Association between childhood maltreatment and cortical folding in women with eating disorders.

Childhood maltreatment (CM) is associated with distinct clinical and biological characteristics in people with eating disorders (EDs). The measurement of local gyrification index (lGI) may help to better characterize the impact of CM on cortical structure. Thus, the present study investigated the association of CM with lGI in women with EDs. Twenty-six women with anorexia nervosa (AN) and 24 with bulimia nervosa (BN) underwent a 3T MRI scan. All participants filled in the Childhood Trauma Questionnaire. All neuroimaging data were processed by FreeSurfer. LGI maps underwent a general linear model to evaluate differences between groups with or without CM. People with AN and BN were merged together. Based on the Childhood Trauma Questionnaire cutoff scores, 24 participants were identified as maltreated and 26 as non-maltreated. Maltreated people with EDs showed a significantly lower lGI in the left middle temporal gyrus compared with non-maltreated people, whereas no differences emerged in the right hemisphere between groups. The present study showed that in people with EDs, CM is associated with reduced cortical folding in the left middle temporal gyrus, an area that could be involved in ED psychopathology. This finding corroborates the hypothesis of a 'maltreated ecophenotype', which argues that CM may allow to biologically, other than clinically, distinguish individuals with the same psychiatric disorder.

Childhood maltreatment is associated with cortical thinning in people with eating disorders.

Childhood maltreatment (CM) is a non-specific risk factor for eating disorders (ED) and is associated with a greater severity in their clinical presentation and poorer treatment outcome. These data suggest that maltreated people with ED may be biologically other than clinically different from non-maltreated people. The aim of the present study was to investigate cortical thickness (CT), a possible biomarker of neurodevelopment, in people with ED with or without history of CM and in healthy women. Twenty-four healthy women, 26 with anorexia nervosa and 24 with bulimia nervosa underwent a 3T MRI scan. All participants filled in the childhood trauma questionnaire. All neuroimaging data were processed by FreeSurfer. Twenty-four participants with ED were identified as maltreated and 26 participants with ED as non-maltreated. All healthy women were non-maltreated. Compared to healthy women, maltreated people with ED showed lower CT in the left rostral anterior cingulate gyrus, while compared to people with ED without history of CM showed lower CT values in the left superior frontal and in right caudal middle frontal and superior parietal gyri. No significant differences emerged in CT measures between healthy women and people with ED without history of CM. The present findings show for the first time that in adult people with ED childhood maltreatment is associated with cortical thinning in areas implicated in the modulation of brain processes that are acknowledged to play a role in the psychopathology of ED.

Sex differences in the taste-evoked functional connectivity network.

The central gustatory pathway encompasses multiple subcortical and cortical regions whose neural functional connectivity can be modulated by taste stimulation. While gustatory perception has been previously linked to sex, whether and how the gustatory network differently responds to basic tastes between men and women is unclear. Here, we defined the regions of the central gustatory network by a meta-analysis of 35 fMRI taste activation studies and then analyzed the taste-evoked functional connectivity between these regions in 44 subjects (19 women) in a separate 3 Tesla activation study where sweet and bitter solutions, at five concentrations each, were administered during scanning. From the meta-analysis, a network model was set up, including bilateral anterior, middle and inferior insula, thalamus, precentral gyrus, left amygdala, caudate and dorsolateral prefrontal cortex. Higher functional connectivity than in women was observed in men between the right middle insula and bilateral thalami for bitter taste. Men exhibited higher connectivity than women at low bitter concentrations and middle-high sweet concentrations between bilateral thalamus and insula. A graph-based analysis expressed similar results in terms of nodal characteristics of strength and centrality. Our findings add new insights into the mechanisms of taste processing by highlighting sex differences in the functional connectivity of the gustatory network as modulated by the perception of sweet and bitter tastes. These results shed more light on the neural origin of sex-related differences in gustatory perception and may guide future research on the pathophysiology of taste perception in humans.

Orientation-selective and directional deep brain stimulation in swine assessed by functional MRI at 3T.

