ORCID Profile
0000-0001-6302-0672
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Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2018.04.020
Abstract: According to a large neuropsychological and neuroimaging literature, the bilateral anterior temporal lobe (ATL) is a core region for semantic processing. It seems therefore surprising that semantic memory appears to be preserved in temporal lobe epilepsy (TLE) patients with unilateral ATL resection. However, recent work suggests that the bilateral semantic system is relatively robust against unilateral damage and semantic impairments under these circumstances only become apparent with low frequency specific concepts. In addition, neuroimaging studies have shown that the function of the left and right ATLs differ and therefore left or right ATL resection should lead to a different pattern of impairment. The current study investigated hemispheric differences in the bilateral semantic system by comparing left and right resected TLE patients during verbal semantic processing of low frequency concepts. Picture naming and semantic comprehension tasks with varying word frequencies were included to investigate the pattern of impairment. Left but not right TLE patients showed impaired semantic processing, which was particularly apparent on low frequency items. This indicates that, for verbal information, the bilateral semantic system is more sensitive to damage in the left compared to the right ATL, which is in line with theories that attribute a more prominent role to the left ATL due to connections with pre-semantic verbal regions.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-06-2015
Abstract: Functional neuroimaging has established that most cognitive functions are supported by distributed neural networks. Hundreds of studies have investigated the semantic network (SN) and the default mode network (DMN) (neural deactivation when undertaking a variety of tasks). These stable networks are increasingly used as biomarkers in neurological and psychiatric investigations. Despite implicating overlapping neural regions and shared cognitive mechanisms, the relationship between the two networks has received minimal attention. Analyses of a large multitask distortion-corrected functional MRI (fMRI) dataset established that both networks fractionate, depending on the semantic nature of the task, stimulus type, modality, and task difficulty. The implications for the SN, variability in the DMN and its cognitive coherence, and interpretation of resting-state fMRI data are discussed.
Publisher: MDPI AG
Date: 10-03-2023
DOI: 10.3390/HEALTHCARE11060821
Abstract: Over the last two decades, the functional role of the bilateral anterior temporal lobes (bATLs) has been receiving more attention. They have been associated with semantics and social concept processing, and are regarded as a core region for depression. In the past, the role of the ATL has often been overlooked in semantic models based on functional magnetic resonance imaging (fMRI) due to geometric distortions in the BOLD signal. However, previous work has unequivocally associated the bATLs with these higher-order cognitive functions following advances in neuroimaging techniques to overcome the geometric distortions. At the same time, the importance of the neural basis of conceptual knowledge in understanding mood disorders became apparent. Theoretical models of the neural basis of mood and anxiety disorders have been classically studied from the emotion perspective, without concentrating on conceptual processing. However, recent work suggests that the ATL, a brain region underlying conceptual knowledge, plays an essential role in mood and anxiety disorders. Patients with anxiety and depression often cope with self-blaming biases and guilt. The theory is that in order to experience guilt, the brain needs to access the related conceptual information via the ATL. This narrative review describes how aberrant interactions of the ATL with the fronto–limbic emotional system could underlie mood and anxiety disorders.
