Diffusion tensor imaging correlates of memory and language impairments in temporal lobe epilepsy

McDonald, Carrie R.; Ahmadi, Mazyar E.; Hagler, Donald J.; Tecoma, Evelyn S.; Iragui, Vicente J.; Gharapetian, Lusineh; Dale, Anders M.; Halgren, Eric

doi:10.1212/01.wnl.0000327824.05348.3b

Cited by 236 publications

(247 citation statements)

References 33 publications

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“…32,e13 Naming impairments in TLE are thought to arise from abnormal networks linking medial temporal with frontal and posterior temporal structures. 32 Other neurologic conditions compromising lateral temporal circuitry, either of neoplastic e14 or traumatic nature, e15,e16 have also been described to produce anomic aphasia.…”

Section: Selection Of An Abstract Representationmentioning

confidence: 99%

Neuroanatomical foundations of naming impairments across different neurologic conditions

2015

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The ability to name objects or abstract entities is an essential feature of speech and language, being commonly considered a central component of normal neurologic function. For this reason, the bedside testing of naming performance is part of the neurologic examination, especially since naming impairments can signify the early onset of a progressive disease or the occurrence of a more established problem. Modern neuroscience research suggests that naming relies on specific and distributed networks that operate in concert to support various processing stages, spanning from object recognition to spoken words. Likewise, studies evaluating the types of naming impairments in patients with neurologic conditions have contributed to the understanding of acquired forms of naming impairments and the underlying stages during normal language processing. In this article, we review the neurobiological mechanisms supporting naming, with a focus on the clinical application of these concepts. We provide an overview of the stages of cognitive processing that are hypothesized to support naming. For each stage, we explore the evidence revealing its neural basis, drawing parallels to clinical syndromes that commonly disrupt each stage. We review the patterns of naming impairment across various neurologic conditions, including classic language disorders, such as poststroke aphasia or primary progressive aphasia, as well as other diseases where language impairments may be subtle but helpful for the appropriate diagnosis. In this context, we provide a structured and practical guide for the bedside naming assessments rooted in modern neuroscience, aimed at supporting the evaluation and diagnosis of neurologic conditions that affect language. Neurology ® 2015;85:284-292 GLOSSARY AD 5 Alzheimer disease; AoS 5 apraxia of speech; FTLD 5 frontotemporal lobar degeneration; PCA 5 posterior cortical atrophy; PPA-L 5 logopenic variant of primary progressive aphasia; PPA-S 5 semantic variant of primary progressive aphasia; TLE 5 temporal lobe epilepsy; TOT 5 tip of the tongue.The ability to name objects or abstract entities is essential in everyday speech production. Retrieving the correct word that denotes a specific something relies on an orchestrated sequence of brain processes, ranging from perception of a stimulus to the physical articulation of the sounds used to speak its name. While intimately related, each stage of this complex process relies on the activation of distinct neural circuits. Accordingly, naming impairments may emerge following disruption of one or more of the stages thought to support naming.The process of naming most commonly occurs during discourse, when we are constantly required to retrieve abstract concepts to either understand or deliver a message, or by our need to identify an object perceived in the environment. Thus, naming can relate to an object that was seen, smelled, touched, heard, tasted, or any combination of these modalities. Stimulus processing results in the recognition of the stimulus as a famil...

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Section: Selection Of An Abstract Representationmentioning

confidence: 99%

Neuroanatomical foundations of naming impairments across different neurologic conditions

2015

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“…While mesial temporal sclerosis (MTS) is the most commonly observed pathology in TLE, DTI studies have shown white matter abnormalities in several bundles not necessarily limited to the temporal lobe nor the hemisphere ipsilateral to seizure focus (Arfanakis et al, 2002;Gross et al, 2006;Rodrigo et al, 2007;Focke et al, 2008;McDonald et al, 2008;Nilsson et al, 2008;Yogarajah et al, 2008;Schoene-Bake et al, 2009). We have previously demonstrated that TLE patients with unilateral MTS (TLEϩuMTS) have DTI abnormalities of the fimbria-fornix (Concha et al, 2005b) that are not observed in TLE patients who do not have MTS (TLEϪMTS) (Concha et al, 2009).…”

Section: Introductionmentioning

confidence: 96%

In VivoDiffusion Tensor Imaging and Histopathology of the Fimbria-Fornix in Temporal Lobe Epilepsy

Concha¹,

Livy²,

Beaulieu³

et al. 2010

J. Neurosci.

201

165

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While diffusion tensor imaging (DTI) has been extensively used to infer micro-structural characteristics of cerebral white matter in human conditions, correlations between human in vivo DTI and histology have not been performed. Temporal lobe epilepsy (TLE) patients with mesial temporal sclerosis (MTS) have abnormal DTI parameters of the fimbria-fornix (relative to TLE patients without MTS) which are presumed to represent differences in axonal/myelin integrity. Medically intractable TLE patients who undergo temporal lobe resection including the fimbria-fornix provide a unique opportunity to study the anatomical correlates of water diffusion abnormalities in freshly excised tissue. Eleven patients with medically intractable TLE were recruited (six with and five without MTS) for presurgical DTI followed by surgical excision of a small specimen of the fimbria-fornix which was processed for electron microscopy. Blinded quantitative analysis of the microphotographs included axonal diameter, density and area, cumulative axon membrane circumference, and myelin thickness and area. As predicted by DTI the fimbria-fornix of TLE patients with MTS had increased extra-axonal fraction, and reduced cumulative axonal membrane circumference and myelin area. Consistent with the animal literature, water diffusion anisotropy over the crus of the fimbria-fornix was strongly correlated with axonal membranes (cumulative membrane circumference) within the surgical specimen (ϳ15% of what was analyzed with DTI). The demonstration of a correlation between histology and human in vivo DTI, in combination with the observation that in vivo DTI accurately predicted white matter abnormalities in a human disease condition, provides strong validation of the application of DTI as a noninvasive marker of white matter pathology.

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“…Gutman et al studied the action of deep brain stimulation on different targets by examining the connectivity patterns of the DMN regions [107] . In epilepsy, McDonald et al found that multiple tracts associated with memory and language functions are impaired, and the extent of the deterioration correlates with verbal memory performance [108] . Other manifesta- of AD, has also emerged [87] .…”

Section: Dmri Network-based Applications In Neuropsychiatric Diseasementioning

confidence: 99%

Diffusion magnetic resonance imaging for Brainnetome: A critical review

Zuo¹,

Cheng²,

Jiang³

2012

Neurosci. Bull.

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Abstract:Increasing evidence shows that the human brain is a highly self-organized system that shows attributes of smallworldness, hierarchy and modularity. The "connectome" was conceived several years ago to identify the underpinning physical connectivities of brain networks. The need for an integration of multi-spatial and -temporal approaches is becoming apparent. Therefore, the "Brainnetome" (brain-net-ome) project was proposed. Diffusion magnetic resonance imaging (dMRI) is a non-invasive way to study the anatomy of brain networks. Here, we review the principles of dMRI, its methodologies, and some of its clinical applications for the Brainnetome. Future research in this field is discussed.

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Diffusion tensor imaging correlates of memory and language impairments in temporal lobe epilepsy

Cited by 236 publications

References 33 publications

Neuroanatomical foundations of naming impairments across different neurologic conditions

Neuroanatomical foundations of naming impairments across different neurologic conditions

In VivoDiffusion Tensor Imaging and Histopathology of the Fimbria-Fornix in Temporal Lobe Epilepsy

Diffusion magnetic resonance imaging for Brainnetome: A critical review

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