Serial Lesion Effect Research Articles

Successive bilateral frontal controlled cortical impact injuries show behavioral savings

Traumatic brain injuries (TBIs) affect millions of people each year. Research investigating repeated or serial damage in the form of lesions indicates that behavioral deficits are reduced in animals given sequential lesions separated by a sufficient period of recovery. In the lesion literature, this phenomenon is known as the serial lesion effect (SLE). Although the SLE phenomenon is established in the lesion literature, it has not been thoroughly investigated under current models of brain injury. In the current study, a controlled cortical impact of the bilateral frontal cortex was performed in either a single procedure or a serial procedure separated by two weeks. Rats were tested on the Morris water maze, bilateral tactile adhesive removal task, rotarod and Barnes maze task to determine behavioral deficits. Histology was performed to determine lesion size and astrocyte and microglial response. A serial lesion effect was demonstrated across a majority of the behavioral tasks. However, histological analyses did not suggest a clear mechanistic link to the behavioral phenomena. This is the first study to demonstrate the SLE in a model of TBI, suggesting that behavioral deficits may actually be reduced in repeated head injuries, given an adequate time window between injuries.

Multiple Realizability, Identity Theory, and the Gradual Reorganization Principle

In the literature on multiple realizability and the identity theory, cases of neural plasticity have enjoyed a very limited role. The present article attempts to remedy this small influence by arguing that clinical and experimental evidence of quite extensive neural reorganization offers compelling support for the claim that psychological kinds are multiply realized in neurological kinds, thus undermining the identity theory. In particular, cases are presented where subjects with no measurable psychological deficits also have vast, though gradually received, neurological damage. Common objections and concerns are also discussed and rejected. 1 Introduction 2 The GRP, Serial Lesion Effect, and Multiple Realizability 2.1 A case study of the serial lesion effect 2.2 Evaluating the case study’s evidence for multiple realizability 3 The GRP More Generally 4 Objections to the GRP as Evidence for Multiple Realizability 4.1 Small plastic effects and neurological taxonomies 4.2 But do neural regions and locations even matter at all? 4.3 But are there not other options besides location? 5 Conclusion

Brain recovery – towards an unified theory

Brain recovery – towards an unified theory

"Recovery of sensorimotor function after frontal cortex damage in rats: Evidence that the serial lesion effect is due to serial recovery": Correction.

"Recovery of sensorimotor function after frontal cortex damage in rats: Evidence that the serial lesion effect is due to serial recovery": Correction.

Recovery of sensorimotor function after frontal cortex damage in rats: Evidence that the serial lesion effect is due to serial recovery.

Recovery of sensorimotor function after frontal cortex damage in rats: Evidence that the serial lesion effect is due to serial recovery.

Effects of serial lesions of telencephalic components of the visual system in pigeons.

A serial-lesion technique was used to investigate interactions in visual processing between telencephalic components of the pigeon visual system. Pigeons were trained to discriminate pairs of stimuli that differed in color, intensity or pattern. After mastering the discrimination tasks, they were assigned to one of three groups. The first group (WI-EII) received lesions of the visual Wulst and were retested. After the discrimination tasks were again mastered, a second set of lesions was made, this time in the ectostriatum. The birds were tested once again after the second surgery. The second group (EI-WII), underwent the same sequence of events except that the order of the lesions was reversed. In the third group (E + W), lesions of both the visual Wulst and ectostriatum were made in a single operation, followed by retesting. The performance after the first lesion of the subjects in each of the two-stage lesion groups was typical of performance after such lesions; i.e. the birds with visual-Wulst lesions showed little or no impairment on any of the tasks, whereas the pigeons with ectostriatum lesions showed considerable deficits in intensity and pattern discrimination, which diminished after prolonged retraining. In contrast, the pigeons in the one-stage group (E + W) showed profound deficits that appeared to be permanent. The performance after the second operation of the WI-EII group was the same as that of pigeons with lesions of ectostriatum alone; i.e. destruction of ectostriatum first or second resulted in the same duration of impairment. The performance of the EI-WII group after its visual Wulst lesion, however, was similar to that observed in the E + W group. The results are interpreted as a reflection of parallel processing within the avian visual system; i.e. the presence of an intact tectofugal pathway may mask the effects of thalamofugal pathway interruption.

Recovery of sensorimotor function after frontal cortex damage in rats: evidence that the serial lesion effect is due to serial recovery.

