Name: transferring cognitive tasks between brain imaging modalities: implications for task design and results interpretation in fmri studies
Uploaded: 2014-09-22T14:00:00.000+00:00
Duration: 10 min 9 s
Description: Watch this Scientific Journal Video about Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies at JoVE.com

NOTE: The study protocol was approved by the local Human Subjects Review Board at RWTH Aachen University and was carried out in accordance with the Declaration of Helsinki.
1. Task Design
<ol>
	<li>Choose an appropriate task to investigate the cognitive/psychological construct of interest. Use the visual oddball task (Figure 1) to measure target detection responses and the effects of attention on target detection. This allows investigation of the influence of task manipulations on fMRI data.</li>
	<li>Use three versions of the oddball task.
	<ol>
		<li>Passive version: Ask the subject to observe visual stimuli. Do not detect any response.</li>
		<li>Silent count version: Ask the subject to count the target stimuli. This task requires directing attention towards these stimuli and a discriminating process.</li>
		<li>Respond version: Ask the subject to push a response button upon seeing a target stimulus. This task requires attention, discrimination processes, and selection/production of a response to target stimuli.</li>
	</ol>
	</li>
	<li>Consider the appropriate number of trials required for a robust response. The signal to noise ratio in fMRI measurements is relatively low and requires a number of responses to be averaged in order to investigate the effects of interest9. This depends on the task and stimulus modality used. 200 trials are used in this task, 40 of which are target trials sufficient to elicit a robust response.</li>
	<li>Determine the timings for the sequence of stimuli. The timing of stimuli is crucial in an fMRI study for consideration of presentation rate10. Consider the hemodynamic response-delay between stimulus onset and the measured brain response (Figure 2).
	<ol>
		<li>Maintain a balance between delivering sufficient stimuli in a reasonable amount of time and allow sufficient sampling of the hemodynamic response to each stimulus, including the return to baseline. Download, install and run optseq software. Run optseq to optimally distributing the trials across the experiment based on number of trials, stimulus duration and scanning parameters (repetition time and number of volumes).</li>
	</ol>
	</li>
	<li>Implement the order of stimuli (previously determined) in a suitable program for presenting the paradigm to the subject.
	<ol>
		<li>Specify all information relevant to the paradigm in terms of type of stimuli, timing and responses. 
		NOTE: Programming details are not presented here because each paradigm will have different requirements as will different software packages.</li>
	</ol>
	</li>
	<li>Set up the program that will deliver the experimental paradigm so that it will start with a trigger from the scanner. This allows synchronization of the acquired data and the sequence of stimuli presented.</li>
</ol>
2. Setup Experimental Environment
<ol>
	<li>Prepare the scanner room. Connect the bottom part of correct head coil to the scanner bed. Place clean protective covers on the scanner bed and cushions.</li>
	<li>Use a display device to present the experimental paradigm to the subject and record the responses using a hand held device. Switch the display device and a hand held device &#8220;on&#8221;.</li>
	<li>Start the software that will deliver the experimental paradigm and provide a name for the logfile. The logfile contains information about the timing of the stimuli and of the responses made by the subject. Use this information for analyzing the data.</li>
	<li>Register the subject in the MR scanner database. Record data using a unique identification number. Do not store subject&#8217;s name with the data to guarantee privacy.</li>
	<li>Make sure that the MR sequences to be run are set up and ready. Use the following sequences: a localizer scan to obtain the subjects&#8217; head position inside the coil, an EPI sequence for the functional imaging and MPRAGE for a high resolution structural scan.</li>
</ol>
3. Subject Arrival and Entrance to Scanner
<ol>
	<li>Screen the subject for contraindications with MRI prior to the experiment (e.g., during the recruitment procedure).
	<ol>
		<li>Provide MR safety instructions before scanning. Perform screening of subjects (by trained personnel). Ensure subjects&#8217; safety. Make sure they have no metal in their body, do not have devices such as pacemakers and do not meet any other exclusion criteria.</li>
	</ol>
	</li>
	<li>Upon subjects&#8217; arrival check the screening questionnaire and confirm their compatibility before proceeding.</li>
	<li>Explain the experimental procedure to the subject and offer the opportunity to ask questions. Ask the subject to sign the consent and data protection forms.</li>
	<li>If the experiment involves complex tasks requiring training it is recommended that the subject performs a practice run prior to going in the scanner.</li>
	<li>Ensure that the subject is metal free, without any coins, belt, watch and jewelry. Once confirmed, let the subject in the scanner room.</li>
	<li>Ask the subject to sit on the scanner bed wearing earplugs. The earplugs used here provide protection against the noise from the scanner during scanning and also allow the investigator to communicate directly with the subject from the control room. In some facilities headphones are used for communication with the subject.</li>
	<li>Ask the subject to lie down on the scanner bed. Offer the subject a cushion to go under the knees to reduce back pain. The comfort of the subject is important for their well-being and data quality. Movement resulting from discomfort will have a negative impact on the imaging data and distraction caused by discomfort will influence the performance of the task.</li>
	<li>Place the top part of the head coil over the subject&#8217;s head and plug in the connectors. Position the subject&#8217;s head appropriately in the head coil. Align the small marker on the head coil along the subjects&#8217; eyebrows. Ensure the subject is lying straight and comfortable. The coil surface should not touch the face (e.g., pressing on the nose).</li>
	<li>Secure the subject&#8217;s head with small cushions to minimize head movements during scanning. Head movements have negative impact on the quality of the data.</li>
