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N-Methyl-d-aspartate (NMDA)-type glutamate receptors in the hippocampus are important mediators of both memory formation and excitotoxicity. It is thought that glutamatergic neurons of the CA1, CA3 and dentate gyrus regions of the hippocampus contribute differentially to memory formation and are differentially sensitive to excitotoxicity. The subunit and/or splice variant composition of the NMDA receptor controls many aspects of receptor function such as ligand affinity, calcium permeability and channel kinetics, as well as interactions with intracellular anchoring and regulatory proteins. Thus, one possible explanation of the differences in NMDA receptor-dependent processes, such as synaptic plasticity and excitotoxicity, among the hippocampal sub-regions is that they differ in subunit and/or splice variant expression. Here we report that the NMDA receptor subunits NR1 and NR2B, along with the four splice variant cassettes of the NR1 subunit are differentially expressed in the CA1, CA3 and dentate gyrus of the hippocampus. Expression of the AMPA receptor subunits GluR1 and GluR2 also differ. These differences may contribute to functional differences, such as with excitotoxicity and synaptic plasticity, that exist between the sub-regions of the hippocampus.

N-methyl-D-aspartate receptor dysfunction has been strongly suggested to link with the abnormalities seen in fetal alcohol syndrome. Thus, the effects of prenatal ethanol exposure on the total expression of NR1 splice variants and the cell surface expression of both NR1 and NR2 subunits in brain were investigated in rats. Western blot studies of membrane homogenates from cerebral cortices at postnatal days 1 through 21 indicate that prenatal ethanol treatment does not alter total NR1 expression or differential expression of NR1 splice variants during development. However, immunoprecipitation studies using PSD95 suggest that both C2'-terminal variants and NR2A subunits at the cortical postsynaptic membrane of postnatal day 21 were significantly reduced after prenatal ethanol treatment. Moreover, C1-terminal variants were decreased in both pair-fed and ethanol-treated groups, while no significant differences in the levels of total NR1 subunits, NR1 splice variants containing the N- or C2-terminal cassettes, or NR2B subunits were observed. Thus, these results suggest that prenatal exposure to ethanol may influence neuronal function by selective regulation of expression of C2'-terminal variants and NR2A subunits at the cell surface.

This study examined the acute actions of ethanol on recombinant rat GluR6 kainate receptors expressed in Xenopus oocytes and HEK 293 cells. Electrophysiological recordings showed that co-application of ethanol with submaximal kainate concentrations resulted in similar inhibition of kainate-gated currents in both expression systems. Manipulation of intracellular phosphorylation pathways by intracellular dialysis with a solution without ATP and GTP did not modify the inhibitory effects of ethanol. Moreover, co-transfection of GluR6 receptor subunits with PKA-alpha catalytic subunit or the calcium/calmodulin-dependent protein kinase II (CamKII) catalytic fragment did not change the sensitivity of the receptor to ethanol. Treatment of Xenopus oocytes with specific inhibitors of PKC, PKA, CamKII, tyrosine kinases, and serine-threonine protein phosphatases did not affect the 100 mM ethanol-induced inhibition of GluR6 receptor-mediated currents. Biochemical experiments with transiently transfected HEK 293 cells confirmed published reports that GluR6 receptors are minimally phosphorylated under basal conditions in these cells and also revealed that acute ethanol did not increase GluR6 phosphorylation. These results suggest that, under our experimental conditions, ethanol inhibits recombinant GluR6 receptor function by a direct effect on the receptor rather than an indirect action via protein phosphorylation.

Phosphoproteins are considered to be among the most important proteins in the body. They are the proteins that regulate almost all cell processes from cell division in cancer to neuronal signal transduction in learning and memory. This review will describe the development of a revolutionary immunochemical technique that produces antibodies that bind to target proteins only when the protein is in the phosphorylated state. These phospho-specific antibodies can thus be used to track the activity of a protein, not simply its level of expression. In this review, we will discuss both the design of the phosphopeptide immunogen and immunization. The affinity purification of the phospho-specific antibody as well as the methods most suitable for characterizing the phosphospecificity of the antibody will be described here. Taken together, these methods will cover the key procedures and protocols required to produce a phospho-specific antibody that works.

Phosphoproteins are considered to be among the most important proteins in the body. They are the proteins that regulate almost all cell processes from cell division in cancer to neuronal signal transduction in learning and memory. This review will describe the development of a revolutionary immunochemical technique that produces antibodies that bind to target proteins only when the protein is in the phosphorylated state. These phospho-specific antibodies can thus be used to track the activity of a protein, not simply its level of expression. In this review, we will discuss both the design of the phosphopeptide immunogen and immunization. The affinity purification of the phospho-specific antibody as well as the methods most suitable for characterizing the phosphospecificity of the antibody will be described here. Taken together, these methods will cover the key procedures and protocols required to produce a phospho-specific antibody that works.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Finger Skin Histology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 MSI Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Composite Fingerprint Image Generation . . . . . . . . . . . . . . . . . . . . . . . . 8 Biometric Testing and Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Baseline Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Comparative Performance under Adverse Influences . . . . . . . . . . 11 Backward Compatibility with Legacy Data . . . . . . . . . . . . . . . . . . . 13 Spoof Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Summary and Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Biometrics is defined as an automated method of verifying or recognizing the identity of a living person based on physiological or behavioral characteristics [1]. While much research has been done both to determine which traits can differentiate humans and to optimize that differentiation, the problem of determining if the presented trait originates from a living person has received relatively less attention. Between acquiring biometric data and delivering a result, there are various points where the overall security of a biometric access system can be compromised.

