Ryuichi Nakajima

Ryuichi Nakajima
Nagoya University | Meidai · Academic Research & Industry-Academia-Government Collaboration

Ph.D.
Shedding light on the bridge between Academia and Industry.

About

41
Publications
19,302
Reads
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521
Citations
Introduction
Shedding light on the bridge between industry and academia as a University Research Administrator.
Additional affiliations
September 2011 - present
Korea Institute of Science and Technology
Position
  • PostDoc Position
September 2011 - present
Korea Institute of Science and Technology
Position
  • PostDoc Position
Description
  • Acute brain slice preparation of mice Two-photon microscope imaging Optogenetic photostimulation of neurons in slices
April 2007 - May 2011
Dalhousie University
Position
  • PostDoc Position
Description
  • Studying molecular mechanisms of synaptic plasticity

Publications

Publications (41)
Article
Full-text available
The dentate gyrus (DG) plays critical roles in cognitive functions, such as learning, memory, and spatial coding, and its dysfunction is implicated in various neuropsychiatric disorders. However, it remains largely unknown how information is represented in this region. Here, we recorded neuronal activity in the DG using Ca ²⁺ imaging in freely movi...
Article
Full-text available
Aim Experimental animals, such as non-human primates (NHPs), mice, Zebrafish, and Drosophila, are frequently employed as models to gain insights into human physiology and pathology. In developmental neuroscience and related research fields, information about the similarities of developmental gene expression patterns between animal models and humans...
Article
The CA1 area in the mammalian hippocampus is essential for spatial learning. Pyramidal cells are the hippocampus output neurons and their activities are regulated by inhibition exerted by a diversified population of interneurons. Lateral inhibition has been suggested as the mechanism enabling the reconfiguration of pyramidal cell assembly activity...
Article
Full-text available
Aims Neurogranin (NRGN) is a postsynaptic protein kinase substrate that binds calmodulin in the absence of calcium. Recent studies suggest that NRGN is involved in neuropsychiatric disorders, including schizophrenia, ADHD, and Alzheimer's disease. Previous behavioral studies of Nrgn knockout (Nrgn KO) mice identified hyperactivity, deficits in spat...
Poster
Full-text available
The dentate gyrus (DG) plays critical roles in cognitive functions such as learning, memory, and spatial coding, and its dysfunction is implicated in various neuropsychiatric disorders. However, it remains largely unknown how information is represented in this region. Here, we recorded neuronal activity in the DG using Ca2+ imaging in freely moving...
Preprint
Full-text available
The dentate gyrus (DG) plays critical roles in cognitive functions such as learning, memory, and spatial coding, and its dysfunction is implicated in various neuropsychiatric disorders. However, it remains largely unknown how information is represented in this region. Here, we recorded neuronal activity in the DG using Ca ²⁺ imaging in freely movin...
Article
Full-text available
The dentate gyrus (DG) plays critical roles in cognitive functions such as learning, memory, and spatial coding, and its dysfunction is implicated in various neuropsychiatric disorders. However, it remains largely unknown how information is represented in this region. Here, we recorded neuronal activity in the DG using Ca2+ imaging in freely moving...
Article
Full-text available
Aims: Synaptic Ras GTPase-activating protein 1 (SYNGAP1) regulates synaptic plasticity through AMPA receptor trafficking. SYNGAP1 mutations have been found in human patients with intellectual disability (ID) and autism spectrum disorder (ASD). Almost every individual with SYNGAP1-related ID develops epilepsy, and approximately 50% have ASD. SYNGAP...
Article
Full-text available
Impulsivity is closely associated with addictive disorders, and changes in the brain dopamine system have been proposed to affect impulse control in reward-related behaviors. However, the central neural pathways through which the dopamine system controls impulsive behavior are still unclear. We found that the absence of the D2 dopamine receptor (D2...
Article
Full-text available
To understand the circuitry of the brain, it is essential to clarify the functional connectivity among distinct neuronal populations. For this purpose, neuronal activity imaging using genetically-encoded calcium sensors such as GCaMP has been a powerful approach due to its cell-type specificity. However, calcium (Ca²⁺) is an indirect measure of neu...
Article
Full-text available
An improved genetically encoded voltage indicator (GEVI) was achieved by altering the charge composition of the region linking the voltage-sensing domain of the GEVI to a pH-sensitive fluorescent protein. Negatively charged linker segments reduced the voltage-dependent optical signal while positively charged linkers increased the signal size. Argin...
Article
Basal ganglia (BG) circuits orchestrate complex motor behaviors predominantly via inhibitory synaptic outputs. Although these inhibitory BG outputs are known to reduce the excitability of postsynaptic target neurons, precisely how this change impairs motor performance remains poorly understood. Here, we show that optogenetic photostimulation of inh...
Article
Full-text available
The age of genetically encoded voltage indicators has matured to the point that changes in membrane potential can now be observed optically in vivo. Improving the signal size and speed of these voltage sensors has been the primary driving forces during this maturation process. As a result, there is a wide range of probes using different voltage det...
Chapter
Light-activated ion channels and pumps can be employed as optogenetic actuators to control the electrical activity of neurons and other excitable cells. A variety of optogenetic actuators are available that allow light to either turn on electrical activity (photostimulate) or turn off electrical activity (photoinhibit). Because of their genetic tar...
Article
Full-text available
In Pavlovian fear conditioning, the lateral amygdala (LA) has been highlighted as a key brain site for association between sensory cues and aversive stimuli. However, learning-related changes are also found in upstream sensory regions such as thalamus and cortex. To isolate the essential neural circuit components for fear memory association, we tes...
Article
Full-text available
Here we characterize several new lines of transgenic mice useful for optogenetic analysis of brain circuit function. These mice express optogenetic probes, such as enhanced halorhodopsin or several different versions of channelrhodopsins, behind various neuron-specific promoters. These mice permit photoinhibition or photostimulation both in vitro a...
Article
Scanning small spots of laser light allows mapping of synaptic circuits in brain slices from transgenic mice expressing channelrhodopsin-2 (ChR2). These light spots photostimulate presynaptic neurons expressing ChR2, while postsynaptic responses can be monitored in neurons that do not express ChR2. Correlating the location of the light spot with th...
Conference Paper
Full-text available
The lateral amygdala (LA) has been proposed as a critical site of memory storage during auditory fear conditioning, with long-term potentiation (LTP) of LA synapses suggested to be the cellular mechanism underlying fear memory formation. However, similar synaptic changes are also observed in upstream areas, such as the medial geniculate nucleus (MG...
Conference Paper
Full-text available
Studies of the brain promise to be revolutionized by new experimental strategies that harness the combined power of optical techniques and genetics. We have mapped the circuitry of the mouse brain by using both optogenetic actuators that control neuronal activity and optogenetic sensors that detect neuronal activity. Using the light-activated catio...
Article
Full-text available
Calpastatin is an endogenous inhibitor of calpain, intracellular calcium-activated protease. It has been suggested to be involved in molecular mechanisms of long-term plasticity and excitotoxic pathways. However, functions of calpastatin in vivo are still largely unknown. To examine the physiological roles of calpastatin, we subjected calpastatin-k...
Data
Full-text available
Crawley's Sociability and social novelty preference test. We could not detect any significant difference between genotypes in exploratory behavior within either the first trial with one stranger mouse (F1,34 = 1.496, P = 0.2297 in the empty side; F1,34 = 0.242, P = 0.6256 in the stranger side; A), nor the following trial with an additional stranger...
Data
Social interaction in home cage. Social interactions in home cage were normal in clustering (F1,17 = 0.54, P = 0.820; A). Activity level was not significantly different between genotypes either (F1,17 = 0.38, P = 0.547; B).
Data
Full-text available
Comparison of mRNA expression levels of μ-calpain, m-calpain and calpastatin. Using Allen Brain Atlas, an in situ hybridization database of mouse brain, mRNA expression levels were compared among μ-calpain, m-calpain and calpastatin (Arranged to a bar chart by authors). Allen Brain Atlas [Internet]. Seattle (WA): Allen Institute for Brain Science....
Data
Light and dark transition test. CS-KO mice showed no significant differences in the light/dark transition test in distance traveled (F1,36 = 0.011, P = 0.917 in light camber, F1,36 = 0.293, P = 0.592 in the dark chamber; Aa), in stay time in the light chamber (F1,36 = 0.158, P = 0.694; Ab), in the number of transitions (F1,36 = 0.448, P = 0.508; Ac...
Article
Full-text available
A subtle but chronic alteration in metabolic balance between amyloid-β peptide (Aβ) anabolic and catabolic activities is thought to cause Aβ accumulation, leading to a decade-long pathological cascade of Alzheimer disease. However, it is still unclear whether a reduction of the catabolic activity of Aβ in the brain causes neuronal dysfunction in vi...
Article
Full-text available
Although mannitol has been used as an osmotherapeutic drug on brain injury, the clinical efficiency of the drug are still controversial. In the present study, we examined the effects of mannitol on the edema in a hippocampal slice due to brief ischemia. To evaluate the effects, we employed an image analysis system that consists of an infrared-diffe...
Article
Full-text available
We have developed a novel device for the quantification of swelling of cells in acute brain slices. We can also carry out detailed real-time monitoring of hippocampal cells. The device we developed is based on an infrared differential interference contrast microscopy (IR-DIC) and a custom-made real-time computerized image analysis system for the qu...
Article
We have developed a novel device for the quantification of edematous morphology changes in acute brain slices. We can also carry out real-time monitoring of detailed hippocampal cells. The device we developed is based on infrared differential interference contrast microscopy (IR-DIC) and a custom-made real-time computerized image-analysis system fo...

