ワーキングメモリに統語の負荷：両半球のモジュレーション

読 language syntax WM

Taxing working memory with syntax: bihemispheric modulations.
Santi A, Grodzinsky Y.
Hum Brain Mapp. 2007 Nov;28(11):1089-97.

二つの統語的な dependeny の効果を比較

  • 移動 movement のある文: Which boy does the girl think [t] examined Steven?
  • 束縛 binding のある文：Jill thinks the boy examined himself

結果

  • 健常者
  • 脳損傷患者
    • 二つの統語機能の障害は異なる部位の脳損傷による

N400 に関わる分散した脳内言語ネットワーク

読 MEG language semantics N400

Localizing the distributed language network responsible for the N400 measured by MEG during auditory sentence processing.

Maess B, Herrmann CS, Hahne A, Nakamura A, Friederici AD.

Brain Res. 2006 Jun 22;1096(1):163-72.



前頭：意味の違反で BA45/47
側頭：BA20/21/22 は意味的な正誤に関わらず活動
　意味的に正しい文では活動が 32 ms 早い
　⇒ 文脈が処理を簡単にしている
全体的に意味に誤りのある文は活動が遅く、強く、長い
　⇒ 統合により時間・コストがかかる

MEG と BOLD 信号の線型コンボリューション・モデルを用いた統合

未 MEG BOLD

A novel method for integrating MEG and BOLD fMRI signals with the linear convolution model in human primary somatosensory cortex.

Nangini C, Tam F, Graham SJ.

Hum Brain Mapp. 2008 Jan;29(1):97-106.

Characterizing the neurovascular coupling between hemodynamic signals and their neural origins is crucial to functional neuroimaging research, even more so as new methods become available for integrating results from different functional neuroimaging modalities. We present a novel method to relate magnetoencephalography (MEG) and BOLD fMRI data from primary somatosensory cortex within the context of the linear convolution model. This model, which relates neural activity to BOLD signal change, has been widely used to predict BOLD signals but typically lacks experimentally derived measurements of neural activity. In this study, an fMRI experiment is performed using variable-duration (

文理解における動詞処理の脳内表象：補部の数、下位範疇、意味フレーム

読 language syntax

Cortical representation of verb processing in sentence comprehension: number of complements, subcategorization, and thematic frames.

Cereb Cortex. 2007 Aug;17(8):1958-69. Epub 2006 Nov 13.

Shetreet E, Palti D, Friedmann N, Hadar U.

The processing of various attributes of verbs is crucial for sentence comprehension. Verb attributes include the number of complements the verb selects, the number of different syntactic phrase types (subcategorization options), and the number of different thematic roles (thematic options). Two functional magnetic resonance imaging experiments investigated the cerebral location and pattern of activation of these attributes. Experiment 1 tested the effect of number of complements. Experiment 2 tested the number of options of subcategorization and of thematic frames. A group of mismatch verbs with different number of options for subcategorization and thematic frames was included to distinguish between the effects of these attributes. Fourteen Hebrew speakers performed a semantic decision task on auditorily presented sentences. Parametric analysis revealed graded activations in the left superior temporal gyrus and the left inferior frontal gyrus in correlation with the number of options. By contrast, the areas that correlated with the number of complements, the right precuneus and the right cingulate, were not conventionally linguistic. This suggests that processing the number of options is more specifically linguistic than processing the number of complements. The mismatch verbs showed a pattern of activation similar to that of the subcategorization group but unlike that of the thematic frames group. By implication, and contrary to claims by some linguists, subcategorization seems indispensable in verb processing.

ヘブライ語での実験

  • 実験1：補部の数の効果
  • 実験2：下位範疇と意味フレームのオプションの数



結果

  • 左上側頭回、左下前頭回でオプション数と相関
  • 右楔前部と右帯状回で補部の数と相関(どちらも言語野ではない)

⇒オプションの数の処理は補部の数の処理に比べ言語特異的


言語学者の主張とは反対に下位範疇化は動詞の処理に必須。


結果はともかく主張には賛同しかねる。もうちょい読みます。

神経活動の増加に伴う負の BOLD 信号

未 fMRI

Negative BOLD with Large Increases in Neuronal Activity.

Schridde U, Khubchandani M, Motelow JE, Sanganahalli BG, Hyder F, Blumenfeld H

Cereb Cortex. 2007 Dec 5;


Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used in neuroscience to study brain activity. However, BOLD fMRI does not measure neuronal activity directly but depends on cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO(2)) consumption. Using fMRI, CBV, CBF, neuronal recordings, and CMRO(2) modeling, we investigated how the signals are related during seizures in rats. We found that increases in hemodynamic, neuronal, and metabolic activity were associated with positive BOLD signals in the cortex, but with negative BOLD signals in hippocampus. Our data show that negative BOLD signals do not necessarily imply decreased neuronal activity or CBF, but can result from increased neuronal activity, depending on the interplay between hemodynamics and metabolism. Caution should be used in interpreting fMRI signals because the relationship between neuronal activity and BOLD signals may depend on brain region and state and can be different during normal and pathological conditions.

ラットの脳血流量 (CBF)、脳血液量(CBV)、脳酸素消費量 (CMRO2)、神経活動 と fMRI の BOLD 信号を比較。


血行動態・神経活動・代謝の増加

  • 皮質：正の BOLD
  • 海馬：負の BOLD



負の BOLD は必ずしも神経活動の低下を意味しない。
神経活動と代謝の相互作用に依存し、部位や状態、病態によって変化するので注意。