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講演者

Neural activity manipulation and behavioral change in gloss perception of the macaque monkey

We can easily recognize whether the surface of an object is smooth or rough, just by seeing. In recent study, it is shown that neurons selectively respond to specific gloss are present in the central part of the inferior temporal (IT) cortex of macaque monkey (Nishio et. al. 2012, 2014). Although the population activity of such neurons represents the perceptual gloss space, the involvement of their activity in gloss perception has not been directly tested. In the present study, we examined the causal relationship between the activities of gloss-selective neurons and gloss perception by applying electrical microstimulation or injection of small amounts of muscimol (GABAA agonist) to manipulate neural activities while monkeys performed a gloss discrimination task. We found that microstimulation and muscimol injection influenced on the monkey’s gloss discrimination behavior.

Cross-species view of cortical myeloarchitecture in non-human primates

Cross-species comparisons of primate brain is an important means to understand the structure, function, and evolution of human brain. We developed a brain MRI data acquisition and the analysis pipeline for non-human primate (NHP) adapted from human connectome project (HCP) (Glasser et al., 2013, Autio et al., 2020; Hayashi et al.,2021). Here we present cortical myeloarchitecture in three NHPs: rhesus monkey (Macaca mulatta, n = 32), owl monkey (Autos lemurinus, n = 9), and common marmoset (Callithrix jacchus, n = 20). The myelin contrast was estimated by a ratio of T1-weighted/T2-weighted MRI (Glasser and Van Essen, 2011), and its cortical surface mapping demonstrated shared pattern in all three species: high myelin in the primary motor and somatosensory areas, early visual areas, auditory areas, and middle temporal areas (MT), and low myelin in association areas such as prefrontal, medial parietal, insular, and lateral temporal areas. On the other hand, quantitative analysis of myelin-based parcellation showed difference in areal size between species: Owl monkeys have relatively large surface areas of MT compared to other species, which might reflect their nocturnal nature. The results suggest the future possibility of the cortical myeloarthitecture analysis for quantitative comparative neuroscience.

How IT cortex gets its spots

We are remarkably good at recognizing objects and faces in our environment, even after just a brief glimpse. How do we develop the neural circuitry that supports such robust perception? The biological im-portance of faces for social primates and the stereotyped location of face-selective brain regions across individuals has engendered the idea that face regions are innate neural structures. I will present data chal-lenging this view, where ventral-stream modules do not represent clusters of circuits that each evolved to process some specific object category but instead reflect the effects of experience on a domain-general architecture that evolved to be able to adapt, within a lifetime, to its particular environment. Within this framework, topographic maps play a fundamental role, governing the development of specializations across systems and providing an early scaffolding that guides postnatal experience-driven modifications.