	<li>Place a mirror on top of the head coil for the subject to see the experimental paradigm displayed on the screen behind. Ensure the subject can see the whole screen. Move the mounted mirror according to the subject&#8217;s position. Subjects with glasses must wear MR compatible eyewear. Most MRI research facilities have compatible lenses or goggles. In this case, mount MR compatible lenses on the frame that holds the mirror. Determine the appropriate lens strength before the subject enters the scanner room.</li>
	<li>Hand the subject an emergency call button to stop the scan if required. Make sure the subject knows where the button is and that they can easily reach it.</li>
	<li>Move the subject to the entrance of the bore of the scanner. Ask the subject to close their eyes during this procedure. Align the light with the small marks on the head coil to establish the correct position.</li>
	<li>Move the subject into the bore of the scanner until the display reads &#8216;0 mm&#8217;. This means that the head of the subject is at the isocenter&#160;of the scanner.</li>
	<li>Hand the subject the response device.</li>
</ol>
4. Experimental Procedure
<ol>
	<li>Check if the subject can hear the experimenter via the intercom and that the subject is comfortable and ready to start.</li>
	<li>Perform a localizer scan to obtain the position of the subject&#8217;s head in the scanner. Use this to position the field of view of all of the remaining measurements to determine the parts of the brain to be measured.</li>
	<li>First perform a high resolution structural scan. Open the MPRAGE sequence/program and position the field of view. Ensure the entire subject&#8217;s head is within the field of view. MP-RAGE parameters: TR/TE = 2,250 / 3.03 msec, flip angle = 9&#176;, 176 sagittal slices, FOV 256 x 256 mm, 64 x 64 matrix, voxel size 1 x 1 x 1 mm).</li>
	<li>Let the subject know that the scan will start and then begin the measurement.</li>
	<li>Perform functional MRI scan.
	<ol>
		<li>Open the EPI sequence on the scanner computer and align the field of view to cover the entire brain. EPI parameters: 33 slices, slice thickness 3 mm, FOV 200 x 200 mm, 64 x 64 matrix, repetition time 2,000 msec, echo time 30 msec, flip angle 79&#176;.</li>
		<li>Run a single volume test measurement. Make sure that the whole (or as much as possible) of the subject&#8217;s brain is contained within the field of view. 
		NOTE: Subjects have different shapes and sizes of heads (and brains). Hence, optimally position the field of view for each subject.</li>
		<li>Copy the fMRI sequence so that the positioned field of view remains the same for the next measurement. Enter the number of volumes required for the measurement, 304 in this case.</li>
		<li>Make sure the software presenting the paradigm is waiting for a trigger from the scanner. The paradigm will not start without a trigger from the scanner so it can be loaded and set to wait.</li>
		<li>Inform the subject that the experiment is about to start. Start the measurement.</li>
		<li>Check that the software presenting the paradigm starts at the appropriate time (i.e. that it is triggered by the scanner).</li>
		<li>Perform three versions of the oddball task. Passive, Count,&#160;and Respond.</li>
		<li>Speak to the subject in between runs to provide reassurance. Ensure their comfort. Ask if the subject permits to continue with the study. Instruct the subject of the upcoming task.</li>
		<li>First run the passive condition to ensure true passive viewing without knowledge that the target stimuli are indeed target stimuli. Counterbalance the order of the count and respond conditions across subjects to prevent order effects.</li>
	</ol>
	</li>
</ol>
5. End of Experiment
<ol>
	<li>Inform the subject that the experiment is finished enter the scanner room.</li>
	<li>Slide the subject out of scanner.</li>
	<li>Remove head coil and cushions.</li>
	<li>Ask the subject to sit up slowly. Once they are comfortable, the subject can stand up and leave the scanner room.</li>
	<li>Administer any questionnaires/paperwork that needs to be completed after the experiment</li>
	<li>Debrief the subject: provide the subject with an explanation about the aims and purpose of the study if this was not fully possible prior to the experiment and offer the opportunity to ask questions</li>
</ol>
6. Data Analysis
<ol>
	<li>Use a software package that is suitable for analyzing fMRI data. Perform first level data analysis for each subject and each condition separately. 
	NOTE: Use the FMRIB Software Library (FSL) for fMRI data analysis.</li>
	<li>Apply standard preprocessing steps to prepare the data for further analysis. 
	NOTE: Apply the following steps: motion correction, slice timing correction, coregistration of structural and function data, spatial smoothing, highpass temporal filtering, normalization of individual into standard (e.g., MNI) space. Find a summary of these steps in fMRI textbooks Huettel et al, (2008)9 and Jezzard et al, (2001)11. Specific information on how to perform preprocessing steps is available on the website and in the supporting documentation for each individual software package.</li>
	<li>For the statistical analysis specify the onset times and durations of all events. These are termed explanatory variables (EVs), or regressors.</li>
	<li>Set up contrasts to determine which EVs are compared. To identify the BOLD activation specific to detection of target stimuli set up the following contrast: target &#62; non-target stimuli. 
	NOTE: Optionally use other contrasts: target stimuli against baseline; non-target stimuli against baseline; target stimuli &#62; non-target stimuli; non-target stimuli &#62; target stimuli</li>
	<li>Perform the first level statistical analysis for each subject and each condition separately. The output of the analysis shows the active brain regions for each of the respective contrast.</li>
	<li>Compare the three conditions using a second level, or group level, analyses. Use the output of the first level analysis as the input for the group level analysis. 
	NOTE: In the original paper7 the differences between conditions on the target &#62; frequent contrast using a Tripled Two-Group Difference design involving the following contrasts: respond &#62; passive, count &#62; passive, respond &#62; count. These contrasts reveal brain activity associated with the variation in cognitive processes across the three response modalities.</li>
</ol>

