Corticospinal, rubrospinal and rubro-olivary projections: a unifying hypothesis

Kennedy, Philip R.

doi:10.1016/0166-2236(90)90079-p

Cited by 192 publications

(102 citation statements)

References 38 publications

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“…As already mentioned, the CST and RST share many functional similarities (39), and electrical stimulation experiments have shown that cortically evoked movements of the hand remain after pyramidotomy in the monkey (40) and the cat (41), although at higher current thresholds. To test the hypothesis of a compensatory takeover of CST function by the RST, we transiently inactivated both red nuclei by injecting the ␥-aminobutyric acid agonist muscimol.…”

Section: Electrophysiological Evidences For Rewiring Of the Lesioned mentioning

confidence: 99%

Functional switch between motor tracts in the presence of the mAb IN-1 in the adult rat

Raineteau

Fouad

Noth

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

149

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Fine finger and hand movements in humans, monkeys, and rats are under the direct control of the corticospinal tract (CST). CST lesions lead to severe, long-term deficits of precision movements. We transected completely both CSTs in adult rats and treated the animals for 2 weeks with an antibody that neutralized the central nervous system neurite growth inhibitory protein Nogo-A (mAb IN-1). Anatomical studies of the rubrospinal tracts showed that the number of collaterals innervating the cervical spinal cord doubled in the mAb IN-1-but not in the control antibody-treated animals. Precision movements of the forelimb and fingers were severely impaired in the controls, but almost completely recovered in the mAb IN-1-treated rats. Low threshold microstimulation of the motor cortex induced a rapid forelimb electromyography response that was mediated by the red nucleus in the mAb IN-1 animals but not in the controls. These findings demonstrate an unexpectedly high capacity of the adult central nervous system motor system to sprout and reorganize in a targeted and functionally meaningful way. In the case of incomplete injuries of the central nervous system (CNS), spontaneous recovery processes can be observed in humans (1, 2) as well as in different animal models (3, 4). However, in the adult mammalian CNS, this recovery remains largely incomplete. This inability of the CNS to fully recover from an incomplete lesion appears gradually during development at a time coincident with the appearance of myelin (5, 6). Several myelin-associated proteins and proteoglycans show inhibitory properties to neurite growth; among them are Nogo-A͞NI-250 (7, 8), myelin-associated glycoprotein (9, 10), tenascin-R (J1 160͞180; janusin) (11), and sulfated proteoglycans (12, 13). The inhibitory effect of these proteins can be overcome in different ways: e.g., by a direct masking of the inhibitory substrate. Neutralization of Nogo-A by mAb IN-1 leads to a large decrease in the inhibitory activity of oligodendrocytes and myelin in vitro (14, 15) as well as in vivo, resulting in long-distance regeneration of lesioned spinal cord (16).Recent experiments have also pointed to a role of Nogo-A in inhibiting the plastic reorganization of the lesioned adult CNS. Infusion of the Nogo-A-neutralizing mAb IN-1 into the cerebrospinal fluid of unilaterally pyramidotomized rats induced corticorubral and corticopontine fibers to sprout across the midline and establish bilateral, anatomically specific projections (17). At spinal cord level, the unlesioned corticospinal tract (CST) sprouted into the contralateral denervated spinal cord (18). These anatomical changes were associated with an almost complete functional recovery in different behavioral tasks. These studies, however, focused on the CST, i.e., the lesioned system, and raised the interesting question of the limits of such repair processes. Thus, after complete transection of the CST, other descending motor tracts may also undergo reorganization and thereby contribute to the functional recovery. The ru...

