The basal ganglia: an overview of circuits and function

Dynamic functional changes upon thalamotomy in essential tremor depend on baseline brain morphometry

Patients with drug-resistant essential tremor (ET) may undergo Gamma Knife stereotactic radiosurgical thalamotomy (SRS-T), where the ventro-intermediate nucleus of the thalamus (Vim) is lesioned by focused beams of gamma radiations to induce clinical improvement. Here, we studied SRS-T impacts on left Vim dynamic functional connectivity (dFC, n = 23 ET patients scanned before and 1 year after intervention), and on surface-based morphometric brain features (n = 34 patients, including those from dFC analysis). In matched healthy controls (HCs), three dFC states were extracted from resting-state functional MRI data. In ET patients, state 1 spatial stability increased upon SRS-T (F1,22 = 19.13, p = 0.004). More frequent expression of state 3 over state 1 before SRS-T correlated with greater clinical recovery in a way that depended on the MR signature volume (t6 = 4.6, p = 0.004). Lower pre-intervention spatial variability in state 3 expression also did (t6 = - 4.24, p = 0.005) and interacted with the presence of familial ET so that these patients improved less (t6 = 4.14, p = 0.006). ET morphometric profiles showed significantly lower similarity to HCs in 13 regions upon SRS-T (z ≤ - 3.66, p ≤ 0.022), and a joint analysis revealed that before thalamotomy, morphometric similarity and states 2/3 mean spatial similarity to HCs were anticorrelated, a relationship that disappeared upon SRS-T (z ≥ 4.39, p < 0.001). Our results show that left Vim functional dynamics directly relates to upper limb tremor lowering upon intervention, while morphometry instead has a supporting role in reshaping such dynamics.

Rectal temperature after hypoxia-ischemia predicts white matter and cortical pathology in the near-term ferret

BACKGROUND

Neonatal encephalopathy (NE) remains a common cause of infant morbidity and mortality. Neuropathological corollaries of NE associated with acute hypoxia-ischemia include a central injury pattern involving the basal ganglia and thalamus, which may interfere with thermoregulatory circuits. Spontaneous hypothermia (SH) occurs in both preclinical models and clinical hypoxic-ischemic NE and may provide an early biomarker of injury severity. To determine whether SH predicts the degree of injury in a ferret model of hypoxic-ischemic NE, we investigated whether rectal temperature (RT) 1 h after insult correlated with long-term outcomes.

METHODS

Postnatal day (P)17 ferrets were presensitized with Escherichia coli lipopolysaccharide before undergoing hypoxia-ischemia/hyperoxia (HIH): bilateral carotid artery ligation, hypoxia-hyperoxia-hypoxia, and right ligation reversal. One hour later, nesting RTs were measured.

RESULTS

Animals exposed to HIH were separated into normothermic (NT; ≥34.4 °C) or spontaneously hypothermic (SH; <34.4 °C) groups. At P42, cortical development, ex vivo MRI, and neuropathology were quantitated. Whole-brain volume and fractional anisotropy in SH brains were significantly decreased compared to control and NT animals. SH brains also had significantly altered gyrification, greater cortical pathology, and increased corpus callosum GFAP staining relative to NT and control brains.

CONCLUSION

In near-term-equivalent ferrets, nesting RT 1 h after HIH may predict long-term neuropathological outcomes.

IMPACT

High-throughput methods to determine injury severity prior to treatment in animal studies of neonatal brain injury are lacking. In a gyrified animal model of neonatal inflammation-sensitized hypoxic-ischemic brain injury in the ferret, rectal temperature 1 h after hypoxia predicts animals who will have increased cortical pathology and white matter changes on MRI. These changes parallel similar responses in rodents and humans but have not previously been correlated with long-term neuropathological outcomes in gyrified animal models. Endogenous thermoregulatory responses to injury may provide a translational marker of injury severity to help stratify animals to treatment groups or predict outcome in preclinical studies.

Neuroanatomical and cellular degeneration associated with a social disorder characterized by new ritualistic belief systems in a TDP-C patient vs. a Pick patient

Frontotemporal dementia (FTD) is a spectrum of clinically and pathologically heterogenous neurodegenerative dementias. Clinical and anatomical variants of FTD have been described and associated with underlying frontotemporal lobar degeneration (FTLD) pathology, including tauopathies (FTLD-tau) or TDP-43 proteinopathies (FTLD-TDP). FTD patients with predominant degeneration of anterior temporal cortices often develop a language disorder of semantic knowledge loss and/or a social disorder often characterized by compulsive rituals and belief systems corresponding to predominant left or right hemisphere involvement, respectively. The neural substrates of these complex social disorders remain unclear. Here, we present a comparative imaging and postmortem study of two patients, one with FTLD-TDP (subtype C) and one with FTLD-tau (subtype Pick disease), who both developed new rigid belief systems. The FTLD-TDP patient developed a complex set of values centered on positivity and associated with specific physical and behavioral features of pigs, while the FTLD-tau patient developed compulsive, goal-directed behaviors related to general themes of positivity and spirituality. Neuroimaging showed left-predominant temporal atrophy in the FTLD-TDP patient and right-predominant frontotemporal atrophy in the FTLD-tau patient. Consistent with antemortem cortical atrophy, histopathologic examinations revealed severe loss of neurons and myelin predominantly in the anterior temporal lobes of both patients, but the FTLD-tau patient showed more bilateral, dorsolateral involvement featuring greater pathology and loss of projection neurons and deep white matter. These findings highlight that the regions within and connected to anterior temporal lobes may have differential vulnerability to distinct FTLD proteinopathies and serve important roles in human belief systems.

Striatal and thalamic automatic segmentation, morphology, and clinical correlates in Parkinsonism: Parkinson's disease, multiple system atrophy and progressive supranuclear palsy

Parkinson's disease (PD), multisystem atrophy (MSA), and progressive supranuclear palsy (PSP) present similarly with bradykinesia, tremor, rigidity, and cognitive impairments. Neuroimaging studies have found differential changes in the nigrostriatal pathway in these disorders, however whether the volume and shape of specific regions within this pathway can distinguish between atypical Parkinsonian disorders remains to be determined. This paper investigates striatal and thalamic volume and morphology as distinguishing biomarkers, and their relationship to neuropsychiatric symptoms. Automatic segmentation to calculate volume and shape analysis of the caudate nucleus, putamen, and thalamus were performed in 18 PD patients, 12 MSA, 15 PSP, and 20 healthy controls, then correlated with clinical measures. PSP bilateral thalami and right putamen were significantly smaller than controls, but not MSA or PD. The left caudate and putamen significantly correlated with the Neuropsychiatric Inventory total score. Bilateral thalamus, caudate, and left putamen had significantly different morphology between groups, driven by differences between PSP and healthy controls. This study demonstrated that PSP patient striatal and thalamic volume and shape are significantly different when compared with controls. Parkinsonian disorders could not be differentiated on volumetry or morphology, however there are trends for volumetric and morphological changes associated with PD, MSA, and PSP.

Facial and upper-limb movement abnormalities in individuals with psychotic-like experiences: a motion analysis study

Slow movements and irregular muscle contraction have been reported separately in different studies targeting individuals with psychotic-like experiences (PLEs). To date, it remains unknown whether these two movement abnormalities, possibly associated with hypo- and hyper-dopaminergia, respectively, co-existed in one sample with PLEs and interrelated in the early stage of psychotic progression. Therefore, this study was to examine if facial and upper-limb slow movements and irregular muscle contraction co-existed in individuals with PLEs, interrelated, and were associated with PLEs. A total of 26 individuals with PLEs, who were identified using the 16-item Prodromal Questionnaire, and 26 age- and gender-matched healthy controls received the facial and upper-limb movement measurement. A motion capture system was used to record the movement procedure and thus calculate kinematic variables that represented severity of slow movements and irregular muscle contraction. Results showed that facial and upper-limb slow movements and facial irregular muscle contraction existed in individuals with PLEs. For the total sample, slower facial movements were associated with less regular facial muscle contraction; slower upper-limb movements were associated with less regular upper-limb muscle contraction. Slower and less regular facial and upper-limb movements were associated with more severe PLEs. Compensatory changes in dopaminergic neural pathways in response to elevated dopamine might explain connection between slow movements and irregular muscle contraction. Because of the ability to detect facial and upper-limb movement abnormalities objectively and sensitively, motion analysis has great applicability to sensorimotor studies for people in the psychosis continuum.

