Formulation Of The FIRIS-P Professional Core-Competency Framework For Flexible Academic Curricula: The Biomedical Engineering Program

Introduction – How to formulate the goals of an academic educational program in such a way that they reflect the identity of the profession, but at the same time allow the flexibility required for self-responsible and self-directed individual study paths that can initiate lifelong learning and successful interdisciplinary collaboration after graduation? Here, we present a novel competency framework that (1) reflects the identity and academic level of the interdisciplinary Biomedical Engineering (BME) profession, (2) permits the alignment of program intended learning outcomes that accommodate the content of the different specialisation tracks of the BME program and (3) guides students and staff by improved curriculum mapping and optimization. Methods – We collected input from teaching staff members who are actively practicing their BME profession in the interdisciplinary ecosystem around our university. Using their feedback, we iteratively formulated a set of core competencies that characterize the work and role of the BME professional. We obtained preliminary face-validity by performing curriculum mappings from several courses from BME-tracks and by asking feedback from students. Results – The iterations resulted in the FIRIS-P competency framework including five successive core professional competencies of which specified subcompetencies carry the BME identity: (1) Fundamental competencies, (2) Instrumental competencies, (3) Reasoning competencies, (4) Interventional competencies, and (5) Societal competencies. These core professional competencies are completed and supported by transferable Personal competencies. Discussion: Preliminary validation indicates that the FIRIS-P framework carries all three characteristics mentioned above, warranting future evaluation of its merits for education of lifelong learning BME professionals

Extracellular stimulation window explained by a geometry-based model of the neuron-electrode contact

Extracellular stimulation of single cultured neurons which are completely sealing a microelectrode is usually performed using anodic or biphasic currents of at least 200 nA. However, recently obtained experimental data demonstrate the possibility to stimulate a neuron using cathodic current pulses with less amplitude. Also, a stimulation window is observed. These findings can be explained by a finite-element model which permits geometry-based electrical representation of the neuron-electrode interface and can be used to explore the required conditions for extracellular stimulation in detail. Modulation of the voltage sensitive channels in the sealing part of the membrane appears to be the key to successful cathodic stimulation. Furthermore, the upper limit of the stimulation window can be explained as a normal consequence of the neuronal membrane electrophysiology

Geometry-based finite-element modeling of the electrical contact between a cultured neuron and a microelectrode

The electrical contact between a substrate embedded microelectrode and a cultured neuron depends on the geometry of the neuron-electrode interface. Interpretation and improvement of these contacts requires proper modeling of all coupling mechanisms. In literature, it is common practice to model the neuron-electrode contact using lumped circuits in which large simplifications are made in the representation of the interface geometry. In this paper, the finite-element method is used to model the neuron-electrode interface, which permits numerical solutions for a variety of interface geometries. The simulation results offer detailed spatial and temporal information about the combined electrical behavior of extracellular volume, electrode-electrolyte interface and neuronal membrane

Modeled channel distributions explain extracellular recordings from cultured neurons sealed to microelectrodes

Amplitudes and shapes of extracellular recordings from single neurons cultured on a substrate embedded microelectrode depend not only on the volume conducting properties of the neuron-electrode interface, but might also depend on the distribution of voltage-sensitive channels over the neuronal membrane. In this paper, finite-element modeling is used to quantify the effect of these channel distributions on the neuron-electrode contact. Slight accumulation or depletion of voltage-sensitive channels in the sealing membrane of the neuron results in various shapes and amplitudes of simulated extracellular recordings. However, estimation of channel-specific accumulation factors from extracellular recordings can be obstructed by co-occuring ion currents and defect sealing. Experimental data from cultured neuron-electrode interfaces suggest depletion of sodium channels and accumulation of potassium channels

A dynamic neural model of localization of brief successive stimuli in saltation

Somatosensory saltation is an illusion robustly generated using short tactile stimuli [1,2]. There is a perceived displacement of a first stimulus if followed by a subsequent nearby stimulus with a short stimulus onset asynchrony (SOA). Experimental reports suggest that this illusion results from spatiotemporal integration in early processing stages, but the exact neural mechanism is unknown. The neuronal mechanism involved is probably quite generic as similar phenomena occur in other modalities, audition for example [3]

