Sang Hun Lee

In several experiments, it was found that global perception of spatial form can arise exclusively from unpredictable but synchronized changes among local features. Within an array of nonoverlapping apertures, contours move in one of two directions, with direction reversing randomly over time. When contours within a region of the array reverse directions in synchrony, they stand out conspicuously from the rest of the array where direction reversals are unsynchronized. Clarity of spatial structure

During binocular rivalry, one of two incompatible monocular stimuli is erased from perceptual awareness for seconds at a time. To examine whether this "rivalry suppression" occurs in V1, we measured functional magnetic resonance imaging activity during binocular rivalry and compared it with those in the two reference conditions: one representing complete suppression and the other representing no suppression. We found that the amplitude of V1 activity during rivalry fell midway between those in t

Pupillometry, thanks to its strong relationship with cognitive factors and recent advancements in measuring techniques, has become popular among cognitive or neural scientists as a tool for studying the physiological processes involved in mental or neural processes. Despite this growing popularity of pupillometry, the methodological understanding of pupillometry is limited, especially regarding potential factors that may threaten pupillary measurements' validity. Eye blinking can be a factor bec

The reciprocal synaptic relationship between the relay thalamus and surrounding thalamic reticular nucleus can lead to the generation of various rhythmic activities that are associated with different levels of behavioral states as well as certain pathophysiological conditions. Intrathalamic rhythmic activities may be attenuated by numerous neuromodulators that arise from a variety of brain stem nuclei. This study focuses on the potential role of a particular neuropeptide, vasoactive intestinal p

Our brain is inexorably confronted with a dynamic environment in which it has to fine-tune spatiotemporal representations of incoming sensory stimuli and commit to a decision accordingly. Among those representations needing constant calibration is interval timing, which plays a pivotal role in various cognitive and motor tasks. To investigate how perceived time interval is adjusted by experience, we conducted a human psychophysical experiment using an implicit interval-timing task in which obser

Prolonged exposure to a single direction of motion alters perception of subsequent static or dynamic stimuli and induces substantial changes in behaviors of motion-sensitive neurons, but the origin of neural adaptation and neural correlates of perceptual consequences of motion adaptation in human brain remain unclear. Using functional magnetic resonance imaging, we measured motion adaptation tuning curves in a fine scale by probing changes in cortical activity after adaptation for a range of dir

Intrinsic, rhythmic subthreshold oscillations have been described in neurons of regions throughout the brain and have been found to influence the timing of action potentials induced by synaptic inputs. Some oscillations are sodium channel-dependent while others are calcium channel-dependent. These oscillations allow neurons to fire coherently at preferred frequencies and represent the main mechanism for maintaining high frequency network activity, especially in the cortex. Because cortical circu

경험은 전문성 발달에 있어서 핵심적인 요소로 인식되어 왔으나 전문성 발달과 경험의 관계에 관한 실증 연구들은 일관성 있는 결론을 내리지 못하고 있다. 이에 본 연구는 전문성 발달 과정에서 경험이 어떤 역할을 하는 지를 살펴보고 관련 쟁점을 분석하였다. 전문성의 발달에서 경험의 역할을 경험적 지식, 지식의 맥락적 활용 능력, 암묵지, 자동성 획득의 네 가지 측면으로 나누어 살펴보았다. 전문성과 경험의 관계에 관한 쟁점은 크게 세 가지로 첫째, 경험과 지식의 관계, 둘째, 경험과 학습의 관계, 셋째, 경험의 깊이와 폭에 관한 것이다. 쟁점의 분석 결과 전문성의 발달에서 경험은 분석적 지식과 서술적 지식 보다는 절차적 지식에 영향을 미치고, 경험이 학습으로 연계되는 데는 특정 조건이 필요하며, 비구조화된 문제상황에서는 경험이 깊이와 함께 폭이 중요하다는 점이 확인되었다. 본 연구는 전문성과 경험에 관한 이론적, 실천적 시사점을 제공해준다는 점, 특히 최근 전문성 연구에서 주목되고 있는 적

Processing units are interconnected in the visual system, where a sensory organ and downstream cortical regions communicate through hierarchical connections, and local sites within the regions communicate through horizontal connections. In such networks, neural activities at local sites are likely to influence one another in complex ways and thus are intricately correlated. Recognizing the functional importance of correlated activity in sensory representation, spontaneous activities have been st

The surface characteristics of thin films of poly(tetrafluoroethylene) (PTFE) melts were investigated by molecular dynamics simulations, employing the recent explicit atomic force field, including partial charges, which was fine-tuned to the experimental PVT data, the chain conformation and the crystal structure ( Macromolecules 2003, 36, 5331). Surface tension was calculated from the virial equation of the pressure tensor, taking into full account of the long-range correction terms, in good agr