Left Anterior Temporal Cortex Research Articles

Hippocampal resting-state connectivity is associated with posterior-cortical cognitive impairment in Parkinson's disease.

Frontal and posterior-cortical cognitive subtypes in Parkinson's disease (PD) present with executive/attention and memory/visuospatial deficits, respectively. As the posterior-cortical subtype is predicted to progress rapidly toward dementia, the present study aimed to explore biological markers of this group using resting-state functional magnetic resonance imaging (rs-fMRI). K-means cluster analysis delineated subtypes (cognitively intact, frontal, posterior-cortical, and globally impaired) among 85 people with PD. A subset of PD participants (N=42) and 20 healthy controls (HCs) underwent rs-fMRI. Connectivity of bilateral hippocampi with regions of interest was compared between posterior-cortical, cognitively intact, and HC participants using seed-based analysis, controlling for age. Exploratory correlations were performed between areas of interest from the group analysis and a series of cognitive tests. The posterior-cortical subtype (N=19) showed weaker connectivity between the left hippocampus and right anterior temporal fusiform cortex compared to the cognitively intact (N=11) group, p-false discovery rate (FDR)=.01, and weaker connectivity between bilateral hippocampi and most fusiform regions compared to HCs (N=20). No differences were found between HCs and cognitively intact PD. Exploratory analyses revealed strongest associations between connectivity of the right anterior temporal fusiform cortex and left hippocampus with category fluency (p-FDR=.01). Results suggest that weakened connectivity between the hippocampus and fusiform region is a unique characteristic of posterior-cortical cognitive deficits in PD. Further exploration of hippocampal and fusiform functional integrity as a marker of cognitive decline in PD is warranted.

Sensory processing of native and non-native phonotactic patterns in the alpha and beta frequency bands

The phonotactic patterns of one's native language are established within cortical network processing during development. Sensory processing of native language phonotactic patterns established in memory may be modulated by top-down signals within the alpha and beta frequency bands. To explore sensory processing of phonotactic patterns in the alpha and beta frequency bands, electroencephalograms (EEGs) were recorded from native Polish and native English-speaking adults as they listened to spoken nonwords within same and different nonword pairs. The nonwords contained three phonological sequence onsets that occur in the Polish and English languages (/pət/, /st/, /sət/) and one onset sequence /pt/, which occurs in Polish but not in English onsets. Source localization modeling was used to transform 64-channel EEGs into brain source-level channels. Spectral power values in the low frequencies (2–29 Hz) were analyzed in response to the first nonword in nonword pairs within the context of counterbalanced listening-task conditions, which were presented on separate testing days. For the with-task listening condition, participants performed a behavioral task to the second nonword in the pairs. For the without-task condition participants were only instructed to listen to the stimuli. Thus, in the with-task condition, the first nonword served as a cue for the second nonword, the target stimulus. The results revealed decreased spectral power in the beta frequency band for the with-task condition compared to the without-task condition in response to native language phonotactic patterns. In contrast, the task-related suppression effects in response to the non-native phonotactic pattern /pt/ for the English listeners extended into the alpha frequency band. These effects were localized to source channels in left auditory cortex, the left anterior temporal cortex and the occipital pole. This exploratory study revealed a pattern of results that, if replicated, suggests that native language speech perception is supported by modulations in the alpha and beta frequency bands.

Verbal Working Memory-Balance program training alters the left fusiform gyrus resting-state functional connectivity: A randomized clinical trial study on children with dyslexia.

