-a cup of earl grey in the morning, with honey and soy milk
-another cup of earl grey in the afternoon when I come home, with honey
-a cup of earl grey before I sit in front my desk, no honey or sugar
-another cup during the break from studying
-a cup of decafe earl grey 40 minutes before going to bed
Tuesday, March 21, 2006
Tuesday, March 14, 2006
周杰倫、七里香、蕭邦、與其他
最近不知為何突然開始喜歡聽周杰倫。以我這種即使還算年輕但是常年沒在看電視聽流行音樂的人來說，真是非常不尋常的事。也許是一種奇特的台灣情懷吧…在LA說會有鄉愁是不太容易的事，畢竟華人那麼多，要吃中國菜，台灣菜也到處都有。不過聽慣了從中國來的華人口音，等到自己一開口說中文，才赫然發現，哇，我的口音還真台灣啊。周杰倫式讓人聽不懂在唱什麼講什麼的歌曲，那種懶懶的率性又像在把妹那種不在乎的說話方式，仿佛讓我想起某些對台灣的記憶:大學生活、台大公館、夜市。前一陣子還想說要來研究一下周杰倫歌詞的韻腳，看看他的押韻是否因他特殊的唱歌咬字方式而有變化。
前一陣子發現李雲迪要來學校裡表演，結果等我發現時，學生票已經賣完了，只剩一般票價。掙扎了一陣子還是決定放棄了。本來就滿喜歡蕭邦的音樂，但是李雲迪的演奏是從來沒聽過，搜尋了一下，只覺得他最近的照片居然出奇的神似木村拓哉在日劇"長假"裡的造型。李雲迪是在蕭邦鋼琴大賽出頭，而木村也是在長假裡彈奏著蕭邦的曲子。更巧的是，周杰倫的一張專輯也叫十一月的蕭邦。
也許這些百般聊賴的話題只是我逃避現實的方式吧…
研究所的生活從第一年進來，好像有無止盡的報告和reading，我也一直在忙碌中，一股傻傻的衝勁讓我可以過著四天內趕三分期末報告的超人生活。也可以為了準備教課忙到半夜。但是，到了這個學期，我好像失去了那樣的動力。依照往常的我，是可以一個晚上寫出個幾頁的論文的，但是我就是做不到，坐在電腦前面發呆，然後開始覺得負面，覺得自己寫不出來，一定畢不了業…
我覺得之前的日子好像是想要証明自己有足夠的聰明才智可以研究所，走學術研究。常常在缺乏自信與發現新思考的興奮兩極之間擺盪。一個小時前才覺得今天上課的討論真是有趣啊，如果再繼續往下怎樣怎樣不知會發現什麼結果。一個小時之後覺得自己好像是個笨蛋，連paper都不會寫的笨蛋，也沒有發表過什麼文章，走學術一定沒辦法生存。
也許上學期沒有申請博士班是個正確的選擇…我很高興我當初選擇來念了這裡的碩士班，但至於是否要念博士班，也許就不是那麼確定了。我覺得我好像生命中到目前為止，只知道念書這一件事。念書有快樂的地方，也有痛苦的地方，特別是大學時念了自己不喜歡念的科系。但痛苦的地方，還有那些跟別人的比較和壓力，似乎念書對我來說，不見得是完全單純的一件事，還混雜了很多自我形象、完美主義等等。在台灣的教育環境下，書念得越多，還算是一件光榮的事。所以如果能力和金錢資源夠讓你拿到一學入學許可，也許便投向研究所去了。
我常在想，到底上帝所要給我的人生，是像什麼樣子的呢?
從高中起，我就在想，是否上帝會要我去做某種工作，在某個位置去服事祂? 所以在那之前，一切就像是準備工作似的，我有點摸不著上帝在幹什麼，總覺得答案可能就在後頭，所以一直等待下去。但是我的人生就在這當中又過了好幾年。有些經歷好像是一點都不相干，我自己也不覺得能夠拿來幹什麼。轉個方向來想，又或者我的人生就是現在，是此刻，我應該好好把握?