Functional MRI (fMRI) has become an important tool for probing network-level effects of deep brain stimulation (DBS). Previous DBS-fMRI studies have shown that electrical stimulation of the ventrolateral (VL) thalamus can modulate sensorimotor cortices in a frequency and amplitude dependent manner. Here, we investigated, using a swine animal model, how the direction and orientation of the electric field, induced by VL-thalamus DBS, affects activity in the sensorimotor cortex. Adult swine underwent implantation of a novel 16-electrode (4 rows x 4 columns) directional DBS lead in the VL thalamus. A within-subject design was used to compare fMRI responses for (1) directional stimulation consisting of monopolar stimulation in four radial directions around the DBS lead, and (2) orientation-selective stimulation where an electric field dipole was rotated 0°-360° around a quadrangle of electrodes. Functional responses were quantified in the premotor, primary motor, and somatosensory cortices. High frequency electrical stimulation through leads implanted in the VL thalamus induced directional tuning in cortical response patterns to varying degrees depending on DBS lead position. Orientation-selective stimulation showed maximal functional response when the electric field was oriented approximately parallel to the DBS lead, which is consistent with known axonal orientations of the cortico-thalamocortical pathway. These results demonstrate that directional and orientation-selective stimulation paradigms in the VL thalamus can tune network-level modulation patterns in the sensorimotor cortex, which may have translational utility in improving functional outcomes of DBS therapy.

Spinal cord fMRI with MB-SWIFT for assessing epidural spinal cord stimulation in rats.

PURPOSE: Electrical epidural spinal cord stimulation (SCS) is used as a treatment for chronic pain as well as to partially restore motor function after a spinal cord injury. Monitoring the spinal cord activity during SCS with fMRI could provide important and objective measures of integrative responses to treatment. Unfortunately, spinal cord fMRI is severely challenged by motion and susceptibility artifacts induced by the implanted electrode and bones. This pilot study introduces multi-band sweep imaging with Fourier transformation (MB-SWIFT) technique for spinal cord fMRI during SCS in rats. Given the close to zero acquisition delay and high bandwidth in 3 dimensions, MB-SWIFT is demonstrated to be highly tolerant to motion and susceptibility-induced artifacts and thus holds promise for fMRI during SCS. METHODS: MB-SWIFT with 0.78 × 0.78 × 1.50 mm3 spatial resolution and 3-s temporal resolution was used at 9.4 Tesla in rats undergoing epidural SCS at different frequencies. Its performance was compared with spin echo EPI. The origin of the functional contrast was also explored using suppression bands. RESULTS: MB-SWIFT was tolerant to electrode-induced artifacts and respiratory motion, leading to substantially higher fMRI sensitivity than spin echo fMRI. Clear stimulation frequency-dependent responses to SCS were detected in the rat spinal cord close to the stimulation site. The origin of MB-SWIFT fMRI signals was consistent with dominant inflow effects. CONCLUSION: fMRI of the rat spinal cord during SCS can be consistently achieved with MB-SWIFT, thus providing a valuable experimental framework for assessing the effects of SCS on the central nervous system.

Orientation selective deep brain stimulation of the subthalamic nucleus in rats.

Deep brain stimulation (DBS) has become an important tool in the management of a wide spectrum of diseases in neurology and psychiatry. Target selection is a vital aspect of DBS so that only the desired areas are stimulated. Segmented leads and current steering have been shown to be promising additions to DBS technology enabling better control of the stimulating electric field. Recently introduced orientation selective DBS (OS-DBS) is a related development permitting sensitization of the stimulus to axonal pathways with different orientations by freely controlling the primary direction of the electric field using multiple contacts. Here, we used OS-DBS to stimulate the subthalamic nucleus (STN) in healthy rats while simultaneously monitoring the induced brain activity with fMRI. Maximal activation of the sensorimotor and basal ganglia-thalamocortical networks was observed when the electric field was aligned mediolaterally in the STN pointing in the lateral direction, while no cortical activation was observed with the electric field pointing medially to the opposite direction. Such findings are consistent with mediolateral main direction of the STN fibers, as seen with high resolution diffusion imaging and histology. The asymmetry of the OS-DBS dipolar field distribution using three contacts along with the potential stimulation of the internal capsule, are also discussed. We conclude that OS-DBS offers an additional degree of flexibility for optimization of DBS of the STN which may enable a better treatment response.