Dorsolateral Striatum is a Bottleneck for Responding to Task-Relevant Stimuli in a Learned Whisker Detection Task in Mice

A learned sensory-motor behavior engages multiple brain regions, including the neocortex and the basal ganglia. How a target stimulus is detected by these regions and converted to a motor response remains poorly understood. Here, we performed electrophysiological recordings and pharmacological inactivations of whisker motor cortex and dorsolateral striatum to determine the representations within, and functions of, each region during performance in a selective whisker detection task in male and female mice. From the recording experiments, we observed robust, lateralized sensory responses in both structures. We also observed bilateral choice probability and preresponse activity in both structures, with these features emerging earlier in whisker motor cortex than dorsolateral striatum. These findings establish both whisker motor cortex and dorsolateral striatum as potential contributors to the sensory-to-motor (sensorimotor) transformation. We performed pharmacological inactivation studies to determine the necessity of these brain regions for this task. We found that suppressing the dorsolateral striatum severely disrupts responding to task-relevant stimuli, without disrupting the ability to respond, whereas suppressing whisker motor cortex resulted in more subtle changes in sensory detection and response criterion. Together these data support the dorsolateral striatum as an essential node in the sensorimotor transformation of this whisker detection task.SIGNIFICANCE STATEMENT Selecting an item in a grocery store, hailing a cab - these daily practices require us to transform sensory stimuli into motor responses. Many decades of previous research have studied goal-directed sensory-to-motor transformations within various brain structures, including the neocortex and the basal ganglia. Yet, our understanding of how these regions coordinate to perform sensory-to-motor transformations is limited because these brain structures are often studied by different researchers and through different behavioral tasks. Here, we record and perturb specific regions of the neocortex and the basal ganglia and compare their contributions during performance of a goal-directed somatosensory detection task. We find notable differences in the activities and functions of these regions, which suggests specific contributions to the sensory-to-motor transformation process.

A large-scale brain network of species-specific dynamic human body perception

This ultrahigh field 7 T fMRI study addressed the question of whether there exists a core network of brain areas at the service of different aspects of body perception. Participants viewed naturalistic videos of monkey and human faces, bodies, and objects along with mosaic-scrambled videos for control of low-level features. Independent component analysis (ICA) based network analysis was conducted to find body and species modulations at both the voxel and the network levels. Among the body areas, the highest species selectivity was found in the middle frontal gyrus and amygdala. Two large-scale networks were highly selective to bodies, dominated by the lateral occipital cortex and right superior temporal sulcus (STS) respectively. The right STS network showed high species selectivity, and its significant human body-induced node connectivity was focused around the extrastriate body area (EBA), STS, temporoparietal junction (TPJ), premotor cortex, and inferior frontal gyrus (IFG). The human body-specific network discovered here may serve as a brain-wide internal model of the human body serving as an entry point for a variety of processes relying on body descriptions as part of their more specific categorization, action, or expression recognition functions.

Basal ganglia network dynamics and function: Role of direct, indirect and hyper-direct pathways in action selection

Basal ganglia (BG) are a widely recognized neural basis for action selection, but its decision-making mechanism is still a difficult problem for researchers. Therefore, we constructed a spiking neural network inspired by the BG anatomical data. Simulation experiments were based on the principle of dis-inhibition and our functional hypothesis within the BG: the direct pathway, the indirect pathway, and the hyper-direct pathway of the BG jointly implement the initiation execution and termination of motor programs. Firstly, we studied the dynamic process of action selection with the network, which contained intra-group competition and inter-group competition. Secondly, we focused on the effects of the stimulus intensity and the proportion of excitation and inhibition on the GPi/SNr. The results suggested that inhibition and excitation shape action selection. They also explained why the firing rate of GPi/SNr did not continue to increase in the action-selection experiment. Finally, we discussed the experimental results with the functional hypothesis. Uniquely, this paper summarized the decision-making neural mechanism of action selection based on the direct pathway, the indirect pathway, and the hyper-direct pathway within BG.

Rhythmic auditory stimulation incorporated in training improved movements in individuals with psychotic-like experiences

Movement abnormalities, including movement slowing and irregular muscle contraction, exist in individuals with psychotic-like experiences (PLEs) and serve as vulnerable factors of developing psychotic diseases in the psychosis continuum. To date scarce studies have developed early intervention programs tackling these initial impairments, which may be caused by basal ganglia alterations, in the early stage of the psychosis course. Rhythmic auditory stimulation (RAS) is a technique of neurological music therapy and has been proved effective in inducing faster movements in patients with psychotic diseases. This pilot study examined if RAS incorporated in functional movement training reduced severity of movement slowing and irregular muscle contraction in individuals with PLEs. Seventeen individuals with PLEs were randomly allocated to receiving RAS or receiving no RAS and underwent daily 40-min movement training (picking up beans) for three weeks. This study used motion analysis to measure movement performance at pretest and posttest. Eighteen age- and gender-matched individuals without PLEs were also recruited to provide data of intact movements. Results showed that RAS may reduce severity of movement slowing and irregular muscle contraction in individuals with PLEs. This pilot study is one of the pioneering studies validating effectiveness of early intervention programs tackling movement abnormalities, which are initial impairments in the psychosis continuum, in individuals with PLEs.

Translating neuroimaging changes to neuro-endophenotypes of autistic spectrum disorder: a narrative review

Background

Autism-spectrum disorder is a neurodevelopmental disorder with heterogeneity in etiopathogenesis and clinical presentation. Neuroanatomical and neurophysiological abnormalities may represent neural endophenotypes for autism spectrum disorders which may help identify subgroups of patients seemingly similar in clinical presentation yet different in their pathophysiological underpinnings. Furthermore, a thorough understanding of the pathophysiology of disease can pave the way to effective treatments, prevention, and prognostic predictions. The aim of this review is to identify the predominant neural endophenotypes in autism-spectrum disorder. The evidence was researched at the following electronic databases: Pubmed, PsycINFO, Scopus, Web of Science, and EMBASE.

Results

Enlarged brain, especially frontotemporal cortices have been consistently reported by structural neuroimaging, whereas functional neuroimaging has revealed frontotemporal dysconnectivity.

Conclusions

Regrettably, many of these findings have not been consistent. Therefore, translating these findings into neural endophenotype is by far an attempt in its budding stage. The structural and functional neuroimaging changes may represent neural endophenotypes unique to autism-spectrum disorder. Despite inconsistent results, a clinically meaningful finding may require combined efforts of autism-spectrum-disorder researchers focused on different aspects of basic, genetic, neuroimaging, and clinical research.

Case Series of Isolated Deep Gray Matter Injuries in Preterm Infants

Hypoxic-ischemic encephalopathy in neonates is an important cause of brain damage that leads to severe neurological sequelae or death. Brain injury patterns on magnetic resonance imaging (MRI) scans are used to predict neurodevelopmental outcome severity. This case series describes the clinical manifestations and neurologic outcomes of four preterm infants with isolated deep gray matter injuries. Basal ganglia and thalamic lesions were noted without white matter and cerebral cortex lesion on brain MRI. All patients were preterm infants born at less than 33 weeks’ gestation and required resuscitation in the delivery room. All had seizures during the neonatal period requiring anti-seizure medications. Severe neurologic disability was identified in three patients using neurodevelopmental assessment tools. Another patient has not been evaluated with assessment tools yet as he was 2 months’ corrected age, but he was supported by home ventilation via a tracheostomy due to insufficient self-respiration. This case series demonstrates that isolated deep gray matter injuries in preterm infants could predict severe neurodevelopmental outcomes.

Movement Disorders Associated With Cerebral Artery Stenosis: A Nationwide Study

Background

Studies of secondary movement disorder (MD) caused by cerebrovascular diseases have primarily focused on post-stroke MD. However, MD can also result from cerebral artery stenosis (CAS) without clinical manifestations of stroke. In this study, we aimed to investigate the clinical characteristics of MD associated with CAS.

Materials and Methods

A nationwide multicenter retrospective analysis was performed based on the data from patients with CAS-associated MDs from 16 MD specialized clinics in South Korea, available between January 1999 and September 2019. CAS was defined as the >50% luminal stenosis of the major cerebral arteries. The association between MD and CAS was determined by MD specialists using pre-defined clinical criteria. The collected clinical information included baseline demographics, features of MD, characteristics of CAS, treatment, and MD outcomes. Statistical analyses were performed to identify factors associated with the MD outcomes.