Sufficient activation of the left fusiform gyrus is important in reading ability acquisition due to its role in reading and naming, working memory (WM), and balance tasks. Recently, a newly-designed training program, Verbal Working Memory-Balance (VWM-B), has been evaluated on children with dyslexia, and its positive effects were shown on reading ability, WM capacity, and postural control. In the present study, we aimed to estimate the functional connectivity alterations of the left fusiform gyrus following training by the VWM-B. Before and after 15 sessions of training, the fMRI and other tools data were collected on a sample of children with dyslexia, who were allocated into two control and experiment groups. Data analyses showed the increased functional connectivity of the left fusiform gyrus between the left anterior temporal fusiform cortex, left and right Crus II regions of the cerebellum, and the left middle frontal gyrus. Moreover, VWM-B training significantly improved the reading and naming ability, WM capacity, and postural control of participants in the experiment group in comparison to the control. The current study findings emphasize the critical role of the left fusiform gyrus in reading ability. Moreover, it provides evidence to support the existence of cerebellar deficits in dyslexia.

Lesion‐network mapping for post‐stroke cognitive impairment

AbstractBackgroundTo overcome difficulty obtaining functional neuroimaging data directly from acute stroke patients, researchers have developed a new mapping approach called the “indirect lesion‐network mapping.” This mapping approach uses a priori network information obtained from normative samples to account for brain areas functionally connected to patients’ local lesions. This new method has successfully mapped some peculiar stroke symptoms, such as aphasia and post‐stroke pain. However, it remains unclear whether this method can produce sensible mapping results for the post‐stroke cognitive impairment of community samples.MethodA total of 1,431 patients were enrolled from two university hospitals. They underwent a comprehensive neuropsychological test within one year post‐stroke. We used the Verbal Learning Test to examine memory performance and the trail‐making test‐A and digit symbol coding task to assess the speed of processing. We classified the patients into two groups— cognitively‐impaired (CI) (< ‐2.0 standard deviation) and cognitively‐unimpaired (CU) (> ‐1.0 SD)—based on the task performance. We calculated the lesion‐affected networks based on patients’ stroke lesions combined with the normative functional network data from the Human Connectome Project‐Aging cohort, n = 687. Then, we obtained and compared the lesion network maps for patients with versus without cognitive impairment.ResultA total of 348 patients showed impairment in the memory task, while 247 patients demonstrated impairment in the speed‐of‐processing task. For both tasks, the conventional lesion‐network mapping approach produced highly similar results between the CI versus CU groups—both groups were localized to the major hubs of the large‐scale functional networks, such as mid‐cingulate and insular cortices. However, the mapping results became more sensible when we contrasted the lesion‐network maps between the CI versus CU groups. For example, the memory impairment was localized to the functional network including the left medial and anterior temporal, inferior and dorsolateral frontal cortices, whereas the speed‐of‐processing impairment was localized to the network including both occipital and anterior temporal cortices.ConclusionWe suggest that some additional analysis steps to the conventional lesion‐network mapping, including the contrast analysis, can help improve the specificity and sensitivity of the results when targeting the stroke‐induced cognitive impairment of community samples.

Dependence of cognitive ability on synchronous neural interactions determined by magnetoencephalography.

Previous studies have shown that synchronous neural interactions (SNIs) underlying healthy brain function can be readily distinguished from neural anomalies associated with diseases including dementia; however, it is imperative to identify biomarkers that facilitate early identification of individuals at risk for cognitive decline before the onset of clinical symptoms. Here, we evaluated whether variation in brain function, controlling for age, corresponds with subtle decrements in cognitive performance in cognitively healthy women. A total of 251 women (age range 24-102 yr) who performed above established cutoffs on the Montreal cognitive assessment (MoCA) also underwent a task-free magnetoencephalography scan from which SNIs were computed. The results demonstrated that increased SNI was significantly associated with decreased cognitive performance (r2 = 0.923, P = 0.009), controlling for age. Compared with the lowest performers with normal cognition (MoCA = 26), SNI of the highest performers (MoCA = 30) was associated with decorrelation primarily in the right anterior temporal cortex region, with additional (weaker) foci in left anterior temporal cortex, right posterior temporal cortex, and cerebellum. The findings highlight the relevance of neural network decorrelation on cognitive functioning and suggest that subtle increases in SNI may presage future cognitive impairment.NEW & NOTEWORTHY This study in cognitively healthy women showed that decreased cognitive performance is associated with increased neural network correlations, particularly involving the temporal cortices. As healthy brain function relies on dynamic neural network communication, these findings suggest that subtle increases in correlated neural network activity may be a useful early indicator of decrements in cognitive function.