Headache in beta-thalassemia: An Italian multicenter clinical, conventional MRI and MR-angiography case-control study.

OBJECTIVES: A strikingly increased headache prevalence was recently noted in Sri Lankan beta-thalassemia patients, raising several concerns regarding long-term neurological involvement in this condition. METHODS: We interviewed on headache occurrence and characteristics 102 Italian beta-thalassemia patients and 129 healthy controls. 3T-MRI, MR-angiography, MR-venography, cognitive and psychiatric findings were considered. RESULTS: Headache was diagnosed in 39/102 (38.2%) beta-thalassemia patients without significant phenotype-related differences and in 51/129 (39.5%) controls. Patients and controls did not differ significantly regarding episode number (5.9 ± 6.2 vs 5.4 ± 4.4 days/month), subjective severity-score (6.8 ± 1.4 vs 7.1 ± 1.3), age-at-onset (24.3 ± 13.0 vs 19.5 ± 9.6 years) and headache-subtype rate. No main demographic, clinical or laboratory data was associated with headache but female gender. Headache was not associated with white matter lesions (number or maximal diameter), intracranial aneurysms, intracranial artery stenoses or venous sinus thrombosis. Cognitive and psychiatric evaluations were worse in beta-thalassemia, however, headache did not correlate with full-scale Intelligence Quotient (75.4 ± 18.0 vs 76.7 ± 15.3, with and without headache, respectively) or Brief Psychiatric Rating Scale scores (29.1 ± 2.7 vs 28.5 ± 3.4). CONCLUSIONS: Among Italian beta-thalassemia patients, headache does not seem to be more common or severe than in the general population. In addition, patients with headache do not seem to present increased conventional MRI, MR-angiography and cognitive/psychiatric changes.

No evidence of increased cerebrovascular involvement in adult neurologically-asymptomatic ß-Thalassaemia. A multicentre multimodal magnetic resonance study.

Multi-factorial causes jeopardize brain integrity in ß-thalassaemia. Intracranial parenchymal and vascular changes have been reported among young ß-thalassaemia patients but conventional magnetic resonance imaging (MRI) findings are contradictory making early MRI and magnetic resonance angiography (MRA)/venography monitoring a matter of debate. This study prospectively investigated 75 neurologically asymptomatic ß-thalassaemia patients (mean-age 35·2 ± 10·7 years; 52/75 transfusion-dependent; 41/75 splenectomised) using a 3T magnetic resonance scanner; clinical, laboratory and treatment data were also collected. White matter ischaemic-like abnormalities, intracranial artery stenoses, aneurysms and sinus venous thrombosis were compared between patients and 56 healthy controls (mean-age 33·9 ± 10·8 years). No patient or control showed silent territorial or lacunar strokes, intracranial artery stenoses or signs of sinus thrombosis. White matter lesions were found both in patients (35/75, 46·7%) and controls (28/56, 50·0%), without differences in terms of number (4·0 ± 10·6 vs. 4·6 ± 9·1, P = 0·63), size and Fazekas' Score. Intracranial aneurysms did not differ between patients and controls for incidence rate (7/75, 9·3% vs. 5/56, 8·9%), size and site. Vascular and parenchymal abnormality rate did not differ according to treatments or clinical phenotype. According to this study, asymptomatic ß-thalassaemia patients treated according to current guidelines do not seem to carry an increased risk of brain and intracranial vascular changes, thus weakening recommendations for regular brain MRI monitoring.

Brain functional impairment in beta-thalassaemia: the cognitive profile in Italian neurologically asymptomatic adult patients in comparison to the reported literature.

