Numerical processing in parietal cortex

描述(申请人提供)：该提案旨在了解数值处理的神经基础。为了做到这一点，动物受试者将接受训练，根据闪烁的次数对视觉线索进行分类。他们将通过对与选择相对应的两个可能的视觉目标中的一个进行眼动来报告闪光的次数是多于还是少于五次。数字线索的其他刺激维度将受到控制，以确保决策基于数字。顶叶皮质参与了数字处理和决策。有人假设，后顶叶皮质(PPC)的暂时失活将干扰根据数字而不是颜色信息形成决策的能力。PPC中的神经元在一个选择的空间区域内对视觉刺激做出反应，并在眼球运动到该位置之前，即响应场(RF)。PPC中神经元的反应表明，它们整合信息以引导眼球运动。单个PPC神经元的活动将被记录下来，以确定它们是否代表数字线索本身和关于数字的决定。为了深入了解数字在神经结构中是如何表示的，数字线索将被放置在神经元的RF中，与数字相关的活动的轮廓将被量化。此外，选择目标将被放置在神经元的RF中，以测量与指导动物选择的离散信息脉冲整合相关的神经活动。

DESCRIPTION (provided by applicant): The proposal is aimed at understanding the neural basis of numerical processing. To accomplish this, animal subjects will be trained to categorize a visual cue on the basis of the number of times it flashes. They will report whether the number of flashes is greater or less than five by making an eye movement to one of two possible visual targets that correspond to the choices. Other stimulus dimensions of the number cue will be controlled to insure that decisions are based on number. Parietal cortex has been implicated in both numerical processing and decision-making. It is hypothesized that temporary inactivation of posterior parietal cortex (PPC) will interfere with the ability to form decisions on the basis of number, but not color, information. Neurons in PPC respond to visual stimuli in a selective region of space and before eye movements to that location, the response field (RF). The responses of neurons in PPC suggest that they integrate information in order to guide eye movements. The activity of single PPC neurons will be recorded to determine if they represent the number cue itself and decisions about number. To gain insight into how number is represented in neural structures, the number cue will be placed in the neuron's RF and the profile of activity associated with number will be quantified. In addition, the choice target will be placed in the neuron's RF to measure neural activity associated with the integration of discrete pulses of information that guide the animal's choice.