BUSM News and Notes

Monthly newsletter providing updates of interest to the Boston University School of Medicine community

A neural network model of normal and abnormal learning and memory consolidation

The amygdala and hippocampus interact with thalamocortical systems to regulate cognitive-emotional learning, and lesions of amygdala, hippocampus, thalamus, and cortex have different effects depending on the phase of learning when they occur. In examining eyeblink conditioning data, several questions arise: Why is the hippocampus needed for trace conditioning where there is a temporal gap between the conditioned stimulus offset and the onset of the unconditioned stimulus, but not needed for delay conditioning where stimuli temporally overlap and co-terminate? Why do amygdala lesions made before or immediately after training decelerate conditioning while those made later have no impact on conditioned behavior? Why do thalamic lesions degrade trace conditioning more than delay conditioning? Why do hippocampal lesions degrade recent learning but not temporally remote learning? Why do cortical lesions degrade temporally remote learning, and cause amnesia, but not recent or post-lesion learning? How is temporally graded amnesia caused by ablation of medial prefrontal cortex? How are mechanisms of motivated attention and the emergent state of consciousness linked during conditioning? How do neurotrophins, notably Brain Derived Neurotrophic Factor (BDNF), influence memory formation and consolidation? A neural model, called neurotrophic START, or nSTART, proposes answers to these questions. The nSTART model synthesizes and extends key principles, mechanisms, and properties of three previously published brain models of normal behavior. These three models describe aspects of how the brain can learn to categorize objects and events in the world; how the brain can learn the emotional meanings of such events, notably rewarding and punishing events, through cognitive-emotional interactions; and how the brain can learn to adaptively time attention paid to motivationally important events, and when to respond to these events, in a context-appropriate manner. The model clarifies how hippocampal adaptive timing mechanisms and BDNF may bridge the gap between stimuli during trace conditioning and thereby allow thalamocortical and corticocortical learning to take place and be consolidated. The simulated data arise as emergent properties of several brain regions interacting together. The model overcomes problems of alternative memory models, notably models wherein memories that are initially stored in hippocampus move to the neocortex during consolidation

The theory of a finite God and emergent evolution as a solution to the problem of evil

Thesis (M.A.)--Boston UniversityEvil is a phenomenon not easily accounted for. It has been variously ignored, denied, rationalized, and perenially endured. It presents particular difficulties for the different religions. Any theological concept of man, the universe and God must make a satisfactory consideration of this phenomenon. But how are God and evil to be reconceled Within the context of Christianity several explanations have developed. Some modification or combination of these views has been accepted by most orthodox Christians. Among the most common of these explanations are: (1) evil is unreal. The Christian Scientists, along with some Hindus, adhere to this view that evil is an illusion, a temporary mistaking. (2) Evil is inc0111plete good. ..l judgment that a thing is bad results from a partial view of the thing. Or it is a simple lack of perfection, not a real thing in itself, but a lack of something. (3) Evil is necessary as a contrast to good. We would not know or appreciate the good if we had not the evil. Life would be frightfully dull with no contrast to add interest. (4) Evil is sometimes explained as being necessary for punishment or discipline. Men deserve the evil they suffer because of some wrong they are guilty ~f. Or, 'evil is necessary to challenge, reformo r test a person. Hum.cin nature at its best emerges by being urged on by obstacles. (5) Probably the most common view is the one that evil is the result of human freedom. If man is to have any free will, and he must have freedom to be a moral being, there must be both good and evil for him to choose between. Otherwise man would be simply mechanical, and his existence becomes meaningless, lacking purpose. [TRUNCATED

Socio-psychological factors influencing psychosomatic disturbances: a study of fifteen World War II veterans seen at the Worcester Psychosomatic Clinic

Thesis (M.S.)--Boston University, 1947. This item was digitized by the Internet Archive

Value of a school teacher in one town on a school committee in another town

Thesis (Ed.M.)--Boston University, 1933. This item was digitized by the Internet Archive

Modeling and model-aware signal processing methods for enhancement of optical systems

Theoretical and numerical modeling of optical systems are increasingly being utilized in a wide range of areas in physics and engineering for characterizing and improving existing systems or developing new methods. This dissertation focuses on determining and improving the performance of imaging and non-imaging optical systems through modeling and developing model-aware enhancement methods. We evaluate the performance, demonstrate enhancements in terms of resolution and light collection efficiency, and improve the capabilities of the systems through changes to the system design and through post-processing techniques. We consider application areas in integrated circuit (IC) imaging for fault analysis and malicious circuitry detection, and free-form lens design for creating prescribed illumination patterns. The first part of this dissertation focuses on sub-surface imaging of ICs for fault analysis using a solid immersion lens (SIL) microscope. We first derive the Green's function of the microscope and use it to determine its resolution limits for bulk silicon and silicon-on-insulator (SOI) chips. We then propose an optimization framework for designing super-resolving apodization masks that utilizes the developed model and demonstrate the trade-offs in designing such masks. Finally, we derive the full electromagnetic model of the SIL microscope that models the image of an arbitrary sub-surface structure. With the rapidly shrinking dimensions of ICs, we are increasingly limited in resolving the features and identifying potential modifications despite the resolution improvements provided by the state-of-the-art microscopy techniques and enhancement methods described here. In the second part of this dissertation, we shift our focus away from improving the resolution and consider an optical framework that does not require high resolution imaging for detecting malicious circuitry. We develop a classification-based high-throughput gate identification method that utilizes the physical model of the optical system. We then propose a lower-throughput system to increase the detection accuracy, based on higher resolution imaging to supplement the former method. Finally, we consider the problem of free-form lens design for forming prescribed illumination patterns as a non-imaging application. Common methods that design free-form lenses for forming patterns consider the input light source to be a point source, however using extended light sources with such lenses lead to significant blurring in the resulting pattern. We propose a deconvolution-based framework that utilizes the lens geometry to model the blurring effects and eliminates this degradation, resulting in sharper patterns

The literature of English Jacobinism

Thesis (M.A.)--Boston University, 1935. This item was digitized by the Internet Archive

Effects of ultra-violet rays and vitamin D with particular reference to skeletal growth

Thesis (M.A.)--Boston University, 1929. This item was digitized by the Internet Archive

A follow-up study of the 1950-1958 business graduates of Dover High School, Dover, New Hampshire

Thesis (Ed.M.)--Boston Universit