Results

The data from a total of 81 patients with CAS-associated MD were analyzed. The mean age of MD onset was 60.5 ± 19.7 years. Chorea was the most common MD (57%), followed by tremor/limb-shaking, myoclonus, and dystonia. Atherosclerosis was the most common etiology of CAS (78%), with the remaining cases attributed to moyamoya disease (MMD). Relative to patients with atherosclerosis, those with MMD developed MD at a younger age (p < 0.001) and had a more chronic mode of onset (p = 0.001) and less acute ischemic lesion (p = 0.021). Eight patients who underwent surgical treatment for CAS showed positive outcomes. Patients with acute MD onset had a better outcome than those with subacute-to-chronic MD onset (p = 0.008).

Conclusions

This study highlights the spectrum of CAS-associated with MD across the country. A progressive, age-dependent functional neuronal modulation in the basal ganglia due to CAS may underlie this condition.

Neural substrates of psychosis revealed by altered dependencies between brain activity and white-matter architecture in individuals with 22q11 deletion syndrome

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Function-structural dependency is altered in patients with 22q11 deletion syndrome.

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Stronger dependency in subcortical regions correlates with psychotic symptoms.

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Weaker dependency in cingulate cortex correlates with psychotic symptoms.

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Multimodal and not unimodal indexes were correlated with psychosis emergence.

Background

Dysconnectivity has been consistently proposed as a major key mechanism in psychosis. Indeed, disruptions in large-scale structural and functional brain networks have been associated with psychotic symptoms. However, brain activity is largely constrained by underlying white matter pathways and the study of function-structure dependency, compared to conventional unimodal analysis, allows a biologically relevant assessment of neural mechanisms. The 22q11.2 deletion syndrome (22q11DS) constitutes a remarkable opportunity to study the pathophysiological processes of psychosis.

Methods

58 healthy controls and 57 deletion carriers, aged from 16 to 32 years old, underwent resting-state functional and diffusion-weighted magnetic resonance imaging. Deletion carriers were additionally fully assessed for psychotic symptoms. Firstly, we used a graph signal processing method to combine brain activity and structural connectivity measures to obtain regional structural decoupling indexes (SDIs). We use SDI to assess the differences of functional structural dependency (FSD) across the groups. Subsequently we investigated how alterations in FSDs are associated with the severity of positive psychotic symptoms in participants with 22q11DS.

Results

In line with previous findings, participants in both groups showed a spatial gradient of FSD ranging from sensory-motor regions (stronger FSD) to regions involved in higher-order function (weaker FSD). Compared to controls, in participants with 22q11DS, and further in deletion carriers with more severe positive psychotic symptoms, the functional activity was more strongly dependent on the structure in parahippocampal gyrus and subcortical dopaminergic regions, while it was less dependent within the cingulate cortex. This analysis revealed group differences not otherwise detected when assessing the structural and functional nodal measures separately.

Conclusions

Our findings point toward a disrupted modulation of functional activity on the underlying structure, which was further associated to psychopathology for candidate critical regions in 22q11DS. This study provides the first evidence for the clinical relevance of function-structure dependency and its contribution to the emergence of psychosis.

Classification of Chemotherapy-Related Subjective Cognitive Complaints in Breast Cancer Using Brain Functional Connectivity and Activity: A Machine Learning Analysis

The aim of this study was combining multi-level resting-state functional magnetic resonance imaging (rs-fMRI) features with machine learning method to distinguish breast cancer patients with chemotherapy-related subjective cognitive complaints (SCC) from non-chemotherapy (BC) and healthy controls (HC). Forty subjects in SCC group, forty-nine in BC group and thirty-four in HC group were recruited and underwent rs-fMRI scanning. Based on the anatomical automatic labeling brain atlas, the functional metrics of all subjects included functional connectivity, amplitude of low frequency fluctuation and fractional amplitude of low frequency fluctuation, regional homogeneity, voxel-mirrored homotopic connectivity and degree centrality were calculated and extracted as features set. Then, the rs-fMRI features were selected by two-sample t-test, removing variables with a high pairwise correlation and least absolute shrinkage and selection operator regression. Finally, the support vector machine models were built for classification (SCC vs. BC, SCC vs. HC). Thirty-eight features (SCC vs. BC) and seventeen features (SCC vs. HC) were selected separately, and the accuracy of the models were 82.0% and 91.9%, respectively. These findings demonstrated a valid machine learning approach that effectively distinguished breast cancer patients with chemotherapy-related SCC from non-chemotherapy and healthy controls, providing potential neuroimaging evidence for early diagnosis and clinical intervention of chemotherapy-related SCC.

Effects of rhythmic auditory stimulation on upper-limb movement speed in patients with schizophrenia spectrum disorders

Movement slowness, linked to dysfunctional basal ganglia and cerebellum, is prevalent but lacks effective therapy in patients with schizophrenia spectrum disorders. This study was to examine immediate effects of rhythmic auditory stimulation (RAS) on upper-limb movement speed in patients. Thirty patients and 30 psychiatrically healthy people executed the right-hand task and the both-hand task of the Purdue Pegboard Test when listening to RAS with two tempi: normal (equal to the fastest movement tempo for each participant without RAS) and fast (120% of the normal tempo). The testing order of the RAS tempi for each participant was randomized. Patients had lower scores of right-hand and both-hand tasks than did psychiatrically healthy people. Scores of right-hand and both-hand tasks were higher in the fast-RAS condition than the normal-RAS condition in participants. This is the first study to explore the possibility of applying RAS to movement therapy for patients with schizophrenia spectrum disorders. The results demonstrated that faster RAS was effective in inducing faster upper-limb movements in patients and psychiatrically healthy people, suggesting that manipulating RAS may be a feasible therapeutic strategy utilized to regulate movement speed. The RAS may involve alternative neural pathways to modulate movement speed and thus to compensate for impaired function of basal ganglia and cerebellum in patients.

Impact of Pretreatment Ischemic Location on Functional Outcome after Thrombectomy

Pretreatment ischemic location may be an important determinant for functional outcome prediction in acute ischemic stroke. In total, 143 anterior circulation ischemic stroke patients in the THRACE study were included. Ischemic lesions were semi-automatically segmented on pretreatment diffusion-weighted imaging and registered on brain atlases. The percentage of ischemic tissue in each atlas-segmented region was calculated. Statistical models with logistic regression and support vector machine were built to analyze the predictors of functional outcome. The investigated parameters included: age, baseline National Institutes of Health Stroke Scale score, and lesional volume (three-parameter model), together with the ischemic percentage in each atlas-segmented region (four-parameter model). The support vector machine with radial basis functions outperformed logistic regression in prediction accuracy. The support vector machine three-parameter model demonstrated an area under the curve of 0.77, while the four-parameter model achieved a higher area under the curve (0.82). Regions with marked impacts on outcome prediction were the uncinate fasciculus, postcentral gyrus, putamen, middle occipital gyrus, supramarginal gyrus, and posterior corona radiata in the left hemisphere; and the uncinate fasciculus, paracentral lobule, temporal pole, hippocampus, inferior occipital gyrus, middle temporal gyrus, pallidum, and anterior limb of the internal capsule in the right hemisphere. In conclusion, pretreatment ischemic location provided significant prognostic information for functional outcome in ischemic stroke.

