Effects of Inactivating Individual Cerebellar Nuclei on the Performance and Retention of an Operantly Conditioned Forelimb Movement

Abstract

These experiments were designed to examine the effects of inactivating separately each of the major cerebellar nuclear regions in cats on the execution and retention of a previously learned, operantly conditioned volitional forelimb movement. The experiments test the postulates that the cerebellar nuclei, and particularly the interposed nuclei, contribute substantially to the spatial and temporal features of the interjoint coordination required to execute the task and that the engram necessary for the retention of this task is not located in any one of the cerebellar nuclei. All cats were trained to perform a task in which they were required to reach for and grasp a vertical bar at the sound of a tone and move the bar to a reward zone through a template consisting of two straight grooves in the shape of an inverted "L." After the task was learned, the effects of inactivating separately each nuclear region (the fastigial, interposed, and dentate nuclei) using muscimol microinjections were determined. Data were analyzed by quantifying several features of the movement's kinematics and by determining changes in the organization of the reaching component of the movement using an application of dimensionality analysis, an analysis that examines the correlation among the changes in joint angles and limb segment positions during the task. The retention of the previously learned task also was assessed after each injection. Injections of each nuclear region affected temporal and spatial features of the learned movement. However, the largest effects resulted from inactivating the interposed nuclei. These effects included an increased length of the reach trajectory, an accentuated deviation of the wrist trajectory from a straight line, cyclic movement of the distal extremity as the target was approached, a difficulty in grasping the bar, altered temporal features of the movement, and a highly characteristic change in the dimensionality measurements. The changes in dimensionality reflected a decreased correlation (linear interdependence) of the joint angular velocities coupled with an increased correlation among the linear velocities of markers located on the joints themselves. Related but less consistent changes in dimensionality resulted from fastigial injections. The motor sequence required to negotiate the template could be executed after the nuclear microinjections, indicating that retention of the motor sequence was not affected by the inactivation of any of the cerebellar nuclei. However, in two of the five animals, some decreases in performance were observed after dentate injection that were not characteristic of changes related to an effect on retention. These data suggest that the cerebellum plays an important role in regulating the consistent, stereotypic organization of complex goal-directed movements, including the temporal correlation among joint angle velocities. The data also indicate that the retention of the task is not dependent on any of the individual cerebellar nuclear regions. Consequently, these struct...

Functional Relations of Cerebellar Modules of the Cat

“…Some reports indicate that interpositus inactivation produces paw drag, hypermetria, underreaching, slipping, and deficits in grasping (Kolb et al, 1997;Milak et al, 1997;Bracha et al, 1999), which is similar to rDAO inactivation. In contrast, Cooper et al (2000) reported alterations in reach trajectory but no grasping deficits.…”

Medial cerebellar nucleus projects to feeding-related neurons in the ventromedial hypothalamic nucleus in rats

“…In fact, an intact feeding behavior comprises both somatic and visceral components and obviously needs a somatic-visceral integration. During a meal, some feeding-related somatic movement information, such as forelimb movements in reaching and grasping food (Milak et al 1997;Martin et al 2000), may be feed-forwarded from cerebellar deep nucleus to hypothalamus through the direct cerebellohypothalamic projections, and merge with some ingestion-related visceral signals (gastric vagal afferents, glycemia and ghrelin) on the neurons in the LHA, VMN, and DMN. Thus, a somatic-visceral integration of cerebellar and visceral signals that occurs in the LHA, VMN, and DMN may trigger an appropriate behavioral response to regulate food intake, body weight and energy homeostasis and play a substantial role in feeding control.…”

Finger movement at birth in brachial plexus birth palsy

“…There are numerous reports in the literature relating finger movements to brain region and brain damage [18][19][20][21][22] , stroke [23][24][25] , cerebral palsy [26][27][28] , Parkinson's disease [29,30] , carpal tunnel syndrome [31,32] , traumatic injury [21,[33][34][35][36][37] . However, there are only few reports correlating finger movements and obstetric brachial plexus injury [2,38] and hand injuries, despite the hands are important in performing daily activities [36] .…”