Central Neural Mechanisms of Touch and Proprioception

1994 ◽  
Vol 72 (5) ◽  
pp. 542-545 ◽  
Author(s):  
John F. Kalaska
Keyword(s):  
Similar Case ◽  
Mechanical Stimulus ◽  
Muscle Contractions ◽  
Neural Mechanisms ◽  
Neural Representation ◽  
Perceptual Process ◽  
Active Muscle ◽  
Motivational State ◽  
Tactile Discrimination ◽  
Neuronal Mechanisms

The argument is made that somesthesia is not a strictly passive process, and its central neuronal mechanisms cannot be studied in all their complexity and subtlety by applying passive stimuli to uninterested or unconscious animals. The case is clear for kinesthesia. Peripheral proprioceptive signals are altered by active muscle contractions, and the central mechanisms of kinesthetic sensations should be studied during active movements. A similar case can be made for tactile discrimination. Ascending tactile afferents are subject to modulation during movement. Moreover, the generation of a central neural representation of the mechanical stimulus is only part of the tactile perceptual process. It is also influenced by the behavioral, attentive, and motivational state of the animal, whose effects can only be revealed in awake animals actively participating in discrimination tasks.Key words: tactile discrimination, proprioception, gating, attention, active touch.

Parallel Neuronal Mechanisms Underlying Physiological Force Tremor in Steady Muscle Contractions of Humans

2006 ◽  
Vol 95 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Constantinos N. Christakos ◽  
Nikos A. Papadimitriou ◽  
Sophia Erimaki
Keyword(s):  
Muscle Contractions ◽  
Force Tremor ◽  
Neuronal Mechanisms

scholarly journals Mice are not automatons; subjective experience in premotor circuits guides behavior

2021 ◽  
Author(s):  
Drew C. Schreiner ◽  
Christian Cazares ◽  
Rafael Renteria ◽  
Christina M Gremel
Keyword(s):  
Decision Making ◽  
Motor Cortex ◽  
Adaptive Behavior ◽  
Subjective Experience ◽  
Contextual Factors ◽  
Neural Mechanisms ◽  
Neural Representation ◽  
Recent Experience ◽  
Checking Behavior ◽  
Corticostriatal Circuits

Subjective experience is a powerful driver of decision-making and continuously accrues. However, most neurobiological studies constrain analyses to task-related variables and ignore how continuously and individually experienced internal, temporal, and contextual factors influence adaptive behavior during decision-making and the associated neural mechanisms. We show mice rely on learned information about recent and longer-term subjective experience of variables above and beyond prior actions and reward, including checking behavior and the passage of time, to guide self-initiated, self-paced, and self-generated actions. These experiential variables were represented in secondary motor cortex (M2) activity and its projections into dorsal medial striatum (DMS). M2 integrated this information to bias strategy-level decision-making, and DMS projections used specific aspects of this recent experience to plan upcoming actions. This suggests diverse aspects of experience drive decision-making and its neural representation, and shows premotor corticostriatal circuits are crucial for using selective aspects of experiential information to guide adaptive behavior.

Perception and Imagery

Brain-Mind ◽  
2019 ◽  
pp. 50-71
Author(s):  
Paul Thagard
Keyword(s):  
Neural Mechanisms ◽  
Neural Representation ◽  
Sensory Inputs ◽  
General Account ◽  
Binding Competition ◽  
Mental Operations

This chapter provides a general account of imagery that applies to both external senses such as vision and internal senses such as pain. It identifies five mental operations that occur in all kinds of imagery: intensification, focusing, combination, juxtaposition, and decomposition. Each of these operations results from neural mechanisms that are part of the Semantic Pointer Architecture, including storage, retrieval, neural representation, binding, competition, and transformation. There is abundant psychological and neural evidence that imagery is real and that the brain’s computations employ special patterns of neural representation that develop from sensory inputs. This development requires binding into semantic pointers that are susceptible to symbol-like manipulation that exploits the different sensory characters of visual, auditory, and other sorts of representation.