Striatal topographical organization: Bridging the gap between molecules, connectivity and behavior

The striatum represents the major hub of the basal ganglia, receiving projections from the entire cerebral cortex and it is assumed to play a key role in a wide array of complex behavioral tasks. Despite being extensively investigated during the last decades, the topographical organization of the striatum is not well understood yet. Ongoing efforts in neuroscience are focused on analyzing striatal anatomy at different spatial scales, to understand how structure relates to function and how derangements of this organization are involved in various neuropsychiatric diseases. While being subdivided at the macroscale level into dorsal and ventral divisions, at a mesoscale level the striatum represents an anatomical continuum sharing the same cellular makeup. At the same time, it is now increasingly ascertained that different striatal compartments show subtle histochemical differences, and their neurons exhibit peculiar patterns of gene expression, supporting functional diversity across the whole basal ganglia circuitry. Such diversity is further supported by afferent connections which are heterogenous both anatomically, as they originate from distributed cortical areas and subcortical structures, and biochemically, as they involve a variety of neurotransmitters. Specifically, the cortico-striatal projection system is topographically organized delineating a functional organization which is maintained throughout the basal ganglia, subserving motor, cognitive and affective behavioral functions. While such functional heterogeneity has been firstly conceptualized as a tripartite organization, with sharply defined limbic, associative and sensorimotor territories within the striatum, it has been proposed that such territories are more likely to fade into one another, delineating a gradient-like organization along medio-lateral and ventro-dorsal axes. However, the molecular and cellular underpinnings of such organization are less understood, and their relations to behavior remains an open question, especially in humans. In this review we aimed at summarizing the available knowledge on striatal organization, especially focusing on how it links structure to function and its alterations in neuropsychiatric diseases. We examined studies conducted on different species, covering a wide array of different methodologies: from tract-tracing and immunohistochemistry to neuroimaging and transcriptomic experiments, aimed at bridging the gap between macroscopic and molecular levels.

Disrupted basal ganglia output during movement preparation in hemiparkinsonian mice is consistent with behavioral deficits

Parkinsonian motor deficits are associated with elevated inhibitory output from the basal ganglia (BG). However, several features of Parkinson's disease (PD) have not been accounted for by this simple "classical rate model" framework, including the observation in patients with PD that movements guided by external stimuli are less impaired than otherwise identical movements generated based on internal goals. Is this difference due to divergent processing within the BG itself or due to the recruitment of extra-BG pathways by sensory processing? In addition, surprisingly little is known about precisely when, in the sequence from selecting to executing movements, BG output is altered by PD. Here, we address these questions by recording activity in the substantia nigra pars reticulata (SNr), a key BG output nucleus, in hemiparkinsonian mice performing a well-controlled behavioral task requiring stimulus-guided and internally specified directional movements. We found that hemiparkinsonian mice exhibited a bias ipsilateral to the side of dopaminergic cell loss that was stronger when movements were internally specified rather than stimulus guided, consistent with clinical observations in patients with Parkinson's disease. We further found that changes in parkinsonian SNr activity during movement preparation were consistent with the ipsilateral behavioral bias, as well as its greater magnitude for internally specified movements. Although these findings are inconsistent with some aspects of the classical rate model, they are accounted for by a related "directional rate model" positing that SNr output phasically overinhibits motor output in a direction-specific manner. These results suggest that parkinsonian changes in BG output underlying movement preparation contribute to the greater deficit in internally specified than stimulus-guided movements.NEW & NOTEWORTHY Movements of patients with Parkinson's disease are often less impaired when guided by external stimuli than when generated based on internal goals. Whether this effect is due to distinct processing in the basal ganglia (BG) or due to compensation from other motor pathways is an open question with therapeutic implications. We recorded BG output in behaving parkinsonian mice and found that BG activity during movement preparation was consistent with the differences between these forms of movement.

Altered Effective Connectivity within an Oculomotor Control Network in Unaffected Relatives of Individuals with Schizophrenia

The ability to rapidly stop or change a planned action is a critical cognitive process that is impaired in schizophrenia. The current study aimed to examine whether this impairment reflects familial vulnerability to schizophrenia across two experiments comparing unaffected first-degree relatives to healthy controls. First, we examined performance on a saccadic stop-signal task that required rapid inhibition of an eye movement. Then, in a different sample, we investigated behavioral and neural responses (using fMRI) during a stop-signal task variant that required rapid modification of a prepared eye movement. Here, we examined differences between relatives and healthy controls in terms of activation and effective connectivity within an oculomotor control network during task performance. Like individuals with schizophrenia, the unaffected relatives showed behavioral evidence for more inefficient inhibitory processes. Unlike previous findings in individuals with schizophrenia, however, the relatives showed evidence for a compensatory waiting strategy. Behavioral differences were accompanied by more activation among the relatives in task-relevant regions across conditions and group differences in effective connectivity across the task that were modulated differently by the instruction to exert control over a planned saccade. Effective connectivity parameters were related to behavioral measures of inhibition efficiency. The results suggest that individuals at familial risk for schizophrenia were engaging an oculomotor control network differently than controls and in a way that compromises inhibition efficiency.

A computational neuroethology perspective on body and expression perception

Survival prompts organisms to prepare adaptive behavior in response to environmental and social threat. However, what are the specific features of the appearance of a conspecific that trigger such adaptive behaviors? For social species, the prime candidates for triggering defense systems are the visual features of the face and the body. We propose a novel approach for studying the ability of the brain to gather survival-relevant information from seeing conspecific body features. Specifically, we propose that behaviorally relevant information from bodies and body expressions is coded at the levels of midlevel features in the brain. These levels are relatively independent from higher-order cognitive and conscious perception of bodies and emotions. Instead, our approach is embedded in an ethological framework and mobilizes computational models for feature discovery.

The neural underpinnings of facial emotion recognition in ischemic stroke patients

Deficits in facial emotion recognition occur frequently after stroke, with adverse social and behavioural consequences. The aim of this study was to investigate the neural underpinnings of the recognition of emotional expressions, in particular of the distinct basic emotions (anger, disgust, fear, happiness, sadness and surprise). A group of 110 ischaemic stroke patients with lesions in (sub)cortical areas of the cerebrum was included. Emotion recognition was assessed with the Ekman 60 Faces Test of the FEEST. Patient data were compared to data of 162 matched healthy controls (HC's). For the patients, whole brain voxel-based lesion-symptom mapping (VLSM) on 3-Tesla MRI images was performed. Results showed that patients performed significantly worse than HC's on both overall recognition of emotions, and specifically of disgust, fear, sadness and surprise. VLSM showed significant lesion-symptom associations for FEEST total in the right fronto-temporal region. Additionally, VLSM for the distinct emotions showed, apart from overlapping brain regions (insula, putamen and Rolandic operculum), also regions related to specific emotions. These were: middle and superior temporal gyrus (anger); caudate nucleus (disgust); superior corona radiate white matter tract, superior longitudinal fasciculus and middle frontal gyrus (happiness) and inferior frontal gyrus (sadness). Our findings help in understanding how lesions in specific brain regions can selectively affect the recognition of the basic emotions.

Looking beneath the surface: the importance of subcortical structures in frontotemporal dementia

Whilst initial anatomical studies of frontotemporal dementia focussed on cortical involvement, the relevance of subcortical structures to the pathophysiology of frontotemporal dementia has been increasingly recognized over recent years. Key structures affected include the caudate, putamen, nucleus accumbens, and globus pallidus within the basal ganglia, the hippocampus and amygdala within the medial temporal lobe, the basal forebrain, and the diencephalon structures of the thalamus, hypothalamus and habenula. At the most posterior aspect of the brain, focal involvement of brainstem and cerebellum has recently also been shown in certain subtypes of frontotemporal dementia. Many of the neuroimaging studies on subcortical structures in frontotemporal dementia have been performed in clinically defined sporadic cases. However, investigations of genetically- and pathologically-confirmed forms of frontotemporal dementia are increasingly common and provide molecular specificity to the changes observed. Furthermore, detailed analyses of sub-nuclei and subregions within each subcortical structure are being added to the literature, allowing refinement of the patterns of subcortical involvement. This review focuses on the existing literature on structural imaging and neuropathological studies of subcortical anatomy across the spectrum of frontotemporal dementia, along with investigations of brain–behaviour correlates that examine the cognitive sequelae of specific subcortical involvement: it aims to ‘look beneath the surface’ and summarize the patterns of subcortical involvement have been described in frontotemporal dementia.

