Cerebellar modulation of reflex gain

MacKay, William A.; Murphy, John T.

doi:10.1016/0301-0082(79)90004-2

Cited by 192 publications

(32 citation statements)

References 273 publications

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“…The cerebellar influence on reflex gain has been known for some time (MacKay and Murphy, 1979;Kolb et al, 1997). However, in recent decades the role of the cerebellum has been studied most extensively in relation to the adaptation of compensatory eye movements (Blazquez et al, 2004) and eye blink paradigms (De Zeeuw and Yeo, 2005).…”

Section: Implications For Modular Cerebellar Functioningmentioning

confidence: 99%

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

Pijpers¹,

Winkelman²,

Bronsing³

et al. 2008

J. Neurosci.

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The cerebellum is divided into multiple parasagittally organized modules, which are thought to represent functional entities. How individual modules participate in cerebellar control of complex movements such as locomotion remains largely unknown. To a large extent, this is caused by the inability to study the contribution of individual modules during locomotion. Because of the architecture of modules, based on narrow, elongated cortical strips that may be discontinuous in the rostrocaudal direction, lesion of a complete module, without affecting neighboring modules, has not been possible. Here, we report on a new method for inducing a selective dysfunction of spatially separated parts of a single module using a small cortical injection of a retrogradely transported neurotoxin, cholera toxin b-subunit-saporin. We show that such a local injection into the C1 module results in climbing fiber and partial mossy fiber deafferentation of functionally related areas of this module, thereby resulting in a severe impairment of the whole module without affecting neighboring modules. A subsequent functional analysis indicates that such an impairment of the hindlimb part of the C1 module did not have a significant impact on skilled walking or overall stepping pattern. However, the modulation of cutaneously induced reflexes during stepping was severely diminished. We propose that the C1 module is specifically involved in the adaptive control of reflexes.

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Section: Implications For Modular Cerebellar Functioningmentioning

confidence: 99%

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

Pijpers¹,

Winkelman²,

Bronsing³

et al. 2008

J. Neurosci.

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“…The cerebellum has been implicated in both feedback and feedforward control of movement. In the one case, it regulates feedback gains (MacKay and Murphy 1979) and in the other it represents the system dynamics (Nezafat et al 2001). That there was no activation of the cerebellum under the stable condition compared with the resting baseline could be interpreted as indicating that in the stable state the object is balanced with little feedback regulation and without the need for representation of the manipulation dynam-ics.…”

Section: Activity In Cerebellum and Primary Motor Cortexmentioning

confidence: 99%

Central Representation of Dynamics When Manipulating Handheld Objects

Milner¹,

Franklin²,

Imamizu³

et al. 2006

Journal of Neurophysiology

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. To explore the neural mechanisms related to representation of the manipulation dynamics of objects, we performed whole-brain fMRI while subjects balanced an object in stable and highly unstable states and while they balanced a rigid object and a flexible object in the same unstable state, in all cases without vision. In this way, we varied the extent to which an internal model of the manipulation dynamics was required in the moment-to-moment control of the object's orientation. We hypothesized that activity in primary motor cortex would reflect the amount of muscle activation under each condition. In contrast, we hypothesized that cerebellar activity would be more strongly related to the stability and complexity of the manipulation dynamics because the cerebellum has been implicated in internal model-based control. As hypothesized, the dynamics-related activation of the cerebellum was quite different from that of the primary motor cortex. Changes in cerebellar activity were much greater than would have been predicted from differences in muscle activation when the stability and complexity of the manipulation dynamics were contrasted. On the other hand, the activity of the primary motor cortex more closely resembled the mean motor output necessary to execute the task. We also discovered a small region near the anterior edge of the ipsilateral (right) inferior parietal lobule where activity was modulated with the complexity of the manipulation dynamics. We suggest that this is related to imagining the location and motion of an object with complex manipulation dynamics.

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“…The next group of models are known variously as metasystems, parameter adjustors, or gain controllers. The ideas behind these models (McKay & Murphy, 1979;Prochazka, 1989) are that the cerebellum holds control parameters of reflex arcs and of voluntary control pathways-parameters such as the gain of a reflex, or the amplitude/velocity relationship of a movement (Brooks, Kozlovskaya, Atkin, Horvath, & Uno, 1973). The behaviors can then be executed without the need for continuous feedback control.…”

Section: Theories Of the Cerebellummentioning

confidence: 99%

Is the Cerebellum a Smith Predictor?

Miall¹,

Weir²,

Wolpert³

et al. 1993

Journal of Motor Behavior

948

624

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ABSTRACT. The motor system may use intemal predictive models of the motor apparatus to achieve better control than would be possible by negative feedback. Several theories have proposed that the cerebellum may form these predictive representations, In this article, we review these theories and try to unify them by reference to an engineering control model known as a Smith Pre dictor. We suggest that the cerebellum forms two types of internal model. One model is a forward predictive model of the motor apparatus (e.g. , limb and muscle), providing a rapid prediction of the sensory consequences of each movement. The second model is of the time delays in the control loop (due to receptor and effector delays, axona] conductances, and cognitive processing delays). This model delays a copy of the rapid prediction so that it can be compared in temporal register with actual sensory feedback from the movement. The result of this comparison is used both to correct for errors in perf.ormance and as a training signal to learn the first model We discuss evidence that the cerebellum could form both of these models and suggest that the cerebellum may hold at least two separate Smith Predictors. One, in the lateral cerebellum, would predict the movement outcome in visual, egocentric, or peripersonaJ coordinates. Another, in the intermediate cerebellum, would predict the consequences in motor coordinates. Generalization of the Smith Predictor theory is discussed in ]ight of cerebellar involvement in nonmotor control systems, including autonomic functions and cognition

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Cerebellar modulation of reflex gain

Cited by 192 publications

References 273 publications

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

Central Representation of Dynamics When Manipulating Handheld Objects

Is the Cerebellum a Smith Predictor?

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