[Abstract Title]. - Society for Neuroscience

Inst. of Neurol., London, United Kingdom; 4 Symbolic Cognitive Develop., 5 FMRI Support Unit,
6 Cognitive Brain Mapping, RIKEN Brain Sci. Inst., Wako-shi, Saitama, Japan
Abstract: There are few reports of macaques using tools in the wild. However macaque
monkeys can be trained to use a rake to retrieve out-of-reach food (Ishibashi et al, 2000). It takes
approximately 15 days for the monkeys to reach a level where the food can be retrieved
efficiently. Neurophysiological and anatomical studies suggest that training to use a rake induces
changes in macaque cortex: receptive fields of neurons in the intraparietal sulcus (IPS) adapt to
include the tool in the body schema (Maravita & Iriki, 2004), and expression of BDNF, its
receptor trkB and NT-3 is increased during tool-use training (Ishibashi et al, 2002). Following
training, cortico-cortical projections are revealed from the higher visual centres to the
intraparietal area (Hihara et al, 2006). We used non-invasive structural MRI and voxel based
morphometry (VBM) to confirm whether learning to use a tool causes long-term structural
changes in the cortex. Three tool-use naive young Japanese macaques (4.1, 5.1, 5.6 kg) were
trained to use the rake. Each monkey was scanned on 6 occasions over a period of 6 weeks with
3 scans taken during each session, using a 4T Varian MRI scanner. During training, which began
in the third week, there was a timed test period of 50 trials, each trial was assigned a score of 1-3
(3: food retrieved on first attempt; 2: food obtained on the second attempt and 1: food obtained
only after multiple attempts). A VBM analysis revealed structural increases in a number of
cortical regions that were significantly correlated (p