Cerebellar Contributions to Verbal Working Memory

There is increasing evidence for a cerebellar role in working memory. Clinical research has shown that working memory impairments after cerebellar damage and neuroimaging studies have revealed task-specific activation in the cerebellum during working memory processing. A lateralisation of cerebellar function within working memory has been proposed with the right hemisphere making the greater contribution to verbal processing and the left hemisphere for visuospatial tasks. We used continuous theta burst stimulation (cTBS) to examine whether differences in post-stimulation performance could be observed based on the cerebellar hemisphere stimulated and the type of data presented. We observed that participants were significantly less accurate on a verbal version of a Sternberg task after stimulation to the right cerebellar hemisphere when compared to left hemisphere stimulation. Performance on a visual Sternberg task was unaffected by stimulation of either hemisphere. We discuss our results in the context of prior studies that have used cerebellar stimulation to investigate working memory and highlight the cerebellar role in phonological encoding.     

Cerebellar Contributions to the Processing of Saccadic Errors

Saccades are fast eye movements that direct the point of regard to a target in the visual field. Repeated post-saccadic visual errors can induce modifications of the amplitude of these saccades, a process known as saccadic adaptation. Two experiments using the same paradigm were performed to study the involvement of the cerebrum and the cerebellum in the processing of saccadic errors using functional magnetic resonance imaging and in-scanner eye movement recordings. In the first active condition, saccadic adaptation was prevented using a condition in which the saccadic target was shifted to a variable position during the saccade towards it. This condition induced random saccadic errors as opposed to the second active condition in which the saccadic target was not shifted. In the baseline condition, subjects looked at a stationary dot. Both active conditions compared with baseline evoked activation in the expected saccade-related regions using a stringent statistical threshold [the frontal and parietal eye fields, primary visual area, MT/V5, and the precuneus (V6) in the cerebrum; vermis VI–VII; and lobule VI in the cerebellum, known as the oculomotor vermis). In the direct comparison between the two active conditions, significantly more cerebellar activation (vermis VIII, lobules VIII-X, left lobule VIIb) was observed with random saccadic errors (using a more relaxed statistical threshold). These results suggest a possible role for areas outside the oculomotor vermis of the cerebellum in the processing of saccadic errors. Future studies of these areas with, e.g., electrophysiological recordings, may reveal the nature of the error signals that drive the amplitude modification of saccadic eye movements.     

Normal Motor Adaptation in Cervical Dystonia: A Fundamental Cerebellar Computation is Intact

The potential role of the cerebellum in the pathophysiology of dystonia has become a focus of recent research. However, direct evidence for a cerebellar contribution in humans with dystonia is difficult to obtain. We examined motor adaptation, a test of cerebellar function, in 20 subjects with primary cervical dystonia and an equal number of aged matched controls. Adaptation to both visuomotor (distorting visual feedback by 30°) and forcefield (applying a velocity-dependent force) conditions were tested. Our hypothesis was that cerebellar abnormalities observed in dystonia research would translate into deficits of cerebellar adaptation. We also examined the relationship between adaptation and dystonic head tremor as many primary tremor models implicate the cerebellothalamocortical network which is specifically tested by this motor paradigm. Rates of adaptation (learning) in cervical dystonia were identical to healthy controls in both visuomotor and forcefield tasks. Furthermore, the ability to adapt was not clearly related to clinical features of dystonic head tremor. We have shown that a key motor control function of the cerebellum is intact in the most common form of primary dystonia. These results have important implications for current anatomical models of the pathophysiology of dystonia. It is important to attempt to progress from general statements that implicate the cerebellum to a more specific evidence-based model. The role of the cerebellum in this enigmatic disease perhaps remains to be proven.     