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.NEUROIMAGE.2015.06.052
Abstract: The interplay between attention and multisensory integration has proven to be a difficult question to tackle. There are almost as many studies showing that multisensory integration occurs independently from the focus of attention as studies implying that attention has a profound effect on integration. Addressing the neural expression of multisensory integration for attended vs. unattended stimuli can help disentangle this apparent contradiction. In the present study, we examine if selective attention to sound pitch influences the expression of audiovisual integration in both behavior and neural activity. Participants were asked to attend to one of two auditory speech streams while watching a pair of talking lips that could be congruent or incongruent with the attended speech stream. We measured behavioral and neural responses (fMRI) to multisensory stimuli under attended and unattended conditions while physical stimulation was kept constant. Our results indicate that participants recognized words more accurately from an auditory stream that was both attended and audiovisually (AV) congruent, thus reflecting a benefit due to AV integration. On the other hand, no enhancement was found for AV congruency when it was unattended. Furthermore, the fMRI results indicated that activity in the superior temporal sulcus (an area known to be related to multisensory integration) was contingent on attention as well as on audiovisual congruency. This attentional modulation extended beyond heteromodal areas to affect processing in areas classically recognized as unisensory, such as the superior temporal gyrus or the extrastriate cortex, and to non-sensory areas such as the motor cortex. Interestingly, attention to audiovisual incongruence triggered responses in brain areas related to conflict processing (i.e., the anterior cingulate cortex and the anterior insula). Based on these results, we hypothesize that AV speech integration can take place automatically only when both modalities are sufficiently processed, and that if a mismatch is detected between the AV modalities, feedback from conflict areas minimizes the influence of this mismatch by reducing the processing of the least informative modality.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.BANDL.2013.05.009
Abstract: Neuroimaging studies of audiovisual speech processing have exclusively addressed listeners' native language (L1). Yet, several behavioural studies now show that AV processing plays an important role in non-native (L2) speech perception. The current fMRI study measured brain activity during auditory, visual, audiovisual congruent and audiovisual incongruent utterances in L1 and L2. BOLD responses to congruent AV speech in the pSTS were stronger than in either unimodal condition in both L1 and L2. Yet no differences in AV processing were expressed according to the language background in this area. Instead, the regions in the bilateral occipital lobe had a stronger congruency effect on the BOLD response (congruent higher than incongruent) in L2 as compared to L1. According to these results, language background differences are predominantly expressed in these unimodal regions, whereas the pSTS is similarly involved in AV integration regardless of language dominance.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2019
Publisher: MIT Press - Journals
Date: 06-2010
Abstract: The role of the anterior temporal lobes (ATLs) in semantic cognition is not clear from the current literature. Semantic dementia patients show a progressive and a specific semantic impairment, following bilateral atrophy of the ATLs. Neuroimaging studies of healthy participants, however, do not consistently show ATL activation during semantic tasks. Consequently, several influential theories of semantic memory do not ascribe a central role to the ATLs. We conducted a meta-analysis of 164 functional neuroimaging studies of semantic processing to investigate factors that might contribute to the inconsistency in previous results. Four factors influenced the likelihood of finding ATL activation: (1) the use of PET versus fMRI, reflecting the fact that fMRI but not PET is sensitive to distortion artifacts caused by large variations in magnetic susceptibility in the area of the ATL (2) a field of view (FOV) of more than 15 cm, thereby ensuring whole-brain coverage (3) the use of a high baseline task to prevent subtraction of otherwise uncontrolled semantic activation (4) the inclusion of the ATL as an ROI. The type of stimuli or task did not influence the likelihood of ATL activation, consistent with the view that this region underpins an amodal semantic system. Spoken words, written words, and picture stimuli produced overlapping ATL peaks. On average, these were more inferior for picture-based tasks. We suggest that the specific pattern of ATL activation may be influenced by stimulus type due to variations across this region in the degree of connectivity with modality-specific areas in posterior temporal cortex.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2018
Publisher: Springer Science and Business Media LLC
Date: 17-08-2018
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2021
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.CORTEX.2018.02.017
