The role of the cerebellum in unconsciuos and conscious processing of emotions: a review

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data have been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing

Brain structural and functional correlates with balance/gait in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder with major clinical sensorimotor signs, including bradykinesia (slowed movements), rigidity, tremor and postural instability with gait disability. It affects multiple aspects (domains) of balance and gait, namely, anticipatory postural adjustments prior to voluntary movements, automatic postural responses to external perturbations, postural sway in stance and dynamic stability during gait. The goal of the present work is to improve our understanding of brain networks involved in balance and gait disorders by studying the associations between structural/functional characteristics of the brain with motor behaviors in people with PD and older adults

Neurobiological investigations of autism symptomatology and cerebellar pathology

The cerebellum is the most commonly reported brain region to demonstrate pathology in autism. Multiple reports have indicated a lower density of Purkinje cells (PCs) in the posterolateral cerebellar hemispheres. We performed a stereological technique to precisely quantify PCs in postmortem autism cases compared to age- and sex-matched controls. We found that although PC density was lower in all cerebellar regions studied, the most significant difference was in lobule VIIa of the posterior lobe. The PCs in this region project to deep cerebellar nuclei that reciprocally connect to all aspects of the established broader sensorimotor gating network. Sensorimotor gating abnormalities are commonly observed in individuals diagnosed with autism, and may contribute to problems with sensory processing and behavioral inhibition in these individuals. We studied a rat model of sensorimotor gating impairment, in which the histamine H1 receptor antagonist, pyrilamine, improved sensorimotor gating. Using autoradiography, we found that pyrilamine treatment altered H1 receptor and α7 nicotinic receptor binding in the anterior cingulate and insular cortex, respectively, an effect which correlated with improved sensorimotor gating. Histamine functions as both a neurotransmitter as well as a regulator of glial activity throughout the brain. Using western blots, we quantified H1 receptor levels in lobule VIIa from postmortem autism cases but found no difference compared to controls. We further quantified additional proteins to investigate theories of neuroimmune and neuroendocrine dysregulation in the cerebellum in autism. These included IBA-1, GFAP, IL-6, androgen receptor, estrogen receptor β, and aromatase. We found no evidence to support these theories: all protein levels tested were found to be similar in the autism and control groups. We suggest further studies to better understand cerebellar pathogenesis and regulation of sensorimotor gating in autism. The implications of sensorimotor gating impairment in autism are discussed in relation to the established symptomatology of this neurodevelopmental behavioral disorder

Unique Features and Neuronal Properties in a Multisensory Cortex

UNIQUE FEAUTRES OF ORGANIZATION AND NEURONAL PROPERTIES IN A MULTISENSORY CORTEX Multisensory processing is a ubiquitous sensory effect that underlies a wide variety of behaviors, such as detection and orientation, as well as perceptual phenomena from speech comprehension to binding. Such multisensory perceptual effects are presumed to be based in cortex, especially within areas known to contain multisensory neurons. However, unlike their lower-level/primary sensory cortical counterparts, little is known about the connectional, functional and laminar organization of higher-level multisensory cortex. Therefore, to examine the fundamental features of neuronal processing and organization in the multisensory cortical area of the posterior parietal cortex (PPr) of ferrets, the present experiments utilized a combination of immunohistological, neuroanatomical and multiple single-channel electrophysiological recording techniques. These experiments produced four main results. First, convergence of extrinsic inputs from unisensory cortical areas predominantly in layers 2-3 in PPr corresponded with the high proportion of multisensory neurons in those layers. This is consistent with multisensory responses in this higher-level multisensory region being driven by cortico-cortical, rather than thalamo-cortical connections. Second, the laminar organization of the PPr differed substantially from the pattern commonly observed in primary sensory cortices. The PPr has a reduced layer 4 compared to primary sensory cortices, which does not receive input from principal thalamic nuclei. Third, the distribution of unisensory and multisensory neurons and properties differs significantly by layer. Given the laminar-dependent input-output relationships, this suggests that unisensory and multisensory signals are processed in parallel as they pass through the circuitry of the PPr. Finally, specific functional properties of bimodal neurons differed significantly from those of their unisensory counterparts. Thus, despite their coextensive distribution within cortex, these results differentiate bimodal from unisensory neurons in ways that have never been examined before. Together these experiments represent the first combined anatomical-electrophysiological examination of the laminar organization of a multisensory cortex and the first systematic comparison of the functional properties of bimodal and unisensory neurons. These results are essential for understanding the neural bases of multisensory processing and carry significant implications for the accurate interpretation of macroscopic studies of multisensory brain regions (i.e. fMRI, EEG), because bimodal and unisensory neurons within a given neural region can no longer be assumed to respond similarly to a given external stimulus

The neural architecture of emotional intelligence.

