Echoic memory of a single pure tone indexed by change-related brain activity

<p>Abstract</p> <p>Background</p> <p>The rapid detection of sensory change is important to survival. The process should relate closely to memory since it requires that the brain separate a new stimulus from an ongoing background or past event. Given that sensory memory monitors current sensory status and works to pick-up changes in real-time, any change detected by this system should evoke a change-related cortical response. To test this hypothesis, we examined whether the single presentation of a sound is enough to elicit a change-related cortical response, and therefore, shape a memory trace enough to separate a subsequent stimulus.</p> <p>Results</p> <p>Under a paradigm where two pure sounds 300 ms in duration and 800 or 840 Hz in frequency were presented in a specific order at an even probability, cortical responses to each sound were measured with magnetoencephalograms. Sounds were grouped to five events regardless of their frequency, 1D, 2D, and 3D (a sound preceded by one, two, or three different sounds), and 1S and 2S (a sound preceded by one or two same sounds). Whereas activation in the planum temporale did not differ among events, activation in the superior temporal gyrus (STG) was clearly greater for the different events (1D, 2D, 3D) than the same event (1S and 2S).</p> <p>Conclusions</p> <p>One presentation of a sound is enough to shape a memory trace for comparison with a subsequent physically different sound and elicits change-related cortical responses in the STG. The STG works as a real-time sensory gate open to a new event.</p

A transition from unimodal to multimodal activations in four sensory modalities in humans: an electrophysiological study

<p>Abstract</p> <p>Background</p> <p>To investigate the long-latency activities common to all sensory modalities, electroencephalographic responses to auditory (1000 Hz pure tone), tactile (electrical stimulation to the index finger), visual (simple figure of a star), and noxious (intra-epidermal electrical stimulation to the dorsum of the hand) stimuli were recorded from 27 scalp electrodes in 14 healthy volunteers.</p> <p>Results</p> <p>Results of source modeling showed multimodal activations in the anterior part of the cingulate cortex (ACC) and hippocampal region (Hip). The activity in the ACC was biphasic. In all sensory modalities, the first component of ACC activity peaked 30–56 ms later than the peak of the major modality-specific activity, the second component of ACC activity peaked 117–145 ms later than the peak of the first component, and the activity in Hip peaked 43–77 ms later than the second component of ACC activity.</p> <p>Conclusion</p> <p>The temporal sequence of activations through modality-specific and multimodal pathways was similar among all sensory modalities.</p

Schematic diagram showing the differentiation protocols from human iPS cells to mature neurons.

<p>Neurons of the peripheral nervous system (PNS; A) and the central nervous system (CNS; B) were induced from human induced pluripotent stem (iPS) cells with several compounds dissolved in serum-free media. Each medium and compound was added at the time indicated in (A) or (B).</p

Reconstruction of neuronal networks innervating the heart using iPS cells co-cultured in a microfabricated device.

<p>(A) Schematic diagram of the differentiation protocol for iPS cell-derived cardiomyocytes. (B) Calcium imaging of cardiomyocyte-aggregates on day 16. Contracting embryonic bodies (EBs) showed sustained calcium dynamics. The color bar shows fluorescence intensity, and the change in fluorescence signals confirms that these cell-aggregates contained cardiomyocytes. The graph is showing the kinetics of calcium transients during the recording. (C) Co-culture of peripheral nervous system (PNS) neurons and cardiomyocytes on day 44 after plating PNS neurons. PNS-derived bundles extended from left chamber (arrow) and reached a cardiomyocyte-aggregate, which was in the right chamber (within white dash line). (D) Immunostaining for the cardiomyocyte marker cTnT and the synaptic vesicle marker Synapsin-1 on day 24 after plating PNS neurons. Top, the positional relationship of the axon from PNS neurons and cardiomyocyte. Bottom, localization of Synapsin-1 on a cardiomyocyte (dot line region). Scale bar: 100 μm.</p

Differentiation of human PNS and CNS neurons.

<p>(A) Phase-contrast image of pre-differentiated human induced pluripotent stem (iPS) cells under a feeder-free condition. (B) Phase-contrast image of embryonic bodies (EBs) before chemical induction on day 0. (C, D) Phase-contrast image of differentiated peripheral nervous system (PNS) neurons (C) and central nervous system (CNS) neurons (D). Induced neurites were detected on day 23 (C) and day 15 (D) in PNS and CNS neurons, respectively. (E, F) Immunofluorescent labeling with antibodies specific for class III beta-tubulin (TUJ1) and Peripherin in PNS (E) and CNS neurons (F) on day 22. Cell nuclei were counterstained with Hoechst 33342. Scale bar: 100 μm.</p

Structural and functional analysis of co-cultured neuronal networks.

