Medial Frontal Cortex Research Articles

The altered hypothalamic network functional connectivity in chronic insomnia disorder and regulation effect of acupuncture: a randomized controlled neuroimaging study.

The hypothalamus has been recognized as a core structure in the sleep-wake cycle. However, whether the neuroplasticity of the hypothalamus is involved in the acupuncture treatment of insomnia remains elusive. We recruited 42 patients with chronic insomnia disorder (CID) and 23 matched healthy controls (HCs), with CID patients randomly assigned to receive real acupuncture (RA) or sham acupuncture (SA) for four weeks. Insomnia severity was evaluated using the Pittsburgh Sleep Quality Index (PSQI) score, and the resting-state functional connectivity (rsFC) of the hypothalamus was assessed via functional magnetic resonance imaging (fMRI). In the cross-sectional investigation, CID patients showed increased rsFC between the medial hypothalamus (MH) and left lateral orbital frontal cortex (LOFC), and bilateral medial orbital frontal cortex (MOFC) compared to HCs. In the longitudinal experiment, PSQI scores significantly decreased in the RA group (p = 0.03) but not in the SA group. Interestingly, the increased MH-LOFC connectivity was found to be reduced following RA treatment. In addition, the altered rsFC of MH-LOFC significantly correlated with clinical improvement in the RA group (r = -0.692, p = 0.006). This randomized neuroimaging study provides preliminary evidence that acupuncture may improve insomnia symptoms by restoring circuits associated with hypothalamic subregions. This trial has been registered on the Chinese Clinical Trial Registry ( www.chictr.org.cn ) with the identifier (ChiCTR1800017092). Registered date: 11/07/2018.

Improved patient identification by incorporating symptom severity in deep learning using neuroanatomic images in first episode schizophrenia.

Brain alterations associated with illness severity in schizophrenia remain poorly understood. Establishing linkages between imaging biomarkers and symptom expression may enhance mechanistic understanding of acute psychotic illness. Constructing models using MRI and clinical features together to maximize model validity may be particularly useful for these purposes. A multi-task deep learning model for standard case/control recognition incorporated with psychosis symptom severity regression was constructed with anatomic MRI collected from 286 patients with drug-naïve first-episode schizophrenia and 330 healthy controls from two datasets, and validated with an independent dataset including 40 first-episode schizophrenia. To evaluate the contribution of regression to the case/control recognition, a single-task classification model was constructed. Performance of unprocessed anatomical images and of predefined imaging features obtained using voxel-based morphometry (VBM) and surface-based morphometry (SBM), were examined and compared. Brain regions contributing to the symptom severity regression and illness identification were identified. Models developed with unprocessed images achieved greater group separation than either VBM or SBM measurements, differentiating schizophrenia patients from healthy controls with a balanced accuracy of 83.0% with sensitivity = 76.1% and specificity = 89.0%. The multi-task model also showed superior performance to single-task classification model without considering clinical symptoms. These findings showed high replication in the site-split validation and external validation analyses. Measurements in parietal, occipital and medial frontal cortex and bilateral cerebellum had the greatest contribution to the multi-task model. Incorporating illness severity regression in pattern recognition algorithms, our study developed an MRI-based model that was of high diagnostic value in acutely ill schizophrenia patients, highlighting clinical relevance of the model.

A cellular basis for mapping behavioural structure.

To flexibly adapt to new situations, our brains must understand the regularities in the world, as well as those in our own patterns of behaviour. A wealth of findings is beginning to reveal the algorithms that we use to map the outside world1-6. However, the biological algorithms that map the complex structured behaviours that we compose to reach our goals remain unknown. Here we reveal a neuronal implementation of an algorithm for mapping abstract behavioural structure and transferring it to new scenarios. We trained mice on many tasks that shared a common structure (organizing a sequence of goals) but differed in the specific goal locations. The mice discovered the underlying task structure, enabling zero-shot inferences on the first trial of new tasks. The activity of most neurons in the medial frontal cortex tiled progress to goal, akin to how place cells map physical space. These 'goal-progress cells' generalized, stretching and compressing their tiling to accommodate different goal distances. By contrast, progress along the overall sequence of goals was not encoded explicitly. Instead, a subset of goal-progress cells was further tuned such that individual neurons fired with a fixed task lag from a particular behavioural step. Together, these cells acted as task-structured memory buffers, implementing an algorithm that instantaneously encoded the entire sequence of future behavioural steps, and whose dynamics automatically computed the appropriate action at each step. These dynamics mirrored the abstract task structure both on-task and during offline sleep. Our findings suggest that schemata of complex behavioural structures can be generated by sculpting progress-to-goal tuning into task-structured buffers of individual behavioural steps.

