scholarly journals Regional and hemispheric susceptibility of the temporal lobe to FTLD-TDP type C pathology

2019 ◽  
Author(s):  
V. Borghesani ◽  
G. Battistella ◽  
M.L. Mandelli ◽  
A. Welch ◽  
E. Weis ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Primary Progressive Aphasia ◽  
Semantic Knowledge ◽  
Similar Distribution ◽  
Anterior Temporal Lobe ◽  
Temporal Pole ◽  
Neuroimaging Data ◽  
Type C ◽  
Left And Right ◽  
Anterior Temporal Pole

AbstractPost-mortem studies show that focal anterior temporal lobe (ATL) neurodegeneration is most often caused by frontotemporal lobar degeneration TDP-43 type C pathology. Clinically, these patients are described with different terms, such as semantic variant primary progressive aphasia (svPPA), semantic dementia (SD), or right temporal variant frontotemporal dementia (FTD) depending on whether the predominant symptoms affect language, semantic knowledge for object or people, or socio-emotional behaviors. ATL atrophy presents with various degrees of lateralization, with right-sided cases considered rarer even though estimation of their prevalence is hampered by the paucity of studies on well-characterized, pathology-proven cohorts. Moreover, it is not clear whether left and right variants show a similar distribution of atrophy within the ATL cross-sectionally and longitudinally.Here we study the largest cohort to-date of pathology-proven TDP-43-C cases diagnosed during life as svPPA, SD or right temporal variant FTD. We analyzed clinical, cognitive, and neuroimaging data from 30 cases, a subset of which was followed longitudinally. Guided by recent structural and functional parcellation studies, we constructed four bilateral ATL regions of interest (ROIs). The computation of an atrophy lateralization index allowed the comparison of atrophy patterns between the two hemispheres. This led to an automatic, imaging-based classification of the cases as left-predominant or right-predominant. We then compared the two groups in terms of regional atrophy patterns within the ATL ROIs (cross-sectionally) and atrophy progression (longitudinally).Results showed that 40% of pathology proven cases of TDP-43-C diagnosed with a temporal variant presented with right-lateralized atrophy. Moreover, the findings of our ATL ROI analysis indicated that, irrespective of atrophy lateralization, atrophy distribution within both ATLs follows a medial-to-lateral gradient. Finally, in both left and right cases, atrophy appeared to progress to the contralateral ATL, and from the anterior temporal pole to posterior temporal and orbitofrontal regions.Taken together, our findings indicate that incipient right predominant ATL atrophy is common in TDP-43-C pathology, and that distribution of damage within the ATLs appears to be the same in left- and right- sided variants. Thus, regardless of differences in clinical phenotype and atrophy lateralization, both temporal variants of FTD should be viewed as a spectrum presentation of the same disease.Highlights⍰ Anterior temporal lobe (ATL) degeneration is most often caused by FTLD-TDP type C pathology⍰ Cases can present with predominantly left (60%) or right (40%) ATL atrophy⍰ Within ATLs, medial regions are more vulnerable than lateral ones⍰ The observed spectrum of clinical phenotypes is driven by atrophy lateralization⍰ Left and right temporal variants of FTD should be considered the same disease

scholarly journals The Timing of Anterior Temporal Lobe Involvement in Semantic Processing

2015 ◽  
Vol 27 (7) ◽  
pp. 1388-1396 ◽  
Author(s):  
Rebecca L. Jackson ◽  
Matthew A. Lambon Ralph ◽  
Gorana Pobric
Keyword(s):  
Temporal Lobe ◽  
Semantic Processing ◽  
Semantic Representation ◽  
Critical Role ◽  
Stimulus Presentation ◽  
Middle Temporal Gyrus ◽  
Anterior Temporal Lobe ◽  
Temporal Pole ◽  
Modal Semantic

Despite indications that regions within the anterior temporal lobe (ATL) might make a crucial contribution to pan-modal semantic representation, to date there have been no investigations of when during semantic processing the ATL plays a critical role. To test the timing of the ATL involvement in semantic processing, we studied the effect of double-pulse TMS on behavioral responses in semantic and difficulty-matched control tasks. Chronometric TMS was delivered over the left ATL (10 mm from the tip of the temporal pole along the middle temporal gyrus). During each trial, two pulses of TMS (40 msec apart) were delivered either at baseline (before stimulus presentation) or at one of the experimental time points 100, 250, 400, and 800 msec poststimulus onset. A significant disruption to performance was identified from 400 msec on the semantic task but not on the control assessment. Our results not only reinforce the key role of the left ATL in semantic representation but also indicate that its contribution is especially important around 400 msec poststimulus onset. Together, these facts suggest that the ATL may be one of the neural sources of the N400 ERP component.

scholarly journals Beta modulation reflects name retrieval in the human anterior temporal lobe: an intracranial recording study