Cognitive involvement in beta-thalassaemia is strikingly controversial and poorly studied in adulthood. This multicentre prospective study investigated 74 adult neurologically-asymptomatic beta-thalassaemia patients (mean-age 34·5 ± 10·3 years; 53 transfusion-dependent [TDT], 21 non-transfusion dependent [NTDT]) and 45 healthy volunteers (mean-age 33·9 ± 10·7 years). Participants underwent testing with Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), Brief Psychiatric Rating Scale (BPRS) and multiparametric brain 3T-magnetic resonance imaging (MRI) for parenchymal, vascular and iron content evaluation. Patients had lower Full-Scale Intelligence Quotient (FSIQ) than controls (75·5 ± 17·9 vs. 97·4 ± 18·1, P < 0·0001) even after correction for education level. Compared to TDT, NTDT showed a trend of higher FSIQ (P = 0·08) but a similar cognitive profile at WAIS-subtests. FSIQ correlated with total and indirect bilirubin (P < 0·0001 and P = 0·002, respectively); no correlation was found with splenectomy, intracranial MRI/magnetic resonance-angiography findings, brain tissue iron content or other disease-related clinical/laboratory/treatment data. FSIQ did not correlate with BPRS scores, although the latter were higher among patients (28·74 ± 3·1 vs. 27·29 ± 4·8, P = 0·01) mainly because of increased depression and anxiety levels. Occupation rate was higher among controls (84·4% vs. 64·9%, P = 0·004) and correlated with higher FSIQ (P = 0·001) and education level (P = 0·001). In conclusion, Italian adult beta-thalassaemia patients seem to present a characteristic cognitive profile impairment and an increased rate of psychological disorders with possible profound long-term socio-economic consequences.

Intensity-related distribution of sweet and bitter taste fMRI responses in the insular cortex.

The human gustatory cortex analyzes the chemosensory properties of tastants, particularly the quality, intensity, and affective valence, to determine whether a perceived substance should be ingested or rejected. Among previous studies, the spatial distribution of taste intensity-related activations within the human insula has been scarcely addressed. To spatially characterize a specialized or distributed nature of the cortical responses to taste intensities, a functional magnetic resonance imaging study was performed at 3 T in 44 healthy subjects where sweet and bitter tastants were administered at five increasing concentrations and cortex-based factorial and parametric analyses were performed. Two clusters in the right middle-posterior and left middle insula were found specialized for taste intensity processing, exhibiting a highly nonlinear profile across concentrations. Multiple clusters were found activated by sweet and bitter taste stimuli at most concentrations, in the anterior, middle-posterior, and inferior portion of the bilateral insula. Across these clusters, respectively, for the right and left insula, a superior-to-inferior and an anterior-to-posterior spatial gradient for high-to-low concentrations were observed for the most responsive intensity of both tastes. These findings may gather new insights regarding how the gustatory cortex is spatially organized during the perceptual processing of taste intensity for two basic tastants.

No increased cerebrovascular involvement in adult beta-thalassemia by advanced MRI analyses.

Beta-thalassemia-related anemia and chronic hypercoagulative state are supposed to cause cumulative cerebrovascular damage with consequent parenchymal/vascular changes and functional impairment. However, recent conventional MRI/MR-angiography investigations failed to show an increased cerebrovascular involvement in beta-thalassemia patients managed according to current treatment guidelines, in spite of significantly decreased full-scale IQ scores. We therefore investigated those patients and controls by means of advanced quantitative MRI analyses (based on magnetization transfer and diffusion tensor imaging) searching for signs of possible cerebrovascular injuries undetected by conventional MRI/MR-angiography. The 3 T-MRI study protocol included diffusion tensor imaging and 3D-multi-echo FLASH sequences for magnetization transfer analysis. Whole-brain voxel-based analyses showed that magnetization transfer, fractional anisotropy, and mean, radial and axial diffusivity do not differ between healthy controls and beta-thalassemia patients (considered as a whole group or as distinct transfusion dependent and non-transfusion dependent subgroups). No correlation emerged between all the considered MRI metrics and cognitive findings (full-scale IQ) or the main clinical and laboratory data. According to our findings, adult neurologically-asymptomatic beta-thalassemia patients (regardless of clinical severity) do not seem to present an increased disease-related cerebrovascular vulnerability compared to healthy controls downsizing the need of regular brain MRI monitoring, at least when the current treatment guidelines are followed.

