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Studies of photoreceptor throughput to visual cortex
No full textThe work in this dissertation aims to (1) examine the presence of a functional map in the mouse visual cortex by measuring its variable cone M-opsin and S-opsin inputs, as predicted by the graded dorsoventral cone opsin expression in the retina (Rhim et al., 2017), (2) devise a method for measuring rod saturation and utilize it to characterize differential spatio-temporal tuning between rod-mediated and cone-mediated vision in V1 (Rhim et al., 2021), and (3) study the representation of color and form. We report that the dorsoventral cone opsin expression gradient in the retina is recapitulated in the mouse visual cortex, including primary visual cortex (V1) and higher visual areas (HVAs). This provides a first finding of a functional map in the mouse cortex, next to retinotopy map. Next, we exploit this feature in the mouse cortex to measure variable opsin inputs to the cortex to provide a model to estimate rod saturation. This is a much-needed foundation in mouse vision research, which will help future studies to differentially quantify inputs from the three photoreceptor opsins found in mice: rhodopsin, S-opsin, and M-opsin. We exemplify this by studying the spatio-temporal tuning of rod-mediated vs. cone-mediated vision in V1. Cone-mediated V1 responds to 2.5-fold higher temporal frequencies than rod-mediated V1, highlighting differences in rod vs. cone information throughput. Lastly, we study the mechanisms underlying spatio-chromatic processing in the cortex. We find that V1's spatial frequency (SF) tuning is more low-pass to color contrast than brightness (i.e., luminance) contrast. Furthermore, our data can be accounted by a random wiring model with rhodopsin and cone S-opsin inputs to single-opponent V1 neurons. While classic models of single-opponency require selective wiring for ON and OFF subfields from each photoreceptor class, we find this to be inconsistent with our data. This provides a new insight to mechanism underlying color vision.Psycholog
Enhanced neuronal activity in the medial prefrontal cortex during social approach behavior
No full textAlthough the medial prefrontal cortex (mPFC) is known to play a crucial role in rodent social behavior, little is known aboutmPFCneural correlates of social behavior. In the present study,weexamined single-neuron activity in themPFCof mice performing a modified version of the three-chamber test. We found that a subset of mPFC neurons elevate discharge rates when approaching a stranger mouse but not when approaching an inanimate object or an empty chamber. Our results reveal mPFC neural activity that is correlated with social approach behavior in a widely used social-interaction paradigm. These findings might be helpful for future investigations ofmPFCneural processes underlying social interaction in health and disease. © 2016 The Authors7711Nsciescopu
Representations of color and form in mouse visual cortex
No full textSpatial transitions in color can aid any visual perception task, and its neural representation – an "integration of color and form" – is thought to begin at primary visual cortex (V1). Color and form integration is untested in mouse V1, yet studies show that the ventral retina provides the necessary substrate from green-sensitive rods and UV-sensitive cones. Here, we used two-photon imaging in V1 to measure spatial frequency (SF) tuning along four axes of rod and cone contrast space, including luminance and color. We first reveal that V1 has similar responsiveness to luminance and color, yet average SF tuning is significantly shifted lowpass for color. Next, guided by linear models, we used SF tuning along all four color axes to estimate the proportion of neurons that fall into classic models of color opponency – "single-", "double-", and "non-opponent". Few neurons (~6%) fit the criteria for double-opponency, which are uniquely tuned for chromatic borders. Most of the population can be described as a unimodal distribution ranging from strongly single-opponent to non-opponent. Consistent with recent studies of the rodent and primate retina, our V1 data is well-described by a simple model in which ON and OFF channels to V1 sample the photoreceptor mosaic randomly.See uploaded README files for details.
Below is the top of README_for_dataset.doc.
This describes the uploaded data set used in Rhim and Nauhaus: "Joint representations of color and form in mouse visual cortex described by random pooling from rods and cones". It is a MATLAB .mat file, where each structure pertains to a given figure. In addition to the source data for the figures, it also has the following additions:
The same data set, but prior to culling the population according to the dashed box in the Figure 2 scatter plot. See variables appended with "…_all"
Region-of-interest ID associated with each neuron.