2016 ◽  
Vol 115 (6) ◽  
pp. 3052-3061 ◽  
Author(s):  
Taylor J. Abel ◽  
Ariane E. Rhone ◽  
Kirill V. Nourski ◽  
Timothy K. Ando ◽  
Hiroyuki Oya ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Beta Band ◽  
Anterior Temporal Lobe ◽  
Famous People ◽  
Human Ability ◽  
Neurosurgical Patients ◽  
Focus Localization ◽  
Left And Right ◽  
Intracranial Recording ◽  
Name Retrieval

Naming people, places, and things is a fundamental human ability that is often impaired in patients with language-dominant anterior temporal lobe (ATL) dysfunction or ATL resection as part of epilepsy treatment. Convergent lines of evidence point to the importance of the ATL in name retrieval. The physiologic mechanisms that mediate name retrieval in the ATL, however, are not well understood. The purpose of this study was to characterize the electrophysiologic responses of the human ATL during overt cued naming of famous people and objects. Eight neurosurgical patients with suspected temporal lobe epilepsy who underwent implantation of intracranial electrodes for seizure focus localization were the subjects of this study. Specialized coverage of the ATL was achieved in each subject. The subjects named pictures of U.S. presidents and images of common hand-held tools. Event-related band power was measured for each ATL recording site. Both the left and right ATL demonstrated robust and focal increases in beta-band (14–30 Hz) power during person and tool naming. The onset of this response typically occurred at 400 ms but sometimes as early as 200 ms. Visual naming of famous people and tools is associated with robust and localized modulation of the beta band in both the left and right ATL. Measurement of visual naming responses may provide the groundwork for future mapping modalities to localize eloquent cortex in the ATL.

scholarly journals Semantics of the Visual Environment Encoded in Parahippocampal Cortex

2016 ◽  
Vol 28 (3) ◽  
pp. 361-378 ◽  
Author(s):  
Michael F. Bonner ◽  
Amy Rose Price ◽  
Jonathan E. Peelle ◽  
Murray Grossman
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Critical Role ◽  
Primary Progressive Aphasia ◽  
Semantic Knowledge ◽  
Individual Variability ◽  
Visual Environment ◽  
Parahippocampal Cortex ◽  
Visual Concepts ◽  
High Level

Semantic representations capture the statistics of experience and store this information in memory. A fundamental component of this memory system is knowledge of the visual environment, including knowledge of objects and their associations. Visual semantic information underlies a range of behaviors, from perceptual categorization to cognitive processes such as language and reasoning. Here we examine the neuroanatomic system that encodes visual semantics. Across three experiments, we found converging evidence indicating that knowledge of verbally mediated visual concepts relies on information encoded in a region of the ventral-medial temporal lobe centered on parahippocampal cortex. In an fMRI study, this region was strongly engaged by the processing of concepts relying on visual knowledge but not by concepts relying on other sensory modalities. In a study of patients with the semantic variant of primary progressive aphasia (semantic dementia), atrophy that encompassed this region was associated with a specific impairment in verbally mediated visual semantic knowledge. Finally, in a structural study of healthy adults from the fMRI experiment, gray matter density in this region related to individual variability in the processing of visual concepts. The anatomic location of these findings aligns with recent work linking the ventral-medial temporal lobe with high-level visual representation, contextual associations, and reasoning through imagination. Together, this work suggests a critical role for parahippocampal cortex in linking the visual environment with knowledge systems in the human brain.

scholarly journals Distinct roles for the Anterior Temporal Lobe and Angular Gyrus in the spatio-temporal cortical semantic network

2019 ◽  
Author(s):  
Seyedeh-Rezvan Farahibozorg ◽  
Richard N. Henson ◽  
Anna M. Woollams ◽  
Olaf Hauk
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe ◽  
Time Window ◽  
Inferior Frontal Gyrus ◽  
Semantic Knowledge ◽  
Angular Gyrus ◽  
Anterior Temporal Lobe ◽  
Sensory Motor ◽  
Semantic Variables ◽  
Spatio Temporal

AbstractIt is now well recognised that human semantic knowledge is supported by a large neural network distributed over multiple brain regions, but the dynamic organisation of this network remains unknown. Some studies have proposed that a central semantic hub coordinates this network. We explored the possibility of different types of semantic hubs; namely “representational hubs”, whose neural activity is modulated by semantic variables, and “connectivity hubs”, whose connectivity to distributed areas is modulated by semantic variables. We utilised the spatio-temporal resolution of source-estimated Electro-/Magnetoencephalography data in a word-concreteness task (17 participants, 12 female) in order to: (i) find representational hubs at different timepoints based on semantic modulation of evoked brain activity in source space; (ii) identify connectivity hubs among left Anterior Temporal Lobe (ATL), Angular Gyrus (AG), Middle Temporal Gyrus and Inferior Frontal Gyrus based on their functional connectivity to the whole cortex, in particular sensory-motor-limbic systems; and (iii) explicitly compare network models with and without an intermediate hub linking sensory input to other candidate hub regions using Dynamic Causal Modelling (DCM) of evoked responses. ATL’s activity was modulated as early as 150ms post-stimulus, while both ATL and AG showed modulations of functional connectivity with sensory-motor-limbic areas from 150-450ms. DCM favoured models with one intermediate hub, namely ATL in an early time window and AG in a later time-window. Our results support ATL as a single representational hub with an early onset, but suggest that both ATL and AG function as connectivity hubs depending on the stage of semantic processing.

