Mechanisms and targets of deep brain stimulation in movement disorders

Chronic electrical stimulation of the brain, known as deep brain stimulation (DBS), has become a preferred surgical treatment for medication-refractory movement disorders. Despite its remarkable clinical success, the therapeutic mechanisms of DBS are still not completely understood, limiting opportunities to improve treatment efficacy and simplify selection of stimulation parameters. This review addresses three questions essential to understanding the mechanisms of DBS. 1) How does DBS affect neuronal tissue in the vicinity of the active electrode or electrodes? 2) How do these changes translate into therapeutic benefit on motor symptoms? 3) How do these effects depend on the particular site of stimulation? Early hypotheses proposed that stimulation inhibited neuronal activity at the site of stimulation, mimicking the outcome of ablative surgeries. Recent studies have challenged that view, suggesting that although somatic activity near the DBS electrode may exhibit substantial inhibition or complex modulation patterns, the output from the stimulated nucleus follows the DBS pulse train by direct axonal excitation. The intrinsic activity is thus replaced by high-frequency activity that is time-locked to the stimulus and more regular in pattern. These changes in firing pattern are thought to prevent transmission of pathologic bursting and oscillatory activity, resulting in the reduction of disease symptoms through compensatory processing of sensorimotor information. Although promising, this theory does not entirely explain why DBS improves motor symptoms at different latencies. Understanding these processes on a physiological level will be critically important if we are to reach the full potential of this powerful tool.

Correlative studies of structural and functional imaging in primary progressive aphasia

RATIONALE

To compare and contrast structural and functional imaging in primary progressive aphasia (PPA).

METHODS

A cohort of 8 patients diagnosed with PPA presenting with nonfluency were prospectively evaluated. All patients had structural imaging in the form of MRI and in 1 patient CAT scanning on account of a cardiac pacemaker. All patients had single-photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging.

RESULTS

SPECT and PET imaging had 100% correlation. Anatomical imaging was abnormal in only 6 of the 8 patients. Wernicke's area showed greater peak Z score reduction and extent of area affected than Broca's area (McNemar paired test: P = .008 for Z score reduction; P = .0003 for extent). PET scanning revealed significant involvement of the anterior cingulum.

CONCLUSION

Functional imaging in PPA: (a) identified more patients correctly than anatomic imaging highlighting the importance of SPECT and PET in the diagnosis; and (b) demonstrated the heterogeneous involvement of disordered linguistic networks in PPA suggesting its syndromic nature.

Enhanced fluorescent immunoassays on silver fractal-like structures

Using the effect of the fluorescence enhancement in close proximity to metal nanostructures, we have been able to demonstrate ultrasensitive immunoassays suitable for the detection of biomarkers. Silver fractal-like structures have been grown by electrochemical reduction of silver on the surface of glass slides. A model immunoassay was performed on the slide surface with rabbit IgG (antigen) noncovalently immobilized on the slide, and rhodamine red-X-labeled antirabbit IgG conjugate was subsequently bound to the immobilized antigen. The fluorescence signal was measured from the glass-fractal's surface using a confocal microscope, and the images were compared to the images from the same surface not coated with fractals. Our results showed significant enhancement (more than 100-fold) of the signal detected on fractals compared to bare glass. We thus demonstrate that such fractal-like structures can assist in improving the signals from assays used in medical diagnostics, especially those for analytes with molecular weight under 100 kDa.

Liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury, which leads to portal hypertension and end-stage liver disease. Recent advances in the understanding of the natural history and pathophysiology of cirrhosis, and in treatment of its complications, have resulted in improved management, quality of life, and life expectancy of patients. Liver transplantation remains the only curative option for a selected group of patients, but pharmacological treatments that can halt progression to decompensated cirrhosis or even reverse cirrhosis are currently being developed. This Seminar focuses on the diagnosis, complications, and management of cirrhosis, and new clinical and scientific developments.

Ultrasound simulation of real-time temperature estimation during radiofrequency ablation using finite element models

Radiofrequency ablation is the most common minimally invasive therapy used in the United States to treat hepatocellular carcinoma and liver metastases. The ability to perform real-time temperature imaging while a patient is undergoing ablation therapy may help reduce the high recurrence rates following ablation therapy. Ultrasound echo signals undergo time shifts with increasing temperature due to sound speed and thermal expansion, which are tracked using both 1D cross correlation and 2D block matching based speckle tracking methods. In this paper, we present a quantitative evaluation of the accuracy and precision of temperature estimation using the above algorithms on both simulated and experimental data. A finite element analysis simulation of radiofrequency ablation of hepatic tissue was developed. Finite element analysis provides a method to obtain the exact temperature distribution along with a mapping of the tissue displacement due to thermal expansion. These local displacement maps were combined with the displacement due to speed of sound changes and utilized to generate ultrasound radiofrequency frames at specified time increments over the entire ablation procedure. These echo signals provide an ideal test-bed to evaluate the performance of both speckle tracking methods, since the estimated temperature results can be compared directly to the exact finite element solution. Our results indicate that the 1D cross-correlation (CC) method underestimates the cumulative displacement by 0.20mm, while the underestimation with 2D block matching (BM) is about 0.14 mm after 360 s of ablation. The 1D method also overestimates the size of the ablated region by 5.4% when compared to 2.4% with the 2D method after 720 s of ablation. Hence 2D block matching provides better tracking of temperature variations when compared to the 1D cross-correlation method over the entire duration of the ablation procedure. In addition, results obtained using 1D cross-correlation diverge from the ideal finite element results after 7 min of ablation and for temperatures greater than 65 degrees C. In a similar manner, experimental results presented using a tissue-mimicking phantom also demonstrate that the maximum percent difference with 2D block matching was 5%, when compared to 31% with the 1D method over the 700 s heating duration on the phantom.