Multiple-staged brain lesions produce fewer and smaller behavioral effects than does damage produced in a single surgery. This is called the serial lesion effect. Two hypotheses were tested, the reduced deficit hypothesis and the serial recovery hypothesis, which attempt to explain the serial lesion effect. The effects of lesions of the medial frontal cortex on sensorimotor behavior were investigated in rats that received bilateral damage in a single surgery (n = 7), in two unilateral stages separated by 3 weeks (n = 16), or unilateral damage followed 3 weeks later by a sham surgery (n = 5). Unilateral damage produced deficits on the contralateral side in responsivity to visual, tactile, and olfactory stimuli and impairments in roll-over and paw withdrawal motor responses. All behavioral impairments except visual placement recovered over the next 3 weeks. A second unilateral lesion on the contralateral side produced the same symptoms but on the opposite side of the body. There was no reinstatement of the previously recovered deficits. Bilateral damage incurred in a single stage produced these same deficits on both sides. Because the effects of the second unilateral lesion in the two-stage group produced comparable contralateral effects to those produced in the single-stage group, but no reinstatement of ipsilateral deficits occurred, the reduced deficit hypothesis was rejected. It was concluded that at least for medial frontal cortex damage, the serial lesion effect occurred as a result of serial recovery of the deficits.

Serial lesion effect in rat medial frontal cortex as a function of age

—This experiment examined the potential for behavioral recovery in juvenile, adult, and senescent rats following serial lesions of medial frontal cortex. The subjects were trained on spatial delayed alternation in a T-maze under conditions designed to enhance the probability of a a serial lesion effect. All subjects were given extensive handling and adaptation to the maze, interoperative training, and long interoperative and postoperative intervals. There were several major behavioral findings: (a) the aged intact subjects were not impaired in their ability to learn spatial delayed alternation, (b) one-stage bilateral lesions of frontal cortex produced equivalent deficits on spatial delayed alternation at all ages, (c) subjects in all of the ages, (c) subjects in all of the age categories demonstrated a serial lesion effect, but (d) the 150 day and 570 day serial lesion groups demonstrated significantly better performances than the 35 day serial lesions group on several measures of performance.

Effects of one- and two-stage lesions of the posterior hypothalamus on temperature regulation in the rat

Rats received 1-stage bilateral or sequential unilateral (serial) lesions of the posterior hypothalamus and were tested for the ability to regulate body temperature after a lengthy recovery period. The groups with lesion differed from the sham-operated groups in the cold, although not under ambient or warm conditions. The fact that the serial lesion group performed the same as the 1-stage lesion groups in the cold is significant because earlier tests on these same animals revealed much better recovery after serial lesions in swimming, and a partial serial lesion effect in open field performance.

The differential effects of additional cortical lesions in rats with single- or multiple-stage lesions of the visual cortex

Male albino rats relearned a black-white discrimination for food after posterior neocortex was bilaterally removed in a single operation (“single stage”) or in two unilateral operations (“multiple stage”). Single-stage animals showed no savings in relearning (relearning errors = learning errors). Multiple-stage animals showed positive savings (relearning errors < learning errors). To assess cortical reorganization, the rats were given additional lesions and again retrained. Cortex either contiguous or noncontiguous with the posterior lesion was removed bilaterally. Contiguous and noncontiguous lesions produced different effects only among animals with prior multiple-stage posterior lesions. Rats with single-stage posterior lesions and contiguous or noncontiguous lesions showed positive savings and did not differ from each other or from rats with multiple-stage posterior and noncontiguous lesions. Rats with multiple-stage posterior and contiguous lesions made more errors and showed negative savings. The role of contiguous cortex in the serial lesion effect was also tested with two additional groups. Rats given noncontiguous cortex lesions prior to multiple-stage posterior lesions showed positive savings in retraining. Rats given contiguous cortex lesions prior to multiple-stage posterior lesions showed negative savings.

Age and serial ablations of somatosensory cortex in the rat

The present study investigated the effects of one-stage and two-stage ablations of somatosensory cortex at 30 days, 270 days and 570 days of age on the acquisition of tactile discriminations in rats. Deficits in the ability to acquire tactile discriminations following such cortical lesions appeared to be similar regardless of the age at which the damage was sustained. Serial placement of the lesions did not attenuate the deficits in 30-day or 570-day-old rats. Some mitigation of the impairment was present in animals sustaining serial surgery at 270 days of age. In contrast, rats sustaining one-stage lesions at 570 days of age performed somewhat better than their age-mates sustaining two-stage lesions. Factors possibly relevant to the serial lesion effect and to recovery of function in general are suggested.

A theory of the serial lesion effect

The serial lesion effect is explained as a result of differentiation contingent upon induction by a spared residue. The induction can only take place when the lesion is made since the intact structures repress differentiation when some critical mass is reached. A distinction between the process giving rise to reorganization and reorganization as an outcome is made.

Effects of serial lesions of somatosensory cortex and further neodecortication on retention of a rough-smooth discrimination in rats.