Mapping lesion, structural disconnection, and functional disconnection to symptoms in semantic aphasia

Patients with semantic aphasia have impaired control of semantic retrieval, often accompanied by executive dysfunction following left hemisphere stroke. Many but not all of these patients have damage to the left inferior frontal gyrus, important for semantic and cognitive control. Yet semantic and cognitive control networks are highly distributed, including posterior as well as anterior components. Accordingly, semantic aphasia might not only reflect local damage but also white matter structural and functional disconnection. Here, we characterise the lesions and predicted patterns of structural and functional disconnection in individuals with semantic aphasia and relate these effects to semantic and executive impairment. Impaired semantic cognition was associated with infarction in distributed left-hemisphere regions, including in the left anterior inferior frontal and posterior temporal cortex. Lesions were associated with executive dysfunction within a set of adjacent but distinct left frontoparietal clusters. Performance on executive tasks was also associated with interhemispheric structural disconnection across the corpus callosum. In contrast, poor semantic cognition was associated with small left-lateralized structurally disconnected clusters, including in the left posterior temporal cortex. Little insight was gained from functional disconnection symptom mapping. These results demonstrate that while left-lateralized semantic and executive control regions are often damaged together in stroke aphasia, these deficits are associated with distinct patterns of structural disconnection, consistent with the bilateral nature of executive control and the left-lateralized yet distributed semantic control network.

The role of the anterior temporal cortex in action: evidence from fMRI multivariate searchlight analysis during real object grasping

Intelligent manipulation of handheld tools marks a major discontinuity between humans and our closest ancestors. Here we identified neural representations about how tools are typically manipulated within left anterior temporal cortex, by shifting a searchlight classifier through whole-brain real action fMRI data when participants grasped 3D-printed tools in ways considered typical for use (i.e., by their handle). These neural representations were automatically evocated as task performance did not require semantic processing. In fact, findings from a behavioural motion-capture experiment confirmed that actions with tools (relative to non-tool) incurred additional processing costs, as would be suspected if semantic areas are being automatically engaged. These results substantiate theories of semantic cognition that claim the anterior temporal cortex combines sensorimotor and semantic content for advanced behaviours like tool manipulation.

Anosognosia in Dementia: Evaluation of Perfusion Correlates Using 99mTc-HMPAO SPECT and Automated Brodmann Areas Analysis.

(1) Background: Considerable inconsistency exists regarding the neural substrates of anosognosia in dementia in previous neuroimaging studies. The purpose of this study was the evaluation of anosognosia perfusion correlates across various types of dementia using automated Brodmann areas (BAs) analysis and comparison with a database of normal subjects. (2) Methods: We studied 72 patients: 32 with Alzheimer’s disease, 26 with frontotemporal dementia—FTD (12 behavioral FTD, 9 semantic FTD, 5 Progressive Non-Fluent Aphasia), 11 with corticobasal syndrome, and 3 with progressive supranuclear palsy. Addenbrook’s Cognitive Examination—Revised (ACE-R) mean(±SD) was 55.6(±22.8). For anosognosia measurement, the Anosognosia Questionnaire—Dementia was used. Total anosognosia score mean(±SD) was 22.1(±17.9), cognitive anosognosia score mean(±SD) was 18.1(±15.1) and behavioral–mood anosognosia score mean(±SD) was 3.3(±4.7). (3) Results: Higher anosognosia total score was associated with hypoperfusion in the inferior temporal, anterior cingulate, and inferior frontal cortices of the right hemisphere (BAs 20R, 24R, 32R, 45R). Higher anosognosia cognitive score was correlated with hypoperfusion in the left middle and anterior temporal cortices, and right dorsal anterior cingulate cortex (BAs 21L, 22L, 32R). No association was found with behavioral–mood anosognosia. (4) Conclusions: Automated analysis of brain perfusion Single Photon Emission Computed Tomography could be useful for the investigation of anosognosia neural correlates in dementia.