In vivo MRI detection of gliomas by chlorotoxin-conjugated superparamagnetic nanoprobes

Converging advances in the development of nanoparticle-based imaging probes and improved understanding of the molecular biology of brain tumors offer the potential to provide physicians with new tools for the diagnosis and treatment of these deadly diseases. However, the effectiveness of promising nanoparticle technologies is currently limited by insufficient accumulation of these contrast agents within tumors. Here a biocompatible nanoprobe composed of a poly(ethylene glycol) (PEG) coated iron oxide nanoparticle that is capable of specifically targeting glioma tumors via the surface-bound targeting peptide, chlorotoxin (CTX), is presented. The preferential accumulation of the nanoprobe within gliomas and subsequent magnetic resonance imaging (MRI) contrast enhancement are demonstrated in vitro in 9L cells and in vivo in tumors of a xenograft mouse model. TEM imaging reveals that the nanoprobes are internalized into the cytoplasm of 9L cells and histological analysis of selected tissues indicates that there are no acute toxic effects of these nanoprobes. High targeting specificity and benign biological response establish this nanoprobe as a potential platform to aid in the diagnosis and treatment of gliomas and other tumors of neuroectodermal origin.

Optical clearing of unsectioned specimens for three-dimensional imaging via optical transmission and emission tomography

Optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) are new techniques that enable unprecedented high-resolution 3-D multimodal imaging of tissue structure and function. Applications include imaging macroscopic gene expression and microvasculature structure in unsectioned biological specimens up to 8 cm(3). A key requisite for these imaging techniques is effective sample preparation including optical clearing, which enables light transport through the sample while preserving the signal (either light absorbing stain or fluorescent proteins) in representative form. We review recent developments in optical-CT and optical-ECT, and compatible "fluorescence-friendly" optical clearing protocols.

Dysregulation of glutamate carboxypeptidase II in psychiatric disease

Experimental evidence is beginning to converge on an important role for dysregulation of glutamate carboxypeptidase II (GCPII) in schizophrenia. The goal of this study was to determine GCPII levels in postmortem brain specimens of patients with schizophrenia, bipolar disorder or unipolar depression and age-matched control subjects. We used N-[N-(S)-1,3-dicarboxypropyl]carbamoyl]-S-3-[(125)I]iodo-l-tyrosine ([(125)I]DCIT), a high-affinity radioligand for GCPII, to probe for GCPII expression in prefrontal cortex (PFC) and mesial temporal lobe, two brain regions implicated in the pathophysiology of schizophrenia. We found that GCPII levels measured by [(125)I]DCIT quantitative autoradiography were significantly lower in the PFC and entorhinal cortex in patients with schizophrenia compared to age-matched controls. Patients with bipolar disorder also expressed significantly lower GCPII levels in PFC than controls. The decrease in [(125)I]DCIT binding in schizophrenia and bipolar disorder remained significant after adjusting for drug abuse. A significant difference in GCPII levels was also observed between schizophrenia relative to bipolar disorder and depressed subjects in the hippocampus-stratum lucidum and between schizophrenia and bipolar in the CA2 region of the hippocampus, with bipolar and depressed subjects expressing higher levels of GCPII than subjects with schizophrenia. These differences in hippocampal GCPII levels may implicate differences in the etiologies of these mental disorders. In summary, this study demonstrates a regional dysregulation of GCPII expression in the brain of patients with schizophrenia and other psychiatric disorders and supports a hypoglutamatergic state of the former illness. GCPII may represent a viable therapeutic target for intervention in psychiatric disease.

Application of multivariate spectral analyses in micro-Raman imaging to unveil structural/chemical features of the adhesive/dentin interface

This study presents the application of multivariate analyses to analyze micro-Raman spectral imaging data in reference to the adhesive/dentin interface as well as comparison with univariate analysis. The univariate statistical methods, such as mapping of specific functional group peak intensities, do not always detect functional group positions and quantities due to peak overlapping. A comprehensive chemical analysis of the adhesive/dentin interface, along with the multivariate statistical methods, principal component analysis, and fuzzy c-means clustering, is studied. Compared to univariate analysis, multivariate methods present the entire hyperspectral information from the specimen in a concise and uncorrelated way. Apart from the ease with which information can be extracted and presented, multivariate methods also highlight minute and often important variations in the spectra that are difficult to observe using univariate methods. The results show for the first time the clear chemical and structural classifications in the adhesive/dentin interface at successively greater resolutions.

A review of the discovery, pharmacological characterization, and behavioral effects of the dopamine D2-like receptor antagonist eticlopride

Eticlopride is a substituted benzamide analog with high affinity and selectivity for dopamine (DA) D2-like receptors that was initially developed as a potential antipsychotic agent. A great deal of research has utilized this drug to better understand central DA receptor function, the role of D2-like receptors in behavior, and the influence of blockade of these receptors on several preclinical animal models. This review highlights research utilizing this drug and compares it to typical and atypical antipsychotics used clinically. First, we describe structure-activity relationships as it relates to binding at DA receptors and the consequences on behavior. This is followed by a discussion of several imaging strategies including the use of eticlopride for in vivo, in vitro, and ex vivo examination of DA D2-like receptor densities and function. Finally, we discuss the use of eticlopride in several behavioral models predictive of antipsychotic activity, extrapyramidal side effects (EPS), and learning and memory. While eticlopride is not used clinically, it remains a viable research tool for understanding DA receptor function and behavior.

Imaging phluorin-based probes at hippocampal synapses

Accurate measurement of synaptic vesicle exocytosis and endocytosis is crucial to understanding the molecular basis of synaptic transmission. The fusion of a pH-sensitive green fluorescent protein (pHluorin) to various synaptic vesicle proteins has allowed the study of synaptic vesicle recycling in real time. Two such probes, synaptopHluorin and sypHy, have been imaged at synapses of hippocampal neurons in culture. The combination of these reporters with techniques for molecular interference, such as RNAi allows for the study of molecules involved in synaptic vesicle recycling. Here the authors describe methods for the culture and transfection of hippocampal neurons, imaging of pHluorin-based probes at synapses and analysis of pHluorin signals down to the resolution of individual synaptic vesicles.

Imaging of EGFR and EGFR tyrosine kinase overexpression in tumors by nuclear medicine modalities

Protein tyrosine kinases (PTKs) play a pivotal role in signal transduction pathways and in the development and maintenance of various cancers. They are involved in multiple processes such as transcription, cell cycle progression, proliferation, angiogenesis and inhibition of apoptosis. Among the PTKs, the EGFR is one of the most widely studied and has emerged as a promising key target for the treatment of cancer. Indeed, several drugs directed at this receptor are FDA-approved and many others are at various stages of development. However, thus far, the therapeutic outcome of EGFR-targeted therapy is suboptimal and needs to be refined. Quantitative PET molecular imaging coupled with selective labelled biomarkers may facilitate in vivo EGFR-targeted drug efficacy by noninvasively assessing the expression of EGFR in tumor, guiding dose and regime by measuring target drug binding and receptor occupancy as well as potentially detecting the existence of a primary or secondary mutation leading to either drug interaction or failure of EGFR recognition by the drug. This review describes the attempts to develop labelled EGFR molecular imaging agents that are based either on low molecular weight tyrosine kinase inhibitors or monoclonal antibodies directed to the extracellular binding domain of the receptor to be used in nuclear medicine modalities.