<p>(A, B) Immunofluorescence images of co-cultured neurons 48 days after cell plating (bottom panel). Different regions indicated in the diagram are shown (top panel). Synapsin-1 staining was detected in the chamber with central nervous system (CNS) neurons, but not in the microtunnels. (C, D) Phase-contrast images of cells and the fluorescence images of a calcium probe on day 39. Fluorescence images before (pre stim) and 1 s after applying the electrical stimulation (post stim) are shown. Fluorescence was increased after the stimulus (arrowheads). (E) Calcium response after the stimulation normalized to the signal before the stimulation. The color bar shows fluorescence intensity. Neurites in the microtunnels were induced with electrical stimulation. (F) Kinetics of calcium transient onset during applying the electrical stimulation. Data of 6 peripheral nervous system (PNS) bundles were considered. (G) Identification of CNS neurons that responded to PNS bundle stimulation. Left, a co-culture sample at day 29 labelled with fluo-4. Right, normalized calcium response in CNS neurons following PNS bundle stimulation (dot-dashed line). The color bar indicates fluorescence intensity. White arrowheads identify CNS neurons that exhibited a calcium response to PNS bundle stimulation. (H) Kinetic plots of calcium transients in CNS neurons represented in panel G. The region highlighted by the yellow rectangle indicates the period of electrical stimulation of PNS bundles. (I) The effect of PNS bundle stimulation on the activity of CNS neurons. Calcium spiking in CNS neurons was averaged pre-, during and post-PNS bundle stimulation. Values are reported as mean±S.D. (<i>n</i> = 20 neurons from 3 samples). Statistical analyses using an unpaired t-test are shown here (ns not significant, * <i>p</i> < 0.001; Scale bar: 100 μm).</p

Co-culturing of PNS and CNS neurons in the PDMS chamber device.

<p>(A) Schematic diagram of the polydimethylsiloxane (PDMS) co-culture chamber. Diameter of the chambers was 8 mm. Width of the microtunnels was 50 μm. Although the length of each microtunnel varied depending on its location, the length of each microtunnel was at least 1 mm. The neurites were able to pass through the 5-μm-high microtunnels. (B) Co-cultured neurons close to the microtunnels one day after cell plating. Peripheral nervous system (PNS) neurons were labeled with PKH26 (magenta), and central nervous system (CNS) neurons were labeled with PKH67 (green). (C) Most neurites of PNS neurons passed through the microtunnels 12 days after cell plating. Bundles (magenta) originating from PNS neurons reached the aggregated CNS neurons (green). (D) Phase-contrast images and immunofluorescent staining for class III beta-tubulin (TUJ1) and Peripherin. Neurites that passed through the microchannel originated from PNS neurons, which was confirmed by the expression of TUJ1 and Peripherin (arrowheads) 48 days after cell plating. (E) PNS neurites around the microtunnels 30 days after cell plating. Two different regions, indicated in the diagram, are shown at a high magnification. PNS neurites gathered together and made bundles before and during entering the tunnels. Scale bar: 100 μm.</p

Schematic outline of the microfabrication process to manufacture the co-culturing device.

<p>(A) UV exposure of the photoresist through the photomask. (B) Development of micropatterns to fabricate the master mold. (C) Casting and curing of polydimethylsiloxane (PDMS) onto the maser mold. (D) Cutting, punching, and releasing of the PDMS chamber from the master mold.</p

<i>In Vitro</i> Reconstruction of Neuronal Networks Derived from Human iPS Cells Using Microfabricated Devices

<div><p>Morphology and function of the nervous system is maintained via well-coordinated processes both in central and peripheral nervous tissues, which govern the homeostasis of organs/tissues. Impairments of the nervous system induce neuronal disorders such as peripheral neuropathy or cardiac arrhythmia. Although further investigation is warranted to reveal the molecular mechanisms of progression in such diseases, appropriate model systems mimicking the patient-specific communication between neurons and organs are not established yet. In this study, we reconstructed the neuronal network <i>in vitro</i> either between neurons of the human induced pluripotent stem (iPS) cell derived peripheral nervous system (PNS) and central nervous system (CNS), or between PNS neurons and cardiac cells in a morphologically and functionally compartmentalized manner. Networks were constructed in photolithographically microfabricated devices with two culture compartments connected by 20 microtunnels. We confirmed that PNS and CNS neurons connected via synapses and formed a network. Additionally, calcium-imaging experiments showed that the bundles originating from the PNS neurons were functionally active and responded reproducibly to external stimuli. Next, we confirmed that CNS neurons showed an increase in calcium activity during electrical stimulation of networked bundles from PNS neurons in order to demonstrate the formation of functional cell-cell interactions. We also confirmed the formation of synapses between PNS neurons and mature cardiac cells. These results indicate that compartmentalized culture devices are promising tools for reconstructing network-wide connections between PNS neurons and various organs, and might help to understand patient-specific molecular and functional mechanisms under normal and pathological conditions.</p></div

Exposure to small molecule cocktails allows induction of neural crest lineage cells from human adipose-derived mesenchymal stem cells.

Neural crest cells (NCCs) are a promising source for cell therapy and regenerative medicine owing to their multipotency, self-renewability, and capability to secrete various trophic factors. However, isolating NCCs from adult organs is challenging, because NCCs are broadly distributed throughout the body. Hence, we attempted to directly induce NCCs from human adipose-derived mesenchymal stem cells (ADSCs), which can be isolated easily, using small molecule cocktails. We established a controlled induction protocol with two-step application of small molecule cocktails for 6 days. The induction efficiency was evaluated based on mRNA and protein expression of neural crest markers, such as nerve growth factor receptor (NGFR) and sex-determining region Y-box 10 (SOX10). We also found that various trophic factors were significantly upregulated following treatment with the small molecule cocktails. Therefore, we performed global profiling of cell surface makers and identified distinctly upregulated markers, including the neural crest-specific cell surface markers CD271 and CD57. These results indicate that our chemical treatment can direct human ADSCs to developing into the neural crest lineage. This offers a promising experimental platform to study human NCCs for applications in cell therapy and regenerative medicine