A convex-shaped, PDMS-parylene hybrid multichannel ECoG-electrode array.

Long-term electrode implant is a challenge for successful brain-computer interfaces (BCIs). It is well known that electrocorticography (ECoG) using flexible planar electrodes is more suitable for long-term implants than intracortical neural recordings using penetrative electrodes. In this study, we propose a convex-shaped, PDMS-parylene hybrid multi-electrode array for long-term stable ECoG recording on the brain or the spinal cord. The electrode array consists of 10 gold recording sites which show impedance values between 50 and 70 kOhm at 1 kHz with a diameter of 100 µm. It is designed like octopus's leg to tightly adhere to the ellipsoidal brain. To assess its performance, epidural ECoG recordings were performed from the main olfactory bulb (MOB) of an anesthetized rat during odor stimulation. The odor-evoked response was shown with an increase of the power in the beta band.

Comparison of arylalkylamine N-acetyltransferase and melatonin receptor type 1B immunoreactivity between young adult and aged canine spinal cord

Melatonin affects diverse physiological functions through its receptor and plays an important role in the central nervous system. In the present study, we compared immunoreactivity patterns of arylalkylamine N-acetyltransferase (AANAT), an enzyme essential for melatonin synthesis, and melatonin receptor type 1B (MT2) in the spinal cord of young adult (2~3 years) and aged (10~12 years) beagle dogs using immunohistochemistry and Western blotting. AANAT-specific immunoreactivity was observed in the nuclei of spinal neurons, and was significantly increased in aged dog spinal neurons compared to young adult spinal neurons. MT2-specific immunoreactivity was found in the cytoplasm of spinal neurons, and was predominantly increased in the margin of the neuron cytoplasm in aged spinal cord compared to that in the young adult dogs. These increased levels of AANAT and MT2 immunoreactivity in aged spinal cord might be a feature of normal aging and associated with a feedback mechanism that compensates for decreased production of melatonin during aging.

Neuronal Responses in the Globus Pallidus during Subthalamic Nucleus Electrical Stimulation in Normal and Parkinson's Disease Model Rats

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been widely used as a treatment for the movement disturbances caused by Parkinson's disease (PD). Despite successful application of DBS, its mechanism of therapeutic effect is not clearly understood. Because PD results from the degeneration of dopamine neurons that affect the basal ganglia (BG) network, investigation of neuronal responses of BG neurons during STN DBS can provide informative insights for the understanding of the mechanism of therapeutic effect. However, it is difficult to observe neuronal activity during DBS because of large stimulation artifacts. Here, we report the observation of neuronal activities of the globus pallidus (GP) in normal and PD model rats during electrical stimulation of the STN. A custom artifact removal technique was devised to enable monitoring of neural activity during stimulation. We investigated how GP neurons responded to STN stimulation at various stimulation frequencies (10, 50, 90 and 130 Hz). It was observed that activities of GP neurons were modulated by stimulation frequency of the STN and significantly inhibited by high frequency stimulation above 50 Hz. These findings suggest that GP neuronal activity is effectively modulated by STN stimulation and strongly dependent on the frequency of stimulation.

Comparison of alpha-synuclein immunoreactivity in the spinal cord between the adult and aged beagle dog / 한국실험동물학회지

Alpha-synuclein (alpha-syn) is a presynaptic protein that is richly expressed in the central and peripheral nervous systems of mammals, and it is related to the pathogenesis of Parkinson's disease and other neurodegenerative disorders. In the present study, we compared the distribution of the immunoreactivity of alpha-syn and its related gliosis in the spinal cord of young adult (2-3 years) and aged (10-12 years) beagle dogs. We discovered that alpha-syn immunoreactivity was present in many neurons in the thoracic level of the aged spinal cord, however, its protein level was not distinct inform that of the adult spinal cord. In addition, ionized calcium-binding adapter molecule-1 (a marker for microglia) immunoreactivity, and not glial fibrillary acidic protein (a marker for astrocytes) immunoreactivity, was somewhat increased in the aged group compared to the adult group. These results indicate that alpha-syn immunoreactivity was not dramatically changed in the dog spinal cord during aging.

Odor-Dependent Hemodynamic Responses Measured with NIRS in the Main Olfactory Bulb of Anesthetized Rats

In this study, we characterize the hemodynamic changes in the main olfactory bulb of anesthetized Sprague-Dawley (SD) rats with near-infrared spectroscopy (NIRS, ISS Imagent) during presentation of two different odorants. Odorants were presented for 10 seconds with clean air via an automatic odor stimulator. Odorants are: (i) plain air as a reference (Blank), (ii) 2-Heptanone (HEP), (iii) Isopropylbenzene (IB). Our results indicated that a plain air did not cause any change in the concentrations of oxygenated (Delta[HbO2]) and deoxygenated hemoglobin (Delta[Hbr]), but HEP and IB induced strong changes. Furthermore, these odor-specific changes had regional differences within the MOB. Our results suggest that NIRS technology might be a useful tool to identify of various odorants in a non-invasive manner using animals which has a superb olfactory system.

