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- Alstermark, Bror, et al.
(författare)
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Anders Lundberg (1920-2009)
- 2010
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Ingår i: Experimental Brain Research. - : Springer. - 0014-4819 .- 1432-1106. ; 200:3-4, s. 193-195
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Anders Lundberg was one of the founding editorial board members for EBR when it began its life in 1976 under the editorship of John Eccles. He was also one of the most prolific contributors to the journal with a total of 49 papers, including a series of 16 on the topic of "integration in descending motor pathways controlling the forelimb in the cat". He continued as an editor of the journal until volume 16 when he persuaded his younger colleague Hans Hultborn to take his place. Hans is one of the authors of the obituary. –John Rothwell
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| 2. |
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| 3. |
- Alstermark, Bror, et al.
(författare)
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Building a realistic neuronal model that simulates multi-joint arm and hand movements in 3D space
- 2007
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Ingår i: HFSP Journal. - : Informa UK Limited. - 1955-2068. ; 1:4, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- The question as to how the brain controls voluntary movements of the arm and hand still remains largely unsolved despite much research focused on behavioral studies, neurophysiological investigations, and neuronal modeling in computer science. This is because behavioral studies are usually performed without detailed knowledge of the underlying neuronal networks, neurophysiological studies often lack an understanding of the function, and neuronal models are frequently focused on a particular control problem with restricted knowledge of the underlying neuronal networks involved. Therefore, it seems appropriate to start by trying to integrate knowledge of neuronal networks with known function and computer based neuronal models to seek more realistic models that can better control robots or artificial limbs and hands. We propose to combine knowledge of a behavioral model for reaching with the hand toward an object, which is based on detailed knowledge of the underlying neuronal network, and a neuronal model that includes several functional levels, from the planning level via intermediate levels to the final level of control of motoneurons and muscles.
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| 4. |
- Alstermark, Bror, et al.
(författare)
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Circuits for skilled reaching and grasping
- 2012
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Ingår i: Annual Review of Neuroscience. - Palo alto : ANNUAL REVIEWS. - 1545-4126. - 9780824324353 ; , s. 559-578
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Bokkapitel (refereegranskat)abstract
- From an evolutionary perspective, it is clear that basic motor functions such as locomotion and posture are largely controlled by neural circuitries residing in the spinal cord and brain-stem. The control of voluntary movements such as skillful reaching and grasping is generally considered to be governed by neural circuitries in the motor cortex that connect directly to motoneurons via the corticomotoneuronal (CM) pathway. The CM pathway may act together with several brain-stem systems that also act directly with motoneurons. This simple view was challenged by work in the cat, which lacks the direct CM system, showing that the motor commands for reaching and grasping could be mediated via spinal interneurons with input from the motor-cortex and brain-stem systems. It was further demonstrated that the spinal interneurons mediating the descending commands for reaching and grasping constitute separate and distinct populations from those involved in locomotion and posture. The aim of this review is to describe populations of spinal interneurons that are involved in the control of skilled reaching and grasping in the cat, monkey, and human.
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| 5. |
- Alstermark, Bror, et al.
(författare)
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Endogenous plasticity in neuro-rehabirtation following partial spinal cord lesions
- 2014
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-453X .- 1662-4548. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Currently, much interest in neuro-rehabilitation is focused on mechanisms related to axonal outgrowth and formation of new circuits although still little is known about the functionality in motor behavior. This is a highly exciting avenue of research and most important to consider when dealing with large lesions. Here, we address endogenous mechanisms with the potential of modifying the function of already existing spinal circuits via associative plasticity. We forward a hypothesis based on experimental findings suggesting that potentiation of synaptic transmission in un-injured pathways can be monitored and adjusted by a Cerebellar loop involving the Reticulospinal, Rubrospinal and Corticospinal tracts and spinal interneurons with projection to motoneurons. This mechanism could be of relevance when lesions are less extensive and the integrity of the neural circuits remains in part. Endogenous plasticity in the spinal cord could be of clinical importance if stimulated in an adequate manner, e.g., by using optimal training protocols.
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| 6. |
- Alstermark, Bror, et al.
(författare)
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In vivo recordings of bulbospinal excitation in adult mouse forelimb motoneurons.
- 2004
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Ingår i: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 92:3, s. 1958-62
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Tidskriftsartikel (refereegranskat)abstract
- Here we report on pyramidal and reticulospinal excitation in forelimb motoneurons in the adult mouse using intracellular recordings in vivo. The results have been obtained in BALB/C mice, which were anesthetized with midazolam fentanyl/fluanison. In contrast to the rat, only weak and infrequent pyramidal excitation could be evoked with a minimal trisynaptic linkage. Disynaptic reticulospinal excitation could always be evoked, as well as monosynaptic excitation from the medial longitudinal fasciculus. The results suggest that the reticulospinal pathway in the mouse is important in voluntary motor control of the forelimbs and that the role of the corticospinal tract might be different in mouse compared with rat. Our study provides an opening for studying the effect of genetic manipulation on specified descending systems in the mouse in vivo.
