Postsurgical Testing Research Articles

Neural grafts attenuate behavioral deficits produced by early radiation-induced hypoplasia of fascia dentata granule cells

Localized X-irradiation of the mitotic cells in the neonatal rat hippocampus produces a discrete hypoplasia of the fascia dentata granule cell layer. This brain damage inhibits the acquisition of a passive avoidance task, and stimulates spontaneous perseverative turning (without reversals) in a plastic hemisphere apparatus. Here we report how transplantation of fetal brain tissue can attenuate these radiation-induced behavioral deficits. The partially shielded cerebral hemispheres of neonatal rats received fractionated exposures to 13 Gray (Gy) of X-rays during the first 16 days post partum. This procedure depleted 90% of the hippocampal granule cells while sparing other brain areas. Control animals were sham irradiated. Baseline behavioral tests were conducted when subjects reached an average age of 147 ± 4 days. We recorded behavioral parameters known to be sensitive to hippocampal damage: (1) passive avoidance performance, and (2) perseverative spontaneous turning without reversals. Irradiated subjects later (average age= 182 ± 4days) received intracerebral transplants of either fetal (E20–21) neurons/neuronal precursors from the fascia dentata or cerebral cortex (control grafts). Additional controls (both irradiated and sham-irradiated) experienced sham surgical procedures or received no surgical manipulation. Two post-surgical behavioral retests were accomplished when rats were 265 ± 5 and 351 ± 6 days old. Rats were then sacrificed and brains were treated histologically to assess radiation-induced brain damage, graft survivability and graft locus. Both hippocampaa and cerebral cortex grafts generally facilitated performance on the passive avoidance task. This effect was most prominent during the first post-surgical test. Hippocampal transplants (especially those found to reside in the damaged hippocampus) also significantly attenuated perseverative spontaneous rotation at the time of the final post-surgical test series. Cortex grafts found within the damaged hippocampus did not ameliorate perseverative movements, while cortex grafts located outside the hippocampus significantly reduced this behavioral deficiency. These data suggest that selected behavioral deficits may be attenuated by transplanting fetal neural tissue long after early radiation-induced brain damage. The success of these procedures depends on a number of factors including: (1) the behaviors chosen for analysis, (2) the time after transplantation that behavioral tests are conducted, and (3) the source and final location of the donor neural tissue.

Playback of female rat ultrasonic vocalizations during sexual behavior

Both male and female rats emit ultrasonic vocalizations during mating. In an earlier study, female vocalizations were shown to be associated with female darting: when the female was devocalized, she increased her rate of darting. In a preliminary playback study, tape-recorded female ultrasounds were presented to devocalized females paired with intact males. Darting was reduced towards presurgical control levels. In this study, the playback experiment was replicated using a refined procedure to present female ultrasounds to the mating rats. Taped vocalizations were obtained from females, and were presented in a manner which more closely approximated the patterning of ultrasound production seen in the intact female. Each rat pair was tested three times: once prior to the devocalization of the female, and twice afterwards. In one postsurgical test, taped ultrasounds were presented during mating; in the other, tape hiss was presented. Several patterns of behavior increased in frequency when the female was devocalized relative to the control condition, but decreased when tape recorded ultrasounds were presented. These patterns included female darting and approaches towards the partner by both males and females. The darting results confirm and extend the findings of our earlier paper. Changes in approach behavior were not observed previously because the male was confined in the earlier study. This study contains the first direct evidence that female vocalizations affect the socio-sexual behavior of the male.

Obstetric Brachial Plexus Palsy

This article supplies data related to 11 operated children with obstetric brachial plexus palsy. Discussion of the obstetric background, pathology, pre- and postsurgical testing and of primary and secondary surgical reconstruction also is given. The need for rehabilitation regimen is stressed.

Extinction of response to urine odor as a consequence of vomeronasal organ removal in male guinea pigs.

It has been found that removal of the vomeronasal chemoreceptor organ (VNO) in male guinea pigs disrupted investigatory responses to conspecific odors but this disruption was time-dependent; immediately following surgery, behavior appeared almost normal, whereas several months following surgery, animals became very unresponsive to conspecific odor. It was hypothesized that in the absence of a functional VNO, the main olfactory system (MOS) was capable of maintaining response to conspecific odor but that this response extinguished following repeated exposures. However, postsurgical change in the central nervous system, unrelated to exposure to the bioassay, remained a possible explanation. In order to separate these hypotheses, the VNO was surgically removed in two groups of animals (A and B), and a third group (C) experienced sham surgery. Beginning 3 weeks following surgery, males in Groups A and C were given two standard urine-response tests/week for 24 weeks. Initiation of testing of Group B animals was delayed until Week 15 following surgery. Results indicated that (a) responses of Group A declined relative to those of Group C, (b) at the first postsurgical test, Group B was as responsive to urine as Group C and much more responsive than Group A and (c) a decline in responses for Group B occurred during tests after Week 15. The data therefore strongly supported the extinction hypothesis. The MOS is capable of eliciting a high level of investigatory behavior in response to female urine odors, but in the absence of the VNO, this response wanes, perhaps due to a loss of reinforcing properties associated with VNO stimulation.

Effects of anterior cingulate lesions on sequential behaviors

Rats were trained on a task employing an alternating FR 4 schedule in which the subjects were required to press two bars in a left-right-left-right sequence. Lesions were placed in the anterior cingulate cortex in one group of subjects, and the other group received sham lesions. During postsurgical testing, the lesion group had significantly fewer correct sequential responses than the sham group. The ratio of number of errors to number of completed trials was significantly higher for the brain-damaged subjects, but the number of incompleted trials for the two groups did not differ.

Role of dorsal columns in sequential motor acts requiring precise forelimb projection.

Quantitative evaluation was carried out on the ability of cats to execute a sequential act requiring precise timing for its initiation (jump), accurate projection of the forelimb and appropriate visual tracking during motor performance. Comparison of results before and after section of the Dorsal Columns at the first cervical level revealed obvious postoperative inefficiency in the overall performance of the act. The accuracy of extrapersonally projected movements of the forelimbs (reaching towards a moving target) was seriously affected, as was the capacity to visually track a target in space during the jump. Testing which did not require jumping up towards the target, but merely rearing on the hindlimbs, showed no improvement in the performance of lesioned animals when compared to controls. The deficits mentioned also persisted in animals subjected to preoperative overtraining and prolonged postsurgical testing, a procedure which in certain tasks allows the animal to perform normally after surgery. Physiologically, the Dorsal Columns have been shown to be the exclusive path of fibers from muscle spindles and low threshold joint receptors from the forelimbs. The corresponding fibers from the hindlimbs reach higher centers via different pathways. The loss of this information from forelimbs resulting from high cervical Dorsal Column section may then help to explain the deficits described.