Kay Leslie M
Department of Psychology and Institute for Mind & Biology, The University of Chicago, Chicago, IL 60637, USA.
Chaos. 2003 Sep;13(3):1057-66. doi: 10.1063/1.1596071.
Brain hermeneutics and chaotic itinerancy proposed by Tsuda are attractive characterizations of perceptual dynamics in the mammalian olfactory system. This theory proposes that perception occurs at the interface between itinerant neural representation and interaction with the environment. Quantifiable application of these dynamics has been hampered by the lack of definable history and action processes which characterize the changes induced by behavioral state, attention, and learning. Local field potentials measured from several brain areas were used to characterize dynamic activity patterns for their use as representations of history and action processes. The signals were recorded from olfactory areas (olfactory bulb, OB, and pyriform cortex) and hippocampal areas (entorhinal cortex and dentate gyrus, DG) in the brains of rats. During odor-guided behavior the system shows dynamics at three temporal scales. Short time-scale changes are system-wide and can occur in the space of a single sniff. They are predictable, associated with learned shifts in behavioral state and occur periodically on the scale of the intertrial interval. These changes occupy the theta (2-12 Hz), beta (15-30 Hz), and gamma (40-100 Hz) frequency bands within and between all areas. Medium time-scale changes occur relatively unpredictably, manifesting in these data as alterations in connection strength between the OB and DG. These changes are strongly correlated with performance in associated trial blocks (5-10 min) and may be due to fluctuations in attention, mood, or amount of reward received. Long time-scale changes are likely related to learning or decline due to aging or disease. These may be modeled as slow monotonic processes that occur within or across days or even weeks or years. The folding of different time scales is proposed as a mechanism for chaotic itinerancy, represented by dynamic processes instead of static connection strengths. Thus, the individual maintains continuity of experience within the stability of fast periodic and slow monotonic processes, while medium scale events alter experience and performance dramatically but temporarily. These processes together with as yet to be determined action effects from motor system feedback are proposed as an instantiation of brain hermeneutics and chaotic itinerancy.
津田提出的脑诠释学和混沌游走是对哺乳动物嗅觉系统中感知动力学的引人关注的描述。该理论认为，感知发生在巡回神经表征与环境相互作用的界面处。由于缺乏可定义的历史和行动过程来表征行为状态、注意力和学习所引发的变化，这些动力学的量化应用受到了阻碍。从多个脑区测量的局部场电位被用于表征动态活动模式，以用作历史和行动过程的表征。信号是在大鼠大脑的嗅觉区域（嗅球、OB和梨状皮层）以及海马区域（内嗅皮层和齿状回，DG）记录的。在气味引导行为期间，该系统在三个时间尺度上呈现出动力学特征。短时间尺度的变化是全系统范围的，可在单次嗅吸的时间内发生。它们是可预测的，与行为状态的习得性转变相关，并在试验间隔的尺度上周期性出现。这些变化占据了所有区域内及区域间的θ（2 - 12赫兹）、β（15 - 30赫兹）和γ（40 - 100赫兹）频段。中等时间尺度的变化相对不可预测，在这些数据中表现为OB和DG之间连接强度的改变。这些变化与相关试验块（5 - 10分钟）中的表现密切相关，可能是由于注意力、情绪或所获奖励量的波动所致。长时间尺度的变化可能与学习或因衰老或疾病导致的衰退有关。这些变化可被建模为在数天甚至数周或数年内发生的缓慢单调过程。不同时间尺度的折叠被提议作为混沌游走的一种机制，由动态过程而非静态连接强度来表示。因此，个体在快速周期性和缓慢单调过程的稳定性内保持经验的连续性，而中等尺度的事件会显著但暂时地改变经验和表现。这些过程连同运动系统反馈中尚未确定的行动效应被提议作为脑诠释学和混沌游走的一个实例。