Questions

Questions (3)
Question
One of my colleague is looking for a proper statistical test which is able to take correlational analysis from multiple scatter plots taken from multiple mice.
Each of his scatter plot shows significant correlation between stimulus and response within a mouse. He repeated this experiment with multiple animals.
As an overall conclusion, he wants to conclude that the response is significantly correlated with the stimulus. However, it does not seem to be right if we plot all the data from multiple animals in one scatter plot for Pearson correlational analysis.
If any of you know how to do "overall" correlational analysis including multiple data sets, please let me know.
I hope my explanation was enough, but please do let me know if you need more information to answer this question.
Thanks!
Question
The ASCII file generated by Patchmaseter has unnecessary number in the first column, and they prevent Clampfit from recognizing time column. As a result, the Patchmaster file cannot be recognized as a fixed-length (repeated trials) data.
Because of this, HEKA traces cannot be analyzed by Clampfit.
I will appreciate any hints to solve this problem.
Question
Do anyone know a very good way to avoid the elevation of access resistance while doing whole cell recording for more than 30 minutes? I am recording from neurons in acute slices. I am using normal patch pipettes which resistance are 5-10MOhm.
I assume that re-adjusting the pipette position till ~10 min after getting the whole-cell is a well-known tip. If there are any other tips in your mind, please let me know.
Thank you for your attention!

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