In vivo confocal and multiphoton microendoscopy

The ability to conduct high-resolution fluorescence imaging in internal organs of small animal models in situ and over time can make a significant impact in biomedical research. Toward this goal, we developed a real-time confocal and multiphoton endoscopic imaging system. Using 1-mm-diameter endoscopes based on gradient index lenses, we demonstrate video-rate multicolor multimodal imaging with cellular resolution in live mice.

Synchronous primary tumors of the kidney and the ovaries: Imaging findings

The simultaneous presence of primary carcinomas in the same patient is uncommon and synchronous primary tumors involving the kidney and ovary are extremely rare. There are a few reports in the English literature of synchronous primary malignancies of the kidney and the ovaries, but no data regarding their imaging features. We present a case of an elderly woman, diagnosed with bilateral ovarian clear cell carcinomas and a simultaneous clear cell carcinoma of the right kidney, evaluated by multidetector CT and MR imaging.

Small animal imaging with magnetic resonance microscopy

Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imaging physics to its expanding use today as a tool in noninvasive biomedical investigations. MRM now increasingly provides functional information about living animals, with images of the beating heart, breathing lung, and functioning brain. Unlike clinical MRI, where the focus is on diagnosis, MRM is used to reveal fundamental biology or to noninvasively measure subtle changes in the structure or function of organs during disease progression or in response to experimental therapies. High-resolution anatomical imaging reveals increasingly exquisite detail in healthy animals and subtle architectural aberrations that occur in genetically altered models. Resolution of 100 mum in all dimensions is now routinely attained in living animals, and (10 mum)(3) is feasible in fixed specimens. Such images almost rival conventional histology while allowing the object to be viewed interactively in any plane. In this review we describe the state of the art in MRM for scientists who may be unfamiliar with this modality but who want to apply its capabilities to their research. We include a brief review of MR concepts and methods of animal handling and support, before covering a range of MRM applications-including the heart, lung, and brain-and the emerging field of MR histology. The ability of MRM to provide a detailed functional and anatomical picture in rats and mice, and to track this picture over time, makes it a promising platform with broad applications in biomedical research.

Stars and stripes in the cerebellar cortex: a voltage sensitive dye study

The lattice-like structure of the cerebellar cortex and its anatomical organization in two perpendicular axes provided the foundations for many theories of cerebellar function. However, the functional organization does not always match the anatomical organization. Thus direct measurement of the functional organization is central to our understanding of cerebellar processing. Here we use voltage sensitive dye imaging in the isolated cerebellar preparation to characterize the spatio-temporal organization of the climbing and mossy fiber (MF) inputs to the cerebellar cortex. Spatial and temporal parameters were used to develop reliable criteria to distinguish climbing fiber (CF) responses from MF responses. CF activation excited postsynaptic neurons along a parasagittal cortical band. These responses were composed of slow (∼25 ms), monophasic depolarizing signals. Neither the duration nor the spatial distribution of CF responses were affected by inhibition. Activation of MF generated responses that were organized in radial patches, and were composed of a fast (∼5 ms) depolarizing phase followed by a prolonged (∼100 ms) negative wave. Application of a GABA_A blocker eliminated the hyperpolarizing phase and prolonged the depolarizing phase, but did not affect the spatial distribution of the response, thus suggesting that it is not the inhibitory system that is responsible for the inability of the MF input to generate beams of activity that propagate along the parallel fiber system.

Frontal and limbic activation during inhibitory control predicts treatment response in major depressive disorder

BACKGROUND

Inhibitory control or regulatory difficulties have been explored in major depressive disorder (MDD) but typically in the context of affectively salient information. Inhibitory control is addressed specifically by using a task devoid of affectively-laden stimuli, to disentangle the effects of altered affect and altered inhibitory processes in MDD.

METHODS

Twenty MDD and 22 control volunteer participants matched by age and gender completed a contextual inhibitory control task, the Parametric Go/No-go (PGNG) task during functional magnetic resonance imaging. The PGNG includes three levels of difficulty, a typical continuous performance task and two progressively more difficult versions including Go/No-go hit and rejection trials. After this test, 15 of 20 MDD patients completed a full 10-week treatment with s-citalopram.

RESULTS

There was a significant interaction among response time (control subjects better), hits (control subjects better), and rejections (patients better). The MDD participants had greater activation compared with the control group in frontal and anterior temporal areas during correct rejections (inhibition). Activation during successful inhibitory events in bilateral inferior frontal and left amygdala, insula, and nucleus accumbens and during unsuccessful inhibition (commission errors) in rostral anterior cingulate predicted post-treatment improvement in depression symptoms.

CONCLUSIONS

The imaging findings suggest that in MDD subjects, greater neural activation in frontal, limbic, and temporal regions during correct rejection of lures is necessary to achieve behavioral performance equivalent to control subjects. Greater activation in similar regions was further predictive of better treatment response in MDD.

Whole-body imaging of the musculoskeletal system: the value of MR imaging

In clinical practice various modalities are used for whole-body imaging of the musculoskeletal system, including radiography, bone scintigraphy, computed tomography, magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT). Multislice CT is far more sensitive than radiographs in the assessment of trabecular and cortical bone destruction and allows for evaluation of fracture risk. The introduction of combined PET-CT scanners has markedly increased diagnostic accuracy for the detection of skeletal metastases compared with PET alone. The unique soft-tissue contrast of MRI enables for precise assessment of bone marrow infiltration and adjacent soft tissue structures so that alterations within the bone marrow may be detected before osseous destruction becomes apparent in CT or metabolic changes occur on bone scintigraphy or PET scan. Improvements in hard- and software, including parallel image acquisition acceleration, have made high resolution whole-body MRI clinically feasible. Whole-body MRI has successfully been applied for bone marrow screening of metastasis and systemic primary bone malignancies, like multiple myeloma. Furthermore, it has recently been proposed for the assessment of systemic bone diseases predisposing for malignancy (e.g., multiple cartilaginous exostoses) and muscle disease (e.g., muscle dystrophy). The following article gives an overview on state-of-the-art whole-body imaging of the musculoskeletal system and highlights present and potential future applications, especially in the field of whole-body MRI.

