Brain Mechanisms for the Integration of Posture and Movement

The neuroscientist Alain Berthoz experimented on Russian astronauts in space to answer these questions: How does weightlessness affect motion? How are motion and three-dimensional space perceived? In this erudite and witty book, Berthoz describes how human beings on earth perceive and control bodily movement. Reviewing a wealth of research in neurophysiology and experimental psychology, he argues for a rethinking of the traditional separation between action and perception, and for the division of perception into five senses. In Berthoz’s view, perception and cognition are inherently predictive, functioning to allow us to anticipate the consequences of current or potential actions. The brain acts like a simulator that is constantly inventing models to project onto the changing world, models that are corrected by steady, minute feedback from the world. We move in the direction we are looking, anticipate the trajectory of a falling ball, recover when we stumble, and continually update our own physical position, all thanks to this sense of movement. This interpretation of perception and action allows Berthoz, in The Brain’s Sense of Movement, to focus on psychological phenomena largely ignored in standard texts: proprioception and kinaesthesis, the mechanisms that maintain balance and coordinate actions, and basic perceptual and memory processes involved in navigation.

From recent developments in the rapidly growing area of neuroscience it has become increasingly clear that a simplistic description of brain function as a broad collection of simple input-output relations is quite inadequate. Introspection already tells us that our motor behavior is guided by a complex interplay between many inputs from the outside world and from our internal "milieu," internal models of ourselves and the outside world, memory content, directed attention, volition, and so forth. Also, our motor activity normally involves more than a circumscribed group of muscles, even if we intend to move only one effector organ. For example, a reaching movement or a reorientation of a sensory organ almost invariably requires a pattern of preparatory or assisting activities in other parts of the body, like the ones that maintain the body's equilibrium. The present volume is a summary of the papers presented at the symposium "Sensory Interaction in Posture and Movement Control" that was held at Smolenice Castle near Bratislava, Slovakia, as a Satellite Symposium to the ENA Meeting 1994 in Vienna. The focus of this meeting was not only restricted to the "classical" sensory interactions such as between vestibular and visual signals, or between otolith and semicircular canal inputs. Rather, the symposium tried to consider also the interplay between perception and action, between reflexive and volitional motor acts as well as between sensory driven or self-initi ated motor acts and reafferent inputs.

Relative to the extensive neuroscientific work on seated meditation practices, far less studies have investigated the neural mechanisms underlying movement-based contemplative practices such as yoga or tai chi. Movement-based practices have, however, been found to be effective for relieving the symptoms of several clinical conditions, and to elicit measurable changes in physiological, neural, and behavioral parameters in healthy individuals. An important challenge for neuroscience is therefore to advance our understanding of the neurophysiological and neurocognitive mechanisms underlying these observed effects, and this Research Topic aims to make a contribution in this regard. It showcases the current state of the art of investigations on movement-based practices including yoga, tai chi, the Feldenkrais Method, as well as dance. Featured contributions include empirical research, proposals of theoretical frameworks, as well as novel perspectives on a variety of issues relevant to the field. This Research Topic is the first of its kind to specifically attempt a neurophysiological and neurocognitive characterization that spans multiple mindful movement approaches, and we trust it will be of interest to basic scientists, clinical researchers, and contemplative practitioners alike.

This collection of contributions on the subject of the neural mechanisms of sensorimotor control resulted from a conference held in Cairns, Australia, September 3-6, 2001. While the three of us were attending the International Union of Physiological Sciences (IUPS) Congress in St Petersburg, Russia, in 1997, we discussed the implications of the next Congress being awarded to New Zealand. We agreed to organise a satellite to this congress in an area of mutual interest -the neuroscience of movement and sensation. Australia has a long-standing and enviable reputation in the field of neural mechanisms of sensorimotor control. Arguably this reached its peak with the award of a Nobel Prize to Sir John Eccles in 1963 for his work on synaptic transmission in the central nervous system. Since that time, the subject of neuroscience has progressed considerably. One advance is the exploitation of knowledge acquired from animal experiments to studies on conscious human subjects. In this development, Australians have achieved international prominence, particularly in the areas of kinaesthesia and movement control. This bias is evident in the choice of subject matter for the conference and, subsequently, this book. It was also decided to assign a whole section to muscle mechanics, a subject that is often left out altogether from conferences on motor control. Cairns is a lovely city and September is a good time to visit it.

Goal-directed movement is central to the relationship between brain and behavior in humans and other animals. This book presents a detailed investigation of the topic, one that integrates psychology and physiology. The author's account is based on a large body of experimental data from human and animal work, with particular emphasis on clinical cases. It probes such questions as: Are complex movements organized on the same mode as simple ones? How rigidly organized are coordinated actions like orienting or grasping? Where do visual feedback signals arise? The author's work takes into account the growing acceptance of the idea that movements are not directly dependent upon sensory events, but that they are governed by internal representations which are built according to specific, experimentally accessible rules.

Balance Dysfunction in Parkinson's Disease: Basic Mechanisms to Clinical Management presents the most updated information on a variety of topics. Sections help clinicians evaluate the types of balance control issues, dynamic balance dysfunction during turning, and the effects of medication, deep brain stimulation, and rehabilitation intervention on balance control. This book is the first to review the four main postural control systems and how they are affected, including balance during quiet stance, reactive postural adjustments to external perturbations, anticipatory postural adjustments in preparation for voluntary movements, and dynamic balance control during walking and turning. In addition, the book's authors summarize the effects of levodopa, deep brain stimulation, and rehabilitation intervention for each balance domain. This book is recommended for anyone interested in how and why balance control is affected by PD. - Provides the first comprehensive review of research to date on balance dysfunctions in Parkinson's disease - Discusses how to translate current neuroscience research into practice regarding neural control of balance - Provides evidence on the effects of current interventions on balance control

Sensation of Movement explores the role of sensation in motor control, bodily self-recognition and sense of agency. The sensation of movement is dependent on a range of information received by the brain, from signalling in the peripheral sensory organs to the establishment of higher order goals. Through the integration of neuroscientific knowledge with psychological and philosophical perspectives, this book questions whether one type of information is more relevant for the ability to sense and control movement. Addressing conscious sensations of movement, experimental designs and measures, and the possible functions of proprioceptive and kinaesthetic information in motor control and bodily cognition, the book advocates the integration of neuroscientific knowledge and philosophical perspectives. With an awareness of the diverse ideas and theories from these distinct fields, the book brings together leading researchers to bridge these divides and lay the groundwork for future research. Of interest to both students and researchers of consciousness, Sensation of Movement will be essential reading for those researching motor control, multimodal perception, bodily self-recognition, and sense of agency. It aims to encourage the integration of multiple perspectives in order to arrive at new insights into how sensation of movement can be studied scientifically.