Restorative Neurology and Neuroscience - Volume 2, issue 3

Authors: Kitchigina, V.F. | Vinogradova, O.S. | Bragin, A.G.

Article Type: Research Article

Abstract: Embryonic (E16–17) septal solid grafts were transplanted into acute cavities in the barrel field of somatosensory neocortex of adult rats. Extracellular recording of the graft's neuronal activity was performed in lightly anesthetized rats, or in brain slices in vitro 8–10 months after grafting. Analysis of Nissl and Golgi-Cox stained preparations showed that 81% of the grafts survived. Judging by combined histological and electrophysiological criteria, 69% of surviving grafts were integrated with the host brain. All septal grafts contained neurons with high spontaneous activity (mean 14.9 ± 8.3 spikes · s −1 ). Irregular bursts or rhythmic theta-bursts were present in …background activity. The frequency of theta-bursts varied in parallel with the state of the animal from 3 Hz (deep barbiturate sleep) up to 7–8 Hz (arousal). Somatosensory stimulation evoked initial bursts or suppression of activity, often followed by a period of rhythmic theta-bursts. Though a high level of convergence for stimulation of vibrissae and body surface was typical of the grafted neurons, a certain spatial gradient of body representation was present. Many neurons responded also by initial burst or prolonged suppression of activity to electrical stimulation of thalamus and homolateral motor cortex. In the frontal slices of neocortex the neurons of septal grafts were highly reactive to stimulation of adjacent neocortex, but usually when the distance between the stimulating electrodes and the graft border did not exceed 1–1.5 mm. The data obtained in the septal slices are compared to the results described earlier in homotopic neocortical and heterotopic hippocampal grafts to the barrel field. It is concluded that heterotopic embryonic septal grafts can successfully develop and establish functional afferent connections with the host brain. Their neurons can participate in processing of sensory information, appropriate to the substituted cortical area, though the characteristics of responses are to a great extent determined by intrinsic properties of the septal neurons. Show more

Keywords: Septum, Somatosensory neocortex, Transplantation, Neuronal activity, Functional integration, Theta-bursts

DOI: 10.3233/RNN-1991-2301

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 109-122, 1991

Authors: Sauer, Hansjörg | Brundin, Patrik

Article Type: Research Article

Abstract: Ongoing clinical trials with fetal tissue transplants in Parkinson's disease would be facilitated by an effective tissue storage technique that would allow for temporal separation of the procurement of the fetal donor tissue and implantation surgery. In order to develop such a method, we grafted rat or human fetal ventral mesencephalic tissue to the dopamine-depleted striatum of rats either directly, or following pregraft refrigeration in a ‘hibernation’ medium at 4 °C. Rat tissue transplants were found to normalize amphetamine-induced circling behavior at 6 weeks post-transplantation after having been hibernated for either 2 or 5 days. The number of tyrosine hydroxylase …immunoreactive neurons in these hibernated grafts did not differ significantly from that found in matched grafts of fresh tissue. Hibernation for 10 days resulted both in an absence of functional effects and in decreases of graft survival down to 10–20% of control values. Volume assessment of fresh and hibernated grafts prepared from human fetal tissue revealed no adverse effects of a 3 day hibernation interval at 3 weeks after transplantation into immunosuppressed rats. The results indicate that hibernation of neural tissue may be a convenient and simple tool, which can help to guarantee tissue availability at the planned time of implantation in patients and facilitate transport and bacteriological examination. Furthermore, the method offers a simple means which permits prolonged exposure of the neural tissue to trophic factors and specific markers prior to grafting in experimental animals. Show more

Keywords: Neural transplantation, Neural grafting, Tissue preservation, Parkinson's disease, Cryopreservation, Hibernation, Tyrosine hydroxylase

DOI: 10.3233/RNN-1991-2302

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 123-135, 1991

Authors: Hasan, Sohail J. | Nelson, Brad H. | Valenzuela, J. Ignacio | Keirstead, Hans S. | Shull, Sarah E. | Ethell, Douglas W. | Steeves, John D.