Three-dimensional atlas system for mouse and rat brain imaging data

Tomographic neuroimaging techniques allow visualization of functionally and structurally specific signals in the mouse and rat brain. The interpretation of the image data relies on accurate determination of anatomical location, which is frequently obstructed by the lack of structural information in the data sets. Positron emission tomography (PET) generally yields images with low spatial resolution and little structural contrast, and many experimental magnetic resonance imaging (MRI) paradigms give specific signal enhancements but often limited anatomical information. Side-by-side comparison of image data with conventional atlas diagram is hampered by the 2-D format of the atlases, and by the lack of an analytical environment for accumulation of data and integrative analyses. We here present a method for reconstructing 3-D atlases from digital 2-D atlas diagrams, and exemplify 3-D atlas-based analysis of PET and MRI data. The reconstruction procedure is based on two seminal mouse and brain atlases, but is applicable to any stereotaxic atlas. Currently, 30 mouse brain structures and 60 rat brain structures have been reconstructed. To exploit the 3-D atlas models, we have developed a multi-platform atlas tool (available via The Rodent Workbench, http://rbwb.org) which allows combined visualization of experimental image data within the 3-D atlas space together with 3-D viewing and user-defined slicing of selected atlas structures. The tool presented facilitates assignment of location and comparative analysis of signal location in tomographic images with low structural contrast.

Polarization-based diffuse reflectance imaging for noninvasive measurement of glucose

BACKGROUND

The ability to measure glucose concentration through noninvasive approaches would impact the treatment of diabetes significantly. Polarization-based optical approaches have received considerable interest because of their potential medical applications. Glucose, a chiral molecule, has the ability to rotate the plane of linearly polarized light, commonly referred to as optical activity, as well as changing the refractive index of the media, which therefore affects the overall scattering coefficient in a given media. The magnitude of each effect is related to the concentration of glucose. Although most previous studies have reported on the use of polarimetry in the aqueous humor of the eye because of its nonscattering nature, one would also expect that glucose concentration could be measured in more turbid media such as tissue through a similar approach. This study investigated how each of these effects is correlated to glucose concentration in a physiological range for highly scattering biological media.

METHODS

A custom-designed imaging polarimeter was used to image highly scattering Intralipid-based media containing different concentrations of glucose. Model formation and glucose prediction were performed through the use of partial least squares (PLS) regression. Further insight into the differences between polarization-based image measurements and encoding of glucose information was provided through the use of principal component analysis (PCA).

RESULTS

When coupled with PLS regression, in vitro polarization measurements yielded highly correlated glucose predictions in both calibration and independent validation, 0.999 and 0.998, respectively. Through the use of PCA, it appears that the majority of the image-based signal yielding the most significant glucose information is attributable to changes in the overall scattering coefficient due to glucose concentration and, to a lesser degree, effects of optical activity.

CONCLUSIONS

This study showed how polarimetric-based imaging coupled with PLS regression can be used to quantify glucose concentration in highly scattering media. Such methods may potentially be able to extend the use of noninvasive in vivo polarimetric measurements, normally acquired in the anterior chamber of the eye, to other preferred sensing sites such as the skin.

Brain metabolism of nutritionally essential polyunsaturated fatty acids depends on both the diet and the liver

Plasma alpha-linolenic acid (alpha-LNA, 18:3n-3) and linoleic acid (LA, 18:2n-6) do not contribute significantly to the brain content of docosahexaenoic acid (DHA, 22:6n-3) or arachidonic acid (AA, 20:4n-6), respectively, and neither DHA nor AA can be synthesized de novo in vertebrate tissue. Therefore, measured rates of incorporation of circulating DHA and AA into brain exactly represent their rates of consumption by brain. Positron emission tomography (PET) has been used to show, based on this information, that the adult human brain consumes AA and DHA at rates of 17.8 and 4.6 mg/day, respectively, and that AA consumption does not change significantly with age. In unanesthetized adult rats fed an n-3 PUFA "adequate" diet containing 4.6% alpha-LNA (of total fatty acids) as its only n-3 PUFA, the rate of liver synthesis of DHA was more than sufficient to maintain brain DHA, whereas the brain's rate of DHA synthesis is very low and unable to do so. Reducing dietary alpha-LNA in the DHA-free diet led to upregulation of liver but not brain coefficients of alpha-LNA conversion to DHA and of liver expression of elongases and desaturases that catalyze this conversion. Concurrently, brain DHA loss slowed due to downregulation of several of its DHA-metabolizing enzymes. Dietary alpha-LNA deficiency also promoted accumulation of brain docosapentaenoic acid (22:5n-6), and upregulated expression of AA-metabolizing enzymes, including cytosolic and secretory phospholipases A(2) and cyclooxygenase-2. These changes, plus reduced levels of brain derived neurotrophic factor (BDNF) and cAMP response element-binding protein (CREB) in n-3 PUFA diet deficient rats, likely render their brain more vulnerable to neuropathological insults.

Confocal light absorption and scattering spectroscopic microscopy monitors organelles in live cells with no exogenous labels

This article reports the development of an optical imaging technique, confocal light absorption and scattering spectroscopic (CLASS) microscopy, capable of noninvasively determining the dimensions and other physical properties of single subcellular organelles. CLASS microscopy combines the principles of light-scattering spectroscopy (LSS) with confocal microscopy. LSS is an optical technique that relates the spectroscopic properties of light elastically scattered by small particles to their size, refractive index, and shape. The multispectral nature of LSS enables it to measure internal cell structures much smaller than the diffraction limit without damaging the cell or requiring exogenous markers, which could affect cell function. Scanning the confocal volume across the sample creates an image. CLASS microscopy approaches the accuracy of electron microscopy but is nondestructive and does not require the contrast agents common to optical microscopy. It provides unique capabilities to study functions of viable cells, which are beyond the capabilities of other techniques.