From letters to composed concepts: A magnetoencephalography study of reading

Language comprehension requires the recognition of individual words and the combination of their meanings to yield complex concepts or interpretations. This combinatory process often requires the insertion of unstated semantic material between words, based on thematic or feature knowledge. For example, the phrase horse barn is not interpreted as a blend of a horse and a barn, but specifically a barn where horses are kept. Previous neuroscientific evidence suggests that left posterior and anterior temporal cortex underpin thematic and feature‐based concept knowledge, respectively, but much remains unclear about how these areas contribute to combinatory language processing. Using magnetoencephalography, we contrasted source‐localized responses to modifier‐noun phrases involving thematic relations versus feature modifications, while also examining how lower‐level orthographic processing fed composition. Participants completed three procedures examining responses to letter‐strings, adjective‐noun phrases, and noun–noun combinations that varied the semantic relations between words. We found that sections of the left anterior temporal lobe, posterior temporal lobe, and cortex surrounding the angular gyrus were all engaged in the minimal composition of adjective‐noun phrases, a more distributed network than in most prior studies of minimal composition. Of these regions, only the left posterior temporal lobe was additionally sensitive to implicit thematic relations between composing words, suggesting that it houses a specialized relational processing component in a wider composition network. We additionally identified a left occipitotemporal progression from orthographic to lexical processing, feeding ventral anterior areas engaged in the combination of word meanings. Finally, by examining source signal leakage, we characterized the degree to which these responses could be distinguished from one another using source estimation.

Neurophysiological Subtypes of Depressive Disorders

Background: the clinical polymorphism of depressive disorders, together with the available data on the different responses of patients to treatment, motivate modern neuroscience to search for models that can explain such heterogeneity.Objective: to identify neurophysiological subtypes of depressive disorders.Patients and methods: 189 patients with moderate depression in the structure of a depressive episode (n = 42), recurrent depressive (n = 102) and bipolar affective disorders (n = 45); 56 healthy subjects. Clinical-psychopathological, psychometric, neurophysiological and statistical research methods were used in the work.The results: with the help of coherent EEG analysis, it is possible to identify at least 6 subtypes of the disorder, which characterize various branches of the pathogenesis of affective pathology, which go beyond the currently accepted nomenclature. The selected subtypes were determined by the profi les of dysfunctional interaction of various cortical zones in the alpha, beta and gamma ranges of the EEG. Subtype 1 was characterized by a decrease relative to the norm of imaginary alpha-coherence between the right parietal and left central, right parietal and left anterior temporal, as well as the right parietal and right anterior temporal EEG leads (P4-C3, P4-F7, P4-F8) and explained part of depressions, in the pathogenesis of which the leading role was played by violations of the promotion of positive and suppression of negative affect. Subtype 2 — an increase in beta-2-imaginary-coherence between the frontal leads of the left and right hemispheres, between the left frontal and right central cortex (F3-F4; F3-C4) and its decrease between the central cortical zones (C4-C3), in clinical terms this subtype was characterized by a persistent hedonic response and was associated with the clinical picture of atypical depression. Subtype 3 — an increase in imaginary alpha-coherence between the frontal (F4-F3) and its decrease between the central leads of the left and right hemisphere (C4-C3), correlated with the severity of depressive rumination. Subtype 4 — a decrease in imaginary alpha-coherence between the anterior temporal and frontal, as well as the anterior temporal and central cortex of the right hemisphere (F8-F4 and F8-C4), explained part of the depressions that developed against the background of avoidance personality disorder. Subtype 5 — a decrease in imaginary gamma coherence between the frontal and parietal, as well as the central and occipital cortical zones of the left hemisphere (F3-P3 and C3-O1), was associated with an outwardly oriented utilitarian style of thinking (alexithymia). Subtype 6 — a decrease in imaginary beta-1 coherence between the left central and right anterior temporal cortex (C3-F8), explained part of the depression with phobic and hypochondriacal disorders in the structure of recurrent depressive disorder. Such a clinical and biological typology seems new and promising in terms of searching for specifi c neurophysiological disorders in different types of depression and, accordingly, reaching differentiated therapeutic recommendations.