Directional Subthalamic Deep Brain Stimulation Better Improves Gait and Balance Disorders in Parkinson's Disease Patients: A Randomized Controlled Study.

To investigate the effects of directional subthalamic deep brain stimulation (STN-dDBS) on gait and balance disorders, including freezing of gait (FOG), in patients with advanced Parkinson's disease (PD). We included 10 participants who underwent STN-DBS and presented severe preoperative FOG, in a randomized, double-blind, crossover study. We used segmented DBS electrodes to investigate whether directing the predicted volume of tissue activated (VTA) to overlap the central STN preferentially improved gait and balance disorders compared to directional DBS applied in the more posterior STN (sensorimotor). We also assessed non-directional (ring-mode) STN-DBS. Our primary outcome was gait and balance control measured using instrumented gait recordings. Each patient had a pre-operative structural and diffusion-weighted imaging to model individual VTAs and to examine cortico-subthalamic connectivity. We used linear mixed-effects models to contrast the effects of central STN-dDBS, posterior STN-dDBS, and ring-mode STN-DBS. Central STN-dDBS produced significantly better improvement in gait and balance control compared to posterior STN-dDBS (p = 0.027), with fewer FOG episodes (p < 0.001). Conversely, ring-mode STN-DBS resulted in worsened postural control compared to central STN-dDBS (p = 0.009). The cortico-subthalamic connectivity with the STN VTAs involved mostly primary sensorimotor, premotor, and medial frontal cortices, with a higher overall cortico-STN connectivity with ring-mode STN-DBS. Central STN-dDBS represents the best option to improve gait and balance disorders in PD patients, including FOG. Our findings raise the possibility of reprogramming STN-DBS toward the central area in selected patients with disabling FOG and/or postural instability after surgery. ANN NEUROL 2024.

Childhood neglect is associated with alterations in neural prediction error signaling and the response to novelty.

One in eight children experience early life stress (ELS), which increases risk for psychopathology. ELS, particularly neglect, has been associated with reduced responsivity to reward. However, little work has investigated the computational specifics of this disrupted reward response - particularly with respect to the neural response to Reward Prediction Errors (RPE) - a critical signal for successful instrumental learning - and the extent to which they are augmented to novel stimuli. The goal of the current study was to investigate the associations of abuse and neglect, and neural representation of RPE to novel and non-novel stimuli. One hundred and seventy-eight participants (aged 10-18, M = 14.9, s.d. = 2.38) engaged in the Novelty task while undergoing functional magnetic resonance imaging. In this task, participants learn to choose novel or non-novel stimuli to win monetary rewards varying from $0 to $0.30 per trial. Levels of abuse and neglect were measured using the Childhood Trauma Questionnaire. Adolescents exposed to high levels of neglect showed reduced RPE-modulated blood oxygenation level dependent response within medial and lateral frontal cortices particularly when exploring novel stimuli (p < 0.05, corrected for multiple comparisons) relative to adolescents exposed to lower levels of neglect. These data expand on previous work by indicating that neglect, but not abuse, is associated with impairments in neural RPE representation within medial and lateral frontal cortices. However, there was no association between neglect and behavioral impairments on the Novelty task, suggesting that these neural differences do not necessarily translate into behavioral differences within the context of the Novelty task.

Delineating the neural substrates of autobiographical memory impairment in Huntington's disease.