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Section: Electrophysiological Evidences For Rewiring Of the Lesioned mentioning

confidence: 99%

Functional switch between motor tracts in the presence of the mAb IN-1 in the adult rat

Raineteau

Fouad

Noth

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

149

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Section: Bernstein's Solutionmentioning

confidence: 99%

“…A dapta tions of synaptic strengths and even neuronal sprouting appear now beyond dispute. Synergies can be formed and tried out by the motor cortex within minutes (Sanes and Donoghue, 1993) and are likely to be taken over by older circuits during skill acquisition (Kennedy, 1990).Probably as a consequence of this strong anti-Pavlovian position, Bern stein even seems to reject the idea that automated muscle synergies are constructed on the basis of internal representation stored in specific motor centres. Though this view is gratefully referred to by contemporary sup porters of equilibrium point principles (e.g., Latash and Latash, 1994), we feel that this position is not really consistent with his view of the CNS as a hierarchically ordered multi-storeyed system with relatively autonomously operating subsystems.…”

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confidence: 99%

“…It seems likely that this is associated with our capacity to consciously follow instructions or to imitate our coach or therapist during the early phase of learning a new skill which is usually referred to as the cognitive phase in psychological text books on motor learning (e.g., Schmidt, 1988). Kennedy (1990) provided evidence (for primates) that an important aspect of learning is that cortico-spinal control gradually switches over to rubro-spinal control, especially with respect to timing, velocity and force of the movement. This might point at the red nucleus as one of the pattern generating candidates.…”

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confidence: 99%

“…The combination of the work of Sanes and Donoghue (1993), Kennedy (1990) and Stein (1986, Stein, 1992 provides some idea how this might work. Sanes and Donoghue (1993) showed that in the primary motor cortex, synergies can be formed, tried out and reorganised within minutes.…”

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confidence: 99%

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The control of multi-joint movements relies on detailed internal representations

Schenau

Soest

Gabreëls

et al. 1995

Human Movement Science

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This paper addresses the question what level of detail is required in internal representa tions used in control of multi-joint movements, focusing on contact control tasks. Following Bernstein, we define the central problem to be which strategies are used in the nervous system in order to control the vastly redundant musculoskeletal system. Simplifications based on equilibrium point theories are rejected on the basis that when they are simple they do not lead to adequate behaviour, whereas when they are complex they implicitly introduce the detailed internal representations that they were meant to dispense with. Based on both experimental data and on simulation results, it is argued that timing of muscle activation needs to be precisely tuned to the task at hand and the environmental conditions. It is argued that it is impossible to achieve this without detailed internal representations of the properties of the effector system in relation to the environment. It is attempted to link Bernstein's notion of a hierarchical organization of the nervous system in which tasks are delegated to subsystems as low as possible in the hierarchical structure of the central nervous system, to recent advances in neuroscience. G.. I van Ingen Schenau et al./H um an Movement Science 14 (1995) 1, IntroductionMulti-joint movements are not realized by simply stringing together the movements in the joints involved. D ue to mechanical coupling and the action of poly-articular muscles, motions in one joint affect those in many others as well. Moreover, a human subject moving on one or two feet in a gravitational field can be considered as a highly unstable interlinked inverted pendulum controlled by a redundant set of actuators which are far from ideal force generators. This enormous complexity o f our action system was convincingly discussed already half a century ago by Bernstein (e.g., Bernstein, 1967). Based on his inspiring work and further stimulated by Gibson (e.g., Gibson, 1979) who stressed the guiding role of environmental information on the control of actions, many have tried to identify simplify ing principles in the organisation of movement control.Especially among ecological psychologists the idea o f detailed internal representations or motor programs has been disputed over the past decade (see Meijer and Roth, 1988 for discussion of this and related issues in the motor-action controversy). Since, indeed, it appears very unlikely that the central nervous system contains motor programs that deal with all details necessary to realize all variants of any movement observed in various environmental conditions, we sympathise with what has been defined by Turvey as "Round I of theorising on Bernstein's problem: how to minimize the executive responsibility of the CNS" (Turvey, 1990). We have consider able problems, however, with his " Round II" of theorising where selforganisation is proposed as a general principle underlying the organisation of all types of movement (Turvey, 1990; see also Kelso and Tuller, 1984; Schö...

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