Adaptation,Expertise, and Giftedness: Towards an Understanding of Cortical,Subcortical, and Cerebellar Network Contributions

Current cortico-centric models of cognition lack a cohesive neuroanatomic framework that sufficiently considers overlapping levels of function, from “pathological” through “normal” to “gifted” or exceptional ability. While most cognitive theories presume an evolutionary context, few actively consider the process of adaptation, including concepts of neurodevelopment. Further, the frequent co-occurrence of “gifted” and “pathological” function is difficult to explain from a cortico-centric point of view. This comprehensive review paper proposes a framework that includes the brain’s vertical organization and considers “giftedness” from an evolutionary and neurodevelopmental vantage point. We begin by discussing the current cortico-centric model of cognition and its relationship to intelligence. We then review an integrated, dual-tiered model of cognition that better explains the process of adaptation by simultaneously allowing for both stimulus-based processing and higher-order cognitive control. We consider the role of the basal ganglia within this model, particularly in relation to reward circuitry and instrumental learning. We review the important role of white matter tracts in relation to speed of adaptation and development of behavioral mastery. We examine the cerebellum’s critical role in behavioral refinement and in cognitive and behavioral automation, particularly in relation to expertise and giftedness. We conclude this integrated model of brain function by considering the savant syndrome, which we believe is best understood within the context of a dual-tiered model of cognition that allows for automaticity in adaptation as well as higher-order executive control.     

Cathodal Transcranial Direct Current Stimulation (tDCS) to the Right Cerebellar Hemisphere Affects Motor Adaptation During Gait

The cerebellum appears to play a key role in the development of internal rules that allow fast, predictive adjustments to novel stimuli. This is crucial for adaptive motor processes, such as those involved in walking, where cerebellar dysfunction has been found to increase variability in gait parameters. Motor adaptation is a process that results in a progressive reduction in errors as movements are adjusted to meet demands, and within the cerebellum, this seems to be localised primarily within the right hemisphere. To examine the role of the right cerebellar hemisphere in adaptive gait, cathodal transcranial direct current stimulation (tDCS) was administered to the right cerebellar hemisphere of 14 healthy adults in a randomised, double-blind, crossover study. Adaptation to a series of distinct spatial and temporal templates was assessed across tDCS condition via a pressure-sensitive gait mat (ProtoKinetics Zeno walkway), on which participants walked with an induced ‘limp’ at a non-preferred pace. Variability was assessed across key spatial-temporal gait parameters. It was hypothesised that cathodal tDCS to the right cerebellar hemisphere would disrupt adaptation to the templates, reflected in a failure to reduce variability following stimulation. In partial support, adaptation was disrupted following tDCS on one of the four spatial-temporal templates used. However, there was no evidence for general effects on either the spatial or temporal domain. This suggests, under specific conditions, a coupling of spatial and temporal processing in the right cerebellar hemisphere and highlights the potential importance of task complexity in cerebellar function.     

Cerebellar Contributions to Different Phases of Visceral Aversive Extinction Learning

The cerebellum is increasingly recognized to contribute to non-motor functions, including cognition and emotion. Although fear conditioning has been studied for elucidating the pathophysiology of anxiety, the putative role of the cerebellum is still unknown. Fear conditioning could also be important in the etiology of chronic abdominal pain which often overlaps with anxiety. Hence, in this exploratory analysis, we investigated conditioned anticipatory activity in the cerebellum in a visceral aversive fear conditioning paradigm using functional magnetic resonance imaging. We extended and reanalyzed a previous dataset for different learning phases, i.e., acquisition, extinction, and reinstatement, utilizing an advanced normalizing method of the cerebellum. In 30 healthy humans, visual conditioned stimuli (CS⁺) were paired with painful rectal distensions as unconditioned stimuli (US), while other visual stimuli (CS^?) were presented without US. During extinction, all CSs were presented without US, whereas during reinstatement, a single, unpaired US was presented. During acquisition, posterolateral cerebellar areas including Crus I, Crus II, and VIIb and parts of the dentate nucleus were activated in response to the CS⁺ compared to the CS^?. During extinction, activation related to CS⁺ presentation was detected in Crus I, Crus II, IV, V, VI, VIIb, IX, and vermis. Neural correlates of reinstatement were found in Crus I, Crus II, IV, V, and IX. We could show for the first time that the cerebellum is involved in abdominal pain-related associative learning processes. Together, these findings contribute to our understanding of the cerebellum in aversive learning and memory processes relevant to the pathophysiology of chronic abdominal pain.     

