空間位置的調節與物體特徵的整合於工作記憶的神經機制探討：腦磁圖研究

Neural Correlates for Location-Shared and Feature-Bound Representations in Visual Working Memory: An MEG Study

陳雅苹(Ya-Ping Chen)

指導教授 ： 郭柏呈

國立臺灣大學/理學院/心理學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801580

摘要

過去研究指出具有多重特徵的物體會以整合的形式表徵於工作記憶中。雖然這些研究結果顯示空間位置在視覺工作記憶中的特徵整合扮演重要的角色，然而物體的空間位置與工作記憶中特徵整合表徵的神經機制仍有待進一步的研究。在本研究中，我藉由視覺工作記憶作業典範，並結合修正的「冗餘增益」派典、行為模型和腦磁圖，探討空間位置對物體於工作記憶表徵特徵整合調節的神經機制。共有十八位健康成人參與腦磁圖實驗，在進行實驗的記憶過程中，實驗參與者首先會同時看到並要記住兩個物體，這兩個物體皆具有兩個特徵－字母和顏色，經過短暫的記憶維持階段後，實驗參與者必須在測驗階段中指出此時出現的物體是否具備記憶物體的任一特徵(字母或顏色)，此一判斷不須考慮物體的空間位置。我首先使用「賽跑模式不等式」檢驗受試者的反應時間，反應時間的累積密度函數顯示，當測驗階段呈現的物體同時具有記憶物體的兩個特徵時，會出現特徵共活化的現象並支持特徵連結的假設，而此現象不受到特徵空間位置的影響。無論特徵位置改變與否，當物體以特徵整合的形式呈現時，我在頂葉皆可以觀察到較強烈的Gamma波。最後，我以時間序列的結果支持特徵整合發生在後頂葉與視覺皮質。這些研究結果支持了物體的特徵整合不會受到空間位置改變的影響。

關鍵字

工作記憶 ； 特徵連結 ； 物體位置 ； 冗餘增益 ； Gamma波

並列摘要

Previous studies have shown that feature-integrated object representations are formed in visual working memory (WM). While these findings highlighted the importance of spatial location in feature binding in visual WM, the underlying neural substrates of location-shared and feature-bound representations in visual WM were not fully investigated. Here I address this issue in a visual WM task with a modified redundancy-gain paradigm, using behavioral modeling and magnetoencephalograhy (MEG). In this study, participants (N = 18) performed a WM task in which they viewed two types of feature (colors and letters) in a two-object memory display, following a short delay, and a single object probe. Their task was to indicate whether the probe item contained any feature in the memory display, regardless of its location. I firstly conducted a race model inequality (RMI) test to examine the response time (RT) data. The cumulative density function of the RT suggested feature integration when the probe item contained two features regardless of its location. Next, I found significant gamma activity in the parietal cortex for feature-bound representations in both shared- and unshared-location conditions. Finally, the time-series data confirmed the feature-bound effect in posterior parietal and early visual areas. In conclusion, the results provide novel evidence in behavioral and neural measures and suggest that feature-bound representations can be independent to object location.

並列關鍵字

working memory ； feature binding ； object location ； redundancy gain ； gamma-band activity

參考文獻

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