The research goal of our laboratory is to understand the neural mechanisms underlying higher cognitive functions, including object recognition, attention, working memory, and long-term memory, in the primate cerebral cortex. Cortical areas involved in vision are organized hierarchically, and each has a functionally modular structure (functional domains or columns). In contrast to earlier visual areas (V1 and V2), the functional organization of higher visual and association areas have been less well studied, even though they play important roles in higher cognitive brain functions. We are studying the functional and anatomical organization of higher visual areas from area V4 to the area TE in the ventral visual processing stream, which is important for object recognition, and the prefrontal cortex (PFC), which mediates cognitive and executive controls. The work is conducted in macaque monkeys using a variety of research techniques including Intrinsic Signal Optical Imaging, Electrocorticography (ECoG), Multi-electrode array (MEA) recoding, and Neuronal tracing.
(1) Intrinsic Signal Optical Imaging (ISOI)
ISOI is one of the key technique in our lab. ISOI can visualize cortical hemodynamics related to neural activity changes at columnar resolution (~50 micrometers) in the exposed cortex by measuring changes in the intensity of light reflected from the cortical surface under illumination with certain wavelength. We have used this technique and successfully revealed the functional organization in macaque visual cortices [1-4]. Because this technique is accompanied with exposing the cortical surface, it has good compatibility with the other invasive research techniques used in this project, such as ECoG and MEA recordings, and neuronal tracing.
(2) Electrocorticography (ECoG)
Electrocorticography (ECoG), that enables recording local field potentials (LFPs) from the cortical brain surface, has long been an indispensable tool for the evaluation of epileptic foci in human patients. With advances in high-channel-count data acquisition and mathematical tools for analyzing high-dimensional data, ECoG has become an important tool for investigating brain functions, particularly neuronal oscillatory activity, and recognized as a promising technology for brain-machine interface (BMI). Using this technique, we have revealed the functional organization and its plasticity for long-term memory in the macaque medial temporal lobe (MTL) .
(3) Multi-electrode array (MEA) recoding
A typical MEA consists of multiple penetrating electrodes for recording and stimulating at brain sites. After ISOI and ECoG recording sessions, we plan to penetrate several MEAs into the cortex to examine neuronal properties of the functional organization at a single-cell level.
(4) Neuronal tracing
Neuronal tracing is a technique for anatomically visualizing neural connections in the postmortem brain tissue. Usually, neuronal tracers are injected into the brain of living animals, taken up by neurons, and transported through axons. Anterograde tracers are transported from cell bodies to axon terminals, and retrograde tracers are transported from axon terminals to cell bodies. After a certain period, the animals are perfused with a fixative solution, and brain sections are cut and processed for histological procedures to visualize the distribution of transported tracers. We have studied the anatomical intrinsic network in the inferior temporal cortex (ITC) by using neuronal tracers [6-8].
 Tanigawa H, Lu HD, Roe AW (2010) Functional organization for color and orientation in macaque V4. Nature Neuroscience. 13:1542–1548. Link
 Tanigawa H, Chen G, Roe AW (2016) Spatial Distribution of Attentional Modulation at Columnar Resolution in Macaque Area V4. Frontiers in Neural Circuits. 10:1–13. Link
 Lu HD, Chen G, Tanigawa H, Roe AW (2010) A Motion Direction Map in Macaque V2. Neuron. 68:1002–1013. Link
 Chen G, Lu HD, Tanigawa H, Roe AW (2017) Solving visual correspondence between the two eyes via domain-based population encoding in nonhuman primates. Proc Natl Acad Sci USA. 114:13024–13029. Link
 Nakahara K et al. (2016) Associative-memory representations emerge as shared spatial patterns of theta activity spanning the primate temporal cortex. Nature Communications. 7:11827:1–9. Link
 Tanigawa H, Fujita I, Kato M, Ojima H (1998) Distribution, morphology, and gamma-aminobutyric acid immunoreactivity of horizontally projecting neurons in the macaque inferior temporal cortex. Journal of Comparative Neurology. 401:129–143. Link
 Tanigawa H, Wang Q, Fujita I (2005) Organization of Horizontal Axons in the Inferior Temporal Cortex and Primary Visual Cortex of the Macaque Monkey. Cerebral Cortex. 15:1887–1899. Link
 Wang Q, Tanigawa H (co-first author), Fujita I (2017) Postnatal Development of Intrinsic Horizontal Axons in Macaque Inferior Temporal and Primary Visual Cortices. Cerebral Cortex. 27:2708–2726. Link