This workshop is designed to give participants a broad overview of the entire lesion-symptom mapping pipeline, an introduction to current state-of-the-art methods, concerns and considerations when performing these analyses, and a flavor for some of the interesting analysis variants that are possible.
Manual for Rehabilitation Treatment Specification
Several MRRI staff, along with collaborators at several other institutions in the US and Canada have completed a nearly 10-year effort to develop a manual that guides the specification of rehabilitation treatments in terms of their known or hypothesized active ingredients, thus facilitating clinical training, communication, and evidence synthesis. The Manual was developed under contract from the Patient Centered Outcomes Research Institute with MRRI former Director John Whyte, MD, PhD, as Principal Investigator.
The most recent phase of this work, entitled the Rehabilitation Treatment Specification System, culminated in the publication of 5 interrelated articles in the Archives of Physical Medicine and Rehabilitation, which describe its conceptual framework and potential applications. Click the links below to view each article.
- An End to the Black Box of Rehabilitation? – Dijkers, Marcel P. Archives of Physical Medicine and Rehabilitation, Volume 100, Issue 1, 144 – 145
- The Importance of Voluntary Behavior in Rehabilitation Treatment and Outcomes – Whyte, John et al. Archives of Physical Medicine and Rehabilitation, Volume 100, Issue 1, 156 – 163
- The Rehabilitation Treatment Specification System: Implications for Improvements in Research Design, Reporting, Replication, and Synthesis – Van Stan, Jarrad H. et al. Archives of Physical Medicine and Rehabilitation, Volume 100, Issue 1, 146 – 155
- A Theory-Driven System for the Specification of Rehabilitation Treatments – Hart, Tessa et al. Archives of Physical Medicine and Rehabilitation, Volume 100, Issue 1, 172 – 180
- Advancing Rehabilitation Practice Through Improved Specification of Interventions – Zanca, Jeanne M. et al. Archives of Physical Medicine and Rehabilitation, Volume 100, Issue 1, 164 – 171
Moss Aphasia Psycholinguistics Project Database (MAPPD)
The MAPPD is a large, searchable, web-based database of aphasic performance on picture naming and other tests of cognitive function.
The database contains data from over 170 patients covering a wide range of aphasia subtypes and severity, some of whom were tested multiple times.
The core of the archive consists of a detailed record of individual-trial performance on the Philadelphia (picture) Naming Test. The database also contains basic demographic information about the patients and patients’ overall performance on neuropsychological assessments as well as tests of speech perception, semantics, short-term memory, and sentence comprehension.
MossTalk Words 2 is an evidence-based computer-assisted treatment program developed for individuals with aphasia. It focuses on strengthening the understanding and production of single words using a simple and intuitive, but adult-oriented, interface. It contains modules for auditory comprehension, reading comprehension, and word retrieval in one easy to use program.
An optional speech recognition feature makes it possible for the software to determine and record the accuracy of a spoken response and provide automatic feedback when a picture is named correctly.
Eye movements are among the most frequent of all human movements. Due to their close relation to attentional mechanisms, eye movements provide insight into a wide range of cognitive processes, including language comprehension, conceptual knowledge, memory, mental imagery, attention, and even social cognition.
We use eye tracking to study cognitive processes in a naturalistic context with minimal task demands, which is particularly important for testing neurologically impaired participants, who may have difficulty with complex task demands and may differ in employing compensatory strategies.
Because of their frequency (three to four saccades per second), eye movements also provide a much more sensitive measure than traditional cognitive experimental methods and can provide unique insights into the time course of cognitive processing.
Voxel-based lesion-symptom mapping (VLSM) is the term coined by Bates and colleagues (2003, Nat. Neurosci., 6, 448-450) for whole brain, voxel-by-voxel analysis of the relation between lesion data and behavioral data.
This state-of-the-art approach to lesion analysis takes advantage of advanced brain imaging technologies to obtain three-dimensional lesion maps for each patient, co-register the lesions to a common template, and calculate a statistic for each voxel that measures the strength of the association between lesion status (presence/absence of lesion) and the behavioral measure.
Typically, the statistic is thresholded to some standard of statistical significance and the results are visualized on a colorized map showing the location of voxels that carry a significant association with the behavioral variable. VLSM is a power-intensive method (Kimberg et al., 2007, J. Cognitive Neurosci., 19(7), 1067-1080) that is best done with a large group of patients.