不知不覺中，我也從單身進入婚姻。我不覺得是回頭百年身，反而是有種很神奇且甜蜜的感覺，一個本來完全跟我完全沒有關連的人就這樣一步一步的進入我的生命裡，是我自己怎麼樣也計畫不來的。
高中的時候我曾經和好朋友寫下了一百多件(應該有一百吧?)我們想要做的事情，不管可不可能達成。有一些已經實現了，可是還有好多地方還沒去，好多東西和語言還沒學。我不曉得走哪一條路可以讓我實現那些夢想，但是我好像又快走到了決定的分岔路口。
我想我還是回到現實，把論文寫個幾頁比較實際…
前一陣子發現李雲迪要來學校裡表演，結果等我發現時，學生票已經賣完了，只剩一般票價。掙扎了一陣子還是決定放棄了。本來就滿喜歡蕭邦的音樂，但是李雲迪的演奏是從來沒聽過，搜尋了一下，只覺得他最近的照片居然出奇的神似木村拓哉在日劇"長假"裡的造型。李雲迪是在蕭邦鋼琴大賽出頭，而木村也是在長假裡彈奏著蕭邦的曲子。更巧的是，周杰倫的一張專輯也叫十一月的蕭邦。
也許這些百般聊賴的話題只是我逃避現實的方式吧…
研究所的生活從第一年進來，好像有無止盡的報告和reading，我也一直在忙碌中，一股傻傻的衝勁讓我可以過著四天內趕三分期末報告的超人生活。也可以為了準備教課忙到半夜。但是，到了這個學期，我好像失去了那樣的動力。依照往常的我，是可以一個晚上寫出個幾頁的論文的，但是我就是做不到，坐在電腦前面發呆，然後開始覺得負面，覺得自己寫不出來，一定畢不了業…
我覺得之前的日子好像是想要証明自己有足夠的聰明才智可以研究所，走學術研究。常常在缺乏自信與發現新思考的興奮兩極之間擺盪。一個小時前才覺得今天上課的討論真是有趣啊，如果再繼續往下怎樣怎樣不知會發現什麼結果。一個小時之後覺得自己好像是個笨蛋，連paper都不會寫的笨蛋，也沒有發表過什麼文章，走學術一定沒辦法生存。
也許上學期沒有申請博士班是個正確的選擇…我很高興我當初選擇來念了這裡的碩士班，但至於是否要念博士班，也許就不是那麼確定了。我覺得我好像生命中到目前為止，只知道念書這一件事。念書有快樂的地方，也有痛苦的地方，特別是大學時念了自己不喜歡念的科系。但痛苦的地方，還有那些跟別人的比較和壓力，似乎念書對我來說，不見得是完全單純的一件事，還混雜了很多自我形象、完美主義等等。在台灣的教育環境下，書念得越多，還算是一件光榮的事。所以如果能力和金錢資源夠讓你拿到一學入學許可，也許便投向研究所去了。
我常在想，到底上帝所要給我的人生，是像什麼樣子的呢?
從高中起，我就在想，是否上帝會要我去做某種工作，在某個位置去服事祂? 所以在那之前，一切就像是準備工作似的，我有點摸不著上帝在幹什麼，總覺得答案可能就在後頭，所以一直等待下去。但是我的人生就在這當中又過了好幾年。有些經歷好像是一點都不相干，我自己也不覺得能夠拿來幹什麼。轉個方向來想，又或者我的人生就是現在，是此刻，我應該好好把握?