Lateralized effects of deep brain stimulation in Parkinson's disease: evidence and controversies

The bilateral effects of deep brain stimulation (DBS) on motor and non-motor symptoms of Parkinson's disease (PD) have been extensively studied and reviewed. However, the unilateral effects-in particular, the potential lateralized effects of left- versus right-sided DBS-have not been adequately recognized or studied. Here we summarized the current evidence and controversies in the literature regarding the lateralized effects of DBS on motor and non-motor outcomes in PD patients. Publications in English language before February 2021 were obtained from the PubMed database and included if they directly compared the effects of unilateral versus contralateral side DBS on motor or non-motor outcomes in PD. The current literature is overall of low-quality and is biased by various confounders. Researchers have investigated mainly PD patients receiving subthalamic nucleus (STN) DBS while the potential lateralized effects of globus pallidus interna (GPi) DBS have not been adequately studied. Evidence suggests potential lateralized effects of STN DBS on axial motor symptoms and deleterious effects of left-sided DBS on language-related functions, in particular, the verbal fluency, in PD. The lateralized DBS effects on appendicular motor symptoms as well as other neurocognitive and neuropsychiatric domains remain inconclusive. Future studies should control for varying methodological approaches as well as clinical and DBS management heterogeneities, including symptom laterality, stimulation parameters, location of active contacts, and lead trajectories. This would contribute to improved treatment strategies such as personalized target selection, surgical planning, and postoperative management that ultimately benefit patients.

Altered effective connectivity within an oculomotor control network in individuals with schizophrenia

Rapid inhibition or modification of actions is a crucial cognitive ability, which is impaired in persons with schizophrenia (SZP). Primate neurophysiology studies have identified a network of brain regions that subserves control over gaze. Here, we examine effective connectivity within this oculomotor control network in SZP and healthy controls (HC). During fMRI, participants performed a stop-signal task variant in which they were instructed to saccade to a visual target (no-step trials) unless a second target appeared (redirect trials); on redirect trials, participants were instructed to inhibit the planned saccade and redirect to the new target. We compared functional responses on redirect trials to no-step trials and used dynamic causal modelling (DCM) to examine group differences in network effective connectivity. Behaviorally, SZP were less efficient at inhibiting, which was related to their employment status. Compared to HC, they showed a smaller difference in activity between redirect trials and no-step trials in frontal eye fields (FEF), supplementary eye fields (SEF), inferior frontal cortex (IFC), thalamus, and caudate. DCM analyses revealed widespread group differences in effective connectivity across the task, including different patterns of self-inhibition in many nodes in SZP. Group differences in how effective connectivity was modulated on redirect trials revealed differences between the FEF and SEF, between the SEF and IFC, between the superior colliculus and the thalamus, and self-inhibition within the FEF and caudate. These results provide insight into the neural mechanisms of inefficient inhibitory control in individuals with schizophrenia.

Specific populations of basal ganglia output neurons target distinct brain stem areas while collateralizing throughout the diencephalon

Basal ganglia play a central role in regulating behavior, but the organization of their outputs to other brain areas is incompletely understood. We investigate the largest output nucleus, the substantia nigra pars reticulata (SNr), and delineate the organization and physiology of its projection populations in mice. Using genetically targeted viral tracing and whole-brain anatomical analysis, we identify over 40 SNr targets that encompass a roughly 50-fold range of axonal densities. Retrograde tracing from the volumetrically largest targets indicates that the SNr contains segregated subpopulations that differentially project to functionally distinct brain stem regions. These subpopulations are electrophysiologically specialized and topographically organized and collateralize to common diencephalon targets, including the motor and intralaminar thalamus as well as the pedunculopontine nucleus and the midbrain reticular formation. These findings establish that SNr signaling is organized as dense, parallel outputs to specific brain stem targets concurrent with extensive collateral branches that encompass the majority of SNr axonal boutons.

Sensory Attenuation in Sport and Rehabilitation: Perspective from Research in Parkinson's Disease

People with Parkinson's disease (PD) experience motor symptoms that are affected by sensory information in the environment. Sensory attenuation describes the modulation of sensory input caused by motor intent. This appears to be altered in PD and may index important sensorimotor processes underpinning PD symptoms. We review recent findings investigating sensory attenuation and reconcile seemingly disparate results with an emphasis on task-relevance in the modulation of sensory input. Sensory attenuation paradigms, across different sensory modalities, capture how two identical stimuli can elicit markedly different perceptual experiences depending on our predictions of the event, but also the context in which the event occurs. In particular, it appears as though contextual information may be used to suppress or facilitate a response to a stimulus on the basis of task-relevance. We support this viewpoint by considering the role of the basal ganglia in task-relevant sensory filtering and the use of contextual signals in complex environments to shape action and perception. This perspective highlights the dual effect of basal ganglia dysfunction in PD, whereby a reduced capacity to filter task-relevant signals harms the ability to integrate contextual cues, just when such cues are required to effectively navigate and interact with our environment. Finally, we suggest how this framework might be used to establish principles for effective rehabilitation in the treatment of PD.

Distinct functional and structural connections predict crystallised and fluid cognition in healthy adults

White matter pathways between neurons facilitate neuronal coactivation patterns in the brain. Insight into how these structural and functional connections underlie complex cognitive functions provides an important foundation with which to delineate disease‐related changes in cognitive functioning. Here, we integrate neuroimaging, connectomics, and machine learning approaches to explore how functional and structural brain connectivity relate to cognition. Specifically, we evaluate the extent to which functional and structural connectivity predict individual crystallised and fluid cognitive abilities in 415 unrelated healthy young adults (202 females) from the Human Connectome Project. We report three main findings. First, we demonstrate functional connectivity is more predictive of cognitive scores than structural connectivity, and, furthermore, integrating the two modalities does not increase explained variance. Second, we show the quality of cognitive prediction from connectome measures is influenced by the choice of grey matter parcellation, and, possibly, how that parcellation is derived. Third, we find that distinct functional and structural connections predict crystallised and fluid abilities. Taken together, our results suggest that functional and structural connectivity have unique relationships with crystallised and fluid cognition and, furthermore, studying both modalities provides a more comprehensive insight into the neural correlates of cognition.

Basal ganglia lateralization in different types of reward

Reward processing is a fundamental human activity. The basal ganglia are recognized for their role in reward processes; however, specific roles of the different nuclei (e.g., nucleus accumbens, caudate, putamen and globus pallidus) remain unclear. Using quantitative meta-analyses we assessed whole-brain and basal ganglia specific contributions to money, erotic, and food reward processing. We analyzed data from 190 fMRI studies which reported stereotaxic coordinates of whole-brain, within-group results from healthy adult participants. Results showed concordance in overlapping and distinct cortical and sub-cortical brain regions as a function of reward type. Common to all reward types was concordance in basal ganglia nuclei, with distinct differences in hemispheric dominance and spatial extent in response to the different reward types. Food reward processing favored the right hemisphere; erotic rewards favored the right lateral globus pallidus and left caudate body. Money rewards engaged the basal ganglia bilaterally including its most anterior part, nucleus accumbens. We conclude by proposing a model of common reward processing in the basal ganglia and separate models for money, erotic, and food rewards.

Altered striatum centered brain structures in SHANK3 deficient Chinese children with genotype and phenotype profiling

SHANK3 deficiency represents one of the most replicated monogenic risk factors for autism spectrum disorder (ASD) and SHANK3 caused ASD presents a unique opportunity to understand the underlying neuropathological mechanisms of ASD. In this study, genetic tests, comprehensive clinical and neurobehavioral evaluations, as well as multimodal structural MRI using voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) were conducted in SHANK3 group (N = 14 with SHANK3 defects), ASD controls (N = 26 with idiopathic ASD without SHANK3 defects) and typically developing (TD) controls (N = 32). Phenotypically, we reported several new features in Chinese SHANK3 deficient children including anteverted nares, sensory stimulation seeking, dental abnormalities and hematological problems. In SHANK3 group, VBM revealed decreased grey matter volumes mainly in dorsal striatum, amygdala, hippocampus and parahippocampal gyrus; TBSS demonstrated decreased fractional anisotropy in multiple tracts involving projection, association and commissural fibers, including middle cerebral peduncle, corpus callosum, superior longitudinal fasciculus, corona radiata, external and internal capsule, and posterior thalamic radiation, etc. We report that the disrupted striatum centered brain structures are associated with SHANK3 deficient children. Study of subjects with monogenic cause offer specific insights into the neuroimaging studies of ASD. The discovery may support a path for future functional connectivity studies to allow for more in-depth understandings of the abnormal neural circuits and the underlying neuropathological mechanisms for ASD.

