JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
Cross-Disorder Genome-Wide Analyses Suggest a Complex Genetic Relationship Between Tourette's Syndrome and OCD.
Dongmei Yu, Carol A Mathews, Jeremiah M Scharf, Benjamin M Neale, Lea K Davis, Eric R Gamazon, Eske M Derks, Patrick Evans, Christopher K Edlund, Jacquelyn Crane, Jesen A Fagerness, Lisa Osiecki, Patience Gallagher, Gloria Gerber, Stephen Haddad, Cornelia Illmann, Lauren M McGrath, Catherine Mayerfeld, Sampath Arepalli, Cristina Barlassina, Cathy L Barr, Laura Bellodi, Fortu Benarroch, Gabriel Bedoya Berrió, O Joseph Bienvenu, Donald W Black, Michael H Bloch, Helena Brentani, Ruth D Bruun, Cathy L Budman, Beatriz Camarena, Desmond D Campbell, Carolina Cappi, Julio C Cardona Silgado, Maria C Cavallini, Denise A Chavira, Sylvain Chouinard, Edwin H Cook, M R Cookson, Vladimir Coric, Bernadette Cullen, Daniele Cusi, Richard Delorme, Damiaan Denys, Yves Dion, Valsama Eapen, Karin Egberts, Peter Falkai, Thomas Fernandez, Eduardo Fournier, Helena Garrido, Daniel Geller, Donald Gilbert, Simon L Girard, Hans J Grabe, Marco A Grados, Benjamin D Greenberg, Varda Gross-Tsur, Edna Grünblatt, John Hardy, Gary A Heiman, Sian M J Hemmings, Luis D Herrera, Dianne M Hezel, Pieter J Hoekstra, Joseph Jankovic, James L Kennedy, Robert A King, Anuar I Konkashbaev, Barbara Kremeyer, Roger Kurlan, Nuria Lanzagorta, Marion Leboyer, James F Leckman, Leonhard Lennertz, Chunyu Liu, Christine Lochner, Thomas L Lowe, Sara Lupoli, Fabio Macciardi, Wolfgang Maier, Paolo Manunta, Maurizio Marconi, James T McCracken, Sandra C Mesa Restrepo, Rainald Moessner, Priya Moorjani, Jubel Morgan, Heike Muller, Dennis L Murphy, Allan L Naarden, Erika Nurmi, William Cornejo Ochoa, Roel A Ophoff, Andrew J Pakstis, Michele T Pato, Carlos N Pato, John Piacentini, Christopher Pittenger, Yehuda Pollak, Scott L Rauch, Tobias Renner, Victor I Reus, Margaret A Richter, Mark A Riddle, Mary M Robertson, Roxana Romero, Maria C Rosário, David Rosenberg, Stephan Ruhrmann, Chiara Sabatti, Erika Salvi, Aline S Sampaio, Jack Samuels, Paul Sandor, Susan K Service, Brooke Sheppard, Harvey S Singer, Jan H Smit, Dan J Stein, Eric Strengman, Jay A Tischfield, Maurizio Turiel, Ana V Valencia Duarte, Homero Vallada, Jeremy Veenstra-VanderWeele, Susanne Walitza, Ying Wang, Mike Weale, Robert Weiss, Jens R Wendland, Herman G M Westenberg, Yin Yao Shugart, Ana G Hounie, Euripedes C Miguel, Humberto Nicolini, Michael Wagner, Andrés Ruiz-Linares, Danielle C Cath, William McMahon, Danielle Posthuma, Ben A Oostra, Gerald Nestadt, Guy A Rouleau, Shaun Purcell, Michael A Jenike, Peter Heutink, Gregory L Hanna, David V Conti, Paul D Arnold, Nelson B Freimer, S Evelyn Stewart, James A Knowles, Nancy J Cox, David L Pauls.
Am J Psychiatry
PUBLISHED: 08-26-2014
Show Abstract
Hide Abstract
Obsessive-compulsive disorder (OCD) and Tourette's syndrome are highly heritable neurodevelopmental disorders that are thought to share genetic risk factors. However, the identification of definitive susceptibility genes for these etiologically complex disorders remains elusive. The authors report a combined genome-wide association study (GWAS) of Tourette's syndrome and OCD.