Making Sense of Horror

Engagement is intricately woven into the fabric of development and the fabric of psychoanalysis. However, there has been little effort to describe the process and essence of therapeutic engagement itself, or closely consider its effects. We propose that engagement with others occurs under highly specific circumstances. We identify three conditions: 1) a core positive affective investment; 2) prioritization; and 3) continuity. When these conditions are conjoined in the context of certain relational parameters, they can initiate a process that catalyzes the development of the mental, affective, and social capacities fostered in relationships. Through this process, a “charged other” emerges, a person who holds increased positive value (though not consistently positive affect), with whom this catalyzing of capacities becomes possible.     

Asymmetries in Cerebellar Plasticity and Motor Learning

Synaptic plasticity at the parallel fiber to Purkinje cell synapse has long been considered a cellular correlate for cerebellar motor learning. Functionally, long-term depression and long-term potentiation at these synapses seem to be the reverse of each other, with both pre- and post-synaptic expression occurring in both. However, different cerebellar motor learning paradigms have been shown to be asymmetric and not equally reversible. Here, we discuss the asymmetric reversibility shown in the vestibulo-ocular reflex and eyeblink conditioning and suggest that different cellular plasticity mechanisms might be recruited under different conditions leading to unequal reversibility.     

Shared Mechanisms of Perceptual Learning and Decision Making

Perceptual decisions require the brain to weigh noisy evidence from sensory neurons to form categorical judgments that guide behavior. Here we review behavioral and neurophysiological findings suggesting that at least some forms of perceptual learning do not appear to affect the response properties of neurons that represent the sensory evidence. Instead, improved perceptual performance results from changes in how the sensory evidence is selected and weighed to form the decision. We discuss the implications of this idea for possible sites and mechanisms of training‐induced improvements in perceptual processing in the brain.     

Cerebellar agenesis II: Motor and language functions

In a former study of a patient with cerebellar agenesis (HK) mild motor deficits, problems in delay eyeblink conditioning and mild to moderate deficits in IQ, planning behavior, visuospatial abilities, visual memory, and attention were found. The present study reports additional findings in the same patient. In the motor domain, impairments in fine motor manipulations, trace eyeblink conditioning and motor imagination in a functional magnetic resonance (fMRI) study were found. Based on fMRI findings; however, cortical areas involved in a tapping task did not significantly differ from a healthy control group. In the cognitive domain, deficits in speech comprehension as well as verbal learning and declarative memory were present. No significant affective symptoms were observed. Although problems in executive, visuospatial and language tasks are in agreement with the so-called cerebellar cognitive affective syndrome—other possibilities remain. Non-motor impairments in HK might also be a consequence of lacking motor abilities in development and motor deficits may interfere with the performance of parts of the cognitive tasks. In addition, lack of promotion and learning opportunities in childhood may contribute and mental retardation based on extracerebellar dysfunction cannot be excluded.     

Making Sense of Arson Through Classification

Arson classification efforts are an attempt to make sense of a complex whole. To a greater or lesser extent typologies offered to date have relied on assumed motive. More recently, systems that combine information about offender characteristics and/or offence features have become increasingly popular. The ability to categorise arsonists accurately has significant implications for both mental health professionals and fire authorities. It is important to understand the limitations of arson classification systems generally to be able to apply them judiciously. This article discusses arson classification systems and examines three key approaches before providing an overview of some of the limitations of arson typologies generally.     

Effects of Attention and Perceptual Uncertainty on Cerebellar Activity During Visual Motion Perception

Recent clinical and neuroimaging studies have revealed that the human cerebellum plays a role in visual motion perception, but the nature of its contribution to this function is not understood. Some reports suggest that the cerebellum might facilitate motion perception by aiding attentive tracking of visual objects. Others have identified a particular role for the cerebellum in discriminating motion signals in perceptually uncertain conditions. Here, we used functional magnetic resonance imaging to determine the degree to which cerebellar involvement in visual motion perception can be explained by a role in sustained attentive tracking of moving stimuli in contrast to a role in visual motion discrimination. While holding the visual displays constant, we manipulated attention by having participants attend covertly to a field of random-dot motion or a colored spot at fixation. Perceptual uncertainty was manipulated by varying the percentage of signal dots contained within the random-dot arrays. We found that attention to motion under high perceptual uncertainty was associated with strong activity in left cerebellar lobules VI and VII. By contrast, attending to motion under low perceptual uncertainty did not cause differential activation in the cerebellum. We found no evidence to support the suggestion that the cerebellum is involved in simple attentive tracking of salient moving objects. Instead, our results indicate that specific subregions of the cerebellum are involved in facilitating the detection and discrimination of task-relevant moving objects under conditions of high perceptual uncertainty. We conclude that the cerebellum aids motion perception under conditions of high perceptual demand.     