Computation-Based Feature Representation of Body Expressions in the Human Brain

Humans and other primate species are experts at recognizing body expressions. To understand the underlying perceptual mechanisms, we computed postural and kinematic features from affective whole-body movement videos and related them to brain processes. Using representational similarity and multivoxel pattern analyses, we showed systematic relations between computation-based body features and brain activity. Our results revealed that postural rather than kinematic features reflect the affective category of the body movements. The feature limb contraction showed a central contribution in fearful body expression perception, differentially represented in action observation, motor preparation, and affect coding regions, including the amygdala. The posterior superior temporal sulcus differentiated fearful from other affective categories using limb contraction rather than kinematics. The extrastriate body area and fusiform body area also showed greater tuning to postural features. The discovery of midlevel body feature encoding in the brain moves affective neuroscience beyond research on high-level emotion representations and provides insights in the perceptual features that possibly drive automatic emotion perception.

A high-resolution fMRI approach to characterize functionally distinct neural pathways within dopaminergic midbrain and nucleus accumbens during reward and salience processing

Processing of reward and salience without reward association are known to critically rely on the dopamine system. A growing body of evidence from animal studies suggests that both functions may be subserved by distinct subregions in midbrain and ventral striatum, specifically nucleus accumbens (NAcc). Yet in vivo investigation of these brain structures in humans has been rare. Here we examined blood oxygen level dependent signals in response to frequently presented rewarding events and infrequently presented neutral events in 20 healthy subjects using high-resolution functional magnetic resonance imaging (fMRI) for imaging the human midbrain and NAcc. The present findings revealed distinct activation patterns in brain regions of interest, namely increased activation in substantia nigra pars compacta (SNc) and dorsolateral NAcc in response to neutral events, while the VTA and both the ventromedial and dorsolateral NAcc were significantly activated due to rewarding events. Moreover, psychophysiological interaction analyses demonstrated regionally specialized processing pathways, such as a dorsolateral pathway when processing salience per se, i.e. increased functional interactions between SNc, dorsolateral NAcc and dorsolateral and medial prefrontal cortex (PFC); and a ventromedial pathway during reward processing, i.e. increased functional coupling between VTA and ventromedial NAcc. Thus, these findings may not only accelerate the integration of animal models of brain function with human neuroscience but may also improve diagnosis and treatment in patients with neuropsychiatric disorders such as schizophrenia and depression in which dopaminergic dysfunction and aberrant attribution of salience have been implicated.

Neurological soft signs (NSS) and gray matter volume (GMV) in first-episode psychosis: An analysis of NSS motor subscores

We aimed to study the correlations between gray matter volume and the motor subscores of NSS in first-episode psychosis patients with both, whole brain and region of interest analyses. The structural MRIs of 81 first-episode psychosis patients were analyzed by using voxel-based morphometry (VBM) for SPM. NSS were assessed using the Heidelberg scale. Significant decreases of gray matter volume were correlated to high NSS total scores and, more specifically, frontal, subcortical and cerebellar areas were significantly correlated with increased scores of the subscores Motor Coordination (MoCo) and Complex Motor Tasks (CMT). When applying a stricter statistical correction, only the frontal gyrus and caudate nucleus survived for MoCo; whereas the precentral and superior frontal gyri survived for CMT. When doing regional analyses, using as masks the structures deemed as significant by the whole brain analyses and applying the FWE-correction, the superior frontal gyrus, thalamus and caudate nucleus correlated negatively with MoCo; and the precentral and superior frontal gyri, thalamus and caudate nucleus showed inverse correlations with CMT. These results suggest that cerebral cortex, subcortical structures (thalamus and striatum) and cerebellum are inversely correlated to both motor NSS subscores, the first time a study describes this relationship for all the relevant structures simultaneously. For its part, ROI proves to be effective demonstrating that subcortical structures (thalamus and caudate) are the most affected by motor NSS.

Mapping tracts in the human subthalamic area by 11.7T ex vivo diffusion tensor imaging

The cortico-basal ganglia-thalamo-cortical feedback loops that consist of distinct white matter pathways are important for understanding in vivo imaging studies of functional and anatomical connectivity, and for localizing subthalamic white matter structures in surgical approaches for movement disorders, such as Parkinson's disease. Connectomic analysis in animals has identified fiber connections between the basal ganglia and thalamus, which pass through the fields of Forel, where other fiber pathways related to motor, sensory, and cognitive functions co-exist. We now report these pathways in the human brain on ex vivo mesoscopic (250 μm) diffusion tensor imaging and on tractography. The locations of the tracts were identified relative to the adjacent gray matter structures, such as the internal and external segments of the globus pallidus; the zona incerta; the subthalamic nucleus; the substantia nigra pars reticulata and compacta; and the thalamus. The connectome atlas of the human subthalamic region may serve as a resource for imaging studies and for neurosurgical planning.

Relationship between motor function and psychotic symptomatology in young-adult patients with schizophrenia

Motor abnormalities have been indicated to be a core manifestation of schizophrenia and not just motor side-effects of antipsychotics. However, little is known about whether all of the complete motor function, including fine motor function, muscle strength, and balance is linked to psychotic symptoms. Therefore, this study was to investigate association between complete motor function and psychotic symptoms in young-adult schizophrenia patients who had no extrapyramidal motor symptoms, which were assessed using the Extrapyramidal Symptom Rating Scale. Seventy schizophrenia patients were recruited. Fine motor function, muscle strength, and balance were assessed using The McCarron Assessment of Neuromuscular Development. Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale. Given gender differences in muscle power, the correlation between muscle strength and psychotic symptoms was analyzed by gender separately. Partial correlation controlling for effects of the chlorpromazine equivalent dosage of antipsychotics was conducted. Better fine motor function was correlated with less-severe negative symptoms (r = - 0.49, p < 0.001) in the total sample. In men, better muscle strength was correlated with more severe positive symptoms and less-severe negative symptoms (r = 0.41, p = 0.008; r = - 0.55, p < 0.001). The link between motor function and psychotic symptoms may support the cerebellar and basal ganglia hypotheses of schizophrenia, proposing that diverse schizophrenia symptoms may share the same neural deficiency, that is, dysfunction of cerebellum or basal ganglia. Considering the moderate-to-strong association between muscle strength and psychotic symptoms, muscle strength might be a powerful physical predictor of psychotic progression.

Emotion Recognition in Patients With Parkinson Disease

BACKGROUND

Individuals with Parkinson disease (PD) display cognitive dysfunction. However, few studies have investigated how facial and musical emotion recognition are affected in individuals with PD.

OBJECTIVE

To explore the relationship between facial and musical emotion recognition and executive functions in Chinese individuals with PD.

METHODS

We showed 40 Chinese individuals with PD and 40 Chinese healthy controls 24 black-and-white portraits and 24 musical excerpts that were designed to express happiness, sadness, fear, and anger. Then, we used four tests to assess the participants' executive functions, including the Trail Making Test (TMT), Clock Drawing Test (CDT), semantic Verbal Fluency Test (VFT), and Digit Span Test (DST).

RESULTS

The PD group showed significant impairment in recognizing anger from facial expressions, although their emotion recognition from musical excerpts was similar to that of the control group. Recognition of an angry face was significantly correlated to scores on the TMT and DST. Recognition of happy music was significantly correlated to the Hamilton Rating Scale for Depression score, whereas recognition of angry music was significantly correlated to musical knowledge background. Recognition of happy, sad, or angry music was significantly correlated to tests of executive function, whereas recognition of fearful music was not.

CONCLUSIONS

The PD group showed impaired recognition of angry faces, which may be related to executive dysfunction. However, the PD group did not show any difficulties in recognizing emotions in music. This dissociation indicates that the mechanisms underlying the recognition of emotions in faces and music are partly independent.

Active cooling temperature required to achieve therapeutic hypothermia correlates with short-term outcome in neonatal hypoxic-ischaemic encephalopathy

KEY POINTS

Hypoxic-ischaemic encephalopathy (HIE) affects 2-4/1000 live term births. Treatment with therapeutic hypothermia (TH) improves the long-term neurodevelopmental outcome of neonates with moderate to severe HIE. However, early prediction of outcome still remains challenging, and no reliable and easily obtainable biomarker has been identified to date. Neonates with HIE display impaired thermoregulation, resulting in spontaneous hypothermia. The degree of cooling required to achieve TH may therefore act as a biomarker of injury severity. The present study demonstrates a correlation between servo-controlled mattress temperature during TH and short-term outcome. Neonates with an unfavourable outcome require less cooling to maintain a core temperature between 33 and 34°C during TH compared to neonates with a favourable outcome. The degree of impaired temperature regulation was strongly associated with a high magnetic resonance imaging injury score and death. Cooling device output temperature is a potential and easily obtainable early physiological biomarker of outcome in infants with HIE undergoing TH.

