Ingie Hong

Remarkable progress in positron emission tomography (PET) development has occurred in recent years, in hardware, software, and computer implementation of image reconstruction. Recent development in PET scanners such as the high-resolution research tomograph (HRRT) developed by CTI (now Siemens) represents such a case and is capable of greatly enhanced resolution as well as sensitivity. In these PET scanners, the amount of coincidence line data collected contains more than 4.5 x 10(9) coincidence

The growing class of portable systems, such as personal computing and communication devices, has resulted in a new set of system design requirements, mainly characterized by dominant importance of power minimization and design reuse. The energy efficiency of systems-on-a-chip (SOC) could be much improved if one were to vary the supply voltage dynamically at run time. We developed the design methodology for the low-power core-based real-time SOC based on dynamically variable voltage hardware. The

A consolidated memory can be transiently destabilized by memory retrieval, after which memories are reconsolidated within a few hours; however, the molecular substrates underlying this destabilization process remain essentially unknown. Here we show that at lateral amygdala synapses, fear memory consolidation correlates with increased surface expression of calcium-impermeable AMPA receptors (CI-AMPARs), which are known to be more stable at the synapse, whereas memory retrieval induces an abrupt

The amygdala is known to be a critical storage site of conditioned fear memory. Among the two major pathways to the lateral amygdala (LA), the cortical pathway is known to display a presynaptic long-term potentiation which is occluded with fear conditioning. Here we show that fear extinction results in a net depression of conditioning-induced potentiation at cortical input synapses onto the LA (C-LA synapses). Fear conditioning induced a significant potentiation of excitatory postsynaptic curren

Alzheimer's disease (AD) is characterized by progressive memory loss accompanied by synaptic and neuronal degeneration. Although research has shown that substantial neurodegeneration occurs even during the early stages of AD, the detailed mechanisms of AD pathogenesis are largely unknown because of difficulties in diagnosis and limitations of the analytical methods. The 5XFAD mouse model harbors five early-onset familial AD (FAD) mutations and displays substantial amyloid plaques and neurodegene

Numerous watermarking-based techniques for intellectual property protection of DSP artifacts, such as images, compressed and uncompressed audio and video data, and text documents have been proposed. However, the applicability of all techniques proposed until now are limited to digital data and they either implicitly or explicitly exploit the imperfection of human perception to audio and video. We propose the first watermarking technique for protecting the intellectual property of DSP designs. Th

It is generally believed that after memory consolidation, memory-encoding synaptic circuits are persistently modified and become less plastic. This, however, may hinder the remaining capacity of information storage in a given neural circuit. Here we consider the hypothesis that memory-encoding synaptic circuits still retain reversible plasticity even after memory consolidation. To test this, we employed a protocol of auditory fear conditioning which recruited the vast majority of the thalamic in

The brain helps us survive by forming internal representations of the external world1,2. Excitatory cortical neurons are often precisely tuned to specific external stimuli3,4. However, inhibitory neurons, such as parvalbumin-positive (PV) interneurons, are generally less selective5. PV interneurons differ from excitatory neurons in their neurotransmitter receptor subtypes, including AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors (AMPARs)6,7. Excitatory neurons express cal

SYNGAP1 is a key Ras-GAP protein enriched at excitatory synapses, with mutations causing intellectual disability and epilepsy in humans. Recent studies have revealed that in addition to its role as a negative regulator of G-protein signaling through its GAP enzymatic activity, SYNGAP1 plays an important structural role through its interaction with postsynaptic density proteins. Here, we reveal that intrinsic excitability deficits and seizure phenotypes in heterozygous Syngap1 knockout (KO) mice

Memories are fragile and easily forgotten at first, but after a consolidation period of hours to weeks, are inscribed in our brains as stable traces, no longer vulnerable to conventional amnesic treatments. Retrieval of a memory renders it labile, akin to the early stages of consolidation. This phenomenon has been explored as memory reactivation, in the sense that the memory is temporarily 'deconsolidated', allowing a short time window for amnesic intervention. This window closes again after rec

Motion in PET studies degrades the image quality and introduces bias which is critical for high resolution scanners. There are many publications related to motion correction in PET. Most of these methods rely on external devices to track the motion and register it to the listmode data. This paper describes how to extract rigid-body head motion from only the listmode data using the Centroid Of Distribution (COD). In addition, it introduces the Adjacent-Means Clustering and Merging of Clusters met

Recent developments in PET scanners such as the HRRT (High Resolution Research Tomograph) developed by Siemens greatly enhanced their resolution as well as sensitivity, but they increased coincidence lines of response more than 4.5 times 10 generated by as many nuclear detectors as 120,000. This formidable amount of data poses a real problem in the image reconstruction and its applications. It also has been the major bottleneck in further developments of the higher resolution PET scanners. To re

Motion in PET studies degrades the image quality and introduces bias which is critical for high resolution scanners such as mCT, mMR, and HRRT. There are many publications related to motion correction in PET. They consider either Rigid-body or Non Rigid-body motion and use three methods for motion correction. In this work we will describe and compare three motion correction methods. The first method performs motion correction in image space, while the second method performs motion correction in