Emerging evidence suggests that autobiographical memory (ABM) is altered in Huntington's disease (HD). While these impairments are typically attributed to frontostriatal dysfunction, the neural substrates of ABM impairment in HD remain unexplored. To this end, we assessed ABM in 30 participants with genetically confirmed HD (18 premanifest, 12 manifest) and 24 age-matched healthy controls. Participants completed the Autobiographical Interview to assess free and probed ABM recall and underwent structural brain imaging. Whole-brain voxel-based morphometry (VBM) was used to explore voxel-wise associations between ABM performance and grey matter intensity (False Discovery Rate corrected at q= 0.05). Relative to controls, HD participants displayed significantly less detailed ABM retrieval across free and probed recall conditions, irrespective of disease stage. Recall performance did not differ significantly between manifest and premanifest HD groups. VBM analyses indicated that poorer ABM performance was associated with atrophy of a distributed cortico-subcortical network. Key regions implicated irrespective of ABM condition included the bilateral occipital cortex, left precuneus, right parahippocampal gyrus and right caudate nucleus. In addition, probed ABM recall was associated with the superior and inferior frontal gyri, frontal pole, right hippocampus, nucleus accumbens, paracingulate gyrus and cerebellum. Overall, our findings indicate that ABM impairments in HD reflect the progressive degeneration of a distributed cortico-subcortical brain network comprising medial temporal, frontal, striatal and posterior parietal cortices. Our findings advance our understanding of the neurocognitive profile of HD, providing an important foundation for future interventions to support memory function in this population.

Does sedentary time and physical activity predict chronic back pain and morphological brain changes? A UK biobank cohort study in 33,402 participants

BackgroundThe relationship between sedentary time, physical activity, and chronic back pain remains unclear. The study aims to investigate whether sedentary time and physical activity predict chronic back pain and morphological brain changes.MethodsThis cohort study recruited adults aged 37–73 years enrolled between 2006 and 2010, with follow-up until 2014. The total cohort comprised 33,402 participants (mean age: 54.53). Data were collected on daily sedentary time, physical activity, lifestyle factors, and health outcomes.ResultsAfter nearly 8-year follow-up, 3,006 individuals (9.00%) reported chronic back pain in total. Individuals with daily sedentary time exceeding 6 h had a 33% higher risk of chronic back pain compared to those with sedentary time of 2 h or less (RR, 1.33, 95%CI, 1.17–1.52). Sedentary time was also associated with decreased grey matter volume in several brain regions, including bilateral primary somatosensory cortex (S1), secondary somatosensory cortex, putamen, primary motor cortex (M1), insula, hippocampus, amygdala, as well as right supplementary motor area, left medial frontal cortex, and right anterior cingulate cortex (FDR-corrected p-value < 0.05). Compared to individuals who sat for more than 6 h with light physical activity, those engaging in moderate physical activity with sedentary time of 2 h or less (RR, 0.71, 95%CI, 0.52–0.99) exhibited a significant decrease in chronic back pain risk. In addition, replacing sedentary time with equivalent amount of physical activity also demonstrated a reduction in the risk of chronic back pain (RR, 0.87, 95%CI, 0.77–0.99) and increased the reginal grey matter volumes including the amygdala, insula, M1, putamen and S1.ConclusionsProlonged sedentary time is associated with heightened risks of chronic back pain and deterioration in brain health.

Can you Enhance Visual Learning with Stimulation of the Medial-Frontal Cortex?

Can you Enhance Visual Learning with Stimulation of the Medial-Frontal Cortex?

Changed resting-state connectivity of anterior insular cortex affects subjective pain reduction after knee arthroplasty: A longitudinal study

The mechanism of chronic knee osteoarthritis (OA) pain and postoperative pain due to knee arthroplasty has not been elucidated. This could be involved neuroplasticity in brain connectivity. To clarify the mechanism of chronic knee OA pain and postoperative pain, we examined the relationship between resting-state functional connectivity (rs-FC) and clinical measurements in knee OA before and after knee arthroplasty, focusing on rs-FCs with the anterior insular cortex (aIC) as the key region. Fifteen patients with knee OA underwent resting-state functional magnetic resonance imaging and clinical measurements shortly before and 6 months after knee arthroplasty, and 15 age- and sex-matched control patients underwent an identical protocol. Seed-to-voxel analysis was performed to compare the clinical measurements and changed rs-FCs, using the aIC as a seed region, between the preoperative and postoperative patients, as well as between the operative and control patients. In preoperative patients, rs-FCs of the aIC to the OFC, frontal pole, subcallosal area, and medial frontal cortex increased compared with those of the control patients. The strength of rs-FC between the left aIC and right OFC decreased before and after knee arthroplasty. The decrease in rs-FC between the left aIC and right OFC was associated with decreased subjective pain score. Our study showed a correlation between longitudinally changed rs-FC and clinical measurement before and after knee arthroplasty. Rs-FC between the aIC and OFC have the potential to elucidate the mechanisms of knee OA pain and postoperative pain due to knee arthroplasty.