What lies underneath: The genetics and neurobiology of psychopathy

IntroductionPsychopathy is a personality disorder characterized by lack of empathy, grandiosity, an impulsive lifestyle and antisociality. Anti-social personality disorder (ASPD) and psychopathy are distinct concepts presenting different criteria. Most people with a diagnosis of psychopathy also meet criteria for ASPD while the reverse is not true. Along the years there has been an increasing interest in investigating genetic and neurobiological factors.ObjectivesTo analyze the neurobiological factors involved in psychopathy and anti-social personality disorder according to the scientific knowledge available.MethodsReview of scientific literature via PubMed search, using the terms “anti-social personality disorder”, “biology or etiology or pathophysiology and psychopathy”.ResultsThe strongest evidence base for a genetic pathway is associated with the low-expression variant of the Monoamine Oxidase-A (MAO-A) which is linked to the X chromosome. Other genetic factors involve the 5-HTT gene, dopamine receptor genes (DRD4 and DRD2) and genetic polimorfisms at SNAP25 t-snare protein, OXT gene and the CNR1 and FAAH cannabinoid receptor gene. Structural differences in the brain have been noticed such as reduced gray matter volume in the orbitofrontal cortex, gray matter volume reductions in the mid-anterior insula and left anterior temporal cortex, subtle reductions in gray matter volume across several paralimbic and limbic areas.ConclusionsThere is considerable evidence regarding various possible underlying neurobiological processes in psychopathy although it is insufficient to suggest a single biological etiology and environmental influences cannot be excluded from a complete understanding of this disorder. The neurobiological correlates found hold promise for new research and treatment.

Neural competition between concurrent speech production and other speech perception

Understanding others’ speech while individuals simultaneously produce speech utterances implies neural competition and requires specific mechanisms for a neural resolution given that previous studies proposed opposing signal dynamics for both processes in the auditory cortex (AC). We here used neuroimaging in humans to investigate this neural competition by lateralized stimulations with other speech samples and ipsilateral or contralateral lateralized feedback of actively produced self speech utterances in the form of various speech vowels. In experiment 1, we show, first, that others’ speech classifications during active self speech lead to activity in the planum temporale (PTe) when both self and other speech samples were presented together to only the left or right ear. The contralateral PTe also seemed to indifferently respond to single self and other speech samples. Second, specific activity in the left anterior superior temporal cortex (STC) was found during dichotic stimulations (i.e. self and other speech presented to separate ears). Unlike previous studies, this left anterior STC activity supported self speech rather than other speech processing. Furthermore, right mid and anterior STC was more involved in other speech processing. These results signify specific mechanisms for self and other speech processing in the left and right STC beyond a more general speech processing in PTe. Third, other speech recognition in the context of listening to recorded self speech in experiment 2 led to largely symmetric activity in STC and additionally in inferior frontal subregions. The latter was previously reported to be generally relevant for other speech perception and classification, but we found frontal activity only when other speech classification was challenged by recorded but not by active self speech samples. Altogether, unlike formerly established brain networks for uncompetitive other speech perception, active self speech during other speech perception seemingly leads to a neural reordering, functional reassignment, and unusual lateralization of AC and frontal brain activations.

