Predicting Conceptual Processing Capacity from Spontaneous Neuronal Activity of the Left Middle Temporal Gyrus

Abstract

Conceptual processing is a crucial brain function for humans. Past research using neuropsychological and task-based functional brainimaging paradigms indicates that widely distributed brain regions are related to conceptual processing. Here, we explore the potential contribution of intrinsic or spontaneous brain activity to conceptual processing by examining whether resting-state functional magnetic resonance imaging (rs-fMRI) signals can account for individual differences in the conceptual processing efficiencies of healthy individuals. We acquired rs-fMRI and behavioral data on object conceptual processing tasks. We found that the regional amplitude of spontaneous low-frequency fluctuations in the blood oxygen level-dependent signal in the left (posterior) middle temporal gyrus (LMTG) was highly correlated with participants' semantic processing efficiency. Furthermore, the strength of the functional connectivity between the LMTG and a series of brain regions-the left inferior frontal gyrus, bilateral anterior temporal lobe, bilateral medial temporal lobe, posterior cingulate gyrus, and ventromedial and dorsomedial prefrontal cortices-also significantly predicted conceptual behavior. The regional amplitude of low-frequency fluctuations and functionally relevant connectivity strengths of LMTG together accounted for 74% of individual variance in object conceptual performance. This semantic network, with the LMTG as its core component, largely overlaps with the regions reported in previous conceptual/semantic task-based fMRI studies. We conclude that the intrinsic or spontaneous activity of the human brain reflects the processing efficiency of the semantic system.

The White Matter Structural Network Underlying Human Tool Use and Tool Understanding

“…The extent of damage to these tracts correlated with the degree of impairment in using tools. The tracts that we identified overlap with the anterior/middle parts of left SLF, which has been shown to be involved in tool use (Ramayya et al, 2010;Hoeren et al, 2013) and various language functions such as syntactic processing (Wilson et al, 2011), phonological encoding in speech production (Schwartz et al, 2012;Han et al, 2014), and verbal working memory (Meyer et al, 2014). The present study further confirms that this tract causally contributes to tool use and, more critically, identifies the exact GM regions being connected by this pathway that contribute to tool use.…”

“…Tool conceptual processing ability was assessed by jointly considering performance on three tasks: oral picture naming, picture-associative matching, and word-associative matching. These tasks involve the conceptual component of the tool network but vary in the modalities of input (verbal and nonverbal stimuli) and output (naming and button press) (see similar approach in Jefferies et al, 2008;Schwartz et al, 2012;Wei et al, 2012;Han et al, 2013a). We used the composite score across these three tasks as the tool conceptual score.…”

Top-Down Processing of Symbolic Meanings Modulates the Visual Word Form Area

“…To rule out this alternative interpretation, we trained the participants in this study to use objects to denote actions across modalities. The cross-modality associative learning clearly demonstrates that the prediction signals must derive from higher-order cortical regions beyond either visual or motor cortex, which may be involved in processing abstract concepts in the middle temporal or frontal cortex (Binder et al, 2009;Wei et al, 2012).…”

Tool Selectivity in Left Occipitotemporal Cortex Develops without Vision

“…The resting state scan lasted 6 min and 40 sec for the congenitally blind group and 8 min for the sighted group (data from Wei et al, 2012).…”