Related JoVE Video
Copy number variation in obsessive-compulsive disorder and tourette syndrome: a cross-disorder study.
Lauren M McGrath, Dongmei Yu, Christian Marshall, Lea K Davis, Bhooma Thiruvahindrapuram, Bingbin Li, Carolina Cappi, Gloria Gerber, Aaron Wolf, Frederick A Schroeder, Lisa Osiecki, Colm O'Dushlaine, Andrew Kirby, Cornelia Illmann, Stephen Haddad, Patience Gallagher, Jesen A Fagerness, Cathy L Barr, Laura Bellodi, Fortu Benarroch, O Joseph Bienvenu, Donald W Black, Michael H Bloch, Ruth D Bruun, Cathy L Budman, Beatriz Camarena, Danielle C Cath, Maria C Cavallini, Sylvain Chouinard, Vladimir Coric, Bernadette Cullen, Richard Delorme, Damiaan Denys, Eske M Derks, Yves Dion, Maria C Rosário, Valsama Eapen, Patrick Evans, Peter Falkai, Thomas V Fernandez, Helena Garrido, Daniel Geller, Hans J Grabe, Marco A Grados, Benjamin D Greenberg, Varda Gross-Tsur, Edna Grünblatt, Gary A Heiman, Sian M J Hemmings, Luis D Herrera, Ana G Hounie, Joseph Jankovic, James L Kennedy, Robert A King, Roger Kurlan, Nuria Lanzagorta, Marion Leboyer, James F Leckman, Leonhard Lennertz, Christine Lochner, Thomas L Lowe, Gholson J Lyon, Fabio Macciardi, Wolfgang Maier, James T McCracken, William McMahon, Dennis L Murphy, Allan L Naarden, Benjamin M Neale, Erika Nurmi, Andrew J Pakstis, Michele T Pato, Carlos N Pato, John Piacentini, Christopher Pittenger, Yehuda Pollak, Victor I Reus, Margaret A Richter, Mark Riddle, Mary M Robertson, David Rosenberg, Guy A Rouleau, Stephan Ruhrmann, Aline S Sampaio, Jack Samuels, Paul Sandor, Brooke Sheppard, Harvey S Singer, Jan H Smit, Dan J Stein, Jay A Tischfield, Homero Vallada, Jeremy Veenstra-VanderWeele, Susanne Walitza, Ying Wang, Jens R Wendland, Yin Yao Shugart, Euripedes C Miguel, Humberto Nicolini, Ben A Oostra, Rainald Moessner, Michael Wagner, Andrés Ruiz-Linares, Peter Heutink, Gerald Nestadt, Nelson Freimer, Tracey Petryshen, Danielle Posthuma, Michael A Jenike, Nancy J Cox, Gregory L Hanna, Helena Brentani, Stephen W Scherer, Paul D Arnold, S Evelyn Stewart, Carol A Mathews, James A Knowles, Edwin H Cook, David L Pauls, Kai Wang, Jeremiah M Scharf.
J Am Acad Child Adolesc Psychiatry
PUBLISHED: 03-16-2014
Show Abstract
Hide Abstract
Obsessive-compulsive disorder (OCD) and Tourette syndrome (TS) are heritable neurodevelopmental disorders with a partially shared genetic etiology. This study represents the first genome-wide investigation of large (>500 kb), rare (<1%) copy number variants (CNVs) in OCD and the largest genome-wide CNV analysis in TS to date.
Related JoVE Video
Partitioning the heritability of Tourette syndrome and obsessive compulsive disorder reveals differences in genetic architecture.