Brain aging and speech perception: Effects of background noise and talker variability

Speech perception can be challenging, especially for older adults. Despite the importance of speech perception in social interactions, the mechanisms underlying these difficulties remain unclear and treatment options are scarce. While several studies have suggested that decline within cortical auditory regions may be a hallmark of these difficulties, a growing number of studies have reported decline in regions beyond the auditory processing network, including regions involved in speech processing and executive control, suggesting a potentially diffuse underlying neural disruption, though no consensus exists regarding underlying dysfunctions. To address this issue, we conducted two experiments in which we investigated age differences in speech perception when background noise and talker variability are manipulated, two factors known to be detrimental to speech perception. In Experiment 1, we examined the relationship between speech perception, hearing and auditory attention in 88 healthy participants aged 19 to 87 years. In Experiment 2, we examined cortical thickness and BOLD signal using magnetic resonance imaging (MRI) and related these measures to speech perception performance using a simple mediation approach in 32 participants from Experiment 1. Our results show that, even after accounting for hearing thresholds and two measures of auditory attention, speech perception significantly declined with age. Age-related decline in speech perception in noise was associated with thinner cortex in auditory and speech processing regions (including the superior temporal cortex, ventral premotor cortex and inferior frontal gyrus) as well as in regions involved in executive control (including the dorsal anterior insula, the anterior cingulate cortex and medial frontal cortex). Further, our results show that speech perception performance was associated with reduced brain response in the right superior temporal cortex in older compared to younger adults, and to an increase in response to noise in older adults in the left anterior temporal cortex. Talker variability was not associated with different activation patterns in older compared to younger adults. Together, these results support the notion of a diffuse rather than a focal dysfunction underlying speech perception in noise difficulties in older adults.

Identification of subtypes for the behavioral variant of frontotemporal dementia based on the assessment of disinhibition and compulsion

AbstractBackgroundThe behavioral variant of frontotemporal dementia (bvFTD) is characterized by cognitive and behavioral decline due to the progressive brain damage of frontal and temporal regions. We aimed to: 1. identify bvFTD subtypes through the behavioral assessment of social disinhibition and perseveration/compulsion; 2. disentangle the underlying functional and anatomical correlates.MethodWe assessed occurrences of 19 behaviors (derived from current clinical criteria of bvFTD) linked to disinhibition and perseveration/compulsion in a quasi‐ecological setting in 17 bvFTD patients and 16 healthy controls (HC). Subjects also underwent neurocognitive tests and a structural MRI examination. Dimensions extracted through Principal Component Analysis from the behavior variables were compared between patients and HC. A clustering approach applied to behavioral scores allowed to isolate subgroups within the patients. Voxel based morphometry (VBM) was performed to identify specific grey matter atrophy patterns in each subgroup.ResultWe identified two principal behavioral dimensions significantly different between bvFTD and HC. Using scores on these two components (labelled as Compulsion and Disinhibition), we identified two different subgroups of bvFTD patients (bvFTD‐G1 and bvFTD‐G2). BvFTD‐G1, characterized by high Disinhibition, had a small pattern of atrophy, centered on left medial anterior and posterior temporal cortices. BvFTD‐G2, characterized by high Compulsion and cognitive impulsivity, presented a more diffuse and bilateral atrophy pattern largely involving frontotemporal and subcortical regions.ConclusionThe behavioral assessment of disinhibition and compulsion symptoms allowed the clinical stratification of bvFTD patients into more or less severe stages or forms, and the identification of specific brain circuits associated with disinhibition and compulsion.

State-Independent and -Dependent Structural Connectivity Alterations in Depression.

Some brain abnormalities persist at the remission phase, that is, the state-independent abnormalities, which may be one of the reasons for the high recurrence of major depressive disorder (MDD). Hence, it is of great significance to identify state-independent abnormalities of MDD through longitudinal investigation. Ninety-nine MDD patients and 118 healthy controls (HCs) received diffusion tensor imaging scanning at baseline. After 6-month antidepressant treatment, 68 patients received a second scan, among which 59 patients achieved full clinical remission. Differences in whole-brain structural connectivity (SC) between patients with MDD at baseline and HCs were estimated by two-sample t-tests. Masked with significantly changed SCs in MDD, two-sample t-tests were conducted between the remitted MDD subgroup at follow-up and HCs, and paired t-tests were implemented to compare the differences of SC in the remitted MDD subgroup before and after treatment. Significantly decreased SC between the right insula and the anterior temporal cortex (ATC), between the right ATC and the posterior temporal cortex (PTC), between the left ATC and the auditory cortex as well as increased connectivity between the right posterior cingulate cortex (PCC) and the left medial parietal cortex (MPC) were observed in the MDD group compared with the HC group at baseline (p < 0.05, FDR corrected). The decreased connectivity between the right insula and the ATC and increased connectivity between the right PCC and the left MPC persisted in the remitted MDD subgroup at follow-up (p < 0.05, FDR corrected). The decreased SC between the right insula and the ATC and increased SC between the right PCC and left MPC showed state-independent characters, which may be implicated in the sustained negative attention bias and motor retardation in MDD. In contrast, the decreased SC between the right ATC and the PTC and between the left ATC and the auditory cortex seemed to be state-dependent.