Below is all the information in README_for_simulations.doc.
To run the simulations for Figures 1,6,7, and 8, execute the cells in the high-level scripts of the following: Figure_1.m, Figure_6_7.m, Figure_8.m. Make sure all the other .m files are in your path.Funding provided by: National Institutes of HealthCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000002Award Number: R01EY028657Funding provided by: Whitehall FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100001391Award Number:This data comes from two-photon imaging in mouse primary visual cortex.
There is also Matlab code to run the simulations in figures 1, 6, 7, and 8
Sexually dimorphic behavior, neuronal activity, and gene expression in Chd8-mutant mice
No full textAutism spectrum disorders (ASDs) are four times more common in males than in females, but the underlying mechanisms are poorly understood. We characterized sexually dimorphic changes in mice carrying a heterozygous mutation in Chd8 (Chd8+/N2373K) that was first identified in human CHD8 (Asn2373LysfsX2), a strong ASD-risk gene that encodes a chromatin remodeler. Notably, although male mutant mice displayed a range of abnormal behaviors during pup, juvenile, and adult stages, including enhanced mother-seeking ultrasonic vocalization, enhanced attachment to reunited mothers, and isolation-induced self-grooming, their female counterparts do not. This behavioral divergence was associated with sexually dimorphic changes in neuronal activity, synaptic transmission, and transcriptomic profiles. Specifically, female mice displayed suppressed baseline neuronal excitation, enhanced inhibitory synaptic transmission and neuronal firing, and increased expression of genes associated with extracellular vesicles and the extracellular matrix. Our results suggest that a human CHD8 mutation leads to sexually dimorphic changes ranging from transcription to behavior in mice. © 2018, The Author(s
Social deficits in IRSp53 mutant mice improved by NMDAR and mGluR5 suppression
No full textSocial deficits are observed in diverse psychiatric disorders, including autism spectrum disorders and schizophrenia. We found that mice lacking the excitatory synaptic signaling scaffold IRSp53 (also known as BAIAP2) showed impaired social interaction and communication. Treatment of IRSp53 -/- mice, which display enhanced NMDA receptor (NMDAR) function in the hippocampus, with memantine, an NMDAR antagonist, or MPEP, a metabotropic glutamate receptor 5 antagonist that indirectly inhibits NMDAR function, normalized social interaction. This social rescue was accompanied by normalization of NMDAR function and plasticity in the hippocampus and neuronal firing in the medial prefrontal cortex. These results, together with the reduced NMDAR function implicated in social impairments, suggest that deviation of NMDAR function in either direction leads to social deficits and that correcting the deviation has beneficial effects525411Nsciescopu
Individual differences in dynamic criterion shifts during perceptual decision-making
No full text학위논문 (석사)-- 서울대학교 대학원 : 뇌인지과학과, 2013. 2. 이상훈.Perceptual decision-making involves placing an optimal criterion on the axis of encoded sensory evidence to maximize outcomes for choices. Optimal criterion setting becomes critical particularly when neural representations of sensory inputs are noisy and feedbacks for perceptual choices vary over time in an unpredictable manner. Here, we first induced shifts in criteria by adopting stochastically generated reverse feedbacks, so that subjects sometimes received false feedbacks even for responses they should have gotten correct. Using a reinforcement-learning model, we captured subjects behavior and we investigated rationale for optimal criteria placement, or lack of, in individuals. Utilizing the estimates of model parameters, specifically the shift rate for criteria and subjects sensitivity, we identified the optimal regime. We demonstrate that optimal decision-making is closely correlated with the subjects sensitivity and shift rate. There was a systematic trade-off between the two parameters indicating that sensitivity and shift rate reciprocate, allowing for optimal decision-making in complex environments.Introduction 1
Materials and Methods 3
Results 13
Discussion 23
References 27
Abstract (Korean) 34Maste