<ol>
	<li>Squires, N. K., Squires, K. C., Hillyard, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+varieties+of+long-latency+positive+waves+evoked+by+unpredictable+auditory+stimuli+in+man.">Two varieties of long-latency positive waves evoked by unpredictable auditory stimuli in man.</a> Electroencephalography and clinical neurophysiology. 38, 387-401 (1975).</li><li>Polich, J., Criado, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropsychology+and+neuropharmacology+of+P3a+and+P3b.">Neuropsychology and neuropharmacology of P3a and P3b.</a> International journal of psychophysiology : official journal of the International Organization of Psychophysiology. 60, 172-185 (2006).</li><li>Turetsky, B. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurophysiological+endophenotypes+of+schizophrenia:+the+viability+of+selected+candidate+measures.">Neurophysiological endophenotypes of schizophrenia: the viability of selected candidate measures.</a> Schizophrenia bulletin. 33, 69-94 (2007).</li><li>Mobascher, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+P300+event-related+potential+and+smoking--a+population-based+case-control+study.">The P300 event-related potential and smoking--a population-based case-control study.</a> International journal of psychophysiology : official journal of the International Organization of Psychophysiology. 77, 166-175 (2010).</li><li>Li, L., Gratton, C., Fabiani, M., Knight, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+frontoparietal+changes+during+the+control+of+bottom-up+and+top-down+attention:+an+ERP+study.">Age-related frontoparietal changes during the control of bottom-up and top-down attention: an ERP study.</a> Neurobiology of aging. 34, 477-488 (2013).</li><li>Kirino, E., Belger, A., Goldman-Rakic, P., McCarthy, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prefrontal+activation+evoked+by+infrequent+target+and+novel+stimuli+in+a+visual+target+detection+task:+An+event-related+functional+magnetic+resonance+imaging+study.">Prefrontal activation evoked by infrequent target and novel stimuli in a visual target detection task: An event-related functional magnetic resonance imaging study.</a> Journal of Neuroscience. 20, 6612-6618 (2000).</li><li>Warbrick, T., Reske, M., Shah, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Do+EEG+paradigms+work+in+fMRI?+Varying+task+demands+in+the+visual+oddball+paradigm:+Implications+for+task+design+and+results+interpretation.">Do EEG paradigms work in fMRI? Varying task demands in the visual oddball paradigm: Implications for task design and results interpretation.</a> Neuroimage. 77, 177-185 (2013).</li><li>Warbrick, T., Arrubla, J., Boers, F., Neuner, I., Shah, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Attention+to+Detail:+Why+Considering+Task+Demands+Is+Essential+for+Single-Trial+Analysis+of+BOLD+Correlates+of+the+Visual+P1+and+N1.">Attention to Detail: Why Considering Task Demands Is Essential for Single-Trial Analysis of BOLD Correlates of the Visual P1 and N1.</a> J Cogn Neurosci. 26, 529-542 (2014).</li><li>Huettel, S. A., Song, A. W., McCarthy, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Functional magnetic resonance imaging. , (2008).</li><li>Miezin, F. M., Maccotta, L., Ollinger, J. M., Petersen, S. E., Buckner, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+the+hemodynamic+response:+effects+of+presentation+rate,+sampling+procedure,+and+the+possibility+of+ordering+brain+activity+based+on+relative+timing.">Characterizing the hemodynamic response: effects of presentation rate, sampling procedure, and the possibility of ordering brain activity based on relative timing.</a> Neuroimage. 11, 735-759 (2000).</li><li>Jezzard, P., Matthews, P. M., Smith, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Functional Magnetic Resonance Imaging: An Introduction to Methods. , (2001).</li></ol>

The authors have nothing to disclose.

We show that manipulating the task demands in the visual oddball task results in different patterns of BOLD activation in the count and respond conditions. The functional roles of some of the regions implicated in each condition would have been inappropriately assigned had data from the three versions of the task not been available for comparison. This ambiguity in data interpretation would not necessarily have been the case in the EEG P300 field where the task has its origin, highlighting the need for ...

