Extension of corticocortical afferents into the anterior bank of the intraparietal sulcus by tool-use training in adult monkeys.
When humans use a tool, it becomes an extension of the hand physically and perceptually. Common introspection might occur in monkeys trained in tool-use, which should depend on brain operations that constantly update and automatically integrate information about the current intrinsic (somatosensory) and the extrinsic (visual) status of the body parts and the tools. The parietal cortex plays an important role in using tools. Intraparietal neurones of naïve monkeys mostly respond unimodally to somatosensory stimuli; however, after training these neurones become bimodally active and respond to visual stimuli. The response properties of these neurones change to code the body images modified by assimilation of the tool to the hand holding it. In this study, we compared the projection patterns between visually related areas and the intraparietal cortex in trained and naïve monkeys using tracer techniques. Light microscopy analyses revealed the emergence of novel projections from the higher visual centres in the vicinity of the temporo-parietal junction and the ventrolateral prefrontal areas to the intraparietal area in monkeys trained in tool-use, but not in naïve monkeys. Functionally active synapses of intracortical afferents arising from higher visual centres to the intraparietal cortex of the trained monkeys were confirmed by electron microscopy. These results provide the first concrete evidence for the induction of novel neural connections in the adult monkey cerebral cortex, which accompanies a process of demanding behaviour in these animals.
Hihara
Sayaka
S
Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako 351-0198, Japan. hihara@brain.reken.jp
Notoya
Tomonori
T
Tanaka
Michio
M
Ichinose
Shizuko
S
Ojima
Hisayuki
H
Obayashi
Shigeru
S
Fujii
Naotaka
N
Iriki
Atsushi
A
D000344:Afferent Pathways / Q000502:physiology*; D000578:Amidines / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D001931:Brain Mapping; D003911:Dextrans / Q000378:metabolism; D006651:Histocytochemistry / Q000379:methods; D007858:Learning / Q000502:physiology*; D008252:Macaca fascicularis; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009044:Motor Cortex / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D010296:Parietal Lobe / Q000502:physiology* / Q000648:ultrastructure; D011597:Psychomotor Performance / Q000502:physiology*; D013003:Somatosensory Cortex / Q000166:cytology / Q000378:metabolism; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D000578:Amidines; D003911:Dextrans; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; C076397:biotinylated dextran amine; C031455:diamidino compound 253-50; D001710:Biotin