ABSTRACT

Neonatal hypoxic-ischaemic encephalopathy (HIE) is a leading cause of death and disability in children. Therapeutic hypothermia (TH) at 33.5°C for 72 h is the only therapy to date shown to improve outcome in moderate to severe HIE; however, assessment of severity and prediction of outcome remains challenging. Infants with HIE display significant physiological perturbations, including spontaneous hypothermia. We hypothesized that neonates with more severe brain injury on magnetic resonance imaging (MRI) would exhibit a greater degree of spontaneous hypothermia, and thus require less active cooling to attain TH. Twenty-eight neonates with moderate or severe HIE treated with TH were included in the present study. MRI images obtained on day of life 4-7 were scored according to standardized injury criteria. Unfavourable outcome was defined as death or significant grey matter injury on MRI according to a previously validated scoring system. A significantly higher cooling device output temperature was seen in infants with an unfavourable outcome. All neonates who required the mattress to provide a temperature ≥32°C to maintain their core body temperature at 33.5°C had a high likelihood of unfavourable outcome (likelihood ratio = 14.4). By contrast, infants who never required a device output temperature ≥32°C had a low likelihood of an unfavourable outcome (likelihood ratio = 0.07, P < 0.001). Infants with significant grey matter injury on MRI require less active cooling to maintain target temperature during TH. The cooling device output temperature has the potential to be an easily accessible physiological biomarker and predictor of injury and mortality in neonates with moderate or severe HIE.

Ventral striatum and stuttering: Robust evidence from a case-control study applying DARTEL

A prominent theory of developmental stuttering highlights (dys-)function of the basal ganglia (and in particular the ventral striatum) as a main neural mechanism behind this speech disorder. Although the theory is intriguing, studies on gray matter volume differences in the basal ganglia between people who stutter and control persons have reported heterogeneous findings, either showing more or less gray matter volume of the aforementioned brain structure across the brain's hemispheres. Moreover, some studies did not observe any differences at all. From today's perspective several of the earlier studies are rather underpowered and also used less powerful statistical approaches to investigate differences in brain structure between people who stutter and controls. Therefore, the present study contrasted a comparably larger sample of n = 36 people who stutter with n = 34 control persons and applied the state of the art DARTEL algorithm (Diffeomorphic Anatomical Registration Through Exponentiated Lie algebra) to analyze the available brain data. In the present data set stuttering was associated with higher gray matter volume of the right caudate and putamen region of the basal ganglia in patients. Our observation strongly supports a recent finding reporting a larger nucleus accumbens in the right hemisphere in people who stutter when compared to control persons. The present findings are discussed in the context of both compensatory effects of the brain and putative therapeutic effects due to treatment of stuttering.

Adapting the flow of time with dopamine

The modulation of interval timing by dopamine (DA) has been well established over decades of research. The nature of this modulation, however, has remained controversial: Although the pharmacological evidence has largely suggested that time intervals are overestimated with higher DA levels, more recent optogenetic work has shown the opposite effect. In addition, a large body of work has asserted DA's role as a "reward prediction error" (RPE), or a teaching signal that allows the basal ganglia to learn to predict future rewards in reinforcement learning tasks. Whether these two seemingly disparate accounts of DA may be related has remained an open question. By taking a reinforcement learning-based approach to interval timing, we show here that the RPE interpretation of DA naturally extends to its role as a modulator of timekeeping and furthermore that this view reconciles the seemingly conflicting observations. We derive a biologically plausible, DA-dependent plasticity rule that can modulate the rate of timekeeping in either direction and whose effect depends on the timing of the DA signal itself. This bidirectional update rule can account for the results from pharmacology and optogenetics as well as the behavioral effects of reward rate on interval timing and the temporal selectivity of striatal neurons. Hence, by adopting a single RPE interpretation of DA, our results take a step toward unifying computational theories of reinforcement learning and interval timing. NEW & NOTEWORTHY How does dopamine (DA) influence interval timing? A large body of pharmacological evidence has suggested that DA accelerates timekeeping mechanisms. However, recent optogenetic work has shown exactly the opposite effect. In this article, we relate DA's role in timekeeping to its most established role, as a critical component of reinforcement learning. This allows us to derive a neurobiologically plausible framework that reconciles a large body of DA's temporal effects, including pharmacological, behavioral, electrophysiological, and optogenetic.

Cause or effect: Altered brain and network activity in cervical dystonia is partially normalized by botulinum toxin treatment

Background

Idiopathic cervical dystonia (CD) is a chronic movement disorder characterized by impressive clinical symptoms and the lack of clear pathological findings in clinical diagnostics and imaging. At present, the injection of botulinum toxin (BNT) in dystonic muscles is an effective therapy to control motor symptoms and pain in CD.

Objectives

We hypothesized that, although it is locally injected to dystonic muscles, BNT application leads to changes in brain and network activity towards normal brain function.

Methods

Using 3 T functional MR imaging along with advanced analysis techniques (functional connectivity, Granger causality, and regional homogeneity), we aimed to characterize brain activity in CD (17 CD patients vs. 17 controls) and to uncover the effects of BNT treatment (at 6 months).

Results

In CD, we observed an increased information flow within the basal ganglia, the thalamus, and the sensorimotor cortex. In parallel, some of these structures became less responsive to regulating inputs. Furthermore, our results suggested an altered somatosensory integration. Following BNT administration, we noted a shift towards normal brain function in the CD patients, especially within the motor cortex, the somatosensory cortex, and the basal ganglia.

Conclusion

The changes in brain function and network activity in CD can be interpreted as related to the underlying cause, the effort to compensate or a mixture of both. Although BNT is applied in the last stage of the cortico-neuromuscular pathway, brain patterns are shifted towards those of healthy controls.

•

we characterized brain activity in CD and the effects of BNT using 3T fMR imaging and network analysis techniques

•

following treatment with botulinum toxin (BNT), abnormal brain activity patterns in primary dystonia are attenuated

•

critical key regions for both the pathophysiology and BNT-induced improvement in cervical dystonia are the BG

Functional neuroanatomical review of the ventral tegmental area

The ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) are assumed to play a key role in dopamine-related functions such as reward-related behaviour, motivation, addiction and motor functioning. Although dopamine-producing midbrain structures are bordering, they show significant differences in structure and function that argue for a distinction when studying the functions of the dopaminergic midbrain, especially by means of neuroimaging. First, unlike the SNc, the VTA is not a nucleus, which makes it difficult to delineate the structure due to lack of clear anatomical borders. Second, there is no consensus in the literature about the anatomical nomenclature to describe the VTA. Third, these factors in combination with limitations in magnetic resonance imaging (MRI) complicate VTA visualization. We suggest that developing an MRI-compatible probabilistic atlas of the VTA will help to overcome these issues. Such an atlas can be used to identify the individual VTA and serve as region-of-interest for functional MRI.

On the Motion of Spikes: Turbulent-Like Neuronal Activity in the Human Basal Ganglia

Neuronal signals are usually characterized in terms of their discharge rate, a description inadequate to account for the complex temporal organization of spike trains. Complex temporal properties, which are characteristic of neuronal systems, can only be described with the appropriate, complex mathematical tools. Here, I apply high order structure functions to the analysis of neuronal signals recorded from parkinsonian patients during functional neurosurgery, recovering multifractal properties. To achieve an accurate model of such multifractality is critical for understanding the basal ganglia, since other non-linear properties, such as entropy, depend on the fractal properties of complex systems. I propose a new approach to the study of neuronal signals: to study spiking activity in terms of the velocity of spikes, defining it as the inverse function of the instantaneous frequency. I introduce a neural field model that includes a non-linear gradient field, representing neuronal excitability, and a diffusive term to consider the physical properties of the electric field. Multifractality is present in the model for a range of diffusion coefficients, and multifractal temporal properties are mirrored into space. The model reproduces the behavior of human basal ganglia neurons and shows that it is like that of turbulent fluids. The results obtained from the model predict that passive electric properties of neuronal activity, including ephaptic coupling, are far more relevant to the human brain than what is usually considered: passive electric properties determine the temporal and spatial organization of neuronal activity in the neural tissue.

