Descending projections from the insular cortex to the lateral parabrachial nucleus were abundant in the external lateral parabrachial subnucleus, where cholinergic neurons are distributed, and exhibited a distinct input pattern compared to that from the trigeminal spinal nucleus caudalis. We demonstrated that activation of this pathway enhances facial pain.

We revealed that orofacial pain can be controlled by selectively activating parvalbumin-positive neurons in the insular cortex and inducing long-term potentiation of inhibitory postsynaptic currents. Although there are three Kobayashi among the authors, there is no blood or marital relationship.

We published a paper approaching the central mechanism of the placebo effect. Besides the difficulty of the patch-clamp experiments I was in charge of, experiencing the review system of a top journal and the difficulty of getting through it. It was an extremely valuable experience. “Science” was so close, yet so far.

We clarified the mechanism by which nitric oxide acts on presynaptic terminals to induce LTP in excitatory synaptic transmission in the insular cortex.

We clarified that long-term potentiation in inhibitory synaptic transmission in the insular cortex is dependent on P2X receptors and NMDA receptors.

This is the third paper in a series on the modulatory function of synaptic transmission by insulin, following leptin and orexin, which are hormones related to feeding. Although series papers tend to be somewhat sideways, in this paper, we investigated the intracellular cascade in detail, and we believe that our understanding of the local insular cortex circuit has advanced one step further in this regard.

The periaqueductal gray is a major region controlling the descending pain inhibitory system. We revealed the possibility that cholinergic neurons are scattered in this region and suppress the activity of these neurons themselves by activating GIRK currents via M2 receptors.

We revealed the distribution and response characteristics of periodontal ligament responsive neurons in the insular cortex and primary and secondary somatosensory cortices using in vivo calcium imaging with a two-photon microscope in GcaMP6S mice.

The insular cortex, which receives somatosensory input from the orofacial region, has dense projections to the trigeminal spinal nucleus caudalis. We clarified the role of this descending projection in pain from the cellular level to the behavioral level using optogenetic and chemogenetic techniques.

It was supposed to be a compact experiment started as an undergraduate student's research project. However, after many twists and turns, it finally became a study showing that the projection pattern to nucleus accumbens cholinergic neurons differs significantly between the insular cortex and the medial prefrontal cortex.

This research on the synchronicity of inhibitory synaptic transmission in the somatosensory cortex had been shelved for a long time.

We revealed that substance P suppresses excitatory neurotransmitter release probability via NK1 receptors in the local neural circuit of the insular cortex, and that nitric oxide synthesis is involved in this process.

Using the multi-channel whole-cell patch-clamp recording method that our lab has been working on for many years, we searched for local neural circuits where one inhibitory neuron projects to multiple pyramidal cells. We then revealed a part of the mechanism by which propofol creates α rhythms. This is considered an important achievement for understanding the basic properties of anesthetic-induced control mechanisms in neural local circuits.

In the visual cortex, auditory cortex, and somatosensory cortex, it is known that neural circuits are largely reorganized by changes in the external environment. Orthodontic treatment by attaching a coil spring to the tooth has been performed for a long time, but many aspects of its effect on the central nervous system remain unclear. In this study, we clarified the changes in neural circuits, particularly in the insular cortex and secondary somatosensory cortex, in a rat orthodontic model at the cellular level using a two-photon laser scanning microscope.

We showed the possibility that taste and olfactory information are integrated in the agranular insular cortex using optical recording. This is a labor-intensive work that analyzed the cortical responses obtained by electrical stimulation of primary or secondary neurons for each sense.

We compiled a special issue in the Journal of Oral Science to commemorate the retirement of Professor Koichi Iwata from the Department of Physiology, Nihon University School of Dentistry. Many disciples and colleagues contributed articles.

This is a result from the AMED project aiming to develop a new treatment for chronic pain caused by trigeminal nerve injury. We revealed that chronic pain induced by partial ligation of the infraorbital nerve causes hyperexcitation in the somatosensory cortex and insular cortex, and that pre-surgical administration of minocycline suppresses this.