro , we are making the data available to other researchers, together with Matlab code to facilitate access.

This paper presents a refined method and design fabricating parylene neurocages for in vitro studies of live neural networks. This fabrication process is less complex than previous neurocage and neurowell fabrication processes. Parylene neurocages are biocompatible and very robust, making them ideally suited for studying the synaptic connections between individual neurons to gain insight into learning and memory. TThe study showed that biocompatible and robust neurocages can be created that achieve significantly higher neuronal survival and outgrowth rate than previous versions. Previous neurocage designs achieved limited neuronal outgrowth; the long-term cell survival rate was <25%. As outlined here, the incorporation of new materials and different anchoring techniques, in addition to some design modifications, have improved the long-term cell survival rate to >50%.

We present a novel process to produce parylene cages for the in vitro study of cultured neural networks. For the first time, a neuro-cage fabrication technology is demonstrated that is scalable to high density cage arrays and able to withstand the chemical and mechanical rigors of supporting cellular cultures for long-term study.

The neurochip is a silicon micromachined device upon which cultured mammalian neurons can be continuously and individually monitored and stimulated. The neurochip is based upon a 4×4 array of metal electrodes, each of which has a caged well structure designed to hold a single mature cell body while permitting normal outgrowth of neural processes. We demonstrate that this device is capable of maintaining cell survival, and that the electrodes can both record and stimulate electrical activity in individual cells with no crosstalk between channels.

A description is given of a functional silicon micromachined device that permits non-invasive, bidirectional, highly specific communication with cultured mammalian neurons. The heart of the system is a well structure that holds the cell in close proximity to a metal extracellular electrode while permitting normal outgrowth of axons and dendrites. An iterative approach is used to create a design that allows normal growth of the neurons while preventing their escape. An array of 16 such neurowells makes it possible to perform studies of biological neural network development and function with unprecedented detail.

A new type of multielectrode array for studies of cultured neural networks is described. It is a silicon microstructure, a "neurochip': which embodies wells on the surface of a chip that are designed to contain single neurons. Each well has a platinized gold electrode which can be used for stimulating a neuron in the well or for recording from it. Each well is covered with a structure which provides tunnels through which axons and dendrites can grow out and a central hole through which the neurons can be loaded into the well. The processes thus trap the cells in the wells. The first application of this method is described: A4 x4 array of wells spaced 100 mu m apart. Results are described which show long term survival and outgrowth of neurons from the wells, and the use of well electrodes to both record and stimulate electrical activity of individual neurons.

Specificity in neuron targeting during stimulation and recording is essential in executing complex neuronal network studies. Physiological experiments have shown that young (less than one week old) cultured neurons can escape through a 0.5 μm-square hole. Through iterative physiological experimentation, a functional MEMS structure we call a canopy neurowell has been developed. Essentially a micromechanical cage, the structure consists of a well, an electrode bottom, and a nitride canopy cover with integrated micro-tunnels. It is able to physically confine, and make electrical contact with, a neuron. Potentially, neurowells are capable of multi-site studying of long-term, in vitro and in vivo neural systems. Experiments show that the canopy neurowell is mechanically functional and biologically compatible.

The successful design and fabrication of a novel neuroprobe structure for in vivo extracellular stimulation and recording of cerebral neurons is presented. The neuroprobe has 15 neuron wells, 50μm apart, fabricated near the tip of the 20-μm-thick shank. The fabrication includes double-sided photolithography and micromachining on both sides of a membrane, which is the bottom of the 500-μm-deep cavity to form probes and neuron wells. The novel feature of the use of the cultured neuron probe is the implantation of cultured neurons into the probe’s neuron wells. This represents, for the first time, a systematic attempt to find out whether neurons can be cultured, implanted and sustained in a host central nervous system (a brain) by using a silicon device, as well as do they establish functional synaptic connections. More specific recording and stimulation of the nervous system could for the first time become possible if the probes work electrophysiologically.

ABSTRACT Educational reform in the United States has been stymied, in part, by the mismatch between curricular reform (with its emphasis on problem solving and process) and traditional accountability systems (with multiple‐choice tests, largely of factual recall). If teachers teach to the test, and they do, curricular reform is blunted. The purpose of this study was to create and evaluate alternative technologies for assessing science process understanding of elementary school students, technologies that align with curricular reform. Hands‐on science investigations and their surrogates (laboratory notebooks, computer simulation, paper‐and‐pencil exercises) were developed and then evaluated as to their reliability, validity, and utility for use in large scale assessment. In addition, each of the alternative technologies was compared with a traditional science achievement test. Evidence presented suggests that they are reliable, valid, and measure aspects of science achievement not tapped by traditional multiple‐choice tests.

The call for alternative assessments of science achievement grows out of the current constructivist reform in science curriculum and cognitive research. This article presents and applies guidelines for developing performance assessments aligned with this research and reform. We sample classroom activities or tasks from a domain of activities and construct performance assessments with them. Using this approach, three hands-on science investigations were constructed so that each could be scored by observers in real time. These investigations were considered benchmarks for performance assessments. Because these investigations are costly to develop and administer, surrogates were developed: student notebooks in lieu of observers, computer simulations of the investigations, free response questions paralleling parts of the investigation, and multiple-choice items with alternatives keyed to student hands-on performance. Data have been collected from over 300 fifth- and sixth-grade students using these assessments. We found that hands-on assessments can be developed through an extensive, iterative, development process; hands-on assessments are very delicate instruments. Moreover, they can be scored reliably, even in real time. However, with both benchmarks and surrogates, task heterogeneity -variations in an individual student's performance among tasks-limits the generalizability of performance to the larger domain of interest. Similarly, method heterogeneity-variations in an individual student's performance depending on whether the hands-on investigation, computer simulation or pencil-and-paper exercises was used-limits the exchangeability of the surrogates for the benchmarks.

Voltage-sensitive dyes offer the promise of noninvasive multicell recording of electrical activity, and should therefore be useful for studying the synaptic interactions of small networks of cultured neurons. We have designed and built a system for recording from microcultures of 1–15 neurons from the rat superior cervical ganglion (SCG), using voltage-sensitive fluorescent dyes of the styryl class. The apparatus comprises a standard inverted epifluorescence microscope; a mercury arc lamp with an optical feedback regulator; a 256-pixel fiber-optic camera with individual photodiode detectors and very low-noise amplifiers; and a personal computer-based data acquisition system. Its dark noise and illumination fluctuations are low enough that at typical fluorescence levels for these cells, it is limited by shot noise (the inherent physical limit of detection). Recording from SCG neurons, the signal-to-noise ratio is high enough to see large subthreshold synaptic potentials without signal averaging. This apparatus should be useful for studying long-term synaptic plasticity in cultures of vertebrate neurons, and several of its features should apply to optical recording from other preparations.