不知不覺中，我也從單身進入婚姻。我不覺得是回頭百年身，反而是有種很神奇且甜蜜的感覺，一個本來完全跟我完全沒有關連的人就這樣一步一步的進入我的生命裡，是我自己怎麼樣也計畫不來的。
高中的時候我曾經和好朋友寫下了一百多件(應該有一百吧?)我們想要做的事情，不管可不可能達成。有一些已經實現了，可是還有好多地方還沒去，好多東西和語言還沒學。我不曉得走哪一條路可以讓我實現那些夢想，但是我好像又快走到了決定的分岔路口。
我想我還是回到現實，把論文寫個幾頁比較實際…
Saturday, March 04, 2006
無題一
我最近變得很討厭寫東西。如果真的要我寫，我通常都是假裝在電腦上打字，然後其實是在寫blog或是到最後跟朋友聊天。我覺得是寫論文的壓力所造成的。我也不知道為何寫作變得那麼難。本來用英文寫學術的東西對我就不太容易，但這並非是件難事。最困難的部分我覺得是心理的礙障，覺得寫出來沒人看、這世界上99%看不懂又不會關心、投稿也沒人要登出來之類的負面思想讓我常常對著一片空白的螢光幕發呆…
在我來UCLA之前，我對人類的大腦和語言的關係很有興趣。儘管這世界有不少人是右撇子，很奇特的，幾乎大部分的人都是左腦為主(dominant)，而不是像許多感覺和運動的連結在腦部是和身体左右相反。更特別一點是語言的作用幾乎都是集中在左腦。但是真正的腦部功能真的比我們想像要複雜許多。所以像那種什麼腦主情感，什麼腦主理性，或是人的腦只有35%被使用到，其他都有待開發之類的，都是不合實情的謬論。人類除了有個精密的腦和神經系統之外，最有別於其他動物的是人類擁有語言。也許有人會爭辯說他家的狗除了不會說話，但是可以了解他主人說的話。或是也許有的動物有特別的叫聲可以通知其他同類躲避危險之類。但是這裡講的語言是一種無限的可能性;可以不斷重組創造出新的意涵，也是一種超越時間空間的指向性，可以談論過去，也可以想像未來。鳥兒不會告訴其他鳥兒昨天那個獵人如何如何。
我本來以為我會來這裡學怎麼跑fMRI，給一個人看一些句子，做一些實驗操弄，看看那些地方的大腦皮層有反應，也許我可以推論那些部位是語言的特別功能區，像是處理語意、文法等等…
結果發現這個program意外地跟我想像的完全不一樣。這裡沒有人在做造影…但是也算是個好的意外。因為我才發覺這種想從造影看語言功能是有點無知的想法。如果我們完全不了解腦的結構和神經元的聯絡，所以表面的推論也是枉能。也許語言的處理只是個物理性的過程?因為語言完全是個聲波;訊息的傳達完全是物理化學的反應。到底是什麼讓人類擁有語言?
回到我的論文…我想要探討的是語言和記憶的關係。特別是那種很短暫的，如快速複述一段電話號碼，在你快忘記之前趕快寫下來的那種記憶。特別是在學一個外語的時候，你可以跟著老師念一個單字或片語，可是有的時候過了幾分鐘就會忘記的那種短暫的記憶。也許你會羨慕有的人似乎可以將這種記憶轉成比較長期的，有著過目不忘或過耳不忘似的天分，這對學習似乎是個很大的優勢。
心理學有一些記憶的模型可以解釋這種短暫記憶轉化成長期記憶的過程，但是我所想要探討的是到底在腦裡面發生了什麼事? 是否除了描述這種記憶的現象之外，可以用另一種比較生物性的方式來描述這種"記憶"的本質是什麼。
在我來UCLA之前，我對人類的大腦和語言的關係很有興趣。儘管這世界有不少人是右撇子，很奇特的，幾乎大部分的人都是左腦為主(dominant)，而不是像許多感覺和運動的連結在腦部是和身体左右相反。更特別一點是語言的作用幾乎都是集中在左腦。但是真正的腦部功能真的比我們想像要複雜許多。所以像那種什麼腦主情感，什麼腦主理性，或是人的腦只有35%被使用到，其他都有待開發之類的，都是不合實情的謬論。人類除了有個精密的腦和神經系統之外，最有別於其他動物的是人類擁有語言。也許有人會爭辯說他家的狗除了不會說話，但是可以了解他主人說的話。或是也許有的動物有特別的叫聲可以通知其他同類躲避危險之類。但是這裡講的語言是一種無限的可能性;可以不斷重組創造出新的意涵，也是一種超越時間空間的指向性，可以談論過去，也可以想像未來。鳥兒不會告訴其他鳥兒昨天那個獵人如何如何。
我本來以為我會來這裡學怎麼跑fMRI，給一個人看一些句子，做一些實驗操弄，看看那些地方的大腦皮層有反應，也許我可以推論那些部位是語言的特別功能區，像是處理語意、文法等等…
結果發現這個program意外地跟我想像的完全不一樣。這裡沒有人在做造影…但是也算是個好的意外。因為我才發覺這種想從造影看語言功能是有點無知的想法。如果我們完全不了解腦的結構和神經元的聯絡，所以表面的推論也是枉能。也許語言的處理只是個物理性的過程?因為語言完全是個聲波;訊息的傳達完全是物理化學的反應。到底是什麼讓人類擁有語言?
