Fri, 04 Jul 2008 23:37:47 BST CiteULike: Group: Glimcher_Lab - with tag chimpanzees http://www.citeulike.org/group/70/tag/chimpanzees CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/group/70/article/1926491 <i>Cereb. Cortex (22 June 2007), bhm089.</i><br /><br />In this study, we assess the possibility that the evolution of human intellectual capacities was supported by changes in the supply of serotonin to the frontal cortex. To this end, quantitative comparative analyses were performed among humans, chimpanzees, and macaques. Immunohistochemical methods were used to visualize serotonin transporter-immunoreactive (SERT-ir) axons within the cerebral cortex. Areas 9 and 32 were chosen for evaluation due to their roles in working memory and theory of mind, respectively. Primary motor cortex was also evaluated because it is not associated with higher cognitive functions. The findings revealed that humans do not display a quantitative increase in serotonin innervation. However, the results indicated region- and layer-specific differences among species in serotonergic innervation pattern. Compared with macaques, humans and chimpanzees together displayed a greater density of SERT-ir axons relative to neuron density in layers V/VI. This change was detected in cortical areas 9 and 32, but not in primary motor cortex. Further, morphological specializations, coils of axons, were observed in humans and chimpanzees that were absent in macaques. These features may represent a greater capacity for cortical plasticity exclusive to hominoids. Taken together, these results indicate a significant reorganization of cortical serotonergic transmission in humans and chimpanzees. 10.1093/cercor/bhm089 Differences in Cortical Serotonergic Innervation among Humans, Chimpanzees, and Macaque Monkeys: A Comparative Study Mary Raghanti Cheryl Stimpson Jennifer Marcinkiewicz Joseph Erwin Patrick Hof Chet Sherwood doi:10.1093/cercor/bhm089 Cereb. Cortex (22 June 2007), bhm089. 2007-11-16T13:58:07-00:00 2007 Cereb. Cortex bhm089 chimpanzees comparative cortex human macaques nonhuman pathway serotonin http://www.citeulike.org/group/70/article/1325589 <i>J Comp Psychol, Vol. 109, No. 1. (March 1995), pp. 18-26.</i><br /><br />Five chimpanzees (Pan troglodytes) were tested to assess their understanding of causality in a tool task. The task consisted of a transparent tube with a trap-hole drilled in its middle. A reward was randomly placed on either side of the hole. Depending on which side the chimpanzee inserted the stick into, the candy was either pushed out of the tube or into the trap. In Experiment 1, the success rate of 2 chimpanzees rose highly above chance, but that of the other subjects did not. Results show that the 2 successful chimpanzees selected the correct side for insertion beforehand. Experiment 2 ruled out the possibility that their success was due to a distance-based associative rule, and the results favor an alternative hypothesis that relates success to an understanding of the causal relation between the tool-using action and its outcome. Comprehension of cause-effect relations in a tool-using task by chimpanzees (Pan troglodytes). L Limongelli ST Boysen E Visalberghi J Comp Psychol, Vol. 109, No. 1. (March 1995), pp. 18-26. 2007-05-24T18:05:50-00:00 1995 J Comp Psychol 0735-7036 109 1 18 26 causal_inference cause_effect chimpanzees inference_judgements tool-using