Lea K Davis, Dongmei Yu, Clare L Keenan, Eric R Gamazon, Anuar I Konkashbaev, Eske M Derks, Benjamin M Neale, Jian Yang, S Hong Lee, Patrick Evans, Cathy L Barr, Laura Bellodi, Fortu Benarroch, Gabriel Bedoya Berrió, Oscar J Bienvenu, Michael H Bloch, Rianne M Blom, Ruth D Bruun, Cathy L Budman, Beatriz Camarena, Desmond Campbell, Carolina Cappi, Julio C Cardona Silgado, Danielle C Cath, Maria C Cavallini, Denise A Chavira, Sylvain Chouinard, David V Conti, Edwin H Cook, Vladimir Coric, Bernadette A Cullen, Dieter Deforce, Richard Delorme, Yves Dion, Christopher K Edlund, Karin Egberts, Peter Falkai, Thomas V Fernandez, Patience J Gallagher, Helena Garrido, Daniel Geller, Simon L Girard, Hans J Grabe, Marco A Grados, Benjamin D Greenberg, Varda Gross-Tsur, Stephen Haddad, Gary A Heiman, Sian M J Hemmings, Ana G Hounie, Cornelia Illmann, Joseph Jankovic, Michael A Jenike, James L Kennedy, Robert A King, Barbara Kremeyer, Roger Kurlan, Nuria Lanzagorta, Marion Leboyer, James F Leckman, Leonhard Lennertz, Chunyu Liu, Christine Lochner, Thomas L Lowe, Fabio Macciardi, James T McCracken, Lauren M McGrath, Sandra C Mesa Restrepo, Rainald Moessner, Jubel Morgan, Heike Muller, Dennis L Murphy, Allan L Naarden, William Cornejo Ochoa, Roel A Ophoff, Lisa Osiecki, Andrew J Pakstis, Michele T Pato, Carlos N Pato, John Piacentini, Christopher Pittenger, Yehuda Pollak, Scott L Rauch, Tobias J Renner, Victor I Reus, Margaret A Richter, Mark A Riddle, Mary M Robertson, Roxana Romero, Maria C Rosário, David Rosenberg, Guy A Rouleau, Stephan Ruhrmann, Andrés Ruiz-Linares, Aline S Sampaio, Jack Samuels, Paul Sandor, Brooke Sheppard, Harvey S Singer, Jan H Smit, Dan J Stein, E Strengman, Jay A Tischfield, Ana V Valencia Duarte, Homero Vallada, Filip Van Nieuwerburgh, Jeremy Veenstra-VanderWeele, Susanne Walitza, Ying Wang, Jens R Wendland, Herman G M Westenberg, Yin Yao Shugart, Euripedes C Miguel, William McMahon, Michael Wagner, Humberto Nicolini, Danielle Posthuma, Gregory L Hanna, Peter Heutink, Damiaan Denys, Paul D Arnold, Ben A Oostra, Gerald Nestadt, Nelson B Freimer, David L Pauls, Naomi R Wray, S Evelyn Stewart, Carol A Mathews, James A Knowles, Nancy J Cox, Jeremiah M Scharf.
PLoS Genet.
PUBLISHED: 10-01-2013
Show Abstract
Hide Abstract
The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained by all SNPs for two phenotypically-related neurobehavioral disorders, obsessive-compulsive disorder (OCD) and Tourette Syndrome (TS), using GCTA. Our analysis yielded a heritability point estimate of 0.58 (se = 0.09, p = 5.64e-12) for TS, and 0.37 (se = 0.07, p = 1.5e-07) for OCD. In addition, we conducted multiple genomic partitioning analyses to identify genomic elements that concentrate this heritability. We examined genomic architectures of TS and OCD by chromosome, MAF bin, and functional annotations. In addition, we assessed heritability for early onset and adult onset OCD. Among other notable results, we found that SNPs with a minor allele frequency of less than 5% accounted for 21% of the TS heritability and 0% of the OCD heritability. Additionally, we identified a significant contribution to TS and OCD heritability by variants significantly associated with gene expression in two regions of the brain (parietal cortex and cerebellum) for which we had available expression quantitative trait loci (eQTLs). Finally we analyzed the genetic correlation between TS and OCD, revealing a genetic correlation of 0.41 (se = 0.15, p = 0.002). These results are very close to previous heritability estimates for TS and OCD based on twin and family studies, suggesting that very little, if any, heritability is truly missing (i.e., unassayed) from TS and OCD GWAS studies of common variation. The results also indicate that there is some genetic overlap between these two phenotypically-related neuropsychiatric disorders, but suggest that the two disorders have distinct genetic architectures.