回到我的論文…我想要探討的是語言和記憶的關係。特別是那種很短暫的，如快速複述一段電話號碼，在你快忘記之前趕快寫下來的那種記憶。特別是在學一個外語的時候，你可以跟著老師念一個單字或片語，可是有的時候過了幾分鐘就會忘記的那種短暫的記憶。也許你會羨慕有的人似乎可以將這種記憶轉成比較長期的，有著過目不忘或過耳不忘似的天分，這對學習似乎是個很大的優勢。
心理學有一些記憶的模型可以解釋這種短暫記憶轉化成長期記憶的過程，但是我所想要探討的是到底在腦裡面發生了什麼事? 是否除了描述這種記憶的現象之外，可以用另一種比較生物性的方式來描述這種"記憶"的本質是什麼。
Wednesday, March 01, 2006
thoughts of the day
Attention vs. working memory:
It seems like that working memory must to some extanct overlap with attention. Some literature treated "working memory" as attention, or part of attention, like Fuster. (Sara Schukert in her article on attention) also choose Fuster's stand point. It makes sense though, when a subject or animal is performing the so called "working memory" tasks, such as "delayed-response task", certain functioning of a focused attention to the stimuli. But can we say that they are equivalent things, two analogus processes in the brain?
Working memory in different representations:
In psychology and SLA research the notion of WM is related to phonological short-term memory. Miyaki and Friedman (1998) even relates the working memory capacity to one central component of language aptitude. In fact, some studies do show that such phonological short term memory has predicting power over individual's future grammar/vocabulary performance in SLA (Nick Ellis). In terms of neuroscience studies, the working memory task was broken down into very basic and simple processes or components, such as visual, spatial, and tactile memories, or guided hand/eye movements. Prefrontal cortex was thought to be the center for many of these working memory related tasks, planning and executive functions. But the picture seems to be more complicated than simply localizing the function of working memory in prefrontal cortex. Fuster does found so called "memory cells" in prefrontal cortex of monkeys, and Goldman-Rakic also found certain neurons in the same area sensitive to spatial memory. But this doesn't give us a conclusion of what's going on in the brain during these tasks. I'm leaning towards to a neural network that's not just confined in prefrontal area, but connects to other cortical and sub-cortical areas as well.
It seems like that working memory must to some extanct overlap with attention. Some literature treated "working memory" as attention, or part of attention, like Fuster. (Sara Schukert in her article on attention) also choose Fuster's stand point. It makes sense though, when a subject or animal is performing the so called "working memory" tasks, such as "delayed-response task", certain functioning of a focused attention to the stimuli. But can we say that they are equivalent things, two analogus processes in the brain?
