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At least 127 records · Page 7Linked to original sources
PubMed1994

Kinematic analyses of classically-conditioned eyelid movements in the cat suggest a brain stem site for motor learning.

Upper eyelid movements were conditioned in the alert cat to the presentation of either tones or short, weak air puffs applied to the ipsi- or contralateral cornea followed by an unconditioned stimulus consisting of a long, strong air puff applied to the ipsilateral cornea. Eyelid movements were measured with the search-coil technique. Electromyographs of the orbicularis oculi muscle were also recorded. Quantitative analysis of the latencies and topographic profiles of eyelid conditioned responses suggests that the primary site for their initiation is the brain stem reflex circuit involved, depending on the sensory modality of and on the side where the conditioning stimulus was applied. However, the kinematic of the conditioned response indicates that other neural structures are involved in its acquisition and consolidation.

Animals↗
PubMed2002

Interactions between human explicit and implicit perceptual motor learning shown by kinematic variables.

The goal of this study was to investigate in non-impaired humans the interaction between explicit and implicit learning in a catching task. The situation presented probabilistic contingencies between visual signals and various final pathways of the target. Subjects were asked to practice the interception task for 320 trials. Explicit instructions describing the probabilistic rules were given prior to (11 subjects), or in the middle of (11 subjects), physical practice. Eleven subjects not provided with verbal instructions served as control subjects. We measured the combination between explicit verbal instructions and implicit learning via kinematics of the end-effector and an outcome measure (i.e. spatial error). The time when explicit instructions were given resulted in systematic changes in the spatio-temporal ordering of the action. These data suggested that analyzing the way the task is executed with scrutiny allows a new understanding of how the aforementioned learning systems interact.

Adult↗
PubMed1996

Motor learning by field approximation.

We investigated how human subjects adapt to forces perturbing the motion of their ams. We found that this kind of learning is based on the capacity of the central nervous system (CNS) to predict and therefore to cancel externally applied perturbing forces. Our experimental results indicate: (i) that the ability of the CNS to compensate for the perturbing forces is restricted to those spatial locations where the perturbations have been experienced by the moving arm. The subjects also are able to compensate for forces experienced at neighboring workspace locations. However, adaptation decays smoothly and quickly with distance from the locations where disturbances had been sensed by the moving limb. (ii) Our experiments also how that the CNS builds an internal model of the external perturbing forces in intrinsic (muscles and / or joints) coordinates.

Adult↗
PubMed1996

The influence of summary knowledge of results and aging on motor learning.

This study examined whether older adults (mean age = 75.0 years) use summary knowledge of results (KR) to facilitate learning in a manner similar to that of young adults (mean age = 22.5 years). All subjects were required to learn a computer-key-pressing task in a specified goal time. During acquisition, subjects received either KR after every trial, or summary KR. All subjects then performed no-KR retention trials. In acquisition, KR after every trial facilitated timing accuracy for both the younger and older groups in comparison to the summary KR groups. The young subjects were equally variable in both KR practice groups. For older subjects summary KR facilitated more consistent performance. In retention, the summary groups were more accurate than those subjects who received KR after every trial. There were no accuracy or variability differences between the two age groups during retention. These results suggest that older adults are able to use summary KR to facilitate learning in a manner similar to that of young adults.

Adult↗
PubMed2003

Gradient of adaptability in four different motor systems performing the same learned motor task in cats.

The ability of four different brainstem motoneuron pools to perform a newly acquired motor task was studied in alert cats. A classical conditioning of eyelid responses was carried out in (i). unoperated animals, and in animals with (ii). transection, 180 degrees rotation, and re-suture of the zygomatic facial nerve branch, (iii). a crossed anastomosis of the buccal to the zygomatic facial nerve branch and (iv). a hypoglossal-facial nerve anastomosis. Animals were conditioned with a delay paradigm using a tone (350 ms, 600 Hz, 90 dB) as conditioned stimulus, followed 250 ms later by an air puff (100 ms, 3 kg/cm2) as unconditioned stimulus. Animals with zygomatic nerve rotation performed conditioned responses (CRs) at control rate, with significantly larger amplitude, area and velocity, but a de-synchronized oscillatory pattern. Animals with buccal-zygomatic anastomosis acquired CRs at control rate, but these CRs had significantly smaller amplitude than those of controls and a de-synchronized pattern. Animals with a hypoglossal-facial anastomosis were unable to perform CRs. The trigeminal hyper-reflexia triggered by the axotomy was probably the origin of the large CRs after zygomatic nerve rotation. Trigeminal hyper-reflexia could also contribute to generation of the small CRs recorded after buccal-zygomatic anastomosis. Although trigeminal hyper-reflexia was also present following hypoglossal-facial anastomosis, hypoglossal motoneurons did not reach their firing threshold to perform CRs. In accordance with the embryonic origin of involved motoneurons, animals with buccal-zygomatic and hypoglossal-facial anastomoses moved the ipsilateral eyelid synchronously to mouth-related activities. It is suggested that there is a gradient of adaptability in motoneuron pools forced to perform new motor tasks through foreign muscles, which depends on their embryological origins and functional properties.

