Pre-movement changes in sensorimotor beta oscillations predict motor adaptation drive

International audienceBeta frequency oscillations in scalp electroencephalography (EEG) recordings over the primary motor cortex have been associated with the preparation and execution of voluntary movements. Here, we test whether changes in beta frequency are related to the preparation of adapted movements in human, and whether such effects generalise to other species (cat). Eleven healthy adult humans performed a joystick visuomotor adaptation task. Beta (15-25 Hz) scalp EEG signals recorded over the motor cortex during a pre-movement preparatory phase were, on average, significantly reduced in amplitude during early adaptation trials compared to baseline, late adaptation, or aftereffect trials. The changes in beta were not related to measurements of reaction time or reach duration. We also recorded local field potential (LFP) activity within the primary motor cortex of three cats during a prism visuomotor adaptation task. Analysis of these signals revealed similar reductions in motor cortical LFP beta frequencies during early adaptation. This effect was present when controlling for any influence of the reaction time and reach duration. Overall, the results are consistent with a reduction in pre-movement beta oscillations predicting an increase in adaptive drive in upcoming task performance when motor errors are largest in magnitude and the rate of adaptation is greatest

Non-invasive Stimulation of the Cerebellum in Health and Disease

The cerebellum is linked to motor, cognitive and affective functions. Anatomically, the cerebellum is part of an interconnected network including a wide range of other brain structures. This chapter reviews ways in which non-invasive stimulation has been used to activate or inhibit these circuits and how this has contributed to our understanding of cerebellar function in both motor and non-motor domains. The utility of non-invasive stimulation of the cerebellum in the treatment of neurological and psychiatric diseases (Parkinson’s disease, cerebellar ataxia, stroke, depression and schizophrenia) is discussed. The chapter concludes with consideration of the challenges that must be overcome if non-invasive cerebellar stimulation is to be adopted in a wider clinical setting

Microbial memories: sex-dependent impact of the gut microbiome on hippocampal plasticity

Germ-free rodents, raised in the absence of a measurable gut microbiome, have been a key model to study the microbiome-gut-brain axis. Germ-free mice exhibit marked behavioural and neurochemical differences to their conventionally raised counterparts. It is as yet unclear how these neurochemical differences lead to the behavioural differences. Here, we test the electrophysiological properties of hippocampal plasticity in adult germ-free mice and compare them to conventionally raised counterparts. Whilst basal synaptic efficacy and pre-synaptic short-term plasticity appear normal, we find a striking alteration of hippocampal long-term potentiation specifically in male germ-free slices. However, the spike output of these neurons remains normal along with altered input-output coupling, potentially indicating homeostatic compensatory mechanisms, or an altered excitation/inhibition balance. To our knowledge this is the first time the electrophysiological properties of the hippocampus have been assessed in a microbiome deficient animal. Our data indicate that the absence of a microbiome alters integration of dendritic signalling in the CA1 region in mice

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Neuronal activity patterns in microcircuits of the cerebellar cortical C3 zone during reaching

Abstract: The cerebellum is the largest sensorimotor structure in the brain. A fundamental organizational feature of its cortex is its division into a series of rostrocaudally elongated zones. These are defined by their inputs from specific parts of the inferior olive and Purkinje cell output to specific cerebellar and vestibular nuclei. However, little is known about how patterns of neuronal activity in zones, and their microcircuit subdivisions, microzones, are related to behaviour in awake animals. In the present study, we investigated the organization of microzones within the C3 zone and their activity during a skilled forelimb reaching task in cats. Neurons in different microzones of the C3 zone, functionally determined by receptive field characteristics, differed in their patterns of activity during movement. Groups of Purkinje cells belonging to different receptive field classes, and therefore belonging to different microzones, were found to collectively encode different aspects of the reach controlled by the C3 zone. Our results support the hypothesis that the cerebellar C3 zone is organized and operates within a microzonal frame of reference, with a specific relationship between the sensory input to each microzone and its motor output. (Figure presented.). Key points: A defining feature of cerebellar organization is its division into a series of zones and smaller subunits termed microzones. Much of how zones and microzones are organized has been determined in anaesthetized preparations, and little is known about their function in awake animals. We recorded from neurons in the forelimb part of the C3 zone ‘in action’ by recording from single cerebellar cortical neurons located in different microzones defined by their peripheral receptive field properties during a forelimb reach–retrieval task in cats. Neurons from individual microzones had characteristic patterns of activity during movement, indicating that function is organized in relation to microcomplexes

Single-Cell Control of Initial Spatial Structure in Biofilm Development Using Laser Trapping

Biofilms are sessile communities of microbes that are spatially structured by an embedding matrix. Biofilm infections are notoriously intractable. This arises, in part, from changes in the bacterial phenotype that result from spatial structure. Understanding these interactions requires methods to control the spatial structure of biofilms. We present a method for growing biofilms from initiating cells whose positions are controlled with single-cell precision using laser trapping. The native growth, motility, and surface adhesion of positioned microbes are preserved, as we show for model organisms Pseudomonas aeruginosa and Staphylococcus aureus. We demonstrate that laser-trapping and placing bacteria on surfaces can reveal the effects of spatial structure on bacterial growth in early biofilm development