Visual long-term memory is not made more precise with medial-frontal direct-current stimulation

ABSTRACT Previous research suggests that applying anodal transcranial direct-current stimulation (tDCS) to the medial-frontal cortex can improve how quickly subjects learn to make simple discriminations (i.e., red from blue). Here, we tested the idea that this enhanced task learning is attributable to superior encoding of relevant information into visual long-term memory. Thirty subjects completed an anodal stimulation session and a sham session, with order counterbalanced across subjects, before performing recognition-memory tasks using pictures of real-world objects and visually presented words or nonwords. These tasks allowed us to detect potential memory differences across types of memoranda. Contrary to the hypothesis that the medial-frontal cortex helps control encoding fidelity, we found that anodal tDCS delivered over this brain region did not significantly improve subjects’ memory for visual stimuli, regardless of stimulus type. Our findings show no evidence that targeting medial-frontal cortex with tDCS changes the fidelity of our visual long-term memories.

A - 10 Selective Serotonin Reuptake Inhibitors Do Not Alter HD-tDCS Effects on Episodic Memory in Cognitively Impaired Older Adults

Abstract Objective High-Definition Transcranial Direct Current Stimulation (HD-tDCS) is a potential new intervention for mild cognitive impairment (MCI) and Alzheimer’s Dementia (ad) involving small doses of electrical stimulation. Prior studies suggest potential interactions with Selective Serotonin Reuptake Inhibitors (SSRIs) that could alter HD-tDCS’s effectiveness on cognitive outcomes. This study evaluated if SSRIs altered HD-tDCS response to episodic memory functioning in individuals with MCI and ad. Method Eighteen individuals (M age = 70.5; 27.8% female; 8 stable on SSRIs), 9 with MCI and 9 with ad, underwent ten 20-minute HD-tDCS sessions of 1 milliampere over the medial frontal cortex. Neuropsychological testing assessed learning and delayed recall for visual (Brief Visuospatial Memory Test-Revised) and verbal (Rey Auditory Verbal Learning Test or Hopkins Verbal Learning Test-Revised) episodic memory at baseline and immediately post-treatment. Linear regressions evaluated SSRI use as a predictor of post-treatment episodic memory performance controlling for baseline scores. Results Ten participants demonstrated improvement on at least one measure by 0.5 standard deviation (SD; 5 T-score points), with 5 showing 1 SD improvement. Eleven showed a decline by 0.5 SD on at least one measure, with 7 showing 1 SD decline. SSRI use did not significantly predict better or worse verbal learning (β = −4.285, p = 0.194), verbal delayed recall (β-0.408, p = 0.883), visual learning (β = −2.788, p = 0.405), and visual delayed recall (β = −6.673, p = 0.150) performance post-HD-tDCS. Conclusion Preliminary findings suggest SSRIs may not impact HD-tDCS outcomes in cognitively impaired older adults, specifically for episodic memory. These results may not translate to other neuropsychological domains; however, larger samples are needed for further investigation.

B - 36 Investigating High-Definition Transcranial Direct Current Stimulation for Remediating Word Finding Difficulty in Civilians with a History of Chronic Traumatic Brain Injury: a Pilot Study

Abstract Objective Verbal-retrieval deficits often occur after traumatic brain injury (TBI), but no effective treatment is available. In this study, High-Definition Transcranial Direct Current Stimulation (HD-tDCS) was applied to examine its potential effects on cognitive, especially verbal-retrieval, performance in individuals with chronic TBI. Method Four adults (mean age 48 years; 3 females) with self-reported word-finding difficulty confirmed by objective measures following mild to moderate non-military TBIs sustained over a year ago underwent a double-blind, cross-over, randomized, sham-controlled trial. Each participant received 10 sessions of active HD-tDCS and sham stimulation over the superior medial frontal cortex. A battery of neuropsychological tests was administered including verbal-retrieval measures (i. e. letter fluency, category fluency, Boston Naming Test/BNT) at baseline, immediately, and 8 weeks post-treatment. Post-treatment performance was compared to baseline using 2-tailed paired t-tests. Results Improvements on letter fluency were observed between baseline and immediate assessments post active HD-tDCS, approaching statistical significance (p = 0.076, Cohen’s d = 0.957, 7.5 ± 5.7 more items). No immediate effects with sham HD-tDCS (p &amp;gt; 0.10, 1.5 ± 3.5 more items) and no sustained effects (8 weeks after) were found with either active or sham HD-tDCS (ps &amp;gt; 0.10). Additionally, no significant changes were observed for category fluency or BNT (all ps &amp;gt; 0.10). Conclusion While our pilot study suggests a potential benefit for improved letter fluency immediately following active HD-tDCS compared to sham, the lack of sustained improvement after 8 weeks and the observed variability across different tests acknowledges the need for future larger-scale investigation across multiple cognitive domains.

