Biomedical subjects

Sayaka Hihara

Publications and source records attributed to Sayaka Hihara.

6 recordsLinked to original sources

PubMed2006

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.

Afferent Pathways↗

PubMed2003

Rapid learning of sequential tool use by macaque monkeys.

Earlier reports have described monkeys in their natural habitat as being capable of purposefully using tools for activities such as obtaining food. However, little is known regarding the extent of macaque monkeys' ability to understand the functional meaning of objects as tools. We have trained Japanese macaques in tool-use behavior to demonstrate their abilities to solve stick problems involving the use of a novel tool and a sequential combination of different tools. Results suggest that macaque monkeys have cognitive abilities, such as (1). flexibility in applying previous experience in accordance with the requirements of the learning situation, (2). the foresight needed to conduct a series of acts in a continuous sequential manner and the ability to internally plan the necessary strategy.

Adaptation, Psychological↗

PubMed2003

Spontaneous vocal differentiation of coo-calls for tools and food in Japanese monkeys.

Vocal production and its usage in nonhuman primates may share common features with primitive human language. We trained two Japanese monkeys to use a rake-shaped tool to retrieve distant food. After the training, the monkeys spontaneously began vocalizing coo-calls in the tool-using context. We then trained one of the monkeys to vocalize to request food or the tool. Three independent acoustic parameters were measured and each parameter was independently analyzed across conditions using a multiple comparison test. We found that the monkey spontaneously differentiated their coo-calls to ask for either food or tool during the course of this training. This process might involve a change from emotional vocalizations into intentionally controlled ones by associating them with consciously planned tool use. We thus established a novel hypothesis about the origin of voluntary vocal control that could be approached from neurophysiological procedures.

Animals↗

PubMed2002

Macaque prefrontal activity associated with extensive tool use.

Macaques can utilize tools sequentially on a single object or they can modify functions effectively in a relevant context. Two Japanese macaques were scanned by positron emission tomography with H(2)15O during a tool combination task and two control tasks (single tool task and simple stick-waving task). In the tool combination task, monkeys were required to use two identical tools properly in different functions. We found increased activity in the bilateral prefrontal cortex (area 9/46), bilateral intraparietal sulcus regions, right cerebellum, and bilateral early visual cortices during the tool combination task with the right hand, compared with the single tool task. These results suggest that interactions between the fronto-cerebellar and the fronto-parietal circuit are responsible for appropriate and effective modifications of tools in their functions.

Animals↗

PubMed2002

Tool-use learning induces BDNF expression in a selective portion of monkey anterior parietal cortex.

Learning but not execution of tool-use induced expression of brain-derived neurotrophic factor (BDNF). The expression was highest in the anterior bank of the intraparietal sulcus, especially in the region posteriorly adjacent to the somatosensory shoulder and forearm region in area 3b, suggesting that BDNF plays a role in altering the body image of the hand to include the repeatedly used tool as its extension.

Animals↗

PubMed2002

Tool-use learning selectively induces expression of brain-derived neurotrophic factor, its receptor trkB, and neurotrophin 3 in the intraparietal multisensorycortex of monkeys.

When humans repeatedly use a tool, our body image alters until the tool finally becomes a part or an extension of the body. This alteration of body image perhaps results from re-integration of somatosensory and visual signals. We trained Japanese monkeys to use a rake-shaped tool to retrieve a distant food pellet, then used a novel tissue-sampling method to suction brain tissue from the anterior bank of their intraparietal sulcus, where somatosensory and visual signals converge. Examination of the messenger RNA expression levels of neurotrophins and their receptors using real-time quantitative polymerase chain reaction revealed learning-selective induction in the expression of brain-derived neurotrophic factor, its receptor trkB, and NT-3 during, but not after, the learning. These results suggest that these factors are involved in the reorganization of the somatosensory and visual signals in the anterior bank of the intraparietal sulcus when monkeys are learning the use of the tool.

Animals↗