Cognitive neuroscience-based approaches to measuring and improving treatment effects on cognition in schizophrenia: the CNTRICS initiative

The goal of this article is to discuss ways to further improve the search for potentially procognitive agents that could be used to enhance cognition and functional outcome in schizophrenia. In particular, we focus on the potential advantages to this process of using a contemporary, cognitive neuroscience-based approach to measuring cognitive function in clinical trials of procognitive agents in schizophrenia. These tools include computer-administered tasks that measure specific cognitive systems (such as attention, working memory, long-term memory, cognitive control) as well as the component cognitive processes that comprise these more overarching systems. The advantages of using these tools include the ability to identify and use homologous animal and human models in the drug discovery and testing process and the ability to incorporate noninvasive functional imaging measures into clinical trial contexts at several different phases of the drug development process. However, despite the clear potential advantages to using such methods, a number of barriers exist to their translation from basic science tools to tools for drug discovery. We discuss the development and implementation of a new project, Cognitive Neuroscience Treatment to Improve Cognition in Schizophrenia, designed to identify and overcome these barriers to the translation of cognitive neuroscience measures and methods into regular use in the drug discovery and development process of cognition-enhancing agents for use in schizophrenia.

Imaging and manipulating the structural machinery of living cells on the micro- and nanoscale

The structure, physiology, and fate of living cells are all highly sensitive to mechanical forces in the cellular microenvironment, including stresses and strains that originate from encounters with the extracellular matrix (ECM), blood and other flowing materials, and neighbouring cells. This relationship between context and physiology bears tremendous implications for the design of cellular micro-or nanotechnologies, since any attempt to control cell behavior in a device must provide the appropriate physical microenvironment for the desired cell behavior. Cells sense, process, and respond to biophysical cues in their environment through a set of integrated, multi-scale structural complexes that span length scales from single molecules to tens of microns, including small clusters of force-sensing molecules at the cell surface, micron-sized cell-ECM focal adhesion complexes, and the cytoskeleton that permeates and defines the entire cell. This review focuses on several key technologies that have recently been developed or adapted for the study of the dynamics of structural micro-and nanosystems in living cells and how these systems contribute to spatially-and temporally-controlled changes in cellular structure and mechanics. We begin by discussing subcellular laser ablation, which permits the precise incision of nanoscale structural elements in living cells in order to discern their mechanical properties and contributions to cell structure. We then discuss fluorescence recovery after photobleaching and fluorescent speckle microscopy, two live-cell fluorescence imaging methods that enable quantitative measurement of the binding and transport properties of specific proteins in the cell. Finally, we discuss methods to manipulate cellular structural networks by engineering the extracellular environment, including microfabrication of ECM distributions of defined geometry and microdevices designed to measure cellular traction forces at micron-scale resolution. Together, these methods form a powerful arsenal that is already adding significantly to our understanding of the nanoscale architecture and mechanics of living cells and may contribute to the rational design of new cellular micro-and nanotechnologies.

Research in hand osteoarthritis: time for reappraisal and demand for new strategies. An opinion paper

BACKGROUND

Osteoarthritis of the hands is a prevalent musculoskeletal disease with a considerable effect on patients' lives, but knowledge and research results in the field of hand osteoarthritis are limited. Therefore, the Disease Characteristics in Hand OA (DICHOA) initiative was founded in early 2005 with the aim of addressing key issues and facilitating research into hand osteoarthritis.

OBJECTIVE

To review and discuss current knowledge on hand osteoarthritis with regard to aetiopathogenesis, diagnostic criteria, biomarkers and clinical outcome measures.

METHODS

Recommendations were made based on a literature review.

RESULTS

Outcomes of hand osteoarthritis should be explored, including patient perspective on the separate components of disease activity, damage and functioning. All imaging techniques should be cross-validated for hand osteoarthritis with clinical status, including disease activity, function and performance, biomarkers and long-term outcome. New imaging modalities are available and need scoring systems and validation. The role of biomarkers in hand osteoarthritis has to be defined.

CONCLUSION

Future research in hand osteoarthritis is warranted.

Resolving vesicle fusion from lysis to monitor calcium-triggered lysosomal exocytosis in astrocytes

Optical imaging of individual vesicle exocytosis is providing new insights into the mechanism and regulation of secretion by cells. To study calcium-triggered secretion from astrocytes, we used acridine orange (AO) to label vesicles. Although AO is often used for imaging exocytosis, we found that imaging vesicles labeled with AO can result in their photolysis. Here, we define experimental and analytical approaches that permit us to distinguish unambiguously between fusion, leakage, and lysis of individual vesicles. We have used this approach to demonstrate that lysosomes undergo calcium-triggered exocytosis in astrocytes.

Fluorescence, XPS, and TOF-SIMS surface chemical state image analysis of DNA microarrays

Performance improvements in DNA-modified surfaces required for microarray and biosensor applications rely on improved capabilities to accurately characterize the chemistry and structure of immobilized DNA molecules on micropatterned surfaces. Recent innovations in imaging X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) now permit more detailed studies of micropatterned surfaces. We have exploited the complementary information provided by imaging XPS and imaging TOF-SIMS to detail the chemical composition, spatial distribution, and hybridization efficiency of amine-terminated single-stranded DNA (ssDNA) bound to commercial polyacrylamide-based, amine-reactive microarray slides, immobilized in both macrospot and microarray diagnostic formats. Combinations of XPS imaging and small spot analysis were used to identify micropatterned DNA spots within printed DNA arrays on slide surfaces and quantify DNA elements within individual microarray spots for determination of probe immobilization and hybridization efficiencies. This represents the first report of imaging XPS of DNA immobilization and hybridization efficiencies for arrays fabricated on commercial microarray slides. Imaging TOF-SIMS provided distinct analytical data on the lateral distribution of DNA within single array microspots before and after target hybridization. Principal component analysis (PCA) applied to TOF-SIMS imaging datasets demonstrated that the combination of these two techniques provides information not readily observable in TOF-SIMS images alone, particularly in identifying species associated with array spot nonuniformities (e.g., "halo" or "donut" effects often observed in fluorescence images). Chemically specific spot images were compared to conventional fluorescence scanned images in microarrays to provide new information on spot-to-spot DNA variations that affect current diagnostic reliability, assay variance, and sensitivity.

Nanomicrobiology

Recent advances in atomic force microscopy (AFM) are revolutionizing our views of microbial surfaces. While AFM imaging is very useful for visualizing the surface of hydrated cells and membranes on the nanoscale, force spectroscopy enables researchers to locally probe biomolecular forces and physical properties. These unique capabilities allow us to address a number of questions that were inaccessible before, such as how does the surface architecture of microbes change as they grow or interact with drugs, and what are the molecular forces driving their interaction with antibiotics and host cells? Here, we provide a flavor of recent achievements brought by AFM imaging and single molecule force spectroscopy in microbiology.