Not All Stroop-Type Tasks Are Alike: Assessing the Impact of Stimulus Material, Task Design, and Cognitive Demand via Meta-analyses Across Neuroimaging Studies.

The Stroop effect is one of the most often studied examples of cognitive conflict processing. Over time, many variants of the classic Stroop task were used, including versions with different stimulus material, control conditions, presentation design, and combinations with additional cognitive demands. The neural and behavioral impact of this experimental variety, however, has never been systematically assessed. We used activation likelihood meta-analysis to summarize neuroimaging findings with Stroop-type tasks and to investigate whether involvement of the multiple-demand network (anterior insula, lateral frontal cortex, intraparietal sulcus, superior/inferior parietal lobules, midcingulate cortex, and pre-supplementary motor area) can be attributed to resolving some higher-order conflict that all of the tasks have in common, or if aspects that vary between task versions lead to specialization within this network. Across 133 neuroimaging experiments, incongruence processing in the color-word Stroop variant consistently recruited regions of the multiple-demand network, with modulation of spatial convergence by task variants. In addition, the neural patterns related to solving Stroop-like interference differed between versions of the task that use different stimulus material, with the only overlap between color-word, emotional picture-word, and other types of stimulus material in the posterior medial frontal cortex and right anterior insula. Follow-up analyses on behavior reported in these studies (in total 164 effect sizes) revealed only little impact of task variations on the mean effect size of reaction time. These results suggest qualitative processing differences among the family of Stroop variants, despite similar task difficulty levels, and should carefully be considered when planning or interpreting Stroop-type neuroimaging experiments.

Patterns of glucose hypometabolism can help differentiate FTLD-FET from other types of FTLD.

FTLD-FET is a newly described subtype of frontotemporal lobar degeneration (FTLD characterized by pathologic inclusions of FET proteins: fused in sarcoma (FUS), Ewing sarcoma, and TATA-binding protein-associated factor 2N (TAF15)). Severe caudate volume loss on MRI has been linked to FTLD-FUS, yet glucose hypometabolism in FTLD-FET has not been studied. We assessed [18F] fluorodeoxyglucose PET (FDG-PET) hypometabolism in FTLD-FET subtypes and compared metabolism to FTLD-tau and FTLD-TDP. We retrospectively reviewed medical records of 26 autopsied FTLD patients (six FTLD-FET, ten FTLD-Tau, and ten FTLD-TDP) who had completed antemortem FDG-PET. We evaluated five regions, caudate nucleus, medial frontal cortex, lateral frontal cortex, and medial temporal using a 0-3 visual rating scale and validated our findings quantitatively using CORTEX-ID suite Z scores. Of the six FTLD-FET cases (three females) with median age at onset = 36, three were atypical FTLD-U (aFTLD-U) and three were neuronal intermediate filament inclusion disease (NIFID). bvFTD was the most common presentation. Four of the six FTLD cases (3 aFTLD-U + 1 NIFID) showed prominent caudate hypometabolism relatively early in the disease course. FTLD-tau and FTLD-TDP did not show early prominent caudate hypometabolism. Hypometabolism in medial and lateral temporal cortex was associated with FTLD-TDP, while FTLD-tau had normal-minimal regional metabolism. Prominent caudate hypometabolism, especially early in the disease course, appears to be a hallmark feature of the aFTLD-U subtype of FTLD-FET. Assessing caudate and temporal hypometabolism on FDG-PET will help to differentiate FTLD-FET from FTLD-tau and FTLD-TDP.