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. This is a logical progression since most neuropsychological concepts (e.g., distinct memory sub-components) have been investigated in the behavioral domain and appropriate experimental tasks for probing specific functions have been developed and tested. As new technology emerges evidence for the neural underpinnings of these behavioral observations is sought with the new brain imaging methods. While it may be tempting to simply draw on well-studied behavioral tasks for imaging studies, several important caveats have to be taken into account. One crucial, though frequently neglected, consideration is the use of the most appropriate imaging technique to further probe the behavioral evidence. In terms of cognitive neuroscience and psychology there are many brain imaging methods available to enhance our understanding of the neural activity underlying concepts of interest; for example electroencephalography (EEG), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). All of these methods have their advantages, disadvantages and appropriate applications. Here transferring a paradigm with a long history of behavioral and EEG experiments to an fMRI experiment is considered. EEG has been used for decades to investigate neural responses associated with perceptual and cognitive processes. As such, many paradigms have been developed for use with this method and have evolved over time. Functional MRI is a technique that emerged more recently in cognitive neuroscience and this has led to some paradigms developed in EEG research being used in fMRI. To build on the knowledge base from EEG experiments with the new techniques is a logical step but nonetheless some important points may be neglected in the transfer. The techniques are very different and tasks need to be designed accordingly. This requires knowledge of how the method works and, in particular, how potential modulations of the paradigm used will influence the measures taken. For further information on the design of fMRI experiments the interested reader is directed to the following link <a href="http://imaging.mrc-cbu.cam.ac.uk/imaging/DesignEfficiency">http://imaging.mrc-cbu.cam.ac.uk/imaging/DesignEfficiency</a>. Task design will be considered in the context of transferring a paradigm developed for EEG research to the fMRI environment. The aims of this paper are: i) to briefly describe fMRI and when its use is appropriate in cognitive neuroscience; ii) to illustrate how task design can influence the results of an fMRI experiment, particularly when that task is borrowed from another imaging modality; and iii) to explain the practical aspects of performing an fMRI experiment.
Functional MRI is now a widely available technique and as such is a common method used in cognitive neuroscience. In order to make a decision as to whether the technique is appropriate for a particular experiment the advantages and disadvantages of fMRI must be considered in relation to other available techniques. A disadvantage of the method is that it is not a direct measure of neural activity, rather it is a correlate of neural activity in that the metabolic response (oxygen requirement) convolved with the haemodynamic response. Thus its temporal resolution is poor in comparison to electrophysiology, for example, where the measured electrical signal is closer to the underlying neural activity rather than a metabolic response. EEG has a temporal resolution in the order of milliseconds compared to a resolution in the order of seconds in fMRI. However, the main advantage of fMRI is that the spatial resolution of the technique is excellent. Furthermore, it is noninvasive and thus subjects do not have to ingest substances such as contrast agents or be exposed to radiation as would be the case in positron emission tomography (PET). Therefore, fMRI is a suitable technique for experiments investigating which brain regions are involved in perception, cognition, and behavior.
In this paper the visual oddball paradigm is taken as an example for the transfer of a well-established EEG-task to fMRI (see Figure 1 for details). It should be noted that the issues discussed could also influence results and data interpretation when other paradigms are used and should technically be considered in the design of all fMRI experiments. The oddball paradigm is frequently used in psychology and cognitive neuroscience to assess attention and target detection performance. The paradigm was developed in EEG research, specifically event related potentials (ERPs), for investigating the so called P300 component1. The P300 represents target detection and is elicited upon recognition of an infrequent target stimulus1. The P300 is used in studies across a number of cognitive and clinical domains2 e.g., patients with schizophrenia and their relatives3, heavy smokers4 and the aging population5. Given that the oddball paradigm (and the P300 elicited by the paradigm) is robust and is also modulated by different disease states, its transfer across different imaging modalities was inevitable.
The widespread activation seen in the brain during an oddball fMRI measurement is known to be the result of multiple cognitive functions, as shown by numerous fMRI studies probing other cognitive concepts. This widespread nature of the activation pattern makes it difficult to determine which brain regions are more (or less) active due to the specific task manipulations or group differences that the experimenter is interested in. Specifically, it is not certain whether observed differences in activation are related to target detection itself, to attention related processes, or whether they are related to other task demands such as ongoing working memory processes or processes related to the production of a motor response. The process of assigning function to the measured activity is easier in the EEG domain where the cognitive component of interest (target detection) is measured in clear cerebral response to the oddball task (P300). Nevertheless, neuroscientists tend to interpret their findings in favor of their own hypothesis and experiment, rather than putting in the effort to rule out alternative explanations. Most experiments, however, will not be able to solve these important questions inherently &#8211; scan time is costly &#8211; which is why we argue for thorough planning and pilot testing of paradigms.
Besides this difficulty in establishing a direct link between brain regions and cognitive components, the nature of the oddball paradigm also presents other possible methodological issues when being transferred to fMRI. For example, the detection of a target stimulus is usually indicated by pressing a response button. This allows the experimenter to record the accuracy and speed of responses but this response may also impact on the fMRI BOLD response to target stimuli. The motor action required for the button press impacts on stimulus-locked fMRI activation given that it happens just a few hundred milliseconds after the presentation of the target stimulus. This can also influence interpretation of that activation, for example brain regions involved in preparing for the motor response might wrongly be assumed to be involved in the detection of the target stimulus, and vice versa. This has led to methodological modifications whereby indirect measures of target detection, not relying on motor responses, are taken. For example, counting target stimuli has been proposed6 as a way to make sure subjects maintain attention on the task; the number of trials missed can indicate how inattentive a subject was. Reporting the number of stimuli counted at the end of the task also means that the experimenter can check whether the subject performed the task correctly. A third alternative is to use a fully passive task design where the subject is given no instructions on how to respond and the novelty of a target stimulus is assumed to inherently elicit a target detection-like response. Despite these versions of the task using the same type of stimuli and basic design, the activation pattern resulting from each variation of the task will be different because the cognitive and motor demands of the tasks are different7,8. For example, there will be working memory processes involved in counting target stimuli e.g., holding the current number of target stimuli in mind, that will not be required during passive viewing. Here these 3 versions of the oddball task, passive, count ,and respond are used to show how careful task design and implementation can account for these changes in task requirements and allow appropriate interpretation of the results.