Differences of apathy perfusion correlates between Alzheimer’s disease and frontotemporal dementia. A 99mTc-HMPAO SPECT study with automated Brodmann areas analysis

Objectives To explore differences of apathy perfusion correlates between Alzheimer’s disease (AD) and Frontotemporal dementia (FTD) using perfusion SPECT. Methods We studied 75 FTD and 66 AD patients. We evaluated apathy using Neuropsychiatric Inventory (NPI). We compared perfusion of BAs on left (L) and right (R) hemisphere in AD and FTD. Results Apathy in AD was significantly and negatively correlated with dorsolateral prefrontal cortex bilaterally, right anterior prefrontal cortex, inferior frontal cortex bilaterally, especially on the right, orbital part of inferior frontal gyrus bilaterally, left dorsal anterior cingulate cortex, right primary and secondary visual cortex, and with bilateral anterior and dorsolateral prefrontal cortex, inferior frontal cortex and orbital part of inferior frontal gyrus, bilaterally, bilateral anterior -ventral and dorsal- cingulate cortex, left posterior ventral cingulate cortex, right inferior, middle and anterior temporal gyri, entorhinal and parahippocampal cortex in FTD. Conclusions Significant overlapping of apathy perfusion correlates between AD and FTD is seen in frontal areas and anterior cingulate. Right occipital cortex is also involved in AD, while right temporal cortex and left posterior cingulate are involved in FTD. Nuclear imaging could be a useful biomarker for revealing apathy underlying mechanisms, resulting in directed treatments. KEYPOINTS Underlying neural networks and clinical manifestation of apathy may differ between AD and FTD. Apathy in AD is correlated with hypoperfusion in bilateral frontal areas, more prominent on the right, left anterior cingulate and right occipital cortex. Apathy in FTD is correlated with hypoperfusion in bilateral frontal areas, bilateral anterior cingulate, left posterior cingulate and right temporal cortex. Brain perfusion SPECT with automated BAs analysis and comparison with normal healthy subjects may provide significant information for apathy mechanisms in neurodegenerative disorders, affecting patients’ treatment.

Reading-Network in Developmental Dyslexia before and after Visual Training

Electroencephalographic studies using graph-theoretic analysis have found aberrations in functional connectivity in dyslexics. How visual nonverbal training (VT) can change the functional connectivity of the reading network in developmental dyslexia is still unclear. We studied differences in the local and global topological properties of functional reading networks between controls and dyslexic children before and after VT. The minimum spanning tree method was used to construct the reading networks in multiple electroencephalogram (EEG) frequency bands. Compared to controls, pre-training dyslexics had a higher leaf fraction, tree hierarchy, kappa, and smaller diameter (θ—γ-frequency bands), and therefore, they had a less segregated neural network than controls. After training, the reading-network metrics of dyslexics became similar to controls. In β1 and γ-frequency bands, pre-training dyslexics exhibited a reduced degree and betweenness centrality of hubs in superior, middle, and inferior frontal areas in both brain hemispheres compared to the controls. Dyslexics relied on the left anterior temporal (β1, γ1) and dorsolateral prefrontal cortex (γ1), while in the right hemisphere, they relied on the occipitotemporal, parietal, (β1), motor (β2, γ1), and somatosensory cortices (γ1). After training, hubs appeared in both hemispheres at the middle occipital (β), parietal (β1), somatosensory (γ1), and dorsolateral prefrontal cortices (γ2), while in the left hemisphere, they appeared at the middle temporal, motor (β1), intermediate (γ2), and inferior frontal cortices (γ1, β2). Language-related brain regions were more active after visual training. They contribute to an understanding of lexical and sublexical representation. The same role has areas important for articulatory processes of reading.