A comparison of infectious and autoimmune meningoencephalitis: Clinical presentation, biochemical markers and MRI findings

Objective: This study investigates distinguishing patterns in lesion distribution, relevant clinical presentation and biochemical markers in MRI to differentiate infective encephalitis (IE) and autoimmune encephalitis (AE). Methods: Retrospective study of adult patients with a confirmed diagnosis of IE and AE admitted to the Neurology unit from January 2012 to December 2020 with MRI Brain. Selected cases with confirmed IE (according to the 2013 Infective Encephalitis Consortium diagnostic criteria) or antibody-positive AE (detection of Neuronal auto-antibody from blood or CSF), coupled by clinical presentation. MRI brain lesion distribution, lobar involvement, enhancement, haemorrhage, vasculopathy and atrophy were analysed. Results: Forty-seven patients (21 IE and 26 AE, respectively) were selected. IE group are older (48.0 ± 16.81) compared to AE (28.4 ± 14.10). Fever and vomiting were significant in IE (p&lt;0.001), whereas psychosis, seizure, movement disorder, and tumour (ovarian teratoma) were significant in the AE cohort. Cerebrospinal fluid (CSF) analysis showed elevated leucocytes with polymorphism and high protein levels in IE (2.081 g/L ± 2.93 vs AE (0.352g/L ± 0.18). MR imaging detected abnormal findings in 61.9% of cases with infectious encephalitis (IE), while 76.9% of cases with autoimmune encephalitis (AE) exhibited normal MRI results. Asymmetrical lesions and inferior frontal lobe distribution (57.1%) were significantly prevalent in IE (p&lt;0.05). Enhancement patterns and haemorrhage were rarely observed in AE patients. Conclusion: IE presented at an older age, with the majority having MRI findings such as asymmetrical lesions, leptomeningeal enhancement, and involvement of medial temporal, hippocampus and inferior frontal cortex. IE clinically presents with fever, vomiting, and elevated CSF leucocytes and protein levels. AE presents at a younger age with seizure, psychosis, movement disorder, tumour (ovarian teratoma). Fewer AE have MRI findings, and if present, tend to be symmetrical in distribution. Lobar involvement in the inferior frontal was the MRI feature that significantly favoured the diagnosis of IE compared to AE. IE and AE have distinct clinical, biochemical, and MRI abnormalities that can be discriminated between the 2 entities.

Clinicopathologic and Neuroimaging Correlations of Nonverbal Oral Apraxia in Patients With Neurodegenerative Disease.

Nonverbal oral apraxia (NVOA) is the inability to plan, sequence, and execute voluntary oromotor movements in the absence of weakness. In the context of neurodegenerative disease, it remains unclear whether it is linked to a specific underlying pathologic, clinical, or neuroimaging finding. Thus, we aimed to assess the clinicopathologic and neuroimaging associations of NVOA. We conducted a retrospective study of autopsy-confirmed patients previously assessed through an NVOA evaluation tool with a previously published cutpoint to screen for NVOA. We compared demographic and clinical characteristics and postmortem pathology between those who developed NVOA and those who did not. We also compared clinicopathologic characteristics in mild vs greater than mild NVOA and early vs late-emerging NVOA. SPM12 was used to assess patterns of gray matter loss in NVOA vs non-NVOA with age and sex included as covariates. A total of 104 patients (median age at symptom onset 63 years, 43% female) were included in the study. 63 (60.6%) developed NVOA. NVOA appeared at a median of 4.3 years from symptom onset. 29% developed NVOA within the first 3 years. Primary progressive apraxia of speech and the nonfluent variant of primary progressive aphasia were the most common baseline diagnoses in the NVOA group while progressive supranuclear palsy (PSP) syndrome and logopenic progressive aphasia (LPA) were the most common in patients without NVOA. Atrophy of the left lateral and medial posterior frontal cortex was related to NVOA. The most common pathologies associated with NVOA were PSP (36.5%) and corticobasal degeneration (CBD) (33.3%). In patients without NVOA, PSP (26.8%) and other pathologies (26.8%) were the most frequent. 11% of patients with NVOA had persistently mild NVOA and were more likely to have baseline diagnoses of LPA, PSP syndrome, or semantic dementia. The most frequent pathologies in this group were Alzheimer disease and PSP. The pathologic associations of greater than mild NVOA were CBD and PSP. NVOA is present in several clinical syndromes. It is most associated with PSP and CBD. NVOA is a manifestation of left lateral and medial posterior frontal cortex damage rather than a particular pathology.