<table><tbody><tr><td>Magnetom Tim Trio 3 T MRI scanner</td><td>Siemens Medical Solutions, Erlangen, Germany&amp;nbsp;</td><td></td><td></td></tr><tr><td>Presentation version 14.8</td><td>Neurobehavioural system, Albany, CA, USA</td><td></td><td></td></tr><tr><td>Lumitouch device</td><td>Photon Control Inc, Burnaby, BC, Canada</td><td></td><td>This device is no longer produced by the manufacturer. Alternative MR compatible response devices are available.</td></tr><tr><td>TFT display</td><td>Apple, Cupertino, CA, USA</td><td>30 inch cinema display</td><td>The screen was custom modified in-house to be MR compatible. However, a number of MR compatible screens are available on the market.</td></tr><tr><td>Optseq</td><td></td><td>surfer.nmr.mgh.harvard.edu/optseq</td><td>program for determining optimal stimulus timing for rapid event related designs</td></tr><tr><td>FMRIB software library (FSL)</td><td>FMRIB, Oxford</td><td>http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/</td><td>Other software tools are available for analyzing fMRI data, for example SPM, AFNI and Brain Voyager.</td></tr></tbody></table>

transferring cognitive tasks between brain imaging modalities: implications for task design and results interpretation in fmri studies

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm (the visual oddball task) with a long history of behavioral and electroencephalography (EEG) experiments to a functional magnetic resonance imaging (fMRI) experiment is considered. The aims of this paper are to briefly describe fMRI and when its use is appropriate in cognitive neuroscience; illustrate how task design can influence the results of an fMRI experiment, particularly when that task is borrowed from another imaging modality; explain the practical aspects of performing an fMRI experiment. It is demonstrated that manipulating the task demands in the visual oddball task results in different patterns of blood oxygen level dependent (BOLD) activation. The nature of the fMRI BOLD measure means that many brain regions are found to be active in a particular task. Determining the functions of these areas of activation is very much dependent on task design and analysis. The complex nature of many fMRI tasks means that the details of the task and its requirements need careful consideration when interpreting data. The data show that this is particularly important in those tasks relying on a motor response as well as cognitive elements and that covert and overt responses should be considered where possible. Furthermore, the data show that transferring an EEG paradigm to an fMRI experiment needs careful consideration and it cannot be assumed that the same paradigm will work equally well across imaging modalities. It is therefore recommended that the design of an fMRI study is pilot tested behaviorally to establish the effects of interest and then pilot tested in the fMRI environment to ensure appropriate design, implementation and analysis for the effects of interest.

The stimulation and analysis method elicited BOLD activation in brain regions associated with a visual oddball task. The target &#62; non-target contrast revealed no activation for the passive condition but did reveal activation in both the count and respond (Figure 3). The data presented in Figure 3 is a qualitative comparison of the count and respond conditions and shows how the activation patterns would look if each version of the task was performed in isolation.
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Watch this Scientific Journal Video about Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies at JoVE.com

Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies

Transferring a paradigm with a history of use in EEG experiments to an fMRI experiment is considered. It is demonstrated that manipulating the task demands in the visual oddball task resulted in different patterns of BOLD activation and illustrated how task design is crucial in fMRI experiments.

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm ...

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13.1K Views.  Research Centre Jülich GmbH. Transferring a paradigm with a history of use in EEG experiments to an fMRI experiment is considered. It is demonstrated that manipulating the task demands in the visual oddball task resulted in different patterns of BOLD activation and illustrated how task design is crucial in fMRI experiments.

Video: Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies

A Method for Investigating Age-related Differences in the Functional Connectivity of Cognitive Control Networks Associated with Dimensional Change Card Sort Performance

The ability to adjust behavior to sudden changes in the environment develops gradually in childhood and adolescence. For example, in the Dimensional Change Card Sort task, participants switch from sorting cards one way, such as shape, to sorting them a different way, such as color. Adjusting behavior in this way exacts a small performance cost, or switch cost, such that responses are typically slower and more error-prone on switch trials in which the sorting rule changes as compared to repeat trials in which the sorting rule remains the same. The ability to flexibly adjust behavior is often said to develop gradually, in part because behavioral costs such as switch costs typically decrease with increasing age. Why aspects of higher-order cognition, such as behavioral flexibility, develop so gradually remains an open question. One hypothesis is that these changes occur in association with functional changes in broad-scale cognitive control networks. On this view, complex mental operations, such as switching, involve rapid interactions between several distributed brain regions, including those that update and maintain task rules, re-orient attention, and select behaviors. With development, functional connections between these regions strengthen, leading to faster and more efficient switching operations. The current video describes a method of testing this hypothesis through the collection and multivariate analysis of fMRI data from participants of different ages.