Working memory in different representations:
In psychology and SLA research the notion of WM is related to phonological short-term memory. Miyaki and Friedman (1998) even relates the working memory capacity to one central component of language aptitude. In fact, some studies do show that such phonological short term memory has predicting power over individual's future grammar/vocabulary performance in SLA (Nick Ellis). In terms of neuroscience studies, the working memory task was broken down into very basic and simple processes or components, such as visual, spatial, and tactile memories, or guided hand/eye movements. Prefrontal cortex was thought to be the center for many of these working memory related tasks, planning and executive functions. But the picture seems to be more complicated than simply localizing the function of working memory in prefrontal cortex. Fuster does found so called "memory cells" in prefrontal cortex of monkeys, and Goldman-Rakic also found certain neurons in the same area sensitive to spatial memory. But this doesn't give us a conclusion of what's going on in the brain during these tasks. I'm leaning towards to a neural network that's not just confined in prefrontal area, but connects to other cortical and sub-cortical areas as well.
Tuesday, February 21, 2006
痛苦的寫作
不知道為什麼，其實很討厭寫東西，尤其是那種報告或是作文之類知道有人會拿來評分的那種文章。如果是像心情抒發或是思考性的隨筆，那就容易得多。目前寫論文最大的困擾就是我根本沒辦法好好坐下來寫。我真希望我只是在寫大眾散文，介紹我到底在研究些什麼。而不是學術性的論文。常常在讀別人寫的學術著作的時候，總覺得為何學術的東西要那麼地讓人讀了不知所云呢? 有沒有可能讓讀者很容易地知道你想要表達些什麼，而同時讓文章有些許學術價值呢? 這兩項要求應該是不相違背吧…
唉…我多麼希望寫我的論文就像在寫部落格一樣啊…
唉…我多麼希望寫我的論文就像在寫部落格一樣啊…
Monday, February 20, 2006
More thoughts on the neurobiological account for working memory
Central executive and attention control
The memory system is generally thought to be composed of two elements, short-term memory and long-term memory. Baddeley and Hitch (1974) developed "working memory" model from the short-term memory system, refering to short-term memory system that is involved in a temporary storage of information and processing (Gastherole & Baddeley, p. 2). The working memory system sublines human cognitive activities, such as "reasoning, language comprehension, long-term learning and mental arithmetic"(p.2). The WM system has three main componants that Baddeley use for explaning relationship between language and memory-with 'central executive' as center componant'; phonological loop', and 'sketchpad'serving as "slave systems" to central executive. The central executive involves in regulating information flow, and retrieval of information from long-term memory. Baddeley also quoted other people's studies in the book that the executive might be involved in planning, task coordination, and consious awareness, and selection and control of action. The concept comes from Shallice's (1988) model of the "attentional control of action." Shallice (quote) reported a paradoxical phenomanon of frontal lobe damage patients. Due to the impairment to the central executive (SAS, "Supervisory Attentional System), the patient can't selectively intervene the activated schemas for apporpriate actions. That is, the patient either have difficulty in inhibiting other distracting schemas, or show perseverance of an already activated schema.
Working memory cells
Coming from neurophysiological point of view, Fuster (2003) looks at memories as cortical networks. The formation of memory is through "the modulation of transmission of information acorss synapses, the neural elements anatomically associating cells with one another" (p. 113). Therefore, memorys are associative with one another. Working memory under such sense is what Fuster called "attention focused on the internal representation of a recent event for a pending action" (p.155). The main propoerties of working memory is not to form a new memory, but to hold active at the need of processing a new action. Thus it's components can be both new items such as sensory inputs, associations; and old, past experience (long-term memory).
The most notable neuronal evidence for this sustained attention is found in monkeys performing a "delayed-response task" (todo:elaboration). Cells in monkeys' prefrontal cortex were found to maintain discharged at a higher level in delayed period (i.e. when the stimulus is obsent from the environment) than in periods between trials. These cells are later called "memory cells". The characteristics of the finding are, first, the delayed-period activation was dependent on the impending need to perform an act "that's contingent on the signal in memory". Second, it was not dependent on the expectation of reward. Third, the accuracy is correlated with the monkey's ability to remember the signal. Forth, the performance could be attenuated when the animal was distracted. (p. 156). In short, these cells discharge selectively to the retention of a stimulus, and they can be distracted by other stimulus concommitently.
