Cuneate nucleus

About: Cuneate nucleus is a research topic. Over the lifetime, 614 publications have been published within this topic receiving 24859 citations. The topic is also known as: cuneate nucleus of spinal cord.

Cerebellar projections to the somatic pretectum in the cat.

Abstract: Neurons in the somatic pretectum receive input from the dorsal column nuclei (DCN) and project to a comparable "somatic" portion of the dorsal accessory nucleus of the inferior olive (DAO). This somatic DAO is reciprocally connected with the anterior interpositus nucleus of the cerebellum. One question that arises is whether this circuitry is further controlled by an output specifically from the anterior interpositus nucleus to the somatic pretectum. Wheatgerm agglutinin conjugated to horseradish peroxidase was injected into various parts of the cat pretectum. Injection sites were interpreted as including the somatic pretectum if neurons in the DCN were retrogradely labeled and if anterograde terminal labeling occurred in somatic DAO. The locations of retrogradely labeled neurons within the deep cerebellar nuclei were then compared in cases in which the injection sites included or excluded the somatic pretectum. In all cases in which the injection site included the somatic pretectum, retrogradely labeled neurons were observed in the anterior interpositus nucleus as well as in the lateral cerebellar nuclei. In some of these cases, neurons in the posterior interpositus and medial nuclei were also labeled. In contrast, in cases in which the pretectal injection site was located outside or at the border of the somatic pretectum, retrogradely labeled neurons were observed only in the lateral, posterior interpositus, and medial nuclei. Thus, the somatic pretectum appears to receive input primarily from neurons in the anterior interpositus nucleus, along with some input from neurons in the lateral nucleus. These results provide additional evidence for a pathway through the DCN in which sequentially processed somatic information has access to and is modulated by cerebellar circuitry. The existence of such a pathway supports the conclusion that neurons in the DCN convey somatic information important not only for cutaneous, kinesthestic, and other bodily sensations, but also for the control of movement.

Evolution of morphological and histochemical changes in the adult cat cuneate nucleus following forelimb denervation

Abstract: Morphological and histochemical changes were studied in the ipsilateral cuneate nucleus between one and 52 weeks after forelimb denervation in adult cats. The deafferented nucleus and neighboring fasciculus were noticeably reduced in size within four weeks and decreased further by 13 weeks. The intensity of acetylcholinesterase staining decreased within one week and was further reduced one month after nerve transections. This reduction in acetylcholinesterase staining was transient, approaching control levels within one year. Parvalbumin immunostaining was also altered by the nerve transections; on the deafferented side, the neuropil staining in the cuneate nucleus and fasciculus decreased, but the number of parvalbumin-positive cells was consistently greater than in the contralateral side. These cell counts returned to normal levels within one year. One month after the injury, cytochrome oxidase activity was reduced. This reduction persisted and was even more apparent after one year. In parallel, the cell clusters of the nucleus became progressively less distinct. These observations in an adult mammal indicate that peripheral nerve injury imposes molecular and morphological changes on second-order sensory neurons which evolve differentially with time. Although some changes developed rapidly after deafferentation, the onset of others was slower; and whereas some seemed irreversible, others eventually regressed. Taken together with the functional studies of others, these findings suggest that early molecular changes observed in cuneate neurons reflect adaptive reactions to lesion-induced alterations in afferent activity. Permanent deprivation of the normal input, however, would eventually lead to chronic, and perhaps irreversible, degenerative changes.