This video presents a method of examining age-related changes in functional connectivity of cognitive control networks engaged by targeted tasks/processes. The technique is based on multi-variate analysis of fMRI data.

The ability to adjust behavior to sudden changes in the environment develops gradually in childhood and adolescence. For example, in the Dimensional ...

Transcranial Direct Current Stimulation and Simultaneous  Functional Magnetic Resonance Imaging

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp to manipulate cortical excitability and, consequently, behavior and brain function. In the last decade, numerous studies have addressed short-term and long-term effects of tDCS on different measures of behavioral performance during motor and cognitive tasks, both in healthy individuals and in a number of different patient populations. So far, however, little is known about the neural underpinnings of tDCS-action in humans with regard to large-scale brain networks. This issue can be addressed by combining tDCS with functional brain imaging techniques like functional magnetic resonance imaging (fMRI) or electroencephalography (EEG).
In particular, fMRI is the most widely used brain imaging technique to investigate the neural mechanisms underlying cognition and motor functions. Application of tDCS during fMRI allows analysis of the neural mechanisms underlying behavioral tDCS effects with high spatial resolution across the entire brain. Recent studies using this technique identified stimulation induced changes in task-related functional brain activity at the stimulation site&#160;and also in more distant brain regions, which were associated with behavioral improvement. In addition, tDCS administered during resting-state fMRI allowed identification of widespread changes in whole brain functional connectivity.
Future studies using this combined protocol should yield new insights into the mechanisms of tDCS action in health and disease and new options for more targeted application of tDCS in research and clinical settings. The present manuscript describes this novel technique in a step-by-step fashion, with a focus on technical aspects of tDCS administered during fMRI.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique. It has successfully been used in basic research and clinical settings to modulate brain function in humans. This article describes the implementation of tDCS and simultaneous functional magnetic resonance imaging (fMRI), to investigate the neural basis of tDCS effects.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp ...

Combining Transcranial Magnetic Stimulation and fMRI to Examine the Default Mode Network

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful rest."1,2,3 It is thought the default mode network corresponds to self-referential or "internal mentation".2,3
It has been hypothesized that, in humans, activity within the default mode network is correlated with certain pathologies (for instance, hyper-activation has been linked to schizophrenia 4,5,6 and autism spectrum disorders 7 whilst hypo-activation of the network has been linked to Alzheimer's and other neurodegenerative diseases 8). As such, noninvasive modulation of this network may represent a potential therapeutic intervention for a number of neurological and psychiatric pathologies linked to abnormal network activation. One possible tool to effect this modulation is Transcranial Magnetic Stimulation: a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability (either increasing or decreasing it) via the application of localized magnetic field pulses.9
In order to explore the default mode network's propensity towards and tolerance of modulation, we will be combining TMS (to the left inferior parietal lobe) with functional magnetic resonance imaging (fMRI). Through this article, we will examine the protocol and considerations necessary to successfully combine these two neuroscientific tools.

In this article, we examine the methodology and considerations relevant to the combination of TMS and fMRI to examine the effects of brain stimulation on the default network.

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful ...

Neuroscience

Brain Imaging Investigation of the Neural Correlates of Observing Virtual Social Interactions

The ability to gauge social interactions is crucial in the assessment of others&#x2019; intentions. Factors such as facial expressions and body language affect our decisions in personal and professional life alike 1. These "friend or foe" judgements are often based on first impressions, which in turn may affect our decisions to "approach or avoid". Previous studies investigating the neural correlates of social cognition tended to use static facial stimuli 2. Here, we illustrate an experimental design in which whole-body animated characters were used in conjunction with functional magnetic resonance imaging (fMRI) recordings. Fifteen participants were presented with short movie-clips of guest-host interactions in a business setting, while fMRI data were recorded; at the end of each movie, participants also provided ratings of the host behaviour. This design mimics more closely real-life situations, and hence may contribute to better understanding of the neural mechanisms of social interactions in healthy behaviour, and to gaining insight into possible causes of deficits in social behaviour in such clinical conditions as social anxiety and autism 3.

This article demonstrates an experimental design in which whole-body animated characters are used in conjunction with functional magnetic resonance imaging (fMRI) to investigate the neural correlates of observing virtual social interactions.

The ability to gauge social interactions is crucial in the assessment of others&#x2019; intentions. Factors such as facial expressions and body language ...