Automated search of control points in surface-based morphometry.

Cortical surface-based morphometry is based on a semi-automated analysis of structural MRI images. In FreeSurfer, a widespread tool for surface-based analyses, a visual check of gray-white matter borders is followed by the manual placement of control points to drive the topological correction (editing) of segmented data. A novel algorithm combining radial sampling and machine learning is presented for the automated control point search (ACPS). Four data sets with 3 T MRI structural images were used for ACPS validation, including raw data acquired twice in 36 healthy subjects and both raw and FreeSurfer preprocessed data of 125 healthy subjects from public databases. The unedited data from a subgroup of subjects were submitted to manual control point search and editing. The ACPS algorithm was trained on manual control points and tested on new (unseen) unedited data. Cortical thickness (CT) and fractal dimensionality (FD) were estimated in three data sets by reconstructing surfaces from both unedited and edited data, and the effects of editing were compared between manual and automated editing and versus no editing. The ACPS-based editing improved the surface reconstructions similarly to manual editing. Compared to no editing, ACPS-based and manual editing significantly reduced CT and FD in consistent regions across different data sets. Despite the extra processing of control point driven reconstructions, CT and FD estimates were highly reproducible in almost all cortical regions, albeit some problematic regions (e.g. entorhinal cortex) may benefit from different editing. The use of control points improves the surface reconstruction and the ACPS algorithm can automate their search reducing the burden of manual editing.

Interhemispheric functional connectivity in anorexia and bulimia nervosa.

The functional interplay between hemispheres is fundamental for behavioral, cognitive, and emotional control. Anorexia nervosa (AN) and bulimia nervosa (BN) have been largely studied with brain magnetic resonance imaging (MRI) in relation to the functional mechanisms of high-level processing, but not in terms of possible inter-hemispheric functional connectivity anomalies. Using resting-state functional MRI (fMRI), voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) were studied in 15 AN and 13 BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA). Compared to HC, AN patients exhibited reduced VMHC in cerebellum, insula, and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the 'Slow-5' band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs. callosal FA correlations were significant in the comparisons between cohorts. These anomalies, not explained by structural changes, indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing. These findings may thus gather novel functional markers to explore aberrant features of these eating disorders.

In vivo dentate nucleus MRI relaxometry correlates with previous administration of Gadolinium-based contrast agents.

OBJECTIVES: To evaluate changes in T1 and T2* relaxometry of dentate nuclei (DN) with respect to the number of previous administrations of Gadolinium-based contrast agents (GBCA). METHODS: In 74 relapsing-remitting multiple sclerosis (RR-MS) patients with variable disease duration (9.8±6.8 years) and severity (Expanded Disability Status Scale scores:3.1±0.9), the DN R1 (1/T1) and R2* (1/T2*) relaxation rates were measured using two unenhanced 3D Dual-Echo spoiled Gradient-Echo sequences with different flip angles. Correlations of the number of previous GBCA administrations with DN R1 and R2* relaxation rates were tested, including gender and age effect, in a multivariate regression analysis. RESULTS: The DN R1 (normalized by brainstem) significantly correlated with the number of GBCA administrations (p<0.001), maintaining the same significance even when including MS-related factors. Instead, the DN R2* values correlated only with age (p=0.003), and not with GBCA administrations (p=0.67). In a subgroup of 35 patients for whom the administered GBCA subtype was known, the effect of GBCA on DN R1 appeared mainly related to linear GBCA. CONCLUSIONS: In RR-MS patients, the number of previous GBCA administrations correlates with R1 relaxation rates of DN, while R2* values remain unaffected, suggesting that T1-shortening in these patients is related to the amount of Gadolinium given. KEY POINTS: • In multiple sclerosis, previous Gadolinium administrations correlate with dentate nuclei T1 relaxometry. • Such correlation is linked to linear Gadolinium chelates and unrelated to disease duration or severity. • Dentate nuclei T2* relaxometry is age-related and independent of previous Gadolinium administrations. • Changes in dentate nuclei T1 relaxometry are not determined by iron accumulation. • MR relaxometry can quantitatively assess Gadolinium accumulation in dentate nuclei.