MRRI, with its effective patient-recruitment infrastructure and collaborative ties to UPenn’s Center for Functional Neurimaging, is at the forefront of basic and applied research using VLSM.
Tensor-based morphometry (TBM) quantifies anatomical volume changes from the properties of the high resolution deformation tensor fields obtained from the non-linear transformations of individual images to the template.
Different from the voxel-based morphometry (VBM) method, the TBM method does not require a segmentation step, avoiding the difficult issue of accurate tissue classification—complicated, in particular, by unpredictable changes in tissue appearance due to brain injury.
TBM has been validated against an expert tracing method and also used to detect group differences between healthy controls and various patient populations. It has been recently shown that, compared to the traditional volumetric method, TBM yields more statistical power to associate structure with other biological and demographic variables. It was also demonstrated that the method is well suited to track longitudinal changes of individual brains.
Perfusion Functional Magnetic Resonance Imaging
Arterial spin labeling (ASL) perfusion fMRI is an emerging methodology that uses magnetically labeled arterial blood water as an endogenous tracer to provide quantitative cerebral blood flow (CBF) measurements. This non-invasive method provides highly reliable measures of CBF, making it particularly suitable for longitudinal studies of treatment (e.g., drug or training) effects or functional recovery processes that require assessment of baseline function and repeated measurements across sessions.
ASL contrast, due to the pairwise subtraction of temporally adjacent images, is also free from the slow signal drifts present in BOLD fMRI contrast. As a result, it is well suited for investigating low frequency brain events such as changes related to practice, mood, and mental set.
In addition, recent evidence suggests that ASL fMRI might provide contrasts with smaller intersubject variability, reduced susceptibility artifacts in regions of high static inhomogeneity, and more specific functional localization than BOLD fMRI.
Due to these advantageous characteristics mentioned, ASL perfusion fMRI has been increasingly adopted for clinical studies of cerebral perfusion during resting states.
The NAT is a clinical assessment of learned, sequential, object-oriented behavior in the service of everyday goals (i.e., multi-step or naturalistic action). Participants perform three tasks under controlled laboratory conditions: make toast and coffee; gift-wrap a present; and pack a child’s lunchbox and schoolbag. Their performance is scored for accuracy and a variety of error types.
The NAT, and its predecessor, the Multi-level Action Test (MLAT), have been used to characterize how naturalistic action is affected by neurological conditions such as traumatic brain injury (TBI), dementia of the Alzheimer type (DAT), and left and right hemisphere stroke.
The data obtained from the NAT has entered into theoretical debates on the cognitive requirements of routine action, the nature of semantic memory for objects, and the meaning of ideational apraxia.
The PNT is a 175-item picture naming test developed for the psycholinguistic exploration of lexical access in nonaphasic and aphasic speakers. The PNT features in numerous publications, including studies that fit aphasic naming data to the interactive two-step model of naming. It was developed in the Language and Aphasia Lab of MRRI under the direction of Myrna Schwartz, Ph.D.
Two 30-item short forms of the 175-item original PNT were developed (A,B) that were shown to yield similar results to the PNT. The short forms can be used to reliably estimate accuracy on the full PNT. The two matched short forms allow for measurement of change in naming ability.
The MARS was designed as an observational rating scale to provide a reliable, quantitative and ecologically valid measure of attention-related behavior after TBI. It was developed by John Whyte, MD, PhD, Tessa Hart, PhD, and colleagues at the Moss TBI Model System at MossRehab Hospital and Moss Rehabilitation Research Institute. Collaborators from other TBI Model System centers were also instrumental in testing the reliability of the MARS.
The VRLAT is a research tool that enables quantification of the severity of left hemispatial neglect in a virtual environment that places realistic demands on attention, visual search, and ability to multitask. The VRLAT allows participants to name objects as they navigate (or are navigated) along a winding virtual path. The VRLAT is easy to administer, demonstrates strong sensitivity and specificity, minimal practice effects, and strong validity, and outperforms traditional paper-and-pencil tests in the prediction of real-world collisions. A shortened version with a five-minute administration time has many of the desireable psychometric properties of the original full-length task.