Brain Imaging Investigation of the Impairing Effect of Emotion on Cognition

Emotions can impact cognition by exerting both enhancing (e.g., better memory for emotional events) and impairing (e.g., increased emotional distractibility) effects (reviewed in 1). Complementing our recent protocol 2 describing a method that allows investigation of the neural correlates of the memory-enhancing effect of emotion (see also 1, 3-5), here we present a protocol that allows investigation of the neural correlates of the detrimental impact of emotion on cognition. The main feature of this method is that it allows identification of reciprocal modulations between activity in a ventral neural system, involved in 'hot' emotion processing (HotEmo system), and a dorsal system, involved in higher-level 'cold' cognitive/executive processing (ColdEx system), which are linked to cognitive performance and to individual variations in behavior (reviewed in 1). Since its initial introduction 6, this design has proven particularly versatile and influential in the elucidation of various aspects concerning the neural correlates of the detrimental impact of emotional distraction on cognition, with a focus on working memory (WM), and of coping with such distraction 7,11, in both healthy 8-11 and clinical participants 12-14.

We present a protocol that allows investigation of the neural mechanisms mediating the detrimental impact of emotion on cognition, using functional magnetic resonance imaging. This protocol can be used with both healthy and clinical participants.

Emotions can impact cognition by exerting both enhancing (e.g., better memory for emotional events) and impairing (e.g., increased emotional ...

Correlating Behavioral Responses to fMRI Signals from Human Prefrontal Cortex: Examining Cognitive Processes Using Task Analysis

The aim of this methods paper is to describe how to implement a neuroimaging technique to examine complementary brain processes engaged by two similar tasks. Participants' behavior during task performance in an fMRI scanner can then be correlated to the brain activity using the blood-oxygen-level-dependent signal. We measure behavior to be able to sort correct trials, where the subject performed the task correctly and then be able to examine the brain signals related to correct performance. Conversely, if subjects do not perform the task correctly, and these trials are included in the same analysis with the correct trials we would introduce trials that were not only for correct performance. Thus, in many cases these errors can be used themselves to then correlate brain activity to them. We describe two complementary tasks that are used in our lab to examine the brain during suppression of an automatic responses: the stroop1 and anti-saccade tasks. The emotional stroop paradigm instructs participants to either report the superimposed emotional 'word' across the affective faces or the facial 'expressions' of the face stimuli1,2. When the word and the facial expression refer to different emotions, a conflict between what must be said and what is automatically read occurs. The participant has to resolve the conflict between two simultaneously competing processes of word reading and facial expression. Our urge to read out a word leads to strong 'stimulus-response (SR)' associations; hence inhibiting these strong SR's is difficult and participants are prone to making errors. Overcoming this conflict and directing attention away from the face or the word requires the subject to inhibit bottom up processes which typically directs attention to the more salient stimulus. Similarly, in the anti-saccade task3,4,5,6, where an instruction cue is used to direct only attention to a peripheral stimulus location but then the eye movement is made to the mirror opposite position. Yet again we measure behavior by recording the eye movements of participants which allows for the sorting of the behavioral responses into correct and error trials7 which then can be correlated to brain activity. Neuroimaging now allows researchers to measure different behaviors of correct and error trials that are indicative of different cognitive processes and pinpoint the different neural networks involved.

The goal of our research is to correlate behavior to brain activity. Accurate behavioral measures and imaging techniques allow us to elucidate brain-behavior relationships.

The aim of this methods paper is to describe how to implement a neuroimaging technique to examine complementary brain processes engaged by two similar ...

Simultaneous Data Collection of fMRI and fNIRS Measurements Using a Whole-Head Optode Array and Short-Distance Channels

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional magnetic resonance imaging (fMRI), which makes it highly suitable for conducting naturalistic studies of brain function and for use with developmental and clinical populations. Both fNIRS and fMRI methodologies detect changes in cerebral blood oxygenation during functional brain activation, and prior studies have shown high spatial and temporal correspondence between the two signals. There is, however, no quantitative comparison of the two signals collected simultaneously from the same subjects with whole-head fNIRS coverage. This comparison is necessary to comprehensively validate area-level activations and functional connectivity against the fMRI gold standard, which in turn has the potential to facilitate comparisons of the two signals across the lifespan. We address this gap by describing a protocol for simultaneous data collection of fMRI&#160;and fNIRS signals that: i) provides whole-head fNIRS coverage; ii) includes short-distance measurements for regression of the non-cortical, systemic physiological signal; and iii) implements two different methods for optode-to-scalp co-registration of fNIRS measurements. fMRI and fNIRS data from three subjects are presented, and recommendations for adapting the protocol to test developmental and clinical populations are discussed. The current setup with adults allows scanning sessions for an average of approximately 40 min, which includes both functional and structural scans. The protocol outlines the steps required to adapt the fNIRS equipment for use in the magnetic resonance (MR) environment, provides recommendations for both data recording and optode-to-scalp co-registration, and discusses potential modifications of the protocol to fit the specifics of the available MR-safe fNIRS system. Representative subject-specific responses from a flashing-checkerboard task illustrate the feasibility of the protocol to measure whole-head fNIRS signals in the MR environment. This protocol will be particularly relevant for researchers interested in validating fNIRS signals against fMRI across the lifespan.