Related JoVE Video
Reduced error-related activation of dorsolateral prefrontal cortex across pediatric anxiety disorders.
J Am Acad Child Adolesc Psychiatry
PUBLISHED: 08-27-2013
Show Abstract
Hide Abstract
Abnormalities of cognitive control functions, such as conflict and error monitoring, have been theorized to underlie obsessive-compulsive symptoms but only recently have been considered a potentially relevant psychological construct for understanding other forms of anxiety. The authors sought to determine whether these cognitive control processes elicit the same abnormalities of brain function in patients with pediatric obsessive-compulsive disorder (OCD) as in those with non-OCD anxiety disorders.
Related JoVE Video
Altered relationship between electrophysiological response to errors and gray matter volumes in an extended network for error-processing in pediatric obsessive-compulsive disorder.
Hum Brain Mapp
PUBLISHED: 02-18-2013
Show Abstract
Hide Abstract
Pediatric patients with obsessive-compulsive disorder (OCD) show an increased electrophysiological response to errors that is thought to be localized to the posterior medial prefrontal cortex (pMFC). However, the relation of this response, the error-related negativity (ERN), to underlying brain structures remains unknown. In an examination of 20 pediatric OCD patients and 20 healthy youth, we found that more negative ERN amplitude was correlated with lower gray matter (GM) density in pMFC and orbital frontal cortex. The association of the ERN with pMFC gray matter volume was driven by the patient group. In addition, a group difference in the association of ERN with gray matter in right insula was observed, showing an association of these measures in healthy youth (more negative ERN amplitude was associated with lower GM density in insula), but not in patients. These findings provide preliminary evidence linking gray matter volumes in an extended network for error processing to the ERN, and suggest that structural alterations in this network may underlie exaggeration of the ERN in pediatric OCD. Hum Brain Mapp, 2014. © 2013 Wiley Periodicals, Inc.
Related JoVE Video
Increased error-related brain activity in youth with obsessive-compulsive disorder and other anxiety disorders.
Neurosci. Lett.
PUBLISHED: 01-23-2013
Show Abstract
Hide Abstract
The error-related negativity (ERN) is a negative deflection in the event-related potential after an incorrect response that is thought to reflect activity in the anterior cingulate cortex (ACC) and is often increased in patients with anxiety disorders. This study measured the ERN and correct response negativity (CRN) during an Eriksen flanker task to assess performance monitoring in 26 youth with obsessive-compulsive disorder (OCD), 13 youth with a non-OCD anxiety disorder consisting of either generalized anxiety disorder or separation anxiety disorder, and 27 age-matched healthy controls ranging in age from 8 to 16 years. Compared to healthy controls, ERN amplitude was significantly increased in patients with either OCD or a non-OCD anxiety disorder. There were no significant group differences in CRN amplitude. Treatment with a serotonergic antidepressant or cognitive-behavior therapy had no effect on the ERN in patients. Scores from the Child Behavior Checklist DSM-oriented anxiety problems scale had a significant correlation with ERN amplitude in all subjects. The results provide further evidence that the pathophysiology of OCD and some non-OCD anxiety disorders involves increased ACC activity and that the ERN may serve as a quantitative phenotype in genetic and longitudinal studies of these complex traits.
Related JoVE Video
The role of glutamate signaling in the pathogenesis and treatment of obsessive-compulsive disorder.
Pharmacol. Biochem. Behav.
PUBLISHED: 03-28-2011
Show Abstract
Hide Abstract
Obsessive-compulsive disorder (OCD) is a common and often debilitating neuropsychiatric condition characterized by persistent intrusive thoughts (obsessions), repetitive ritualistic behaviors (compulsions) and excessive anxiety. While the neurobiology and etiology of OCD has not been fully elucidated, there is growing evidence that disrupted neurotransmission of glutamate within corticalstriatal-thalamocortical (CSTC) circuitry plays a role in OCD pathogenesis. This review summarizes the findings from neuroimaging, animal model, candidate gene and treatment studies in the context of glutamate signaling dysfunction in OCD. First, studies using magnetic resonance spectroscopy are reviewed demonstrating altered glutamate concentrations in the caudate and anterior cingulate cortex of patients with OCD. Second, knockout mouse models, particularly the DLGAP3 and Sltrk5 knockout mouse models, display remarkably similar phenotypes of compulsive grooming behavior associated with glutamate signaling dysfunction. Third, candidate gene studies have identified associations between variants in glutamate system genes and OCD, particularly for SLC1A1 which has been shown to be associated with OCD in five independent studies. This converging evidence for a role of glutamate in OCD has led to the development of novel treatment strategies involving glutamatergic compounds, particularly riluzole and memantine. We conclude the review by outlining a glutamate hypothesis for OCD, which we hope will inform further research into etiology and treatment for this severe neuropsychiatric condition.
