Proprioception From a Spinocerebellar Perspective

Abstract

This review explores how proprioceptive sensory information is organized at spinal cord levels as it relates to a sense of body position and movement. The topic is considered in an historical context and develops a different framework that may be more in tune with current views of sensorimotor processing in other central nervous system structures. The dorsal spinocerebellar tract (DSCT) system is considered in detail as a model system that may be considered as an end point for the processing of proprioceptive sensory information in the spinal cord. An analysis of this system examines sensory processing at the lowest levels of synaptic connectivity with central neurons in the nervous system. The analysis leads to a framework for proprioception that involves a highly flexible network organization based in some way on whole limb kinematics. The functional organization underlying this framework originates with the biomechanical linkages in the limb that establish functional relationships among the limb segments. Afferent information from limb receptors is processed further through a distributed neural network in the spinal cord. The result is a global representation of hindlimb parameters rather than a muscle-by-muscle or joint-by-joint representation.

A Structured Rehabilitation Protocol for Improved Multifunctional Prosthetic Control: A Case Study

“…27 These proprioceptors enable able-bodied humans to know where their hands are in relation to their body without the use of sight. 28 When a limb is lost, these proprioceptors are lost, leading vision to play a stronger role in control than in normal conditions. Amputees must not only relearn how to control hand movements, but also have to do so using a device that provides no feedback other than that obtained visually.…”

Assessing Proprioception

“…Although proprioceptive deficits are known to be a common after several neurological and orthopedic conditions such as stroke, Parkinson's disease, peripheral sensory neuropathies, or injuries to ligaments, joint capsules, and muscles (Bosco & Poppele, 2001), there is no objective, accurate, and reliable method available in clinical settings to assess proprioceptive function (Hillier, Immink, & Thewlis, 2015). In clinical practice many clinicians prefer to test proprioceptive acuity by detecting a patient's capability to discriminate the upwards or downwards position of a finger or toe.…”

Interneuronal Activity in Reflex Pathways from Group II Muscle Afferents Is Monitored by Dorsal Spinocerebellar Tract Neurons in the Cat

“…As established previously, information from proprioceptors reaches DSCT neurons both directly and indirectly, i.e., via monosynaptic actions of primary afferents and via spinal interneurons (for review, see Bosco and Poppele, 2001). However, most studies focused on direct input to DSCT neurons, and very little is still known about interneurons that provide indirect input to them.…”

“…Disynaptic inhibition of DSCT neurons has also been proposed to be evoked by interneurons in reflex pathways from group II muscle afferents (Bloedel and Courville, 1981, their Fig. 5), but this proposal has remained hypothetical ever since it was put forward (Bosco and Poppele, 2001), and early observations by Jansen et al (1967) suggested that inhibition of DSCT neurons by muscle stretches is mediated by group Ia rather than by group II muscle spindle afferents. Using intracellular records from DSCT neurons (Curtis et al, 1958;Eccles et al, 1961) demonstrated inhibition from group I afferents but did not investigate effects from group II afferents, and only scanty observations link inhibition of DSCT neurons with group II afferents, whether activated electrically (Hongo et al, 1983b, their Fig.…”

“…Using intracellular records from DSCT neurons (Curtis et al, 1958;Eccles et al, 1961) demonstrated inhibition from group I afferents but did not investigate effects from group II afferents, and only scanty observations link inhibition of DSCT neurons with group II afferents, whether activated electrically (Hongo et al, 1983b, their Fig. 2) or by passive or active muscle stretches (Bosco and Poppele, 2001).…”