2019-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/702832摘要：從初階感官訊息整合，到高階認知功能包括語言、情緒、決策等，大腦皮質(cerebral cortex)都扮演非常重要角色。在人類與台灣獼猴，大腦皮質佔腦比超過2/3 (齧齒類則少於1/3)，且均由6個鬆散且互聯堆棧的皮質層所組成。過去主要視覺區研究已發現，不同皮質層神經其反應特性有明顯差異—相較於訊號輸入層，輸出層神經反應特性會隨刺激變化，顯示大腦網絡具有高度彈性。然而我們對於造成這些差異的神經基礎，以及不同分層神經網絡的功能性連結仍然很不清楚。本研究計畫透過多頻道電極，同時記錄主要視覺與觸覺區，大腦不同分層之神經訊號及其電位變化，透過分析神經共振(synchrony)和脊波引發電位變化(spike-triggered local field potential)訊號，來瞭解皮質區神經元群體編碼、運算及迴路運作。計畫將以台灣獼猴為實驗動物模型，主要目標: (1)同時記錄主要視覺(V1)與觸覺區(S1)，分析不同皮質層神經迴路是否有差異。(2)神經元在相同皮層內與不同皮層間的功能性連結，如何受到不同刺激型態調控。(3)相似的視觸刺激，在跨感官間處理是否造成差異，視觸訊號彼此會不會相互影響。我們進一步會根據這些結果，建立多神經多層次的計算模型，模擬大腦皮質如何處理外界訊息，進而對大腦處理訊息的一般原則提供寶貴洞見，結果也有助於最佳化視覺與觸覺輔具。<br> Abstract: The cerebral cortex is essential for many brain functions, from process sensory information to form cognition such as language, emotion and decision making. In humans and macaque monkeys, the cerebral cortex occupies more than 2/3 of the brain volume (less than 1/3 in rodents), and is consisted of six distinct laminar structures that differ in cell types and functional connections. Many studies in primary visual cortex (V1) of monkeys found that neurons in different laminar structures differed significantly in their responses properties. In comparison with neurons in the input layer of V1, many neurons in the output layer responded differently when they were stimulated with different stimulus ensembles. These results indicate that V1 circuitry is highly flexible and can adapt accordingly to the change of input signals. However, most sensory neuroscience studies focused only on response properties of single neurons. It remains unclear about the circuitry underlying the contextual change of individual neurons. It’s also unclear how the connectivity within the same layer or across different layers of the neocortex is modulated by different stimuli. We plan to use the multi-electrode system to record simultaneously from multiple neurons in both primary visual cortex (V1) and primary somatosensory cortex (S1). This multi-neuron and multi-area approach allows us to study functional connectivity of neurons within the same cortical layer and across different layers in different sensory modalities. Macaque monkeys are used as the animal model because of the similarity with humans in both visual and somatosensory processing. We will record broad-band signals from multiple channels simultaneously, and study properties of the connectivity mainly with signals of spike-triggered local field potential. Here we propose three specific aims. Aim 1: Characterizing features of the functional connectivity within the same layers and across different layers in both V1 and S1. This aim is essential because neurons in different cortical layers of V1 and S1 show different response properties, but the circuitry underlying these differences is still poorly understood. Aim 2: Investigating how features of the functional connectivity are modulated by different visual and somatosensory stimulus ensembles. Many V1 simple cells, especially for those in the layers with rich recurrent network, show a strong stimulus-dependent effect - their receptive fields change accordingly with different stimulus ensembles. It is possible that the recurrent excitation is responsible for the ample contextual effect. We will also focus on how functional connectivity within the same layer and across different layers of the cerebral cortex is modulated by different stimuli. Aim 3: Studying the effect of multisensory integration in both V1 and S1 circuitries. Visual and somatosensory information must be combined to from precise textile perception. However, it is not clear whether the cross-modality interaction could occur at the earliest stage of cortical processing. Here we study whether visual stimulus along can modulate activity in S1 and vice versa. Results from these projects will be employed to a multi-neuron multi-layer computational model to simulate cortical processing. These results will offer invaluable insight about the general rules of neocortical processing.主要視覺皮質區主要觸覺皮質區神經共振視覺與觸覺受域脊波引發電位變化台灣獼猴primary visual cortex V1primary somatosensory cortex S1synchronyreceptive fieldspike-triggered local field potentialmacaque monkey.