Abstract: Episodic memory impairments caused by temporal lobe epilepsy (TLE) are well documented in the literature. Standard clinical episodic memory tests typically include a 30-min delayed recall test. However, in the past decade, it has become apparent that this standard test does not capture the full range of memory problems in TLE patients. Some patients perform well on a standard 30-min delayed recall test, but show Accelerated Long-term Forgetting (ALF) after 24 h. Although ALF has been investigated in patients with different types of epilepsy, current research on resected TLE patients is missing. In the present study, resected TLE patients were compared to a control group matched on initial learning. They showed normal performance on verbal recall after 30 min, but impairments became apparent after one week. Moreover, the significant interaction between participant group and memory test delay demonstrated that the patients indeed showed an acceleration in forgetting. Furthermore, ALF was present in both left and right resected TLE patients, which contradicts the presence of material-specific hemispheric differences in ALF. In addition, ALF was observed in seizure-free resected TLE patients, thereby demonstrating that this factor is not crucial for long-term memory deficits. The outcome shows that clinicians are likely to underestimate memory deficits in resected TLE patients and, therefore, advocates for the inclusion of ALF tests in standard clinical batteries for both pre- and post-surgery testing sessions.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2018
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2010.02.016
Abstract: The neural basis of semantic memory generates considerable debate. Semantic dementia results from bilateral anterior temporal lobe (ATL) atrophy and gives rise to a highly specific impairment of semantic memory, suggesting that this region is a critical neural substrate for semantic processing. Recent rTMS experiments with neurologically-intact participants also indicate that the ATL are a necessary substrate for semantic memory. Exactly which regions within the ATL are important for semantic memory are difficult to detect from these methods (because the damage in SD covers a large part of the ATL). Functional neuroimaging might provide important clues about which specific areas exhibit activation that correlates with normal semantic performance. Neuroimaging studies, however, have not consistently found anterior temporal lobe activation in semantic tasks. A recent meta-analysis indicates that this inconsistency may be due to a collection of technical limitations associated with previous studies, including a reduced field-of-view and magnetic susceptibility artefacts associated with standard gradient echo fMRI. We conducted an fMRI study of semantic memory using a combination of techniques which improve sensitivity to ATL activations whilst preserving whole-brain coverage. As expected from SD patients and ATL rTMS experiments, this method revealed bilateral temporal activation extending from the inferior temporal lobe along the fusiform gyrus to the anterior temporal regions, bilaterally. We suggest that the inferior, anterior temporal lobe region makes a crucial contribution to semantic cognition and utilising this version of fMRI will enable further research on the semantic role of the ATL.
Publisher: Wiley
Date: 16-01-2013
DOI: 10.1002/HBM.21500
Publisher: MIT Press - Journals
Date: 10-2011
DOI: 10.1162/JOCN_A_00007
Abstract: Studies of semantic dementia and repetitive TMS have suggested that the bilateral anterior temporal lobes (ATLs) underpin a modality-invariant representational hub within the semantic system. However, it is not clear whether all ATL subregions contribute in the same way. We utilized distortion-corrected fMRI to investigate the pattern of activation in the left and right ATL when participants performed a semantic decision task on auditory words, environmental sounds, or pictures. This showed that the ATL is not functionally homogeneous but is more graded. Both left and right ventral ATL (vATL) responded to all modalities in keeping with the notion that this region underpins multimodality semantic processing. In addition, there were graded differences across the hemispheres. Semantic processing of both picture and environmental sound stimuli was associated with equivalent bilateral vATL activation, whereas auditory words generated greater activation in left than right vATL. This graded specialization for auditory stimuli would appear to reflect the input from the left superior ATL, which responded solely to semantic decisions on the basis of spoken words and environmental sounds, suggesting that this region is specialized to auditory stimuli. A final noteworthy result was that these regions were activated for domain level decisions to singly presented stimuli, which appears to be incompatible with the hypotheses that the ATL is dedicated (a) to the representation of specific entities or (b) for combinatorial semantic processes.
Publisher: MIT Press - Journals
Date: 08-2012
DOI: 10.1162/JOCN_A_00244
Abstract: Most contemporary theories of semantic memory assume that concepts are formed from the distillation of information arising in distinct sensory and verbal modalities. The neural basis of this distillation or convergence of information was the focus of this study. Specifically, we explored two commonly posed hypotheses: (a) that the human middle temporal gyrus (MTG) provides a crucial semantic interface given the fact that it interposes auditory and visual processing streams and (b) that the anterior temporal region—especially its ventral surface (vATL)—provides a critical region for the multimodal integration of information. By utilizing distortion-corrected fMRI and an established semantic association assessment (commonly used in neuropsychological investigations), we compared the activation patterns observed for both the verbal and nonverbal versions of the same task. The results are consistent with the two hypotheses simultaneously: Both MTG and vATL are activated in common for word and picture semantic processing. Additional planned, ROI analyses show that this result follows from two principal axes of convergence in the temporal lobe: both lateral (toward MTG) and longitudinal (toward the anterior temporal lobe).
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Maya Visser.