Excitatory synapses and gap junctions cooperate to improve Pv neuronal burst firing and cortical social cognition in Shank2-mutant mice
No full text© 2021, The Author(s).NMDA receptor (NMDAR) and GABA neuronal dysfunctions are observed in animal models of autism spectrum disorders, but how these dysfunctions impair social cognition and behavior remains unclear. We report here that NMDARs in cortical parvalbumin (Pv)-positive interneurons cooperate with gap junctions to promote high-frequency (>80 Hz) Pv neuronal burst firing and social cognition. Shank2–/– mice, displaying improved sociability upon NMDAR activation, show impaired cortical social representation and inhibitory neuronal burst firing. Cortical Shank2–/– Pv neurons show decreased NMDAR activity, which suppresses the cooperation between NMDARs and gap junctions (GJs) for normal burst firing. Shank2–/– Pv neurons show compensatory increases in GJ activity that are not sufficient for social rescue. However, optogenetic boosting of Pv neuronal bursts, requiring GJs, rescues cortical social cognition in Shank2–/– mice, similar to the NMDAR-dependent social rescue. Therefore, NMDARs and gap junctions cooperate to promote cortical Pv neuronal bursts and social cognition.11Nsciescopu
Geometric characterization of anomalous Landau levels of isolated flat bands
No full text© 2021, The Author(s).According to the Onsager’s semiclassical quantization rule, the Landau levels of a band are bounded by its upper and lower band edges at zero magnetic field. However, there are two notable systems where the Landau level spectra violate this expectation, including topological bands and flat bands with singular band crossings, whose wave functions possess some singularities. Here, we introduce a distinct class of flat band systems where anomalous Landau level spreading (LLS) appears outside the zero-field energy bounds, although the relevant wave function is nonsingular. The anomalous LLS of isolated flat bands are governed by the cross-gap Berry connection that measures the wave-function geometry of multi bands. We also find that symmetry puts strong constraints on the LLS of flat bands. Our work demonstrates that an isolated flat band is an ideal system for studying the fundamental role of wave-function geometry in describing magnetic responses of solids.11Nsciescopu
P2-17: Individual Differences in Dynamic Criterion Shifts during Perceptual Decision Making
No full textPerceptual decision-making involves placing an optimal criterion on the axis of encoded sensory evidence to maximize outcomes for choices. Optimal criterion setting becomes critical particularly when neural representations of sensory inputs are noisy and feedbacks for perceptual choices vary over time in an unpredictable manner. Here we monitored time courses of decision criteria that are adopted by human subjects while abruptly shifting the criterion of stochastic feedback to perceptual choices with certain amounts in an unpredictable direction and at an unpredictable point of time. Subjects viewed a brief (0.3 s), thin (.07 deg) annulus around the fixation and were forced to judge whether the annulus was smaller or larger than an unknown boundary. We estimated moment-to-moment criteria by fitting a cumulative Gaussian function to the data within a sliding window of trials that are locked to a shift in feedback criterion. Unpredictable shifts in feedback criterion successfully induced shifts in actual decision criterion towards an optimal criterion for many of subjects, but with time delay and amount of shifts varying across individual subjects. There were disproportionately more numbers of overshooters (reaching and then surpassing the optimal criterion required) than undershooters (subpar reach, with a significant anti-correlation with sensory sensitivity). To find a mechanism that generates these individual differences, we developed a dynamic criterion learning model by modifying a reinforcement learning model, which assumes that a criterion is adjusted every trial by a weighted discrepancy between actual and expected rewards
(A) clinical study of the meningioma
No full text의학과/석사[한글]
두개강내 양성종양중 가장 발생빈도가 높은 것으로 알려져 있는 뇌수막종의 진단 및 치료방법의 개선에 도움이 되고자, 1966년 11월부터 1982년 10월까지 본 연세의료원 신경외과에서 뇌수막종으로 수술받은 총 94명의 환자를 대상으로 병상일지를 근거로한 임상분석을 하였던 바 다음과 같은 결과를 얻었다.