Related JoVE Video
Developmental alterations of frontal-striatal-thalamic connectivity in obsessive-compulsive disorder.
J Am Acad Child Adolesc Psychiatry
PUBLISHED: 03-09-2011
Show Abstract
Hide Abstract
Pediatric obsessive-compulsive disorder is characterized by abnormalities of frontal-striatal-thalamic circuitry that appear near illness onset and persist over its course. Distinct frontal-striatal-thalamic loops through cortical centers for cognitive control (anterior cingulate cortex) and emotion processing (ventral medial frontal cortex) follow unique maturational trajectories, and altered connectivity within distinct loops may be differentially associated with OCD at specific stages of development.
Related JoVE Video
Major depressive disorder in a family study of obsessive-compulsive disorder with pediatric probands.
Depress Anxiety
PUBLISHED: 01-07-2011
Show Abstract
Hide Abstract
This study examined the comorbidity of obsessive-compulsive disorder (OCD) with major depressive disorder (MDD) in a family study of OCD with pediatric probands.
Related JoVE Video
Altered function and connectivity of the medial frontal cortex in pediatric obsessive-compulsive disorder.
Biol. Psychiatry
PUBLISHED: 04-07-2010
Show Abstract
Hide Abstract
Exaggerated concern for correct performance has been linked to hyperactivity of the medial frontal cortex (MFC) in adult obsessive-compulsive disorder (OCD), but the role of the MFC during the early course of illness remains poorly understood. We tested whether hyperactive MFC-based performance monitoring function relates to altered MFC connectivity within task control and default mode networks in pediatric patients.
Related JoVE Video
Glutamate system genes associated with ventral prefrontal and thalamic volume in pediatric obsessive-compulsive disorder.
Brain Imaging Behav
PUBLISHED: 03-01-2009
Show Abstract
Hide Abstract
This pilot study was undertaken to determine if there was a significant association between specific glutamate system genes and regional volumes of interest implicated in the pathogenesis of obsessive-compulsive disorder (OCD). Volumetric magnetic resonance imaging (MRI) and genotyping of 7 polymorphisms in two genes, glutamate receptor, ionotropic, N-methyl-d-aspartate 2B (GRIN2B) and solute linked carrier, family 1, member 1 (SLC1A1) were conducted in 31 psychotropic-naïve pediatric OCD patients. The rs1805476 variant of GRIN2B was associated with left but not right orbital frontal cortex (OFC) (p=0.04) and right but not left anterior cingulate cortex (ACC) volume (p=0.02). The SLC1A1 rs3056 variant was associated with increased total (p=0.01), left (p=0.02) and right (p=0.02) thalamic volume. These results suggest that GRIN2B and SLC1A1 may be associated with regional volumetric alterations in OFC, ACC, and thalamus in children with OCD.
Related JoVE Video
Glutamate receptor gene (GRIN2B) associated with reduced anterior cingulate glutamatergic concentration in pediatric obsessive-compulsive disorder.
Psychiatry Res
PUBLISHED: 01-09-2009
Show Abstract
Hide Abstract
In this preliminary study, 16 psychotropic-naïve pediatric patients with obsessive-compulsive disorder (OCD) were studied using magnetic resonance spectroscopy (MRS) and genotyped for six candidate polymorphisms in two glutamate system genes. A significant association was identified between the rs1019385 polymorphism of the glutamate receptor, ionotropic, N-methyl-d-aspartate 2B (GRIN2B) and decreased anterior cingulate cortex (ACC) glutamatergic concentration (Glx) but not with occipital Glx. These results suggest that GRIN2B may be associated with Glx in the ACC, a region consistently implicated in OCD.
