A multiple-exemplar identity matching-to-sample baseline was established to encourage development of generalized IDMTS performances in three adult male capuchins. Mask (blank comparison) or Shuffled S− procedures were used to promote select (sample-S+) control in baseline relations and to assess stimulus control relations in generalized IDMTS tests. The IDMTS baseline comprised eight 3-stimulus sets or four 4-stimulus sets. Probe trials with new stimulus sets were substituted for baseline sets in successive testing sessions and subsequently converted to new baseline relations. All monkeys exhibited high accuracy on generalized IDMTS tests. A monkey who was given the Mask procedure in training and tests showed generalized IDMTS with select relations predominating. Two monkeys who were given training and testing with the Shuffled S− procedure performed somewhat better on Shuffled S− IDMTS test trials than on test trials that contained non-shuffled test IDMTS trials thus suggesting that exclusion of familiar nonmatching comparison stimuli from baseline in Shuffled S-test trials contributed to the higher accuracy scores with the former procedures. Development of select relations appeared to be a positive predictor of development of generalized IDMTS.

This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys (Cebus apella). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The objective was to transform identity matching into arbitrary matching (i.e., matching not based on common physical features of the sample and comparison stimuli). Experiment 1 used a two-comparison procedure. The shaping procedure was ultimately effective, but occasional high error rates at certain program steps inspired a follow-up study. Experiment 2 used the same basic approach, but with a three-comparison matching task. During shaping, the monkey performed accurately until the final steps of the program. Subsequent experimentation tested the hypothesis that the decrease in accuracy was due to restricted stimulus control by sample stimulus features that had not yet been changed in the shaping program. Results were consistent with this hypothesis, thus suggesting a new approach that may transform the sample stimulus control shaping procedure from a sometimes useful laboratory tool to a more general approach to teaching the first instance of arbitrary matching performances to participants who show protracted difficulties in learning such performances.

O procedimento de exclusão pode expandir repertório relacional arbitrário de crianças, em condições de aprendizagem sem erros. Embora a escolha por exclusão esteja presente em diversas espécies não humanas, ela nem sempre resulta na aprendizagem de novas relações. O objetivo deste trabalho foi verifi car a escolha por exclusão em um macaco-prego e a aquisição das novas relações arbitrárias como um resultado do contexto de exclusão. O sujeito apresentava um repertório de 5 relações arbitrárias A-B e suas simétricas B-A adquirido em estudo prévio, em um procedimento de pareamento ao modelo com atraso, envolvendo cinco ou mais escolhas como comparações. Neste estudo, usando o procedimento de pareamento ao modelo com duas escolhas, novas relações arbitrárias A-C foram introduzidas, usando-se estímulos B como S-, para verifi car exclusão. O sujeito respondeu corretamente nas tentativas de exclusão excluindo o estímulo B e escolhendo o estímulo C. A aprendizagem das novas relações A-C foi avaliada em tentativas compostas apenas por comparações do Conjunto C, e o sujeito respondeu incorretamente nessas tentativas. Um treino com comparação vazia visando estabelecer controle por seleção e rejeição nas relações A-C não foi efetivo em gerar relações de controle por seleção. Em estudos futuros serão usadas mais de duas escolhas por tentativa no treino A-C, em contexto de exclusão, visando obter a aprendizagem das novas relações.

No abstract

Temporal lobe epilepsy (TLE) is the commonest type of focal epilepsy in adult humans. In refractory TLE, patients are indicated for unilateral resection of the affected hippocampus (hippocampectomy), which generally does not cause any cognitive impairment. Once adult hippocampus is a region of endogenous neurogenesis, we have hypothesized that a compensatory increase in hippocampal neurogenesis might occur in the remaining hippocampus after unilateral hippocampectomy. To test this hypothesis, we performed unilateral hippocampectomy in adult Wistar rats (n=12). Sham animals were not hippocampectomized (n=6). Animals were deeply anesthetized and adjacent cortex and hippocampus of the left hemisphere were completely removed. They were perfused at 15 (G15, n=6) or 30 (G30, n=6) days post-surgery. Behavioral tests were performed to address possible cognitive impairments. We did not find any cognitive impairment in the hippocampectomized animals. Histopathology was performed using thionine staining and mature neurons and migratory neuroblasts were immunolabeled using anti-NeuN and anti-doublecortin (DCX) antibodies, respectively. The remaining hippocampus presented higher numbers of DCX positive cells compared to control (p<0.001) at both G15 and G30. The results suggest increased compensatory adult neurogenesis following experimental unilateral hippocampectomy in adult rats, which may contribute to absence of cognitive impairments.