The prognostic value of abnormal findings on radiographic swallowing studies after total laryngectomy

Pharyngocutaneous fistulae are a common complication after total laryngectomy. Our study evaluates the correlation of postoperative radiographic swallowing studies and clinical symptoms. We also propose a grading system to classify leaks radiographically. The records of 45 patients who underwent total laryngectomy were retrospectively reviewed. All patients had a radiographic swallowing study (RSS) on or around the tenth postoperative day. A grading system was developed to classify radiographic findings (grade 0-5). Twenty-two patients had an abnormal RSS (grade 2-5). Three patients (13.6%) had clinical signs of impending fistula whereas radiography showed moderate leakage (grade 3) in one patient and a pharyngocutaneous fistula (grade 5) in two. The other 19 patients with radiographically demonstrated leakage had no clinical signs of anastomotic complications. After total laryngectomy, radiography may reveal anastomotic complications of varying severity. The grading system used in this study enabled us to objectively classify the radiological abnormalities on swallowing studies. Because most radiographic leakages were clinically silent and not all clinically apparent fistula were radiographically visible in our study, the role of routine postoperative radiographic swallowing studies in the absence of clinical signs or fistula remains unclear.

Rapid 3D imaging of contrast flow: demonstration of a dual beam technique

Perfusion imaging in a 3D volume using ultrasound contrast agent may improve vascular characterization compared with 2D imaging. Conventional 3D acquisition requires excessive scan time. A dual transducer technique using conventional systems has been introduced that allows 3D imaging of contrast dynamics with drastically reduced scan times (LeCarpentier et al. 2003). Two transducers are translated across a volume where the leading transducer effects contrast clearance and the following transducer images at desired contrast refill times. With 2D arrays that allow simultaneous clearance and imaging pulses, scan times could be further reduced and the need for two transducers eliminated. The dual transducer technique was demonstrated on a tube phantom, with observed contrast profiles matching those expected. Measured center velocities of (+/- std dev) 1.46 +/- 0.21 and 2.25 +/- 0.5 did not statistically differ from expected values of 1.75 and 2.50 (all mm/s), (p > 0.05). This technique is introduced for rapid acquisition of 3D contrast refill images.

Biophotonic Tools in Cell and Tissue Diagnostics

In order to maintain the rapid advance of biophotonics in the U.S. and enhance our competitiveness worldwide, key measurement tools must be in place. As part of a wide-reaching effort to improve the U.S. technology base, the National Institute of Standards and Technology sponsored a workshop titled "Biophotonic tools for cell and tissue diagnostics." The workshop focused on diagnostic techniques involving the interaction between biological systems and photons. Through invited presentations by industry representatives and panel discussion, near- and far-term measurement needs were evaluated. As a result of this workshop, this document has been prepared on the measurement tools needed for biophotonic cell and tissue diagnostics. This will become a part of the larger measurement road-mapping effort to be presented to the Nation as an assessment of the U.S. Measurement System. The information will be used to highlight measurement needs to the community and to facilitate solutions.

Processing MALDI Mass Spectra to Improve Mass Spectral Direct Tissue Analysis

Profiling and imaging biological specimens using MALDI mass spectrometry has significant potential to contribute to our understanding and diagnosis of disease. The technique is efficient and high-throughput providing a wealth of data about the biological state of the sample from a very simple and direct experiment. However, in order for these techniques to be put to use for clinical purposes, the approaches used to process and analyze the data must improve. This study examines some of the existing tools to baseline subtract, normalize, align, and remove spectral noise for MALDI data, comparing the advantages of each. A preferred workflow is presented that can be easily implemented for data in ASCII format. The advantages of using such an approach are discussed for both molecular profiling and imaging mass spectrometry.

Imaging of giant cell tumor of bone

Giant cell tumor (GCT) of bone is a benign but locally aggressive and destructive lesion generally occurring in skeletally mature individuals. Typically involving the epiphysiometaphyseal region of long bones, the most common sites include the distal femur, proximal tibia and distal radius. On radiographs, GCT demonstrates a lytic lesion centered in the epiphysis but involving the metaphysis and extending at least in part to the adjacent articular cortex. Most are eccentric, but become symmetric and centrally located with growth. Most cases show circumscribed borders or so-called geographical destruction with no periosteal reaction unless a pathological fracture is present. There is no mineralized tumor matrix. Giant cell tumor can produce wide-ranging appearances depending on site, complications such as hemorrhage or pathological fracture and after surgical intervention. This review demonstrates a spectrum of these features and describes the imaging characteristics of GCT in conventional radiographs, computerized tomography scans, magnetic resonance imaging, bone scans, positron emission tomography scans and angiography.

Functional neuroimaging studies in posttraumatic stress disorder: review of current methods and findings

Posttraumatic stress disorder (PTSD) is an anxiety disorder associated with changes in neural circuitry involving frontal and limbic systems. Altered metabolism in these brain structures after a traumatic event is correlated to PTSD. Developments in the field of neuroimaging have allowed researchers to look at the structural and functional properties of the brain in PTSD. Despite the relative novelty of functional imaging and its application to the field of PTSD, numerous publications have brought to light several of the circuits implied in this disorder. This article summarizes the findings with regard to PTSD in the functional imaging techniques of single-photon emission computed tomography (SPECT), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). Furthermore, we discuss strengths and weaknesses of the various techniques and studies. Finally, we explore the future potential of functional neuroimaging studies in PTSD.

Targeting vesicular monoamine transporter Type 2 for noninvasive PET-based β-cell mass measurements

The common pathology in both Types 1 and 2 diabetes is insufficient β-cell mass to meet the metabolic needs of insulin production. The rising worldwide incidence of diabetes, combined with the lack of reliable endpoints of the body's true capacity to produce insulin, constitute a serious dilemma facing healthcare professionals and the pharmaceutical industry. Recent advances in imaging science and molecular imaging chemistry, as well as a broader understanding of basic islet biology, now allow the collection of quantitative information about β cells deep within the pancreas. The ability to noninvasively measure the mass of insulin-producing cells will most likely be of value towards characterizing new drugs and refining the diagnosis and treatment of this burdensome disease.

