Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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Recent findings indicate that neonatal ablations of inferior temporal cortex (area TE) in rhesus macaques (Macaca mulatta) result in altered vocal behavior when assessed around 1 year of age (Newman, J.D. and Bachevalier, J., Brain Res. 758:180, 1997). The present study evaluated the vocal behavior of TE-lesioned infants at earlier ages, with the goal of determining the developmental period at which vocal differences first appeared. Subjects were 7 with neonatal bilateral TE ablations and 7 unoperated controls. Each subject was recorded from in a room away from other conspecifics during 1-6 sessions lasting 5-10 min each, resulting in 1503 vocalizations for analysis. Vocalizations were categorized according to established criteria into coos or noisy calls (screams, leaps, noisy coos). In our earlier study, we found that males but not females with TE ablations made more noisy calls than same-sex controls in their second year of life. At 4-8 weeks of age, no significant differences in calling behavior between TE and Control animals were found. However, in older individuals (24-36 weeks of age), TE males called more frequently than Control males. These results indicate that the calling behavior of rhesus infants with bilateral TE ablations made during the neonatal period differs from that of controls, and that males are affected by the experimental ablations more than females with respect to their rate of calling over the first 1-1/2 years of life.

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Presentation Number SAnewman0520
Keywords: vocalisation, primate, neuroethology, development, neocortex