A comparative study on multiple participants was undertaken to quantify the ability of a multispectral imaging fingerprint sensor to perform reliable biometric matching in the presence of extreme sampling conditions. These extreme conditions included finger wetness, dirt, chalk, acetone, bright ambient light, and low contact pressure during image acquisition. The comparative study included three commercially available total internal reflectance sensors, run in parallel with the multispectral imaging sensor and under identical sampling conditions. Performance assessments showed that the multispectral imaging sensor was able to provide fingerprint images that produced good biometric performance even under conditions in which the performance of the total internal reflectance sensors was severely degraded. Additional analysis showed that the performance advantage of the multispectral images taken under these conditions was maintained even when matched against enrollment images collected on total internal reflectance sensors.

Fingerprint systems are the most widespread form of biometric authentication. Used in locations such as airports and in PDA's and laptops, fingerprint readers are becoming more common in everyday use. As they become more familiar, the security weaknesses of fingerprint sensors are becoming better known. Numerous websites now exist describing in detail how to create a fake fingerprint usable for spoofing a biometric system from both a cooperative user and from latent prints. While many commercial fingerprint readers claim to have some degree of spoof detection incorporated, they are still generally susceptible to spoof attempts using various artificial fingerprint samples made from gelatin or silicone or other materials and methods commonly available on the web. This paper describes a multispectral sensor that has been developed to collect data for spoof detection. The sensor has been designed to work in conjunction with a conventional optical fingerprint reader such that all images are collected during a single placement of the finger on the sensor. The multispectral imaging device captures sub-surface information about the finger that makes it very difficult to spoof. Four attributes of the finger that are collected with the multispectral imager will be described and demonstrated in this paper: spectral qualities of live skin, chromatic texture of skin, sub-surface image of live skin, and blanching on contact. Each of these attributes is well suited to discriminating against particular kinds of spoofing samples. A series of experiments was conducted to demonstrate the capabilities of the individual attributes as well as the collective spoof detection performance.

The level of performance of a biometric fingerprint sensor is critically dependent on the quality of the fingerprint images. One of the most common types of optical fingerprint sensors relies on the phenomenon of total internal reflectance (TIR) to generate an image. Under ideal conditions, a TIR fingerprint sensor can produce high-contrast fingerprint images with excellent feature definition. However, images produced by the same sensor under conditions that include dry skin, dirt on the skin, and marginal contact between the finger and the sensor, are likely to be severely degraded. This paper discusses the use of multispectral sensing as a means to collect additional images with new information about the fingerprint that can significantly augment the system performance under both normal and adverse sample conditions. In the context of this paper, "multispectral sensing" is used to broadly denote a collection of images taken under different illumination conditions: different polarizations, different illumination/detection configurations, as well as different wavelength illumination. Results from three small studies using an early-stage prototype of the multispectral-TIR (MTIR) sensor are presented along with results from the corresponding TIR data. The first experiment produced data from 9 people, 4 fingers from each person and 3 measurements per finger under "normal" conditions. The second experiment provided results from a study performed to test the relative performance of TIR and MTIR images when taken under extreme dry and dirty conditions. The third experiment examined the case where the area of contact between the finger and sensor is greatly reduced.

Automated identification systems based on fingerprint images are subject to two significant types of error: an incorrect decision about the identity of a person due to a poor quality fingerprint image and incorrectly accepting a fingerprint image generated from an artificial sample or altered finger. This paper discusses the use of multispectral sensing as a means to collect additional information about a finger that significantly augments the information collected using a conventional fingerprint imager based on total internal reflectance. In the context of this paper, “multispectral sensing” is used broadly to denote a collection of images taken under different polarization conditions and illumination configurations, as well as using multiple wavelengths. Background information is provided on conventional fingerprint imaging. A multispectral imager for fingerprint imaging is then described and a means to combine the two imaging systems into a single unit is discussed. Results from an early-stage prototype of such a system are shown.

This paper describes a new biometric technology based on the optical properties of skin. The new technology can perform both identity verification and sample authenticity based on the optical properties of human skin. When multiple wavelengths of light are used to illuminate skin, the resulting spectrum of the diffusely reflected light represents a complex interaction between the structural and chemical properties of the skin tissue. Research has shown that these spectral characteristics are distinct traits of human skin as compared to other materials. Furthermore, there are also distinct spectral differences from person to person. Personnel at Lumidigm have developed a small and rugged spectral sensor using solid-state optical components operating in the visible and very near infrared spectral region (400-940nm) that accurately measures diffusely reflected skin spectra. The sensors are used for both biometric determinations of identity as well as the determination of sample authenticity. This paper will discuss both applications of the technology with emphasis on the use of optical spectra to assure sample authenticity.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Multispectral imaging of skin represents a novel method to make an improved biometric determination of identity. Multispectral imaging provides a means to image both the surface characteristics and subsurface skin features, offering the promise of a sensor that has improved performance, works under adverse conditions and is difficult to spoof.