scholarly journals Taking the sublexical route: brain dynamics of reading in the semantic variant of primary progressive aphasia

Brain ◽  
2020 ◽  
Vol 143 (8) ◽  
pp. 2545-2560
Author(s):  
Valentina Borghesani ◽  
Leighton B N Hinkley ◽  
Kamalini G Ranasinghe ◽  
Megan M C Thompson ◽  
Wendy Shwe ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Neural Activity ◽  
Reading Aloud ◽  
Primary Progressive Aphasia ◽  
Anterior Temporal Lobe ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Dual Route ◽  
Semantic Variant ◽  
Dual Route Model

Abstract Reading aloud requires mapping an orthographic form to a phonological one. The mapping process relies on sublexical statistical regularities (e.g. ‘oo’ to |uː|) or on learned lexical associations between a specific visual form and a series of sounds (e.g. yacht to/jɑt/). Computational, neuroimaging, and neuropsychological evidence suggest that sublexical, phonological and lexico-semantic processes rely on partially distinct neural substrates: a dorsal (occipito-parietal) and a ventral (occipito-temporal) route, respectively. Here, we investigated the spatiotemporal features of orthography-to-phonology mapping, capitalizing on the time resolution of magnetoencephalography and the unique clinical model offered by patients with semantic variant of primary progressive aphasia (svPPA). Behaviourally, patients with svPPA manifest marked lexico-semantic impairments including difficulties in reading words with exceptional orthographic to phonological correspondence (irregular words). Moreover, they present with focal neurodegeneration in the anterior temporal lobe, affecting primarily the ventral, occipito-temporal, lexical route. Therefore, this clinical population allows for testing of specific hypotheses on the neural implementation of the dual-route model for reading, such as whether damage to one route can be compensated by over-reliance on the other. To this end, we reconstructed and analysed time-resolved whole-brain activity in 12 svPPA patients and 12 healthy age-matched control subjects while reading irregular words (e.g. yacht) and pseudowords (e.g. pook). Consistent with previous findings that the dorsal route is involved in sublexical, phonological processes, in control participants we observed enhanced neural activity over dorsal occipito-parietal cortices for pseudowords, when compared to irregular words. This activation was manifested in the beta-band (12–30 Hz), ramping up slowly over 500 ms after stimulus onset and peaking at ∼800 ms, around response selection and production. Consistent with our prediction, svPPA patients did not exhibit this temporal pattern of neural activity observed in controls this contrast. Furthermore, a direct comparison of neural activity between patients and controls revealed a dorsal spatiotemporal cluster during irregular word reading. These findings suggest that the sublexical/phonological route is involved in processing both irregular and pseudowords in svPPA. Together these results provide further evidence supporting a dual-route model for reading aloud mediated by the interplay between lexico-semantic and sublexical/phonological neurocognitive systems. When the ventral route is damaged, as in the case of neurodegeneration affecting the anterior temporal lobe, partial compensation appears to be possible by over-recruitment of the slower, serial attention-dependent, dorsal one.

POSITIVE AND NEGATIVE MUSIC RECOGNITION REVEALS A SPECIALIZATION OF MESIO-TEMPORAL STRUCTURES IN EPILEPTIC PATIENTS

2008 ◽  
Vol 25 (4) ◽  
pp. 295-302 ◽  
Author(s):  
STÉÉPHANIE KHALFA ◽  
CHARLES DELBE ◽  
EMMANUEL BIGAND ◽  
EMMANUELLE REYNAUD ◽  
PATRICK CHAUVEL ◽  
...  
Keyword(s):  
Emotion Recognition ◽  
Temporal Lobe ◽  
Positive Emotions ◽  
Negative Emotion ◽  
Parahippocampal Gyrus ◽  
Temporal Pole ◽  
Music Recognition ◽  
Epileptic Patients ◽  
Temporal Structures ◽  
Anterior Temporal Pole

AMYGDALA INVOLVEMENT IN FACIAL NEGATIVE EMOTION processing seems to be lateralized. The aim of the present study was to verify the existence of this phenomenon in the music domain and to study asymmetrical processing of emotions by the anteromedial temporal structures. Thirteen epileptic patients with left unilateral resection in the temporal lobe including the amygdala, hippocampus, parahippocampal gyrus, and anterior temporal pole, and fourteen patients with the same right-sided temporal resection, were asked to identify the emotion conveyed by music selections (happiness, sadness, or anger), and to assess their arousal (relaxing/stimulating aspects) and valence (pleasantness/unpleasantness aspects). The results demonstrated asymmetrical processing of positive emotions towards the left whereas negative (sad and angry) excerpts were either less recognized or confounded in both right and left operations. It seems that this impairment of music emotion recognition is not linked to an impairment of arousal and valence judgments.

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