Physiologically, single neuron recordings (Goldman-Rakic et al.,1996) reveal neurons in prefrontal cortex firing specifically to the same one or a few locations in a two-dimentional visual field when the animal was performing visual delayed response tasks. According to Fuster, the significance of Goldman-Rakic and collegues' work is that they dissociate two subareas of cortex that's specialized in working memory function: neurons engaged in the memory of the object predominate in the ventral aspect of lateral prefrontal cortex, whereas the neurons for memory of special information predominate in the dorsal apspect. This examplifies that the nature of working memory is not a single unit or localization, but more a distributed network(p.158).
Other studies involving tasks during a state of attention, so called "working memory" tasks also found "memory cells" not limited to prefrontal areas. For example, visual memory were found in the inferior temporal cortex (quote) (Fuster & Jervey, 1981; Miller et al., 1993), spatial memory cells in posterior parietal cortex (quote) (Andersen et al., 1990), and tactile memory cells in somatosensory cortex (quote) (Zhou & Fuster, 1996). In human visual cortex, increased activity was found when the stimuli was obsent but the subject was attending a specific visual field (Kastner et al., 1999).
The inferences can be drown from these findings, according to Fuster (2003) are that, working memory consists of a large cognitive network (perceptual and executive memory), and the selective attention during a task of working memory consists of the sustained and selective activation of this network.
Dopamine projection
Dopamine in the prefrontal cortex:
In the study of Goldman-Rakic et al.(1996), they pointed out that pyramidal neurons and non-pyramidal neurons in prefrontal cortex is critical for the formation of a "memory field" found in the area. Dopamine has inhibitory and excitatory effect on the prefronal cells. Prefrontal cortex is also known as the richest in dopamine than any other cortical areas. Tus the role of dopamine projection to prefrontal area and its effect on working memory tasks worths further discussion.
More evidence has been made between the dopamine dysregulation in prefrontal cortex in dschizophrenia(Goldman-Rakic et al. 2004). Working memory deficits have been postulated to be "underlying the myriad impairment of disorders" in schizophrenia (p. 4). In Diamond (1989) young infants still can't perform without errors in working memory plus inhibition tasks due to late developmental maturity of human dorsal lateral prefronal cortex.
The memory system is generally thought to be composed of two elements, short-term memory and long-term memory. Baddeley and Hitch (1974) developed "working memory" model from the short-term memory system, refering to short-term memory system that is involved in a temporary storage of information and processing (Gastherole & Baddeley, p. 2). The working memory system sublines human cognitive activities, such as "reasoning, language comprehension, long-term learning and mental arithmetic"(p.2). The WM system has three main componants that Baddeley use for explaning relationship between language and memory-with 'central executive' as center componant'; phonological loop', and 'sketchpad'serving as "slave systems" to central executive. The central executive involves in regulating information flow, and retrieval of information from long-term memory. Baddeley also quoted other people's studies in the book that the executive might be involved in planning, task coordination, and consious awareness, and selection and control of action. The concept comes from Shallice's (1988) model of the "attentional control of action." Shallice (quote) reported a paradoxical phenomanon of frontal lobe damage patients. Due to the impairment to the central executive (SAS, "Supervisory Attentional System), the patient can't selectively intervene the activated schemas for apporpriate actions. That is, the patient either have difficulty in inhibiting other distracting schemas, or show perseverance of an already activated schema.
Working memory cells
Coming from neurophysiological point of view, Fuster (2003) looks at memories as cortical networks. The formation of memory is through "the modulation of transmission of information acorss synapses, the neural elements anatomically associating cells with one another" (p. 113). Therefore, memorys are associative with one another. Working memory under such sense is what Fuster called "attention focused on the internal representation of a recent event for a pending action" (p.155). The main propoerties of working memory is not to form a new memory, but to hold active at the need of processing a new action. Thus it's components can be both new items such as sensory inputs, associations; and old, past experience (long-term memory).
