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Alain Berthoz

Bio: Alain Berthoz is an academic researcher from Collège de France. The author has contributed to research in topics: Eye movement & Vestibular system. The author has an hindex of 79, co-authored 434 publications receiving 20944 citations. Previous affiliations of Alain Berthoz include University of Limoges & University of Iowa.


Papers
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Journal ArticleDOI
TL;DR: The study emphasizes the importance of head stabilization as part of the postural control system and described as a basis for inertial guidance.
Abstract: Head kinematics were studied in ten normal subjects while they executed various locomotor tasks The movement of the body was recorded with a video system which allowed a computer reconstruction of motion of joint articulations and other selected points on the body in three dimensions Analyses focus on head translation along the vertical axis and rotation in the sagittal plane This was done by recording the displacement of a line approximating the plane of horizontal semi-circular canals (the Frankfort plane: F-P) Four conditions were studied: free walking (W) walking in place (WIP) running in place (R) and hopping (H) In the 4 experimental conditions, amplitude and velocity of head translation along the vertical axis ranged from 1 cm to 25 cm and 015 m/s to 18 m/s In spite of the disparities in the tasks regarding the magnitude of dynamic components, we found a significant stabilization of the F-P around the earth horizontal Maximum amplitude of F-P rotation did not exceed 20° in the 4 situations Vertical angular velocities increased from locomotion tasks to the dynamic equilibrium task although the maximum values remained less than 140°/s Predominant frequencies of translations and rotations in all the tasks were within the range 04–35 Hz and harmonics were present up to 6–8 Hz During walking in darkness, mean head position is tilted downward, with the F-P always below the earth horizontal Darkness did not significantly influence the amplitude and velocity of head angular displacement during W, WIP and R, but during H the amplitude decreased by 37% Residual head angular displacement is found to compensate for head translation during the 4 conditions Our study emphasizes the importance of head stabilization as part of the postural control system and described as a basis for inertial guidance

690 citations

Journal ArticleDOI
TL;DR: This work directly test the hypothesis that transformations of mental images are at least in part guided by motor processes by means of a dual-task paradigm in which subjects perform the Cooper-Shepard mental rotation task while executing an unseen motor rotation in a given direction and at a previously-learned speed.

514 citations

Journal ArticleDOI
TL;DR: From the dynamic relationships between the velocity of the moving visual scene and the amplitude of sway, it was concluded that the postural readjustment is proportional to a low pass filtering of the logarithm of the velocity.
Abstract: Visually induced linear motion sensation (linear vection) was obtained by projection of a visual scene moving linearly in a sagittal plane at the periphery of the visual field of healthy subjects standing erect on a force platform. This linear vection induces postural readjustments characterized by an inclination of the subject, in the same direction as the movement of the visual scene, followed by an after-effect. The amplitude of the postural changes was: a) logarithmically proportional to the image velocity and the density (or the spatial frequency) of the image pattern, at highest image velocities there was a saturation of the postural effect due to limits in image motion perception and not to biomechanical constraints; b) dependent appreciably on the size of the moving scene and its relative location (in the visual field). The frequency analysis of postural readjustments showed a) an increase of the amplitude of postural sway, especially at the low frequencies (from 0.02–0.2 Hz); b) sharp peaks in the power spectrum located between 0.15 and 0.5 Hz. From the dynamic relationships between the velocity of the moving visual scene and the amplitude of sway, it was concluded that the postural readjustment is proportional to a low pass filtering of the logarithm of the velocity. The contribution of Tibialis Anterior and Soleus was to oppose the body inclination with a resistive force. These results are analyzed in regard to the current theories concerning visual, vestibular and preceptive interaction in postural mechanisms.

449 citations

Journal ArticleDOI
TL;DR: Conflicting situations in which visual cues contradict vestibular and other proprioceptive cues show, in the case of linearvection a dominance of vision which supports the idea of an essential although not independent role of vision in self motion perception.
Abstract: The basic characteristics of the sensation of linear horizontal motion have been studied. Objective linear motion was induced by means of a moving cart. Visually induced linear motion perception (linearvection) was obtained by projection of moving images at the periphery of the visual field. Image velocity and luminance thresholds for the appearance of linearvection have been measured and are in the range of those for image motion detection (without sensation of self motion) by the visual system. Latencies of onset are around 1 sec and short term adaptation has been shown. The dynamic range of the visual analyser as judged by frequency analysis is lower than for the vestibular analyser. Conflicting situations in which visual cues contradict vestibular and other proprioceptive cues show, in the case of linearvection a dominance of vision which supports the idea of an essential although not independent role of vision in self motion perception.

441 citations

Journal ArticleDOI
TL;DR: This paper presents navigation strategies within a four-level hierarchical framework based upon levels of complexity of required processing (Guidance, Place recognition-triggered Response, Topological navigation, Metric navigation), and introduces computational models of animal navigation, i.e. of animats.

390 citations


Cited by
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Journal ArticleDOI
TL;DR: This historical survey compactly summarizes relevant work, much of it from the previous millennium, review deep supervised learning, unsupervised learning, reinforcement learning & evolutionary computation, and indirect search for short programs encoding deep and large networks.

14,635 citations

Book ChapterDOI
TL;DR: This chapter demonstrates the functional importance of dopamine to working memory function in several ways and demonstrates that a network of brain regions, including the prefrontal cortex, is critical for the active maintenance of internal representations.
Abstract: Publisher Summary This chapter focuses on the modern notion of short-term memory, called working memory. Working memory refers to the temporary maintenance of information that was just experienced or just retrieved from long-term memory but no longer exists in the external environment. These internal representations are short-lived, but can be maintained for longer periods of time through active rehearsal strategies, and can be subjected to various operations that manipulate the information in such a way that makes it useful for goal-directed behavior. Working memory is a system that is critically important in cognition and seems necessary in the course of performing many other cognitive functions, such as reasoning, language comprehension, planning, and spatial processing. This chapter demonstrates the functional importance of dopamine to working memory function in several ways. Elucidation of the cognitive and neural mechanisms underlying human working memory is an important focus of cognitive neuroscience and neurology for much of the past decade. One conclusion that arises from research is that working memory, a faculty that enables temporary storage and manipulation of information in the service of behavioral goals, can be viewed as neither a unitary, nor a dedicated system. Data from numerous neuropsychological and neurophysiological studies in animals and humans demonstrates that a network of brain regions, including the prefrontal cortex, is critical for the active maintenance of internal representations.

10,081 citations

Journal ArticleDOI
06 Jun 1986-JAMA
TL;DR: The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or her own research.
Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

7,563 citations