Detectors for single-molecule fluorescence imaging and spectroscopy

Single-molecule observation, characterization and manipulation techniques have recently come to the forefront of several research domains spanning chemistry, biology and physics. Due to the exquisite sensitivity, specificity, and unmasking of ensemble averaging, single-molecule fluorescence imaging and spectroscopy have become, in a short period of time, important tools in cell biology, biochemistry and biophysics. These methods led to new ways of thinking about biological processes such as viral infection, receptor diffusion and oligomerization, cellular signaling, protein-protein or protein-nucleic acid interactions, and molecular machines. Such achievements require a combination of several factors to be met, among which detector sensitivity and bandwidth are crucial. We examine here the needed performance of photodetectors used in these types of experiments, the current state of the art for different categories of detectors, and actual and future developments of single-photon counting detectors for single-molecule imaging and spectroscopy.

Acute stress and nicotine cues interact to unveil locomotor arousal and activity-dependent gene expression in the prefrontal cortex

BACKGROUND

This study examines the interactive effects of acute stress and nicotine-associated contextual cues on locomotor activity and activity-dependent gene expression in subregions of the prefrontal cortex.

METHODS

Locomotor activity of rats was measured in a context associated with either low-dose nicotine or saline administration with or without 5 minutes of pre-exposure to ferrets, a nonphysical stressor. After 45 minutes in the test environment, plasma corticosterone levels and mRNA levels of the immediate-early genes Arc, NGFI-B, and c-Fos in prefrontal and primary motor cortical subregions were measured.

RESULTS

Stress alone increased plasma corticosterone and prefrontal cortex gene expression. Low-dose nicotine cues had no effect on corticosterone levels nor did they elicit conditioned motor activation, and they caused minor elevations in gene expression. Stress and low-dose nicotine cues, however, interacted to elicit conditioned motor activation and further increases in early response gene expression in prefrontal but not in the primary motor cortical subregions.

CONCLUSIONS

Stress interacts with nicotine-associated cues to uncover locomotor arousal, a state associated with prefrontal neuronal activation and immediate early gene expression. Thus, in nicotine-experienced individuals, stress may be an important determinant of subjective reactivity and prefrontal cortex activation that occurs in response to nicotine-associated cues.

Anxiety, respiration, and cerebral blood flow: implications for functional brain imaging

Brain functional imaging methods, such as fMRI, are sensitive to changes in cerebral blood flow (CBF) that are normally associated with changes in regional neural activation. However, other endogenous and exogenous factors can alter CBF independently of brain neural activity, thus complicating the interpretation of functional imaging data. The presence of an anxiety disorder, as well as change in state anxiety, is often accompanied by respiratory alterations that affect arterial CO(2) tensions and produce significant changes in CBF that are independent of task-related neural activation. Therefore, the effects of trait and state anxiety need to be given close consideration in interpreting functional imaging findings. In this paper, we review the dependence of most brain functional imaging methods on localized changes in CBF and the potentially confounding effects of anxiety-related alterations of respiration on interpreting patterns of functional activation. Approaches for addressing these effects are discussed.

A novel technique for imaging with inhomogeneous fields

We introduce a simple, efficient, low-SAR method for magnetic resonance imaging in the presence of a static field with a permanent, and possibly large gradient. The technique, which is called slant-slice imaging is essentially a spin-echo imaging sequence except that the imaging slice is oriented such that the static field gradient can be used in conjunction with applied gradients during readout. Data are collected for 2D slices. Unlike single point imaging techniques, entire lines of k-space are acquired with each readout. The slant-slice pulse sequence is used to obtain high quality images, using a clinical scanner to simulate a static field with a large permanent gradient. The effects of the inhomogeneity are quantified by two parameters nu and q, which are useful for assessing the utility of a magnet design for 3D-MR imaging.

Targeting prostate cancer with radiolabelled bombesins

The fact that a number of common human tumours, including those of breast and prostate, express increased levels of the gastrin-releasing peptide receptor (GRP-R) means that this receptor is a potential target for peptide receptor mediated scintigraphy and targeted radionuclide therapy. Although clinical application is yet in its infancy, there is a considerable literature on preclinical studies aimed at developing suitable radioligands for potential clinical application. This brief review provides an overview of this research and also describes some of the limited clinical studies that have been published.

A high-resolution anatomical rat atlas

This paper reports the availability of a high-resolution atlas of the adult rat. The atlas is composed of 9475 cryosectional images captured in 4600 x 2580 x 24-bit TIFF format, constructed using serial cryosection-milling techniques. Cryosection images were segmented, labelled and reconstructed into three-dimensional (3D) computerized models. These images, 3D models, technical details, relevant software and further information are available at our website, http://vchibp.vicp.net/vch/mice/.

Radiation injury: imaging findings in the chest, abdomen and pelvis after therapeutic radiation

Radiation may be used as adjuvant or primary therapy in a variety of tumors in the chest, abdomen and pelvis. Therapeutic radiation affects not only malignant tumors but also surrounding normal tissues. The risk of injury depends on the size, number and frequency of radiation fractions, volume of irradiated tissue, duration of treatment, and method of radiation delivery. Concomitant chemotherapy can act synergistically to produce injury. Other predisposing factors include infection, prior surgery and chronic illness like hypertension, diabetes mellitus and atherosclerosis. Radiation changes vary, based on the target organ and the time from completion of therapy. While most serious complications related to radiotherapy are relatively uncommon, given the number of patients that are treated and the relatively long latency period for development of radiation changes, follow-up imaging studies frequently have findings that should be recognized as radiation related. Familiarity with the spectrum of imaging findings after radiation injury permits differentiation from other etiologies such as recurrent malignancy. The following will discuss imaging findings that may be seen during imaging surveillance in patients with malignancy affecting the chest, abdomen and pelvis.

White matter integrity in kleptomania: a pilot study

This study's goal was to examine microstructural organization of frontal white matter in kleptomania. Ten females with DSM-IV kleptomania and 10 female controls underwent diffusion tensor imaging. Inferior frontal white matter was the a priori region of interest. Trace and fractional anisotropy (FA) were also calculated for frontal and posterior cortical regions in both subject groups. Kleptomania subjects had significantly higher mean frontal Trace, and significantly lower mean frontal FA than control subjects. Group differences remained significant when right and left frontal Trace and FA were analyzed. Groups did not differ significantly in posterior Trace or FA. Kleptomania may be associated with decreased white matter microstructural integrity in inferior frontal brain regions.