Five groups of rats with bilateral lesions of the somatosensory cortex and one of animals sustained only sham operations were tested for retention of a rough-smooth discrimination. Two of the lesion groups had sequential unilateral ablations, in one case with interoperative testing, and three groups had one-stage bilateral lesions. The two groups of animals with serial lesions did not differ from each other or from sham operates in relearning the task. RAts with one-stage lesions and preoperative overtraining also performed well, but the other one-stage groups showed deficits relative to control and serial lesion groups. In the second experiment the sham operated rats from Experiment 1 experiences lesions anterior and posterior to the somatosensory zones. These lesions did not affect retention. Somatosensory cortex then was ablated in one operation and severe performance decrements were seen. Removal of additional neocortex in a sample of animals that had relearned the discrimination after one-stage somatosensory cortex lesions (Exp. 1) also affected retention. In contrast, retention was not impaired on some of the measures in those animals that originally had two-stage ablations. The findings from these two experiments show that some ablation effects can be circumvented with overtraining or serial lesion techniques. The data also indicate that non-somatosensory cortex may play a role in recovery after somatic cortex lesions, but that the substrates underlying recovery might not be the same after one-stage and two-stage ablations.

Effects of serial unilateral and serial bilateral visual cortex lesions on brightness discrimination relearning in rats.

In Experiment 1, rats with serial unilateral (SU), serial bilateral (SB), or one-stage bilateral (B) visual cortex lesions (areas 17, 18 and 18a) were compared in their retention of a preoperatively learned brightness discrimination. Both the first-stage and second-stage lesions for the SU and SB groups involved the same amount of cortical tissue and the same composite areas of visual field projection in primary and extraprimary visual cortex. Groups SU and SB showed substantial savings of the brightness discrimination after the completed bilateral visual cortex removals, while Group B showed a complete postoperative loss. In Experiment 2, the effects of two additional types of serial bilateral visual cortex lesions were investigated. These involved the medial and then lateral aspects of visual cortex in two stages (ML), or vice versa (LM). Once again, the serial bilateral lesion groups (SB, ML, and LM) showed substantial savings of the discrimination after the completed lesion, while Group B showed a complete post-operative loss. These results demonstrate a general advantage of serial damage over one-stage damage to visual cortex in recovery of a preoperatively learned brightness discrimination and indicate that the serial lesion effect is not specific to interhemispheric relationships.

Effects of serial lesions of somatosensory cortex and further neodecortication on tactile retention in rats.

Four groups of rats with bilateral lesions of somatosensory cortex and one of animals sustaining only sham operations were tested for retention of a difficult tactile discrimination. Two of the lesion groups had serial ablations, in one case with interoperative testing, and two had one-stage lesions. Bilateral ablations of somatosensory cortex severely retarded retention in all lesion groups relative to the control group and serial and one-stage groups did not differ from each other. The sham operated rats then experienced lesions of cortex anterior and posterior to the somatosensory areas. These lesions only marginally affected retention. Somatosensory cortex then was ablated and severe performance decrements were seen. Removal of additional neocortex in animals that previously had relearned the discrimination after somatosensory cortex lesions also resulted in very poor retention. These data demonstrate the importance of the somatosensory cortex in mediating tactile discriminations and suggest that non-somatosensory cortex may play a role in recovery after somatosensory cortical lesions.

Effects of serial lesions in cat visual cortex on a brightness discrimination

Studies with many mammalian species have shown that simultaneous, bilateral ablation of the visual cortex in both cerebral hemispheres produces a postoperative deficit in a previously-learned dark-light discrimination but that the habit can be relearned postoperatively with additional training. It has also been reported that, in rats trained in a dark-light discrimination, unilateral ablation of the visual cortex of one hemisphere followed several weeks later by ablation of the contralateral visual cortex results in a postoperative retention deficit less severe than that following simultaneous, bilateral ablations if the animals remain in their normal home environment during the interoperative periodS, 8. This result has been challenged by Thompson 11 who found that interoperative training is necessary if rats with serial, unilateral lesions are to show better retention than rats with one-stage bilateral lesions. Petrinovich and Carew 7 have indicated, however, that the difference in the results of these studies was probably due to larger lesions in Thompson's rats. Other studies have also suggested that sequential cortical lesions in rats 2 and in monkeys s-10 may produce more sparing of learned habits than single stage lesions. In a previous study, Baden et al. 1 reported that simultaneous, bilateral ablation of the principal visual projection areas in the cerebral cortex of the cat produced a postoperative deficit in a previously-learned dark-light discrimination, but that postoperative relearning of the discrimination could be accomplished with a 26 ~ savings in the number of required trials. The present study reports the effects on a dark-light discrimination of serial, unilateral lesions of the visual cortex of cats and compares these results with the previously-reported effects of simultaneous, bilateral lesions. Seven experimentally naive cats of both sexes were studied. They were housed in individual cages under an alternating, 12 h dark-light cycle and were trained in a dark-light discrimination in an automatically-programmed, self-advancing, continuous type 'Y ' maze 1. After initial shaping with the lighter stimulus correct (3.0 ft. cd.), a response to the darker stimulus (1.0 ft. cd.) was rewarded with a small portion of raw spleen, using a training procedure in which errors could be corrected. The animals