The open field behavior and learning capacity of male rats of the Wistar strain was studied 1, 2,... more The open field behavior and learning capacity of male rats of the Wistar strain was studied 1, 2, and 6 months after cerebellectomy (CBX). The results show a decrease in locomotor activity 1 month after CBX and thereafter a slow recovery. Grooming behavior was still normal after 1 month, but it decreased 2 months after CBX. Learning capacity, as assessed by the shuttle-box test, was remarkably decreased in cerebellectomized animals 1 month after operation. A significant impairment of memory capacity was also observed in rats tested for passive avoidance behavior 2 months after CBX. A partial recovery of this parameter was present 6 months after operation. These results support the hypothesis of a possible influence of cerebellum on motivation-related behaviors, independently of its modulatory role on motricity.
The projections from the primary motor and somatic sensory cortex onto the basilar pontine grey w... more The projections from the primary motor and somatic sensory cortex onto the basilar pontine grey were studied in Wistar Rats injecting microvolumes of WGA-HRP solution in sites of the motor and sensory cortex electrophysiologically identified. The main results may be summarized as follows. (a) The projections from both the motor and sensory cortex were found as rostrocaudally oriented columns of terminals in the basilar pontine nuclei. The projection from the motor cortex extended to all over the rostrocaudal extension of the basilar pontine nuclei. To a rostrocaudal shift of the pontine projection field correspond a rostrocaudal displacement in the motor area. The projection from the sensory cortex was mainly restricted to the caudal two thirds of the basilar pontine nuclei, though the hindlimb region of the sensory cortex also showed a discrete representation in the rostral third of the basilar pontine nuclei. (b) The terminal fields of the motor and sensory cortex were segregated ...
The topographical organization of the subnuclear projections towards the thalamus was studied wit... more The topographical organization of the subnuclear projections towards the thalamus was studied with autographic methods in adult Wistar rats. The four cerebellar deep nuclei give rise to projections to the ventral region of the rostra1 thalamus. Most of the fibers end contralaterally, according to a topographical pattern; however, some fibers from each of the cerebellar nuclei recross the midline at the thalamic level and terminate ipsilaterally, within regions symmetric to those receiving the densest contralateral projection. These ipsilateral cerebellothalamic components arise in decreasing order from the caudal nucleus lateralis, the ventrocaudal nucleus medialis and the nucleus interpositus, respectively. The projections of the nucleus lateralis directed to the contralateral thalamus are topographically organized. (I) Within the nucleus ventralis lateralis, the rostra1 and caudal parts of the cerebellar nucleus lateralis project respectively to rostra1 and caudal regions; lateral and medial zones of the nucleus lateralis project. respectively, to medial and central aspects of the nucleus ventralis lateralis. The nucleus ventralis medialis and particularly its caudal portion appears to receive the bulk of its afferents from the ventromedial portion of the nucleus lateralis including the "subnucleus lateralis parvocellularis". The nucleus centralis lateralis receives fibers from most parts of the nucleus lateralis including the "dorsolateral hump". (4) The nucleus interpositus anterior projects to the dorsomedial aspect of the rostra1 nucleus ventralis lateralis. In the latter nucleus, the ventrolateral aspect of the central region receives projections in cases in which the nucleus interpositus posterior is largely involved.
This study analyzed the projections of the basilar pontine nuclei (BPN) and of the nucleus reticu... more This study analyzed the projections of the basilar pontine nuclei (BPN) and of the nucleus reticularis tegmenti pontis (NRTP) to the two sides of the cerebellum in the rat. It showed that the two sides of the cerebellar cortex were innervated by different percentages of BPN (about 82% of the cells project to the contralateral cortex and 18% to the ipsilateral) and NRTP cells (some 60% project to the contralateral cortex and 40% to the ipsilateral). In comparison to projections traced to the cortex, only a few fibers were traced to the nuclei of the same animals. Most of the projections of the BPN to the cerebellar nuclei were traced to the lateralis and posterior interpositus nucleus of the contralateral side (95%), while a few were traced to homologous nuclei of the ipsilateral side (5%). Thus, the BPN principally control the activity of the contralateral cerebellum, with a much less important control over the activity of the ipsilateral cerebellum. Vice versa, the NRTP, which project to the lateralis, interpositus, and medialis nuclei of the two sides, with percentages (64% contra- and 36% ipsilateral) similar to those reported for the projections to the cortex, is more concerned in the bilateral control of the cerebellum, although with a moderate contralateral prevalence. The fact that projections of the BPN were principally traced to the contralateral nuclei, from which the efferent projection fibers from the cerebellum originate, suggests that the BPN are principally involved in the motor control of the contralateral body. Conversely, the bilateral projections of the NRTP to the cerebellar nuclei suggest that the NRTP is mainly involved in bilateral motor activities. The comparison of the projections to the cortex and nuclei of the cerebellum of single animals supports the co-existence of coupled (i.e., projections to the cortex and the corresponding nuclei) and uncoupled (i.e., projections to the cortex but not to the nuclei) projection patterns, from both the BPN and the NRTP. These features of the pontocerebellar projections open new vistas on the functional architecture of this pathway.