Is there a role for planned serial chest radiographs and abdominal ultrasound scans in the resuscitation room following trauma?

INTRODUCTION

Despite advances in trauma care, significant morbidity and mortality exists which could be reduced if all injuries were immediately identified. Two treatable factors are hypoxia and hypovolaemia which may occur secondary to haemorrhage into the chest and abdomen. Pneumothorax is also a frequent cause of preventable trauma death. Clinical examination is limited and we often rely on imaging. Anecdotally, it seemed some patients were investigated too quickly because their injuries had not evolved sufficiently enough to become detectable. In these patients, repeated assessments and imaging would, therefore, be necessary.

PATIENTS AND METHODS

This was a retrospective study looking at all patients over a 15-month period with significant chest and abdominal injuries. Patients with a chest or abdominal Abbreviated Injury Score (AIS) of 3 or above were identified. As a cross reference, those patients who required at least one chest drain, or a laparotomy within 24 h of admission were also identified. Case notes and films were reviewed with particular attention to the presence of initial 'normal' imaging.

RESULTS

A total of 1036 patients were eligible for entry into the trauma database; of these, 170 patients had chest and/or abdominal injuries coded as AIS 3 or more. We were able to identify 7 cases (4%) where initial clinical examination and imaging failed to detect either bleeding (pleural space or abdomen) or a pneumothorax. A further 5 cases were potential missed injuries, but the data were incomplete making confident inclusion in this group impossible.

CONCLUSIONS

Occult injuries are reported to have an incidence of around 2-5%. Serial imaging in the resuscitation room may enable early identification of chest and abdominal injuries. However, only 12 cases were identified making interpretation of suitable candidates for repeat imaging difficult. The question is which group of patients would benefit from planned repeat imaging before leaving the resuscitation room.

Role of T and NK cells and IL7/IL7r interactions during neonatal maturation of lymph nodes

Lymph node (LN) development depends on prenatal interactions occurring between LN inducer and LN organizer cells. We have distinguished defects in LN formation due to failure in embryonic development (aly/aly) from defects in postnatal maturation (Il2rgamma(-/-)Rag2(-/-)). Both mutant strains form normal primordial LNs with differing fate. In aly/aly mice, the LN primordium dissipates irreversibly late in gestation; in contrast, Il2rgamma(-/-)Rag2(-/-) LN anlage persists for a week after birth but disperses subsequently, a process reversible by neonatal transfer of WT IL7r(+) TCR(+) T or natural killer (NK) cells, suggesting a role for IL7/IL7r interactions. Thus, we reveal a unique stage of postnatal LN development during which mature lymphocytes and IL7/IL7r interactions may play an important role.

Imaging of cell migration

Cell migration is an essential process during many phases of development and adult life. Cells can either migrate as individuals or move in the context of tissues. Movement is controlled by internal and external signals, which activate complex signal transduction cascades resulting in highly dynamic and localised remodelling of the cytoskeleton, cell-cell and cell-substrate interactions. To understand these processes, it will be necessary to identify the critical structural cytoskeletal components, their spatio-temporal dynamics as well as those of the signalling pathways that control them. Imaging plays an increasingly important and powerful role in the analysis of these spatio-temporal dynamics. We will highlight a variety of imaging techniques and their use in the investigation of various aspects of cell motility, and illustrate their role in the characterisation of chemotaxis in Dictyostelium and cell movement during gastrulation in chick embryos in more detail.

Intensive follow-up after liver resection for colorectal liver metastases: results of combined serial tumour marker estimations and computed tomography of the chest and abdomen - a prospective study

The aim of the study was to prospectively evaluate an intensive follow-up programme using serial tumour marker estimations and contrast-enhanced computed tomography (CT) of the chest and abdomen in patients undergoing potentially curative resection of colorectal liver metastases. Seventy-six consecutive patients having undergone potentially curative resections of colorectal liver metastases in a single unit were followed up with a protocol of 3 monthly carcinoembryonic antigen and carbohydrate antigen 19-9 estimations and contrast-enhanced spiral CT of the chest, abdomen and pelvis for the first 2 years following surgery and 6 monthly thereafter. The median period of follow-up was 24 months (range 18-60). Recurrent tumour was classed as early if within 6 months of liver resection. Thirty-seven of the 76 patients (49%) developed recurrence on follow-up. Nineteen recurrences were in the liver alone (51%), 16 liver and extrahepatic (43%) and two extrahepatic alone (6%). Of the 19 patients with isolated liver recurrence, eight developed within 6 months of liver resection none of which were resectable. Of the 11 recurrences after 6 months, five (45%) were resectable. Of the 37 recurrences, CT indicated recurrence despite normal tumour markers in 19 patients. Tumour markers suggested recurrence before imaging in 12 and concurrently with imaging in 6. In the 12 patients who presented with elevated tumour markers before imaging, there was a median lag period of 3 months (range 1-21) in recurrence being detected on further serial imaging. Seventeen patients who developed recurrence had normal tumour markers before initial resection of their liver metastases. Of these 17, 10 (58%) had an elevation of tumour markers associated with recurrence. Over a median follow-up of 2 years following liver resection, the use of CT or tumour markers alone would have failed to demonstrate early recurrence in 12 and 18 patients respectively. A combination of tumour markers and CT detected significantly more (P < 0.05) recurrence than either modality alone. Tumour markers and CT should be used in combination in the follow-up of patients with resected colorectal liver metatases, including patients whose markers are normal at the time of initial liver resection.

The role of the thalamus in modulating pain

The thalamus is one of the structures that receives projections from multiple ascending pain pathways. The structure is not merely a relay centre but is involved in processing nociceptive information before transmitting the information to various parts of the cortex. The thalamic nuclei are involved in the sensory discriminative and affective motivational components of pain. Generally each group of nucleus has prominent functions in one component for example ventrobasal complex in sensory discriminative component and intralaminar nuclei in affective-motivational component. The thalamus is also part of a network that projects to the spinal cord dorsal horn and modulates ascending nociceptive information. In the animal models of neuropathic pain, changes in the biochemistry, gene expression, thalamic blood flow and response properties of thalamic neurons have been shown. These studies suggest the important contribution of the thalamus in modulating pain in normal and neuropathic pain condition.