1. 뇌수막종 환자의 연령은 30대와 40대에 가장 많이 분포하여 각각 전체의 30.8%을 씩을 차지하였으며, 성별빈도는 1:1.4로 여자에 다소 많았다.
2. 뇌수막종의 발생부위로는 부상시상동 및 대뇌겸부위가 전체의 37.2.%를 차지하였으며 그 다음이 접형골연( 15.9%), 궁륭부( 14.9%), 안배상부 (10.6% 1) 순이었고, 1979년 세계보건기구가 권장하는 병리조직학적 분류에 따르면, meningotheliomatous형이 전체의 64.9%로 가장 많았으며, 저악성 혹은 악성인 hemangiob1astio, hemangioprioytic, papillary 및 anaplastic형이 모두 9예로 전체의 9.6%에 달하였다.
3. 임상증상은 두통 (55.5%), 시력장애 (17.0%1, 전간 (14.9%) 등의 순이었고, 방사선학적 소견상 단순두개골촬영에서는 반수이상에서 이상소견을 보였다. 뇌전산화단층촬영은 가장 정확하고 안전하게 시행할 수 있는 방법이었고, 뇌혈관조영술로 종양에 분포하는 혈관의 양상이외에도 유출정맥 및 정맥동과의 관계를 알아볼 수 있었다.
4. 뇌기저부 뇌수막종에 해당되는 14예중 6예는 완전제거 되었으나 8예에서 종앙의 부분적출만이 가능하였고 수술후 증세악화가 3예, 사망이 2예로 경과는 매우 나빴다.
5. 재발된 8예중 1예를 제외한 나머지는 모두 부상시상동부위에 위치한 경우였으며, 병리조직학적으로는 hemangiopericytic형 3예, hemangioblastic형 2예, angiomatous형 2예 및 meningitheliomatous형 1예였다.
6. 총 4예에서 수술시 laser를 사용하였던 바 출혈과 주위 정상뇌조직의 손상을 줄일 수 있었고 수술후 뇌부종을 극소화시킬 수 있었다.
[영문]
To Provide a guideline of accurate diagnosis and proper methods of treatment of meningioma, the most common benign intracraninal tumor, the author studied 94 cases of intra & extracranial meningioma who had been diagnosed and operated at the Department of Neurosurgery of Yonsei University of medicine from November 1966 to October 1982.
The results were as followings .
1. The ratio of male to female was 1 to 1.4 and 30.8% of the 94 patients was in the 4th decade of age and another 30.8% in the 5th decade.
2. The predilection states were parasagittal and falx (37.2%), sphenoid ridge (15.9%), convexity(14.9%), and suprasellar(10.6%) area. According to W.H.0. classification (1979), the most common histopathological type was menlngotheliomatous type (64.9%) and 9 cases (9.6%) were meningioma with potential malignancy, ie. hemangloblastic, hemangiopericytic, papillary and anaplastic meningiomas.
3. The common initial clinical features were headache (55.5%), visual disturbance (16.0%) and seizure (14.9%). In radiologic diagnostic tests, there are abnormal findings in over a half on plain skull X-ray and brain CT scan was regarded as a most accurate and safe method. Cerebral angiography provided the informations such as vascularity, venous drainage and relation-ship with sinus of meningioma.
4. Among the 14 cases of basal menlngioma, the surgery could be performed totally in 6 cases and subtotally In 8 and postoperative results were not satisfactory. (3 cases deteriorated and 2 cases dead)
5. In 8 recurrent cases, all the tumors except one case were located at parasagittal area and were 3 hemanglopericytic, 2 hemangioblastic, 2 angiomatous and 1 meningotheliomatous type histologically.
6. The Laser was thought to be very effective surgical tool to remove vascular tumor, such as meningioma, with it's unique properties of non-mechanical bloodless evaporation of tumor and minimizing of brain edema.restrictio
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