Neural correlates of the experience of ugliness.

Previous studies have shown that the experience of beauty is dependent upon the co-activity of field A1 of the medial frontal cortex and sensory areas. This leaves us with the question of ugliness; are the same neural mechanisms involved in this experience, including neural activity patterns, or are different mechanisms at play? This question arises because ugliness, although often regarded as the opposite of beauty, could possibly be a distinct aesthetic category. Subjects were asked to rate faces according to how ugly they found them to be while their brain activity was measured with functional magnetic resonance imaging. There was moderate agreement in the experience of ugliness of faces among subjects. Univariate parametric analyses did not reveal any brain regions with increasing activity as the declared intensity of the experience of ugliness increased. In contrast, increasing activity appeared in the striatum and posterior medial orbitofrontal cortex with decreasing levels of ugliness. As with studies on facial beauty, representational similarity analysis revealed distinct neural activity patterns with the experience of facial ugliness in sensory areas relevant for face processing and in the medial orbitofrontal cortex. Thus, similar neural mechanisms appear to be involved in the experience of facial beauty and ugliness, the difference being the level and distribution of activity within the neural network. This suggests that ugliness and beauty are on the same aesthetic continuum.

Slow ramping emerges from spontaneous fluctuations in spiking neural networks

The capacity to initiate actions endogenously is critical for goal-directed behavior. Spontaneous voluntary actions are typically preceded by slow-ramping activity in medial frontal cortex that begins around two seconds before movement, which may reflect spontaneous fluctuations that influence action timing. However, the mechanisms by which these slow ramping signals emerge from single-neuron and network dynamics remain poorly understood. Here, we developed a spiking neural-network model that produces spontaneous slow ramping activity in single neurons and population activity with onsets ~2 s before threshold crossings. A key prediction of our model is that neurons that ramp together have correlated firing patterns before ramping onset. We confirmed this model-derived hypothesis in a dataset of human single neuron recordings from medial frontal cortex. Our results suggest that slow ramping signals reflect bounded spontaneous fluctuations that emerge from quasi-winner-take-all dynamics in clustered networks that are temporally stabilized by slow-acting synapses.

Gray matter volume of limbic brain structures during the development of chronic back pain: a longitudinal cohort study.

This study set out to investigate in a population-based longitudinal cohort, whether chronification of back pain (BP) is related to structural gray matter changes in corticolimbic brain structures. Gray matter volume (GMV) was measured in participants with chronic BP (CBP, n = 168) and controls without chronic pain (n = 323) at 2 time points with an interval of 7 years (baseline t1, follow-up t2). Over this time period, participants with CBP showed an increase of GMV in the left ventral striatum, whereas controls showed a decrease. By contrast, participants with CBP had a GMV decrease in the left parahippocampal gyrus. Within the CBP group, pain duration was negatively associated with GMV in the left caudate. Those with emerging CBP had less GMV in the right entorhinal area, right amygdala, and left medial frontal cortex. Additional variables differing between those who had BP at t1 and later developed CBP or not were pain intensity, body mass index, and depression score. In sum, these findings are in accordance with the notion that limbic brain properties are both predisposing risk factors and drivers of brain reorganization during the development of CBP.

Abstract representations emerge in human hippocampal neurons during inference

Humans have the remarkable cognitive capacity to rapidly adapt to changing environments. Central to this capacity is the ability to form high-level, abstract representations that take advantage of regularities in the world to support generalization1. However, little is known about how these representations are encoded in populations of neurons, how they emerge through learning and how they relate to behaviour2,3. Here we characterized the representational geometry of populations of neurons (single units) recorded in the hippocampus, amygdala, medial frontal cortex and ventral temporal cortex of neurosurgical patients performing an inferential reasoning task. We found that only the neural representations formed in the hippocampus simultaneously encode several task variables in an abstract, or disentangled, format. This representational geometry is uniquely observed after patients learn to perform inference, and consists of disentangled directly observable and discovered latent task variables. Learning to perform inference by trial and error or through verbal instructions led to the formation of hippocampal representations with similar geometric properties. The observed relation between representational format and inference behaviour suggests that abstract and disentangled representational geometries are important for complex cognition.