Doublecortin-immunoreactive Neuroblasts in Each Layer of the Main Olfactory Bulb After Transient Cerebral Ischemia in Gerbils / 한국실험동물학회지

Neurogenesis in the adult brain occurs continuously throughout life. The main olfactory bulb (MOB) is the first central relay of the olfactory system. We examined proliferation of newly generated cells in each layer of the gerbil MOB after 5 min of transient cerebral ischemia using doublecortin (DCX), a marker of neuronal progenitors. Many DCX immunoreactive neuroblasts were found in the all layers of the MOBs of control and ischemia groups. Ten to 15 days after ischemia/reperfusion, no difference in numbers of DCX immunoreactive neuroblasts was found in the MOB. Thirty days after ischemia/reperfusion, significant increase of DCX immunoreactive cells was observed in all layers of ischemic MOB. This result indicates that neuroblasts increase in the MOB from 30 days after transient cerebral ischemia in gerbils.

Effects of Streptozotocin-Induced Type 1 Diabetes on Cell Proliferation and Neuronal Differentiation in the Dentate Gyrus; Correlation with Memory Impairment / 대한해부학회지

We examined the effects of steptozotocin (STZ)-induced type 1 diabetes on cell proliferation and neuroblasts in the subgranular zone of the hippocampal dentate gyrus (SZDG) of male Wistar rats. Change in memory function was also investigated using the passive avoidance test. In the SZDG, Ki67 (a marker for cell proliferation) positive nuclei were significantly decreased at 2 and 3 weeks and slightly decreased at 4 weeks after STZ treatment. Doublecortin (DCX, a marker for neuronal differentiation)-immunoreactive (+) neuroblasts with tertiary dendrites were significantly decreased in the STZ-treated group compared to those in the vehicle-treated group. However, DCX+ neuroblasts without tertiary dendrites were abundant at 4 weeks after STZ treatment. In addition, retention latency time in STZ-treated group was similar to that of vehicle-treated group at 2 and 3 weeks after STZ treatment. However, the retention latency time was significantly decreased at 4 weeks after STZ treatment. These results suggest that STZ significantly reduced cell proliferation and neuroblasts at 2~3 weeks after STZ treatment, but not at 4 weeks after STZ treatment although memory impairment was detected at 4 weeks after STZ treatment. The gradual reduction of DCX+ neuroblasts with tertiary dendrites may be associated with the impairment of hippocampus-related memory function.

Changes in Calcium-binding Proteins in the Rat Hippocampus after Involuntary Treadmill Exercise / 대한해부학회지

In this study, we investigated the effects of treadmill exercise on hippocampal levels of calcium-binding proteins - calbindin D-28k (CB), calretinin (CR) and parvalbumin (PV) - using immunohistochemistry and Western blot analysis. At 6 weeks of age, male Wistar rats were put on a treadmill with or without running for 1 h/day/5 consecutive days at a pace of 22 m/min for a period of 5 weeks. In sedentary and exercise groups, CB immunoreaction was detected in granule cells of the dentate gyrus, mossy fibers, and CA1 pyramidal cells. In addition, CB immunoreaction was observed in interneurons of the CA1-3 region. Exercise significantly increased CB immunoreactivity in dentate granule cells, CA1 pyramidal cells and CA1-3 interneurons. CR immunoreaction was mainly observed in interneurons of the dentate gyrus and CA1-3 regions. Similar number of CR-immunoreactive neurons was observed in the exercise and sedentary groups. PV immunoreaction was detected in interneurons of the dentate gyrus and CA1-3 regions. PVimmunoreactive fibers were significantly increased in all regions of the hippocampus in the exercise group, as compared to the sedentary group. Similar to the immunohistochemical findings, protein levels of CB and PV were also increased in the exercise group compared to the sedentary group. These increases in CB and PV in the hippocampus may induce neuronal plasticity after treadmill exercise and may be related to the enhancement of synaptic plasticity in the hippocampus by exercise.

NOTICE OF ERRATUM: Effects of Streptozotocin-Induced Type 1 Diabetes on Cell Proliferation and Neuronal Differentiation in the Dentate Gyrus; Correlation with Memory Impairment / 대한해부학회지

Choi JH et al. Effects of Streptozotocin-Induced Type 1 Diabetes on Cell Proliferation and Neuronal Differentiation in the Dentate Gyrus; Correlation with Memory Impairment. Korean J Anat (2009) 42(1): 41-48. Please note that there is error in the above article:On page 47 (ACKNOWLEDGEMENTS) on lines 39-40 in the right column, "(MOEHRD) (KRF-2007-8R07- 0301-064-S000100)" should be "(MOEHRD, Basic Research Promotion Fund) (KRF-2007-412-J00502)"

Immunohistochemical Analysis of Calretinin and Parvalbumin in the Goat Main Olfactory Bulb / 대한해부학회지

The distributions of calretinin (CR)- and parvalbumin (PV)-immunoreactive neurons in the main olfactory bulb (MOB) of the goat were examined in this study. As in other animals, the goat MOB has a characteristic laminar structure with laminar types and distribution patterns in each layer. CR-immunoreaction was observed in all layers of the MOB, except for the olfactory nerve layer. Most of CR-immunoreactive neurons were observed in the glomerular and granule cell layers. Relatively small number of CR-immunoreactive neurons was detected in other layers. These CR-immunoreactive neurons were interneurons. PV-immunoreaction was detected in all layers. In contrast to CR, olfactory nerve bundles were immunostained with PV. Most of PV-immunoreactive neurons were distributed in the glomerular and granule cell layers. PV-immunoreactive neurons were interneurons. This result suggests that CR and PV may play important roles in the olfactory signal modulation through interneurons in the goat MOB.