Contributions of the Life Course Perspective to Research on Food Decision Making

Background

The life course perspective (LCP) has emerged as a powerful organizing framework for the study of health, illness, and mortality. LCP represents a “whole life” analysis perspective which originated in the field of sociology.

Methods

Its concepts are increasingly applied to understanding the development of chronic disease over long periods of time in the human life span. A missing link, however, in the adaptation of the LCP to health research, is the insight the LCP may offer into understanding the societal, social network, and family contexts that frame stability and change in dietary behavior.

Results

This paper reviews key concepts that comprise the LCP but primarily focuses on applications that have relevance to food decision making in social context. A case study of chronic work–family stress and perceived time scarcity as barriers to dietary improvement is included.

Conclusion

Illustrative findings are presented on dietary behavior in a diverse sample of lower-income working parents. This paper also offers ideas on increasing the contributions of the LCP to nutritional research.

     

Hypothalamic Histaminergic and Orexinergic Modulation on Cerebellar and Vestibular Motor Control

Somatic–nonsomatic integration is critical for generation and execution of an appropriate and coordinated behavioral response to changes in internal and external environments. However, the underlying neural substrates and mechanisms are still enigmatic. Intriguingly, the central histaminergic and orexinergic systems originating from the hypothalamus, a high autonomic regulatory center, innervate almost the whole brain including various subcortical motor structures, particularly the cerebellum and vestibular nuclei. Here, we suggest that the hypothalamic histaminergic and orexinergic system bridging the nonsomatic center to somatic motor structures may actively modulate the cerebellar and vestibular nuclear neurons and subsequently participate in motor control and somatic–nonsomatic integration.     

Locomotor Adaptation Is Associated with Microstructural Properties of the Inferior Cerebellar Peduncle

The Cerebellum - In sensorimotor adaptation paradigms, participants learn to adjust their behavior in response to an external perturbation. Locomotor adaptation and reaching adaptation depend on...     

Cerebellar Control of Motor Activation and Cancellation in Humans: An Electrophysiological Study

Execution of rapid ballistic movement is characterized by triphasic, alternating electromyographic bursts in agonist (AG) and antagonist (ANT) muscles. The ability to rapidly initiate movement and cancel ongoing action is a basic requirement for efficient control of motor function. Normal functioning of the cerebellum is necessary for the generation of AG and ANT muscle activity that should be both of appropriate magnitude and timing to control the dynamic phase of arm movements. We studied AG, ANT reaction time (RT), and RT differences in both motor activation (MA) and motor cancellation (MC) tasks, in response to an auditory stimulus. The results showed that right cerebellar transcranial magnetic stimulation (TMS) with a horizontally applied focal coil resulted in decreased AG RT and increased latency difference between AG RT and ANT RT (DIFF) in the ipsilateral upper limb during MC. No effect was apparent during sham stimulation, MA tasks, left upper limb recording, and other coil orientations. While the high correlation between AG and ANT RT suggests a close relationship in both MA and MC, significant DIFF changes point to an alteration of this relationship by TMS during MC. Although TMS resulted in significantly increased DIFF during MC tasks, this was not due to delayed ANT RT. This suggests that the short ANT burst observed invariably during MC may not be a cerebellum-generated response, but is derived from the cortical or subcortical level. The focal nature of our TMS coil and the horizontally effective orientation supports the hypothesis of interference with the parallel fiber system. Our findings contribute to the understanding of cerebellar neural networks involvement in movements, in particular, those pertaining to cessation of an ongoing action not previously addressed.