The most notable neuronal evidence for this sustained attention is found in monkeys performing a "delayed-response task" (todo:elaboration). Cells in monkeys' prefrontal cortex were found to maintain discharged at a higher level in delayed period (i.e. when the stimulus is obsent from the environment) than in periods between trials. These cells are later called "memory cells". The characteristics of the finding are, first, the delayed-period activation was dependent on the impending need to perform an act "that's contingent on the signal in memory". Second, it was not dependent on the expectation of reward. Third, the accuracy is correlated with the monkey's ability to remember the signal. Forth, the performance could be attenuated when the animal was distracted. (p. 156). In short, these cells discharge selectively to the retention of a stimulus, and they can be distracted by other stimulus concommitently.
Physiologically, single neuron recordings (Goldman-Rakic et al.,1996) reveal neurons in prefrontal cortex firing specifically to the same one or a few locations in a two-dimentional visual field when the animal was performing visual delayed response tasks. According to Fuster, the significance of Goldman-Rakic and collegues' work is that they dissociate two subareas of cortex that's specialized in working memory function: neurons engaged in the memory of the object predominate in the ventral aspect of lateral prefrontal cortex, whereas the neurons for memory of special information predominate in the dorsal apspect. This examplifies that the nature of working memory is not a single unit or localization, but more a distributed network(p.158).
Other studies involving tasks during a state of attention, so called "working memory" tasks also found "memory cells" not limited to prefrontal areas. For example, visual memory were found in the inferior temporal cortex (quote) (Fuster & Jervey, 1981; Miller et al., 1993), spatial memory cells in posterior parietal cortex (quote) (Andersen et al., 1990), and tactile memory cells in somatosensory cortex (quote) (Zhou & Fuster, 1996). In human visual cortex, increased activity was found when the stimuli was obsent but the subject was attending a specific visual field (Kastner et al., 1999).
The inferences can be drown from these findings, according to Fuster (2003) are that, working memory consists of a large cognitive network (perceptual and executive memory), and the selective attention during a task of working memory consists of the sustained and selective activation of this network.
Dopamine projection
Dopamine in the prefrontal cortex:
In the study of Goldman-Rakic et al.(1996), they pointed out that pyramidal neurons and non-pyramidal neurons in prefrontal cortex is critical for the formation of a "memory field" found in the area. Dopamine has inhibitory and excitatory effect on the prefronal cells. Prefrontal cortex is also known as the richest in dopamine than any other cortical areas. Tus the role of dopamine projection to prefrontal area and its effect on working memory tasks worths further discussion.
More evidence has been made between the dopamine dysregulation in prefrontal cortex in dschizophrenia(Goldman-Rakic et al. 2004). Working memory deficits have been postulated to be "underlying the myriad impairment of disorders" in schizophrenia (p. 4). In Diamond (1989) young infants still can't perform without errors in working memory plus inhibition tasks due to late developmental maturity of human dorsal lateral prefronal cortex.
Sunday, February 19, 2006
Thoughts on working memory (for self record)
man, I think I picked the hard topic to look at...
If I were to give the definition of "working memory", I would end up burying myself in the literatures of working memory, but still couldn't give out a clear model of definition for it without confusing myself to death. This is how I have been feeling whenever I found any study talking about this topic.
I gradually learned (still not very skillfuly) to first identify which camp they are coming from:
1. Second language acuqistion camp: these people are langauge educators, applied linguists, and people who like to borrow psychological concepts and studies. The implication of WM for them is the predictor for learning a second/foreign language. Intuitively everybody would think that if you can remember a sequence of foreign sounds and be able to repeat promptly, that means you have some kinda "talent" for learning languages.
But knowing this and to prove it doesn't solve my question. What's working meomry in a neurobiological sense?