Subjective localization of electrocutaneous stimuli

Studying the perception of spatiotemporal stimulus patterns in various modalities may yield important information on the way in which humans process sensory information. The perception of tactile and nociceptive cutaneous stimulus patterns have been studied by Stolle et al. [1] and Trojan et al. [2][4] respectively. Among other things, both authors studied subjective localization of single stimuli. In Trojan et al. [4], two types of mislocalization patterns were observed for nociceptive single stimuli when comparing the localization reports with the stimulus locations: (1) overall proximal or distal displacement and (2) expansion or contraction of the stimulus area.\ud It is unknown whether tactile and nociceptive stimuli at the same skin site are perceived as being at the same site. Therefore, comparing the spatial perception of tactile and nociceptive cutaneous stimuli may provide new insights into their processing. This comparison can only be successfully made by applying nociceptive and tactile stimuli at the same skin site in the same experiment. This can be done by using a device which has recently been developed at our institute and which we refer to as the bimodal stimulation electrode [3]. \ud Recording the perceived locations of stimuli can be done by letting subjects report these on a scale. The most intuitive scale for this is the stimulated arm itself. However, this would bias the perception of stimulus location by providing visual information of the electrode locations. The goal of the present research was to (1) create and (2) test a setup which allows subjects to report perceived stimulus locations on their own arm without seeing the electrode positions. This was achieved by building a setup consisting of a touch screen (Provision Visboard) which presents a digital image of the subject’s own arm (without electrodes) and which is positioned over this arm after the electrodes have been attached. Subjects can report the localizations by pointing at the screen using a pointer

Neuroelectronic interfacing with cultured multielectrode arrays toward a cultured probe

Efficient and selective electrical stimulation and recording of neural activity in peripheral, spinal, or central pathways requires multielectrode arrays at micrometer scale. ¿Cultured probe¿ devices are being developed, i.e., cell-cultured planar multielectrode arrays (MEAs). They may enhance efficiency and selectivity because neural cells have been grown over and around each electrode site as electrode-specific local networks. If, after implantation, collateral sprouts branch from a motor fiber (ventral horn area) and if they can be guided and contacted to each ¿host¿ network, a very selective and efficient interface will result. Four basic aspects of the design and development of a cultured probe, coated with rat cortical or dorsal root ganglion neurons, are described. First, the importance of optimization of the cell-electrode contact is presented. It turns out that impedance spectroscopy, and detailed modeling of the electrode-cell interface, is a very helpful technique, which shows whether a cell is covering an electrode and how strong the sealing is. Second, the dielectrophoretic trapping method directs cells efficiently to desired spots on the substrate, and cells remain viable after the treatment. The number of cells trapped is dependent on the electric field parameters and the occurrence of a secondary force, a fluid flow (as a result of field-induced heating). It was found that the viability of trapped cortical cells was not influenced by the electric field. Third, cells must adhere to the surface of the substrate and form networks, which are locally confined, to one electrode site. For that, chemical modification of the substrate and electrode areas with various coatings, such as polyethyleneimine (PEI) and fluorocarbon monolayers promotes or inhibits adhesion of cells. Finally, it is shown how PEI patterning, by a stamping technique, successfully guides outgrowth of collaterals from a neonatal rat lumbar spinal cord explant, after six days in cultur

Observation of time-dependent psychophysical functions and accounting for threshold drifts

Methods to obtain estimates of psychophysical functions are used in numerous fields, such as audiology, vision, and pain. Neurophysiological and psychological processes underlying this function are assumed to remain stationary throughout a psychophysical experiment. However, violation of this assumption (e.g., due to habituation or changing decisional factors) likely affects the estimates of psychophysical parameters. We used computer simulations to study how non-stationary processes, resulting in a time-dependent psychophysical function, affect threshold and slope estimates. Moreover, we propose methods to improve the estimation quality when stationarity is violated. A psychophysical detection experiment was modeled as a stochastic process ruled by a logistic psychophysical function. The threshold was modeled to drift over time and was defined as either a linear or nonlinear function. Threshold and slope estimates were obtained by using three estimation procedures: a static procedure assuming stationarity, a relaxed procedure accounting for linear effects of time, and a threshold tracking paradigm. For illustrative purposes, data acquired from two human subjects were used to estimate their thresholds and slopes using all estimation procedures. Threshold estimates obtained by all estimations procedures were similar to the mean true threshold. However, due to threshold drift, the slope was underestimated by the static procedure. The relaxed procedure only underestimated the slope when the threshold drifted nonlinearly over time. The tracking paradigm performed best and therefore, we recommend using the tracking paradigm in human psychophysical detection experiments to obtain estimates of the threshold and slope and to identify the mode of non-stationarit

Multiple threshold tracking methods for improved observation of nociceptive function

Estimating momentary perception thresholds cannot reveal dynamic properties of underlying mechanisms. However, continuously estimating multiple thresholds can. This talk focussed on the possibility of tracking multiple thresholds over time. A cold pressor model was used to activate descending nociceptive pathways, and a capsaicin defunctionalization model was used to induce nociceptive peripheral changes