Emotional Intelligence (EI) is a nebulous concept that permeates daily interpersonal communication. Despite prolific research into its benefits, EI subjective measurement is difficult, contributing to an enigmatic definition of its core constructs. However, neuroimaging research probing socioaffective brain mechanisms underlying putative EI constructs can add an objective perspective to existing models, thereby illuminating the nature of EI. Therefore, the primary aim of this dissertation is to identify brain networks underlying EI and examine how EI arises from the brain’s functional and structural neuroarchitecture. EI is first defined according to behavioral data, which suggests EI is made up of two core constructs: Empathy and Emotion Regulation (ER). The interaction of brain networks underlying Empathy and ER is then investigated using a novel neuroimaging analysis method: dynamic functional connectivity (dynFC). The results suggest efficient communication and (re)configuration between the CEN, DMN, SN underlie both ER and RME task dynamics, and that these temporal patterns relate to trait empathy and ER tendency. Given the demonstrated behavioral and neurobiological relationship between empathy and ER, our second aim is to examine each of these constructs individually through detailed experiments using a variety of neuroimaging methodologies. The dissertation concludes by proposing EI is an ability that arises from the effective, yet flexible communication between brain networks underlying Empathy and ER. The dissertation is divided into five chapters. Chapter I describes the foundational concept of EI as originally described by a variety of psychological figures and the lacuna that exists in terms of its neural correlates. Chapter II presents behavioral data that proposes EI is best predicted by Empathy and ER. Chapter III explores the dynamic relationship between brain networks underlying Empathy and ER, with the aim of elucidating their neurobiological associations, and investigate how such associations may combine to create EI. Chapter IV examines Empathy closely, by probing its neurobiological relationship to interoception and anxiety. Chapter V examines ER closely, by investigating whether gender plays a role in ER, and its neurobiological relationship to hormones. Chapter VI links the general findings from Chapters III, IV and V, and proposes an integrative neurocognitive EI model. The dissertation concludes by providing clinical and non-clinical applications for the model

Cerebellar contributions to visual attention and working memory

Attention and working memory (WM) are processes that enable the efficient prioritization or storage of a subset of available information. Consequently, a substantial body of work has sought to determine the specific brain structures that support attention and WM. To date, this literature has predominantly focused on the contributions of a limited set of cortical areas referred to as the dorsal attention network (DAN). The cerebellum, a subcortical structure traditionally implicated in motor control, has received scant consideration as a locus of attentional control, despite findings of robust anatomical and functional connectivity between cerebellum and DAN areas. This project comprises several functional magnetic resonance imaging experiments aimed at elucidating the role of the cerebellum in attention and WM (n = 38; 20-38 years). The functional implications of cortico-cerebellar DAN connectivity have received only modest scientific attention. Experiment 1 examined the hypothesis that cortico-cerebellar DAN functional connectivity predicts recruitment by canonical visual WM and attention tasks. Task-driven responses of DAN-coupled cerebellar areas were found to mirror those of their cortical counterparts. These results argue for the reconceptualization of the DAN as a cortico-cerebellar network. Previous work indicates that the functional topography of the cerebellum is relatively coarse compared with cerebral cortex. Experiment 2 examined the organization of closely related aspects of visual attention and WM within the cerebellum, and found that spatial attention and visual WM recruit overlapping yet dissociable portions of cerebellar lobule VIIb/VIIIa. This functional organization was further shown to be predicted by fine-scale patterns of functional connectivity with occipito-parietal cortex. These findings indicate that the functional specificity of cerebellar cortex mirrors that of cerebral cortex and provides direct empirical support for the hypothesis that functional specialization within the cerebellum arises due to variation in afferent input. Experiment 3 tested the hypothesis that the cerebellum can be specifically implicated in the persistent representation of information in WM. Lobule VIIb/VIIIa delay-period activity patterns were shown to exhibit stimulus-selectivity, a critical marker of WM storage processes. These results indicate that lobule VIIb/VIIIa contains a robust representation of a stimulus stored in WM, thereby refuting long-standing cortico-centric models of WM maintenance.2021-02-10T00:00:00

Large-Scale Networks in the Human Brain revealed by Functional Connectivity MRI

The human brain is composed of distributed networks that connect a disproportionately large neocortex to the brainstem, cerebellum and other subcortical structures. New methods for analyzing non-invasive imaging data have begun to reveal new insights into human brain organization. These methods permit characterization of functional interactions within and across brain networks, and allow us to appreciate points of departure between the human brain and non-human primates.Psycholog