Related JoVE Video
Increased error-related brain activity in youth with obsessive-compulsive disorder and unaffected siblings.
Depress Anxiety
Show Abstract
Hide Abstract
The pathophysiology of obsessive-compulsive disorder (OCD) involves increased activity in cortico-striatal circuits connecting the anterior cingulate cortex (ACC) with other brain regions. The error-related negativity (ERN) is a negative deflection in the event-related potential following an erroneous response and is thought to reflect ACC activity. This study was done to assess the ERN as a biomarker for OCD by comparing ERN amplitudes in pediatric OCD patients, unaffected siblings of pediatric OCD patients, and healthy controls.
Related JoVE Video
Glutamate system genes and brain volume alterations in pediatric obsessive-compulsive disorder: a preliminary study.
Psychiatry Res
Show Abstract
Hide Abstract
Obsessive-compulsive disorder (OCD) has been associated with regional volumetric brain abnormalities, which provide promising intermediate phenotypes of the disorder. In this study, volumes of brain regions selected for a priori evidence of association with OCD (orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), thalamus, caudate, putamen, globus pallidus and pituitary) were measured using structural magnetic resonance imaging (MRI) in 20 psychotropic-naïve pediatric OCD patients. We examined the association between these regional brain volumes and a total of 519 single nucleotide polymorphisms (SNPs) from nine glutamatergic candidate genes (DLGAP1, DLGAP2, DLGAP3, GRIN2B, SLC1A1, GRIK2, GRIK3, SLITRK1 and SLITRK5). These genes were selected based on either previous reported association with OCD in humans or evidence from animal models of OCD. After correcting for multiple comparisons by permutation testing, no SNP remained significantly associated with volumetric changes. The strongest trend toward association was identified between two SNPs in DLGAP2 (rs6558484 and rs7014992) and OFC white matter volume. Our other top ranked association findings were with ACC, OFC and thalamus. These preliminary results suggest that sequence variants in glutamate candidate genes may be associated with structural neuroimaging phenotypes of OCD.
Related JoVE Video
Error-related negativity and tic history in pediatric obsessive-compulsive disorder.
J Am Acad Child Adolesc Psychiatry
Show Abstract
Hide Abstract
The error-related negativity (ERN) is a negative deflection in the event-related potential after an incorrect response, which is often increased in patients with obsessive-compulsive disorder (OCD). However, the relation of the ERN to comorbid tic disorders has not been examined in patients with OCD. This study compared ERN amplitudes in patients with tic-related OCD, patients with non-tic-related OCD, and healthy controls.
Related JoVE Video
Genome-wide linkage analysis of obsessive-compulsive disorder implicates chromosome 1p36.
Biol. Psychiatry
Show Abstract
Hide Abstract
Obsessive-compulsive disorder (OCD) has a complex etiology involving both genetic and environmental factors. However, the genetic causes of OCD are largely unknown, despite the identification of several promising candidate genes and linkage regions.
Related JoVE Video
Functional studies and rare variant screening of SLC1A1/EAAC1 in males with obsessive-compulsive disorder.
Psychiatr. Genet.
Show Abstract
Hide Abstract
Several studies have found that the neuronal glutamate transporter gene SLC1A1/EAAC1 is associated with obsessive-compulsive disorder (OCD), with a stronger association in males. Previous studies have primarily focused on common single-nucleotide polymorphisms, rather than rare functional variants that are likely to have larger effects. We screened 184 males with OCD for rare variation in SLC1A1 exons; however, no new coding variation was found. When combined with previous screens, only one SLC1A1 amino acid variant has been detected among the 841 individuals screened, which is less than for other neurotransmitter transporter genes (P=0.0001). We characterized the function of the one SLC1A1 missense variant reported previously in OCD, Thr164Ala, and found that the Ala164 allele leads to decreased Vmax and Km (P<0.0001) in transfected human embryonic kidney cells. Further work will be necessary to understand the impact of this rare SLC1A1/EAAC1 Ala164 variant on neuronal function and circuitry relevant to OCD.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.