Brain perfusion changes in beta-thalassemia.

BACKGROUND: Brain injury in hereditary hemoglobinopathies is commonly attributed to anemia-related relative hypoperfusion in terms of impaired oxygen blood supply. Supratentorial and infratentorial vascular watershed regions seem to be especially vulnerable, but data are very scarce. AIMS: We investigated a large beta-thalassemia sample with arterial spin labeling in order to characterize regional perfusion changes and their correlation with phenotype and anemia severity. METHODS: We performed a multicenter single-scanner cross-sectional 3T-MRI study analyzing non-invasively the brain perfusion in 54 transfusion-dependent thalassemia (TDT), 23 non-transfusion-dependent thalassemia (NTDT) patients and 56 Healthy Controls (HC). Age, hemoglobin levels, and cognitive functioning were recorded. RESULTS: Both TDT and NTDT patients showed globally increased brain perfusion values compared to healthy controls, while no difference was found between patient subgroups. Using age and sex as covariates and scaling the perfusion maps for the global cerebral blood flow, beta-thalassemia patients showed relative hyperperfusion in supratentorial/infratentorial watershed regions. Perfusion changes correlated with hemoglobin levels (p = 0.013) and were not observed in the less severely anemic patients (hemoglobin level > 9.5 g/dL). In the hyperperfused regions, white matter density was significantly decreased (p = 0.0003) in both patient subgroups vs. HC. In NTDT, white matter density changes correlated inversely with full-scale Intelligence Quotient (p = 0.007) while in TDT no correlation was found. CONCLUSION: Relative hyperperfusion of watershed territories represents a hemodynamic hallmark of beta-thalassemia anemia challenging previous hypotheses of brain injury in hereditary anemias. A careful management of anemia severity might be crucial for preventing structural white matter changes and subsequent long-term cognitive impairment.

Functional MRI activation of the nucleus tractus solitarius after taste stimuli at ultra-high field: a proof-of-concept single-subject study.

Using ultra-high field (7 Tesla) functional MRI (fMRI), we conducted the first in-vivo functional neuroimaging study of the normal human brainstem specifically designed to examine neural signals in the Nucleus Tractus Solitarius (NTS) in response to all basic taste stimuli. NTS represents the first relay station along the mammalian taste processing pathway which originates at the taste buds in the oral cavity and passes through the thalamus before reaching the primary taste cortex in the brain. In our proof-of-concept study, we acquired data from one adult volunteer using fMRI at 1.2 mm isotropic resolution and performed a univariate general linear model analysis. During fMRI acquisition, three shuffled injections of sweet, bitter, salty, sour, and umami solutions were administered following an event-related design. We observed a statistically significant blood oxygen level-dependent (BOLD) response in the anatomically predicted location of the NTS for all five basic tastes. The results of this study appear statistically robust, even though they were obtained from a single volunteer. The information derived from a similar experimental strategy may inspire novel research aimed at clarifying important details of central nervous system involvement in eating disorders, at designing and monitoring tailored therapeutic strategies.

Dynamic spectral signatures of mirror movements in the sensorimotor functional connectivity network of patients with Kallmann syndrome.