Acoustic Stimulation↗
PubMed2002

Historical review of the significance of the cerebellum and the role of Purkinje cells in motor learning.

Classic studies of the cerebellum before the middle of the twentieth century established the structural entity of the cerebellum and characterized its function as enabling animals and humans to carry out smooth and accurate movements, even at a high speed and without visual feedback. In the 1960s, neuronal circuit structures of the cerebellum were analyzed in detail, which promoted computational approaches toward the study of neuronal network principles of the cerebellum. In the 1970s and 1980s, vestibulo-ocular reflex adaptation, adaptive locomotion, eye blink conditioning, and learning in hand/arm movement were established as effective experimental paradigms for investigating neural mechanisms of cerebellar functions. In the 1980s, long-term depression (LTD) was discovered and considered as a memory process in the cerebellum; in the 1990s, complex signal transduction processes underlying LTD were revealed. It was also in the 1980s that computational approaches were advanced for modeling control system functions of the cerebellum. Currently, there are two alternative models proposed for VOR adaptation. In this decade, we envisage new developments toward the fusion of knowledge of the cerebellum at molecular and cellular levels and those in systems and computation. Studies of LTD will play a key role in pursuing this direction.

Animals↗
PubMed2002

Transfer of motor learning across arm configurations.

It has been suggested that the learning of new dynamics occurs in intrinsic coordinates. However, it has also been suggested that elements that encode hand velocity, and hence act in an extrinsic frame of reference, play a role in the acquisition of dynamics. To reconcile claims regarding the coordinate system involved in the representation of dynamics, we have used a procedure involving the transfer of force-field learning between two workspace locations. Subjects made point-to-point movements while holding a two-link manipulandum. Subjects were first trained to make movements in a single direction at the left of the workspace. They were then tested for transfer of learning at the right of the workspace. Two groups of subjects were defined. For the subjects in group j, movements at the left and right workspace locations were matched in terms of joint displacements. For the subjects in group h, movements in the two locations had the same hand displacements. Workspace locations were chosen such that for group j, the paths (for training and testing) that were identical in joint space were orthogonal in hand space. The subjects in group j showed good transfer between workspace locations, whereas the subjects in group h showed poor transfer. These results are in agreement with the idea that new dynamics are encoded in intrinsic coordinates and that this learning has a limited range of generalization across joint velocities.

Adult↗
PubMed2006

Age-related effects in sequential motor learning.

BACKGROUND AND PURPOSE: When learning multi-element movement sequences, participants organize individual elements into subsequences. Imposing this type of structure on the elements leads to the efficient production of sequences because the processing of all but the first elements in a subsequence can be completed prior to their execution. The primary purpose of this study was to determine whether older adults organize lengthy movement sequences with the same efficiency as young adults. SUBJECTS AND METHODS: Participants were young adults (N=8, 19-23 years of age) and older adults (N=8, 65-68 years of age). The task required participants to move a lever as quickly as possible to targets sequentially projected on a tabletop. At various stages during practice, random practice blocks were inserted between the repeated sequence blocks. Repeated and random sequence retention tests were administered after 24 hours. RESULTS: The results indicated that the young adults performed the repeated sequences substantially faster than the older adults and that this difference increased over practice. On the retention tests, there were no differences in response time for the random sequence blocks, but the young performers were substantially faster than the older performers when repeated sequences were used. No differences were detected in the interview or on the recognition (chi square=1.22, P>.05) and completion (chi square=0.89, P>.05) tests designed to determine explicit or implicit knowledge of the sequences. DISCUSSION AND CONCLUSION: Analysis of the sequence structure indicated that the older adults did not organize their responses into subsequences as effectively as the young adults. The failure of older adults to optimally organize movement sequences may contribute to the overall slowing of sequential movement production.

Adult↗