Structural and functional correlates of smartphone addiction

Popularity and availability of smartphones have dramatically increased in the past years. This trend is accompanied by increased concerns regarding potentially adverse effects of excessive smartphone use, particularly with respect to physical and mental health. Recently, the term “smartphone addiction” (SPA) has been introduced to describe smartphone-related addictive behavior and associated physical and psychosocial impairment. Here, we used structural and functional magnetic resonance imaging (MRI) at 3 T to investigate gray matter volume (GMV) and intrinsic neural activity in individuals with SPA (n = 22) compared to a control group (n = 26). SPA was assessed using the Smartphone Addiction Inventory (SPAI), GMV was investigated by means of voxel-based morphometry, and intrinsic neural activity was measured by the amplitude of low frequency fluctuations (ALFF). Compared to controls, individuals with SPA showed lower GMV in left anterior insula, inferior temporal and parahippocampal cortex (p < 0.001, uncorrected for height, followed by correction for spatial extent). Lower intrinsic activity in SPA was found in the right anterior cingulate cortex (ACC). A significant negative association was found between SPAI and both ACC volume and activity. In addition, a significant negative association between SPAI scores and left orbitofrontal GMV was found. This study provides first evidence for distinct structural and functional correlates of behavioral addiction in individuals meeting psychometric criteria for SPA. Given their widespread use and increasing popularity, the present study questions the harmlessness of smartphones, at least in individuals that may be at increased risk for developing smartphone-related addictive behaviors.

Neural basis of basic composition: what we have learned from the red–boat studies and their extensions

Language is our mind's most powerful generative system for the expression of meaning and thought. What are the neural mechanisms of our ability to compose complex meanings from simpler representations? This question is impossible to answer unless we decompose the notion of 'meaning composition' in some theoretically guided way and then begin to assess the extent to which brain activity tracks the posited subroutines. Here, I summarize results from a body of MEG research that has begun to address this question from the ground up, first focusing on simple combinations of two words. The work sets off with a hypothesis space offered by theoretical linguistics, positing syntactic and logico-semantic composition as the main combinatory routines, but then reveals that the most consistent and prominent reflection of composition, localized in the left anterior temporal cortex at 200-250 ms, cannot be described with this toolkit. Instead, this activity tracks a much more conceptually driven process, robustly sensitive to the density of the conceptual feature space of the composing items. I will describe our functional understanding of this activity and how it may operate within a broader 'combinatory network.' This article is part of the theme issue 'Towards mechanistic models of meaning composition'.

The Unique Contributions of Verbal Analogical Reasoning and Nonverbal Matrix Reasoning to Science and Maths Problem-Solving in Adolescence.

ABSTRACTRelational reasoning, the ability to detect meaningful patterns, matures through adolescence. The unique contributions of verbal analogical and nonverbal matrix relational reasoning to science and maths are not well understood. Functional magnetic resonance imaging data were collected during science and maths problem‐solving, and participants (N = 36, 11–15 years) also completed relational reasoning and executive function tasks. Higher verbal analogical reasoning associated with higher accuracy and faster reaction times in science and maths, and higher activation in the left anterior temporal cortex during maths problem‐solving. Higher nonverbal matrix reasoning associated with higher science accuracy, higher science activation in regions across the brain, and lower maths activation in the right middle temporal gyrus. Science associations mostly remained significant when individual differences in executive functions and verbal IQ were taken into account, while maths associations typically did not. The findings indicate the potential importance of supporting relational reasoning in adolescent science and maths learning.