In Kallmann syndrome (KS), the peculiar phenomenon of bimanual synkinesis or mirror movement (MM) has been associated with a spectral shift, from lower to higher frequencies, of the resting-state fMRI signal of the large-scale sensorimotor brain network (SMN). To possibly determine whether a similar frequency specificity exists across different functional connectivity SMN states, and to capture spontaneous transitions between them, we investigated the dynamic spectral changes of the SMN functional connectivity in KS patients with and without MM symptom. Brain MRI data were acquired at 3 Tesla in 39 KS patients (32 without MM, KSMM-, seven with MM, KSMM+) and 26 age- and sex-matched healthy control (HC) individuals. The imaging protocol included 20-min rs-fMRI scans enabling detailed spectro-temporal analyses of large-scale functional connectivity brain networks. Group independent component analysis was used to extract the SMN. A sliding window approach was used to extract the dynamic spectral power of the SMN functional connectivity within the canonical physiological frequency range of slow rs-fMRI signal fluctuations (0.01-0.25 Hz). K-means clustering was used to determine (and count) the most recurrent dynamic states of the SMN and detect the number of transitions between them. Two most recurrent states were identified, for which the spectral power peaked at a relatively lower (state 1) and higher (state 2) frequency. Compared to KS patients without MM and HC subjects, the SMN of KS patients with MM displayed significantly larger spectral power changes in the slow 3 canonical sub-band (0.073-0.198 Hz) and significantly fewer transitions between state 1 (less recurrent) and state 2 (more recurrent). These findings demonstrate that the presence of MM in KS patients is associated with reduced spontaneous transitions of the SMN between dynamic functional connectivity states and a higher recurrence and an increased spectral power change of the high-frequency state. These results provide novel information about the large-scale brain functional dynamics that could help to understand the pathologic mechanisms of bimanual synkinesis in KS syndrome and, potentially, other neurological disorders where MM may also occur.

Orientation selective DBS of entorhinal cortex and medial septal nucleus modulates activity of rat brain areas involved in memory and cognition.

The recently introduced orientation selective deep brain stimulation (OS-DBS) technique freely controls the direction of the electric field's spatial gradient by using multiple contacts with independent current sources within a multielectrode array. The goal of OS-DBS is to align the electrical field along the axonal track of interest passing through the stimulation site. Here we utilized OS-DBS with a planar 3-channel electrode for stimulating the rat entorhinal cortex (EC) and medial septal nucleus (MSN), two promising areas for DBS treatment of Alzheimer's disease. The brain responses to OS-DBS were monitored by whole brain functional magnetic resonance imaging (fMRI) at 9.4 T with Multi-Band Sweep Imaging with Fourier Transformation (MB-SWIFT). Varying the in-plane OS-DBS stimulation angle in the EC resulted in activity modulation of multiple downstream brain areas involved in memory and cognition. Contrary to that, no angle dependence of brain activations was observed when stimulating the MSN, consistent with predictions based on the electrode configuration and on the main axonal directions of the targets derived from diffusion MRI tractography and histology. We conclude that tuning the OS-DBS stimulation angle modulates the activation of brain areas relevant to Alzheimer's disease, thus holding great promise in the DBS treatment of the disease.

Cross-modal connectivity effects in age-related hearing loss.

Age-related sensorineural hearing loss (HL) leads to localized brain changes in the primary auditory cortex, long-range functional alterations, and is considered a risk factor for dementia. Nonhuman studies have repeatedly highlighted cross-modal brain plasticity in sensorial brain networks other than those primarily involved in the peripheral damage, thus in this study, the possible cortical alterations associated with HL have been analyzed using a whole-brain multimodal connectomic approach. Fifty-two HL and 30 normal hearing participants were examined in a 3T MRI study along with audiological and neurological assessments. Between-regions functional connectivity and whole-brain probabilistic tractography were calculated in a connectome-based manner and graph theory was used to obtain low-dimensional features for the analysis of brain connectivity at global and local levels. The HL condition was associated with a different functional organization of the visual subnetwork as revealed by a significant increase in global efficiency, density, and clustering coefficient. These functional effects were mirrored by similar (but more subtle) structural effects suggesting that a functional repurposing of visual cortical centers occurs to compensate for age-related loss of hearing abilities.