Mechanisms of Directionally Selective Motion Detection

广泛的大脑活动，从物体识别到姿势调整，都需要神经元和神经回路进行计算。近年来，神经生物学家在两个相关领域取得了令人印象深刻的进展：一个涉及突触的生物物理和分子机制，另一个涉及数学和逻辑运算，后者正式描述了整个神经细胞系统的功能。在视觉系统如何工作的研究中，算法成功地模拟了视觉跟踪和固定、双目视觉和运动检测。进一步了解视觉系统的未来进展取决于生物物理和算法方法的整合。这将需要有关特定计算中涉及的神经元的结构和动态特性的详细信息。许多视觉系统可以计算运动目标的方向和速度。最近的研究表明，定向运动检测是通过嵌入神经元接受野结构的突触操作来实现的。在高等脊椎动物和小龙虾的视觉神经元中分别发现了相同的定向机制。其机制取决于感受野内兴奋和抑制的时空不对称性。本项目着重于支持定向运动检测的突触机制的实验和理论研究。生理测量将量化形成定向机制的突触的特征。模拟将确定突触的测量特性是否足以支持定向机制。

IBN-9507878 Raymon Glantz A broad spectrum of brain activities, from object recognition to postural adjustments, require that neurons and neural circuits make computations. In recent years, neurobiologists have made impressive progress in two related areas: one concerns the biophysical and molecular mechanisms of synapses and the second concerns the mathematical and logical operations which formally describe what whole systems of nerve cells do. In the study of how the visual system works, algorithms successfully model visual tracking and fixation, binocular vision, and motion detection. Future progress in understanding more about the visual system depends upon integrating the biophysical and algorithmic approaches. This will require detailed information about the structure and dynamic properties of neurons involved in particular computations. Many visual systems can compute the direction and velocity of moving targets. Recent studies indicate that directional motion detection is achieved through synaptic operations embedded in the structure of the neuron's receptive field. The same directional mechanisms were independently found in visual neurons in higher vertebrates and in the crayfish. The mechanisms depends upon spatial and temporal asymmetries of the excitation and inhibition within the receptive field. This project focuses on experimental and theoretical studies of the synaptic mechanisms which support directional motion detection. Physiological measurements will quantify the characteristics of the synapses which form the directional mechanism. The simulations will determine if the measured properties of the synapses are sufficient to support the directional mechanism.