Timed synchronization of muscle contraction to heartbeat enhances muscle hyperemia

2020 ◽  
Vol 128 (4) ◽  
pp. 805-812
Author(s):  
Gaia Giuriato ◽  
Stephen J. Ives ◽  
Cantor Tarperi ◽  
Lorenzo Bortolan ◽  
Federico Ruzzante ◽  
...  
Keyword(s):  
Blood Flow ◽  
Muscle Contraction ◽  
Blood Velocity ◽  
Muscle Contractions ◽  
Velocity Spectrum ◽  
Functional Hyperemia ◽  
Central Hemodynamics ◽  
Active Muscle ◽  
Vascular Conductance ◽  
Significant Difference

Blood flow (BF) to exercising muscles is susceptible to variations of intensity, and duration of skeletal muscle contractions, cardiac cycle, blood velocity, and vessel dilation. During cyclic muscle activity, these elements may change proportionally with or without direct optimal temporal alignment, likely influencing BF to active muscle. Ideally, the pulsed delivery of blood to active muscle timed with the inactive phase of muscle duty-cycle would enhance the peak and average BF. To investigate the phenomenon of muscle contraction and pulse synchronicity, electrically evoked muscle contractions (trains of 20 Hz, 200-ms duration) were synchronized with each systolic phase of the anterograde blood velocity spectrum (aBVS). Specifically, unilateral quadriceps contractions matched in-phase (IP) with the aBVS were compared with contractions matched out-of-phase (OP) with the aBVS in 10 healthy participants (26 ± 3 yr). During each trial, femoral BF of the contracting limb and central hemodynamics were recorded for 5 min with an ultrasound Doppler, a plethysmograph, and a cardioimpedance device. At steady state (5th min) IP BF (454 ± 30 mL/min) and vascular conductance (4.3 ± 0.2 mL·min−1·mmHg−1), and OP MAP (108 ± 2 mmHg) were significantly lower ( P < 0.001) in comparison to OP BF (784 ± 25 mL/min) and vascular conductance (6.7 ± 0.2 mL·min−1·mmHg−1), and IP MAP (113 ± 3 mmHg). On the contrary, no significant difference (all, P > 0.05) was observed between IP and OP central hemodynamics (HR: 79 ± 10 vs. 76 ± 11 bpm, CO: 8.0 ± 1.6 vs. 7.3 ± 1.6 L/min), and ventilatory patterns (V̇e:14 ± 2 vs. 14 ± 1 L/min, V̇o2:421 ± 70 vs. 397 ± 34 mL/min). The results suggest that muscle contractions occurring during OP that do not interfere with aBVS elicit a maximization of muscle functional hyperemia. NEW & NOTEWORTHY When muscle contraction is synchronized with the pulsed delivery of blood flow to active muscle, muscle functional hyperemia can be either maximized or minimized. This suggests a possibility to couple different strategies to enhance the acute and chronic effects of exercise on the cardiovascular system.

scholarly journals Mechanical and signaling mechanisms that guide pre-implantation embryo movement

2020 ◽  
Author(s):  
Diana Flores ◽  
Manoj Madhavan ◽  
Savannah Wright ◽  
Ripla Arora
Keyword(s):  
Physical Object ◽  
Reproductive Technologies ◽  
Mechanical Stimulus ◽  
Muscle Contractions ◽  
Confocal Imaging ◽  
Mammalian Embryo ◽  
Unique Challenge ◽  
Equal Distribution ◽  
3D Image Reconstruction ◽  
Unidirectional Movement

ABSTRACTHow a mammalian embryo determines and arrives at its site of attachment is a mystery that has puzzled researchers for decades. Additionally, in multiparous species, embryos face a unique challenge of achieving adequate spacing to avoid competition for maternal resources. Using our enhanced confocal imaging and 3D image reconstruction technology, we evaluate murine embryo location in the uterus along the longitudinal oviductal-cervical axis. Our analysis reveals three distinct pre-implantation stages: a) Embryo entry; b) Unidirectional movement of embryo clusters; and c) Bidirectional scattering and spacing of embryos. We show that unidirectional movement of embryo clusters is facilitated by a mechanical stimulus of the embryo as a physical object and is regulated by adrenergic uterine smooth muscle contractions. Embryo scattering, on the other hand, relies on embryo-uterine communication reliant on the LPAR3 signaling pathway and is independent of adrenergic muscle contractions. We propose that the presence of embryo clusters in the uterine horn provides an opportunity for the uterus to sense and count the embryos, followed by scattering and spacing these embryos along the given length of the horn. Thus, uterine implantation sites in mice are neither random nor predetermined but are guided by the number of embryos entering the uterine lumen. These studies have implications for understanding how embryo-uterine communication is key to determining an optimal implantation site, which is necessary for the success of a pregnancy.Significance StatementIn mammals that carry multiple offspring in one gestation, embryos seemingly acquire even embryo spacing. Such even distribution would imply a guided interaction between the mother and the fetus very early on in pregnancy to allow favorable pregnancy outcomes. Thus, it is essential to understand quantitatively if and when such a uniform distribution of embryos is established. Further, uncovering the physical and biological mechanisms that allow for such equal distribution of embryos, will improve our understanding of early pregnancy events and provide for novel targets for improving pregnancy success in case of infertility and artificial reproductive technologies as well as to develop non-hormonal therapies for contraception.

