Authors: P Girard C Jouffrais C H Kirchner
Publish Date: 2008/02/08
Volume: 11, Issue: 3, Pages: 485-493
Abstract
The visual system of primates is remarkably efficient for analysing information about objects present in complex natural scenes Recent work has demonstrated that they perform this at very high speeds In a choice saccade task human subjects can initiate a first reliable saccadic eye movement response to a target the image containing an animal in only 120 ms after image onset Such fast responses impose severe time constraints if one considers neuronal responses latencies in highlevel ventral areas of the macaque monkey The question then arises are nonhuman primates able to perform the task Two rhesus macaque monkeys Macaca mulatta were trained to perform the same forcedchoice categorization task as the one used in humans Both animals performed the task with a high accuracy and generalized to new stimuli that were introduced everyday accuracy levels were comparable both with new and wellknown images 84 vs 94 More importantly reaction times were extremely fast minimum reaction time 100 ms and median reaction time 152 ms Given that typical single units onset times in Inferotemporal cortex IT are about as long as the shortest behavioural responses measured here we conclude that visual processing involved in ultra rapid categorisations might be based on rather simple shape cue analysis that can be achieved in areas such as extrastriate cortical area V4 The present paper demonstrates for the first time that rhesus macaque monkeys Macaca mulatta are able to match human performance in a forcedchoice saccadic categorisation task of animals in natural scenesMaxime Rosito for eye movement analysis Franck Lefèvre et Sebastien Aragones for animal care Michèle FabreThorpe and Simon Thorpe for helpful discussion All animal procedures complied with guidelines of the European Ethics committee on Use and Care of Animals and complied with French laws
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