We present a method for simultaneously collecting fMRI and fNIRS signals from the same subjects with whole-head fNIRS coverage. The protocol has been tested with three young adults and can be adapted for data collection for developmental studies and clinical populations.

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional ...

Concurrent EEG and Functional MRI Recording and Integration Analysis for Dynamic Cortical Activity Imaging

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are two of the fundamental noninvasive methods for identifying brain activity. Multimodal methods have sought to combine the high temporal resolution of EEG with the spatial precision of fMRI, but the complexity of this approach is currently in need of improvement. The protocol presented here describes the recently developed spatiotemporal fMRI-constrained EEG source imaging method, which seeks to rectify source biases and improve EEG-fMRI source localization through the dynamic recruitment of fMRI sub-regions. The process begins with the collection of multimodal data from concurrent EEG and fMRI scans, the generation of 3D cortical models, and independent EEG and fMRI processing. The processed fMRI activation maps are then split into multiple priors, according to their location and surrounding area. These are taken as priors in a two-level hierarchical Bayesian algorithm for EEG source localization. For each window of interest (defined by the operator), specific segments of the fMRI activation map will be identified as active to optimize a parameter known as model evidence. These will be used as soft constraints on the identified cortical activity, increasing the specificity of the multimodal imaging method by reducing cross-talk and avoiding erroneous activity in other conditionally active fMRI regions. The method generates cortical maps of activity and time-courses, which may be taken as final results, or used as a basis for further analyses (analyses of correlation, causation, etc.) While the method is somewhat limited by its modalities (it will not find EEG-invisible sources), it is broadly compatible with most major processing software, and is suitable for most neuroimaging studies.

An EEG-fMRI multimodal imaging method, known as the spatiotemporal fMRI-constrained EEG source imaging method, is described here. The presented method employs conditionally-active fMRI sub-maps, or priors, to guide EEG source localization in a manner that improves spatial specificity and limits erroneous results.

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are two of the fundamental noninvasive methods for identifying brain ...

Biology

Motor Maps

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
One principle of brain organization is the topographic mapping of information. Especially in sensory and motor cortices, adjacent regions of the brain tend to represent information from adjacent parts of the body, resulting in maps of the body expressed on the surface of the brain. The primary sensory and motor maps in the brain surround a prominent sulcus known as the central sulcus. The cortex anterior to the central sulcus is known as the precentral gyrus and contains the primary motor cortex, while the cortex posterior to the central sulcus is known as the postcentral gyrus and contains the primary sensory cortex (Figure 1).
<img alt="Figure 1" src="/files/ftp_upload/10175/10175fig1.jpg" /> 
Figure 1: Sensory and motor maps around the central sulcus. The primary motor cortex, which contains a motor map of the body&#39;s effectors, is anterior to the central sulcus, in the precentral gyrus of the frontal lobe. The primary somesthetic (sensory) cortex, which receives touch, pain, and temperature information from the external parts of the body, is located posterior to the central sulcus, in the postcentral gyrus of the parietal lobe.
In this experiment, functional neuroimaging is used to demonstrate the motor map in the precentral gyrus. This map is often called the motor homunculus, which is Latin for &#34;little man,&#34; because it is as if there is a little version of one&#39;s self represented in this part of a person&#39;s brain. One interesting property of this map is that more cortical space is devoted to body parts requiring finer control, such as the hands and mouth, which results in disproportionate representation of those appendages in the cortex. Also, because of the anatomy of the motor system, the neurons that control the right side of the body are in the left primary motor cortex, and vice versa. Therefore, when a participant in the experiment is asked to move their right hand or foot, an increased activation on their left precentral gyrus is expected.
In this experiment, participants are asked to alternately move their hands and feet, on the left and right sides, while their brain activity is measured with fMRI. Since the fMRI signal relies on changes in blood oxygenation, which are slow in comparison to the movements the participants make, the periods of movement are separated with periods of stillness to ensure that the various conditions can be distinguished from each other and from the resting baseline. To achieve precise timing of the movements, participants are instructed on when to begin and end each movement with a visual cue. The methods in this video are similar to those used by several fMRI studies that have demonstrated somatotopy in primary motor cortex.1,2

Studying Brain Activation and Motor Maps Using fMRI

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
One principle of brain organization is the topographic ...

Education

JoVE Science Education

Psychology

Neuropsychology

An Introduction to Cognition

Cognition encompasses mental processes such as memory, perception, decision-making reasoning and language. Cognitive scientists are using a combination of behavioral and neuropsychological techniques to investigate the underlying neural substrates of cognition. They are interested in understanding how information is perceived, processed and how does it affect the final execution of behaviors. With this knowledge, researchers hope to develop new treatments for individuals with cognitive impairments.
JoVE's introduction to cognition reviews several components of this phenomenon, such as perception, attention, language comprehension, etc. Key questions in the field of cognition will be discussed along with specific methods currently being used to answer these questions. Finally, specific studies that investigate different aspects of cognition using tools like functional Magnetic Resonance Imaging (fMRI) or Transcranial magnetic stimulation (TMS) will be explained.

Cognitive Processes and Techniques to Study Cognition

Cognition encompasses mental processes such as memory, perception, decision-making reasoning and language. Cognitive scientists are using a combination of ...