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| 7. |
- Alstermark, Bror, et al.
(författare)
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Lack of monosynaptic corticomotoneuronal EPSPs in rats : disynaptic EPSPs mediated via reticulospinal neurons and polysynaptic EPSPs via segmental interneurons.
- 2004
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Ingår i: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 91:4, s. 1832-9
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Tidskriftsartikel (refereegranskat)abstract
- In the rat, some findings have been taken to suggest the existence of monosynaptic corticomotoneuronal (CM) connections. Because this connection is believed to be largely responsible for the ability to make independent digit movements in primates and man, it has been inferred that the monosynaptic CM connection in the rat is likewise important for skilled prehension. Comparison of intra- and extracellular recordings from forelimb motoneurons in anesthetized rats, revealed no monosynaptic CM excitatory postsynaptic potentials (EPSPs). The fastest descending excitation in forelimb motoneurons was disynaptically mediated via a corticoreticulospinal pathway and slowly conducted excitation via corticospinal fibers and segmental interneurons. The findings stress the importance of di- and trisynaptic excitatory corticofugal pathways to forelimb motoneurons in the control of skillful digit movements.
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| 8. |
- Alstermark, Bror, et al.
(författare)
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Motor command for precision grip in the macaque monkey can be mediated by spinal interneurons
- 2011
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Ingår i: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 106:1, s. 122-126
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Tidskriftsartikel (refereegranskat)abstract
- In motor control, the general view is still that spinal interneurons mainly contribute to reflexes and automatic movements. The question raised here is whether spinal interneurons can mediate the cortical command for independent finger movements, like a precision grip between the thumb and index finger in the macaque monkey, or if this function depends exclusively on a direct corticomotoneuronal pathway. This study is a followup of a previous report (Sasaki et al. J Neurophysiol 92: 3142-3147, 2004) in which we trained macaque monkeys to pick a small piece of sweet potato from a cylinder by a precision grip between the index finger and thumb. We have now isolated one spinal interneuronal system, the C3-C4 propriospinal interneurons with projection to hand and arm motoneurons. In the previous study, the lateral corticospinal tract (CST) was interrupted in C4/C5 (input intact to the C3-C4 propriospinal interneurons), and in this study, the CST was interrupted in C2 (input abolished). The precision grip could be performed within the first 15 days after a CST lesion in C4/C5 but not in C2. We conclude that C3-C4 propriospinal interneurons also can carry the command for precision grip.
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| 9. |
- Alstermark, Bror, et al.
(författare)
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Premotoneuronal and direct corticomotoneuronal control in the cat and macaque monkey.
- 2002
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Ingår i: Advances in Experimental Medicine and Biology. - 0065-2598 .- 2214-8019. ; 508, s. 281-97
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Tidskriftsartikel (refereegranskat)abstract
- The literature on premotoneuronal and direct corticomotoneuronal (CM) control in the cat and macaque monkey is reviewed. The available experimental findings are not in accordance with a recently proposed hypothesis that direct CM connections have "replaced" the premotoneuronal pathways. Instead, we propose that premotoneuronal CM control plays an important role in motor control also in primates and that the direct CM connection has been added during phylogeny.
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| 10. |
- Alstermark, Bror, et al.
(författare)
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Skilled reaching and grasping in the rat: Lacking effect of corticospinal lesion
- 2014
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Ingår i: Frontiers in Neurology. - : Frontiers Research Foundation. - 1664-2295. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The corticospinal system is a major motor pathway in the control of skilled voluntary movements such as reaching and grasping. It has developed considerably phylogenetically to reach a peak in humans. Because rodents possess advanced forelimb movements that can be used for reaching and grasping food, it is commonly considered that the corticospinal tract (CST) is of major importance for this control also in rodents. A close homology to primate reaching and grasping has been described but with obvious limitations as to independent digit movements, which are lacking in rodents. Nevertheless, it was believed that there are, as in the primate, direct cortico-motoneuronal connections. Later, it was shown that there are no such connections. The fastest excitatory pathway is disynaptic, mediated via cortico-reticulospinal neurons and in the spinal cord the excitation is mainly polysynaptically mediated via segmental interneurons. Earlier behavioral studies have aimed at investigating the role of the CST by using pyramidotomy in the brainstem. However, in addition to interrupting the CST, a pyramidal transection abolishes the input to reticulospinal neurons. It is therefore not possible to conclude if the deficits after pyramidotomy result from interruption of the CST or the input to reticulospinal neurons or both. We have re-investigated the role of the CST by examining the effect of a CST lesion in the C1-C2 spinal segments on the success rate of reaching and grasping. This lesion spares the cortico-reticulospinal pathway. In contrast to investigations using pyramidal transections, the present study did not demonstrate marked deficits in reaching and grasping. We propose that the difference in results can be explained by the intact cortical input to reticulospinal neurons in our study and thus implicate an important role of this pathway in the control of reaching and grasping in the rat. © 2014 Alstermark and Pettersson.
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