The open field behavior and learning capacity of male rats of the Wistar strain was studied 1, 2,... more The open field behavior and learning capacity of male rats of the Wistar strain was studied 1, 2, and 6 months after cerebellectomy (CBX). The results show a decrease in locomotor activity 1 month after CBX and thereafter a slow recovery. Grooming behavior was still normal after 1 month, but it decreased 2 months after CBX. Learning capacity, as assessed by the shuttle-box test, was remarkably decreased in cerebellectomized animals 1 month after operation. A significant impairment of memory capacity was also observed in rats tested for passive avoidance behavior 2 months after CBX. A partial recovery of this parameter was present 6 months after operation. These results support the hypothesis of a possible influence of cerebellum on motivation-related behaviors, independently of its modulatory role on motricity.
The projections from the primary motor and somatic sensory cortex onto the basilar pontine grey w... more The projections from the primary motor and somatic sensory cortex onto the basilar pontine grey were studied in Wistar Rats injecting microvolumes of WGA-HRP solution in sites of the motor and sensory cortex electrophysiologically identified. The main results may be summarized as follows. (a) The projections from both the motor and sensory cortex were found as rostrocaudally oriented columns of terminals in the basilar pontine nuclei. The projection from the motor cortex extended to all over the rostrocaudal extension of the basilar pontine nuclei. To a rostrocaudal shift of the pontine projection field correspond a rostrocaudal displacement in the motor area. The projection from the sensory cortex was mainly restricted to the caudal two thirds of the basilar pontine nuclei, though the hindlimb region of the sensory cortex also showed a discrete representation in the rostral third of the basilar pontine nuclei. (b) The terminal fields of the motor and sensory cortex were segregated ...
The topographical organization of the subnuclear projections towards the thalamus was studied wit... more The topographical organization of the subnuclear projections towards the thalamus was studied with autographic methods in adult Wistar rats. The four cerebellar deep nuclei give rise to projections to the ventral region of the rostra1 thalamus. Most of the fibers end contralaterally, according to a topographical pattern; however, some fibers from each of the cerebellar nuclei recross the midline at the thalamic level and terminate ipsilaterally, within regions symmetric to those receiving the densest contralateral projection. These ipsilateral cerebellothalamic components arise in decreasing order from the caudal nucleus lateralis, the ventrocaudal nucleus medialis and the nucleus interpositus, respectively. The projections of the nucleus lateralis directed to the contralateral thalamus are topographically organized. (I) Within the nucleus ventralis lateralis, the rostra1 and caudal parts of the cerebellar nucleus lateralis project respectively to rostra1 and caudal regions; lateral and medial zones of the nucleus lateralis project. respectively, to medial and central aspects of the nucleus ventralis lateralis. The nucleus ventralis medialis and particularly its caudal portion appears to receive the bulk of its afferents from the ventromedial portion of the nucleus lateralis including the "subnucleus lateralis parvocellularis". The nucleus centralis lateralis receives fibers from most parts of the nucleus lateralis including the "dorsolateral hump". (4) The nucleus interpositus anterior projects to the dorsomedial aspect of the rostra1 nucleus ventralis lateralis. In the latter nucleus, the ventrolateral aspect of the central region receives projections in cases in which the nucleus interpositus posterior is largely involved.
This study analyzed the projections of the basilar pontine nuclei (BPN) and of the nucleus reticu... more This study analyzed the projections of the basilar pontine nuclei (BPN) and of the nucleus reticularis tegmenti pontis (NRTP) to the two sides of the cerebellum in the rat. It showed that the two sides of the cerebellar cortex were innervated by different percentages of BPN (about 82% of the cells project to the contralateral cortex and 18% to the ipsilateral) and NRTP cells (some 60% project to the contralateral cortex and 40% to the ipsilateral). In comparison to projections traced to the cortex, only a few fibers were traced to the nuclei of the same animals. Most of the projections of the BPN to the cerebellar nuclei were traced to the lateralis and posterior interpositus nucleus of the contralateral side (95%), while a few were traced to homologous nuclei of the ipsilateral side (5%). Thus, the BPN principally control the activity of the contralateral cerebellum, with a much less important control over the activity of the ipsilateral cerebellum. Vice versa, the NRTP, which project to the lateralis, interpositus, and medialis nuclei of the two sides, with percentages (64% contra- and 36% ipsilateral) similar to those reported for the projections to the cortex, is more concerned in the bilateral control of the cerebellum, although with a moderate contralateral prevalence. The fact that projections of the BPN were principally traced to the contralateral nuclei, from which the efferent projection fibers from the cerebellum originate, suggests that the BPN are principally involved in the motor control of the contralateral body. Conversely, the bilateral projections of the NRTP to the cerebellar nuclei suggest that the NRTP is mainly involved in bilateral motor activities. The comparison of the projections to the cortex and nuclei of the cerebellum of single animals supports the co-existence of coupled (i.e., projections to the cortex and the corresponding nuclei) and uncoupled (i.e., projections to the cortex but not to the nuclei) projection patterns, from both the BPN and the NRTP. These features of the pontocerebellar projections open new vistas on the functional architecture of this pathway.
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