scholarly journals Reading positional codes with fMRI: Problems and solutions

2016 ◽  
Author(s):  
Kristjan Kalm ◽  
Dennis Norris
Keyword(s):  
Memory Load ◽  
Large Body ◽  
Neural Mechanisms ◽  
Neural Representation ◽  
Sensory Adaptation ◽  
Neural Data ◽  
Problems And Solutions ◽  
Consistent Manner ◽  
Human Experiments ◽  
Human Neuroimaging

Neural mechanisms which bind items into sequences have been investigated in a large body of research in animal neurophysiology and human neuroimaging. However, a major problem in interpreting this data arises from a fact that several unrelated processes, such as memory load, sensory adaptation, and reward expectation, also change in a consistent manner as the sequence unfolds. In this paper we show that the problem of extracting neural data about the structure of a sequence is especially acute for fMRI, which is almost exclusively the modality used in human experiments. We show that such fMRI results must be treated with caution and in many cases the assumed neural representation might actually reflect unrelated processes.

A Computational Study of Complex Varus Instability of the Human Elbow Joint

2010 ◽  
Author(s):  
Edward M. Spratley ◽  
Jennifer S. Wayne
Keyword(s):  
Elbow Joint ◽  
Computational Study ◽  
Muscle Contractions ◽  
The Body ◽  
Joint Function ◽  
Active Muscle ◽  
Complex Interplay ◽  
Varus Instability

The intact human elbow joint is one of the most inherently stable joints of the body with stability conferred through a complex interplay between highly congruous osseous constraints, capsuloligamentous constraints, and active muscle contractions. [1, 2] Deficits in any of these structures can create instabilities that impede normal joint function.

scholarly journals Mechanical and signaling mechanisms that guide pre-implantation embryo movement

Development ◽  
2020 ◽  
Vol 147 (24) ◽  
pp. dev193490
Author(s):  
Diana Flores ◽  
Manoj Madhavan ◽  
Savannah Wright ◽  
Ripla Arora
Keyword(s):  
Attachment Site ◽  
Mechanical Stimulus ◽  
Muscle Contractions ◽  
Confocal Imaging ◽  
Mammalian Embryo ◽  
Uterine Smooth Muscle ◽  
Unidirectional Movement ◽  
Signaling Mechanisms ◽  
Implantation Sites ◽  
Smooth Muscle Contractions

ABSTRACTHow a mammalian embryo determines and arrives at its attachment site has been studied for decades, but our understanding of this process is far from complete. Using confocal imaging and image analysis, we evaluate embryo location along the longitudinal oviductal-cervical axis of murine uteri. Our analysis reveals three distinct pre-implantation phases: embryo entry, unidirectional movement of embryo clusters and bidirectional scattering and spacing of embryos. We show that unidirectional clustered movement is facilitated by a mechanical stimulus of the embryo and is regulated by adrenergic uterine smooth muscle contractions. Embryo scattering, on the other hand, depends on embryo-uterine communication reliant on the LPAR3 signaling pathway and is independent of adrenergic muscle contractions. Finally, we demonstrate that uterine implantation sites in mice are neither random nor predetermined but are guided by the number of embryos entering the uterine lumen. These studies have implications for understanding how embryo-uterine communication is key to determining an optimal implantation site necessary for the success of a pregnancy.

scholarly journals Neuronal Mechanisms that Drive Organismal Aging Through the Lens of Perception

2020 ◽  
Vol 82 (1) ◽  
pp. 227-249
Author(s):  
Christi M. Gendron ◽  
Tuhin S. Chakraborty ◽  
Brian Y. Chung ◽  
Zachary M. Harvanek ◽  
Kristina J. Holme ◽  
...  
Keyword(s):  
Sensory Perception ◽  
Neural Mechanisms ◽  
Threat Perception ◽  
Food Perception ◽  
Age Related ◽  
Or Groups ◽  
Neuronal Mechanisms ◽  
Perception Time ◽  
Potential Impact ◽  
The Individual

Sensory neurons provide organisms with data about the world in which they live, for the purpose of successfully exploiting their environment. The consequences of sensory perception are not simply limited to decision-making behaviors; evidence suggests that sensory perception directly influences physiology and aging, a phenomenon that has been observed in animals across taxa. Therefore, understanding the neural mechanisms by which sensory input influences aging may uncover novel therapeutic targets for aging-related physiologies. In this review, we examine different perceptive experiences that have been most clearly linked to aging or age-related disease: food perception, social perception, time perception, and threat perception. For each, the sensory cues, receptors, and/or pathways that influence aging as well as the individual or groups of neurons involved, if known, are discussed. We conclude with general thoughts about the potential impact of this line of research on human health and aging.

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