Article Type: Research Article

Abstract: The purpose of this study was to determine the developmental stage of the chick embryo when descending spinal tracts lose the capacity for anatomical and functional repair after complete transection of the thoracic spinal cord. Previous studies have demonstrated that the first reticulospinal projections descend to the lumbar cord by embryonic day (E) 5. A comparison of the distribution and density of retrogradely labelled brainstem–spinal neurons in embryos versus hatchling chicks suggests that the descent of all brainstem–spinal projections is essentially complete to lumbar levels between E10 and El2. Transections and control sham operations were performed on different embryos from …E3 through E14 of development. After a recovery period of 5–18 days, the extent of anatomical repair was assessed by injecting a small volume of a retrograde tract-tracing chemical into the upper lumbar spinal cord, caudal to the transection site. The brainstem nuclei were then examined for the number and distribution of retrogradely labelled brainstem–spinal neurons. In comparison to control animals, anatomical recovery appeared to be complete for embryos transected as late as E12, whereas thoracic cord transections conducted on E13–E14 resulted in reduced labelling of most brainstem–spinal nuclei. In addition, a number of E3–E6 transected embryos were allowed to hatch and with some assistance a few E7–E14 transected embryos also hatched. Functional recovery was assessed by behavioral observations and by focal electrical stimulation of brainstem locomotor regions (known to have direct projections to the lumbar spinal cord). Brainstem stimulation experiments were undertaken on transected and control embryos, either in ovo on E18–E20 or after hatching. Leg and wing muscle electromyographic recordings were used to monitor any brainstem evoked motor activity. Voluntary open-field locomotion (hatchling chicks) or brainstem evoked locomotion (embryonic or hatchling) in animals transected on or before E12 was indistinguishable from that observed in control (i.e. sham-operated or unoperated) chicks, indicating that complete functional recovery had occurred. In contrast, chicks transected on or after El3 showed reduced functional recovery. Since a previous study has shown that neurogenesis in chick brainstem–spinal neurons is complete prior to E5, the possible intrinsic neuronal mechanisms underlying the repair of descending supraspinal pathways are: (1) subsequent projections from later developing (undamaged) neurons, or (2) regrowth of previously axotomized projections (regeneration). For the E5–E12 chick embryos examined in this study, significant descending supraspinal fibers are present within the thoracic cord at the time of transection. Even if the transection is made at E12, when descending projections have completed their development to the lumbar cord, there is still a similar number and distribution of brainstem–spinal neurons labelled afterward (when compared to controls). This suggests that regeneration of previously axotomized projections may account for some of the observed anatomical and functional repair of brainstem–spinal pathways. Show more

Keywords: Chicken, Embryo, Spinal cord, Brainstem, brainstem–spinal pathway, Injury, Repair, Anatomy, Tract tracing, Behavior, Physiology, Electrical stimulation

DOI: 10.3233/RNN-1991-2303

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 137-154, 1991

Authors: Peper, Martin | Seier, Ulrike | Krieger, Derk | Markowitsch, Hans J.

Article Type: Research Article

Abstract: A 39-year-old woman suffered from an extensive bilateral lesion in the region of the thalamus. The damage, caused by a primary thrombosis of the internal cerebral veins, turned out to be reversible to a considerable degree detected by repeated CT-and MR-imaging after 2, 4 and 9 months. In spite of the partial, structural recovery the patient remained severely impaired on both cognitive and affective levels. The key functions involved were an anterograde verbal and figural memory impairment, depressed arousal and attentional levels, affective flattening, lack of prosody and a depressive irritable mood. These findings illustrate that thalamic lesions of a …certain extent not only influence memory functioning, but have in addition, severe consequences for emotional behavior. Show more

Keywords: Sinus thrombosis, Thalamus, Memory, Amnesia, Emotion

DOI: 10.3233/RNN-1991-2304

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 155-162, 1991

Authors: Pritzel, Monika

Article Type: Book Review

DOI: 10.3233/RNN-1991-2305

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 163-163, 1991

Article Type: Research Article

DOI: 10.3233/RNN-1991-2306

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 3, pp. 164-168, 1991