T1-MPRAGE and T2-FLAIR segmentation of cortical and subcortical brain regions-an MRI evaluation study

PURPOSE

Development of a warp-based automated brain segmentation approach of 3D fluid-attenuated inversion recovery (FLAIR) images and comparison to 3D T1-based segmentation.

METHODS

3D FLAIR and 3D T1-weighted sequences of 30 healthy subjects (mean age 29.9 ± 8.3 years, 8 female) were acquired on the same 3T MR scanner. Warp-based segmentation was applied for volumetry of total gray matter (GM), white matter (WM), and 116 atlas regions. Segmentation results of both sequences were compared using Pearson correlation (r).

RESULTS

Correlation of GM segmentation results based on FLAIR and T1 was overall good for cortical structures (mean r across all cortical structures = 0.76). Comparatively weaker results were found in the occipital lobe (r = 0.77), central region (mean r = 0.58), basal ganglia (mean r = 0.59), thalamus (r = 0.30), and cerebellum (r = 0.73). FLAIR segmentation underestimated volume of the central region compared to T1, but showed a better anatomic concordance with the occipital lobe on visual review and subcortical structures, when also compared to manual segmentation. Visual analysis of FLAIR-based WM segmentation revealed frequent misclassification of regions of high signal intensity as GM.

CONCLUSION

Warp-based FLAIR segmentation yields comparable results to T1 segmentation for most cortical GM structures and may provide anatomically more congruent segmentation of subcortical GM structures. Selected cortical regions, especially the central region and total WM, seem to be underestimated on FLAIR segmentation.

Expression of α-synuclein is regulated in a neuronal cell type-dependent manner

α-Synuclein, the major component of Lewy bodies (LBs) and Lewy neurites (LNs), is expressed in presynapses under physiologically normal conditions and is involved in synaptic function. Abnormal intracellular aggregates of misfolded α-synuclein such as LBs and LNs are pathological hallmarks of synucleinopathies, including Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). According to previous studies using pathological models overexpressing α-synuclein, high expression of this protein in neurons is a critical risk factor for neurodegeneration. Therefore, it is important to know the endogenous expression levels of α-synuclein in each neuronal cell type. We previously reported differential expression profiles of α-synuclein in vitro and in vivo. In the wild-type mouse brain, particularly in vulnerable regions affected during the progression of idiopathic PD, α-synuclein is highly expressed in neuronal cell bodies of some early PD-affected regions, such as the olfactory bulb, the dorsal motor nucleus of the vagus, and the substantia nigra pars compacta. Synaptic expression of α-synuclein is mostly accompanied by expression of vesicular glutamate transporter-1, an excitatory synapse marker protein. In contrast, α-synuclein expression in inhibitory synapses differs among brain regions. Recently accumulated evidence indicates the close relationship between differential expression profiles of α-synuclein and selective vulnerability of certain neuronal populations. Further studies on the regulation of α-synuclein expression will help to understand the mechanism of LB pathology and provide an innovative therapeutic strategy to prevent PD and DLB onset.

Preserved but Less Efficient Control of Response Interference After Unilateral Lesions of the Striatum

Previous research on the neural basis of cognitive control processes has mainly focused on cortical areas, while the role of subcortical structures in cognitive control is less clear. Models of basal ganglia function as well as clinical studies in neurodegenerative diseases suggest that the striatum (putamen and caudate nucleus) modulates the inhibition of interfering responses and thereby contributes to an important aspect of cognitive control, namely response interference control. To further investigate the putative role of the striatum in the control of response interference, 23 patients with stroke-induced lesions of the striatum and 32 age-matched neurologically healthy controls performed a unimanual version of the Simon task. In the Simon task, the correspondence between stimulus location and response location is manipulated so that control over response interference can be inferred from the reaction time costs in incongruent trials. Results showed that stroke patients responded overall slower and more erroneous than controls. The difference in response times (RTs) between incongruent and congruent trials (known as the Simon effect) was smaller in the ipsilesional/-lateral hemifield, but did not differ significantly between groups. However, in contrast to controls, stroke patients exhibited an abnormally stable Simon effect across the reaction time distribution indicating a reduced efficiency of the inhibition process. Thus, in stroke patients unilateral lesions of the striatum did not significantly impair the general ability to control response interference, but led to less efficient selective inhibition of interfering responses.

A Brain-Inspired Decision-Making Spiking Neural Network and Its Application in Unmanned Aerial Vehicle

Decision-making is a crucial cognitive function for various animal species surviving in nature, and it is also a fundamental ability for intelligent agents. To make a step forward in the understanding of the computational mechanism of human-like decision-making, this paper proposes a brain-inspired decision-making spiking neural network (BDM-SNN) and applies it to decision-making tasks on intelligent agents. This paper makes the following contributions: (1) A spiking neural network (SNN) is used to model human decision-making neural circuit from both connectome and functional perspectives. (2) The proposed model combines dopamine and spike-timing-dependent plasticity (STDP) mechanisms to modulate the network learning process, which indicates more biological inspiration. (3) The model considers the effects of interactions among sub-areas in PFC on accelerating the learning process. (4) The proposed model can be easily applied to decision-making tasks in intelligent agents, such as an unmanned aerial vehicle (UAV) flying through a window and a UAV avoiding an obstacle. The experimental results support the effectiveness of the model. Compared with traditional reinforcement learning and existing biologically inspired methods, our method contains more biologically-inspired mechanistic principles, has greater accuracy and is faster.

Face-to-trait inferences in patients with Parkinson's disease

Introduction: Parkinson's disease is a progressive neurological disorder characterized by the preferential loss of dopaminergic neurons in the substantia nigra, which project to the striatum. The disease is characterized by prominent motor symptoms, which are its cardinal features. Consequently, Parkinson's disease has been primarily considered a disorder of movement. However, increasing evidence has indicated that Parkinson's disease affects not only the motor domain but also the cognitive domain. Increasing evidence indicates that patients with Parkinson's disease have an impaired ability to recognize emotional facial expressions. Recent studies have reported that other socially relevant information from faces, including face-to-trait inferences for traits such as dominance, competence, and trustworthiness, may be processed in subcortical regions, including the amygdala and caudate nucleus. However, the mechanism underlying the processing of face-to-trait inferences for these traits in patients with Parkinson's disease is still unknown. This study aimed to assess the face-to-trait inference ability in patients with Parkinson's disease. Method: Face-to-trait inference ability was assessed using a forced-choice method in patients with Parkinson's disease and age- and sex-matched healthy controls. Results: Overall correct face-to-trait inferences occurred significantly less frequently in the Parkinson's disease group than in the control group. Further analysis revealed a significant interaction between groups and the extent to which facial features were exaggerated. Conclusions: The present results suggest that the sensitivity of face-to-trait processing was linear in the Parkinson's disease group but not in the healthy controls. These deficits may have resulted from dysfunction in subcortical regions, which may also lead to impairment in other social inferential abilities in patients with Parkinson's disease.

Effects of Parkinson disease and antiparkinson medication on central adaptations to repetitive grasping

Cortical activity during motor task performance is attenuated in individuals with Parkinson disease (PD) relative to age-matched adults without PD, and this activity is enhanced with antiparkinson medication. It remains unclear, however, whether the relative change in cortical activity over the duration of the task, i.e., central adaptation, is affected individuals with PD, and if so, whether medication corrects for any unique behaviors. Movement-related cortical potentials (MRCPs) were recorded from scalp electrode sites Cz and C1 during 150 repetitive handgrip contractions at 70% of maximal voluntary contraction, in individuals with PD (n = 10) both ON and OFF of their PD medication, and neurologically normal age- and sex-matched controls (n = 10). Repetitions were divided into two Blocks (Block 1 and 2: repetitions 1-60 and 91-150, respectively), and the composite MRCP slopes were calculated during periods representing movement initiation (-2 s to movement onset) and execution (movement onset to 1 s). No significant interactions were noted for either comparison (PD OFF vs. control; PD OFF vs. PD ON), irrespective of electrode site (Cz or C1) or movement period (initiation or execution). Despite similar MRCP slopes and task performance, PD OFF endorsed greater perceived exertion during task performance than controls. In the present study, we observed attenuated task-related cortical activity among individuals with PD OFF relative to controls, but a similar relative adaptive response to a fatiguing task. Additionally, although antiparkinson medication enhanced cortical activity (PD OFF vs. PD ON), central adaptation was similar.