2. Psychology camp: they are the people who first brought up the idea of working memory from the concept of short-term memory, including Baddaley himself. Since they made up the term, their studies are being quoted by others all the time, but only at the introduction. After that they just go on whatever directions they like to talk about this term.
3. Neurolinguistic people: looks like these people like fMRI very much. A lot of them believe in UG and language area it seems like. The attempt is to find out the location of working memory, which is prefronal cortex, along with some other regions like temporal gyrus, parietal areas being found in those imaging studies.
Sometimes these localization studies or ROI ("region of interest") look cool but couldn't explain what's going on underneath the cortex. When parietal cortex and cingulate both light up, what does it tell us about the brain?
4. Neuroscientist: Fuster, Goldman-Rakic et al...
These are the people whom I think have cool ideas about working memory. Fuster has this "cognit" neuronetwork explaning cognition in the cortex. He discovered the memory cells when monkeys doing delayed response task. Same kinda cells are found in different regions of the brain when doing other tasks such as tonal, visual-spatial, color, etc. Goldman-Rakic found cells firing at certain "memory field" when monkeys doing delayed response tasks through single cell recordings. Another way to understand WM and the relationship with prefrontal area might be through pathological studies, like autism or schizophrenia. For example, "autism" (though this term needs clear definitions too!) subjects tend to have working memory deficits, same as schizophrenia patients, WM integrity can even predict whether they can reintegrate socially or replase. Some studies connect these deficits to dopamine projection dysfunction in prefrontal cortex, which I am still trying to figure out. I got the feeling this might the direction I want to go just to avoid the endless debate on what working memory does and what it actually is.
If I were to give the definition of "working memory", I would end up burying myself in the literatures of working memory, but still couldn't give out a clear model of definition for it without confusing myself to death. This is how I have been feeling whenever I found any study talking about this topic.
I gradually learned (still not very skillfuly) to first identify which camp they are coming from:
1. Second language acuqistion camp: these people are langauge educators, applied linguists, and people who like to borrow psychological concepts and studies. The implication of WM for them is the predictor for learning a second/foreign language. Intuitively everybody would think that if you can remember a sequence of foreign sounds and be able to repeat promptly, that means you have some kinda "talent" for learning languages.
But knowing this and to prove it doesn't solve my question. What's working meomry in a neurobiological sense?
2. Psychology camp: they are the people who first brought up the idea of working memory from the concept of short-term memory, including Baddaley himself. Since they made up the term, their studies are being quoted by others all the time, but only at the introduction. After that they just go on whatever directions they like to talk about this term.
3. Neurolinguistic people: looks like these people like fMRI very much. A lot of them believe in UG and language area it seems like. The attempt is to find out the location of working memory, which is prefronal cortex, along with some other regions like temporal gyrus, parietal areas being found in those imaging studies.
Sometimes these localization studies or ROI ("region of interest") look cool but couldn't explain what's going on underneath the cortex. When parietal cortex and cingulate both light up, what does it tell us about the brain?
4. Neuroscientist: Fuster, Goldman-Rakic et al...
These are the people whom I think have cool ideas about working memory. Fuster has this "cognit" neuronetwork explaning cognition in the cortex. He discovered the memory cells when monkeys doing delayed response task. Same kinda cells are found in different regions of the brain when doing other tasks such as tonal, visual-spatial, color, etc. Goldman-Rakic found cells firing at certain "memory field" when monkeys doing delayed response tasks through single cell recordings. Another way to understand WM and the relationship with prefrontal area might be through pathological studies, like autism or schizophrenia. For example, "autism" (though this term needs clear definitions too!) subjects tend to have working memory deficits, same as schizophrenia patients, WM integrity can even predict whether they can reintegrate socially or replase. Some studies connect these deficits to dopamine projection dysfunction in prefrontal cortex, which I am still trying to figure out. I got the feeling this might the direction I want to go just to avoid the endless debate on what working memory does and what it actually is.
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