An Empirical Study Of The Neural Mechanism Of Conceptual Metaphor

There is a growing awareness that evidences supporting the validity of linguistic theories,including cognitive linguistic theories,should have recourse to theoretical sources as well as empirical discoveries,e.g.,the results of cognitive or neural experiments.Therefore,this dissertation is mainly an empirical study of the neural basis of the primary conceptual metaphor—DESIRE IS HUNGER.Neuroanatomy states clearly that the afferent division of the human peripheral nervous system primarily receives signals from the visceral sensory receptors and somatic/special sensory receptors and then transmits these signals to the central nervous system.The two sorts of signals form different types of concrete concepts in our brain,which are referred to as “sensory concepts” and “visceral concepts”respectively in this dissertation.The “visceral concepts”,such as HUNGER/THIRST,are generated by the interaction between the visceral stimuli and the corresponding receptors.The visceral stimuli are uncontrollable and beyond our consciousness.On the contrary,the “sensory concepts”,such as GREEN/HOT,come from the interaction between the sensory stimuli and the corresponding receptors.The sensory stimuli are controllable and within our consciousness.In the past,most neuroscientific studies of conceptual metaphors focus on those with the “sensory concepts” as their source domains,for example,COLOR,SPACE,physical motion and action,and WARMTH,etc.Very few studies pay attention to the conceptual metaphors with the “visceral concepts” as their source domains.The present research,by taking the primary metaphor DESIRE IS HUNGER as a specific case,makes efforts to contribute to the already existent converging evidence supporting the conceptual metaphor theory.The main task of this dissertation is centered on the investigation of the following three questions:Q1: In the neural theory of conceptual metaphor,it is presupposed that the same neural mechanism which is responsible for perception,movement,and objectmanipulation(relating to the source domain in CMT)is also responsible for conceptualization and reasoning(relating to the target domain in CMT).Our question is: Does the operation of the neural mechanisms of different concrete concepts recruit the whole range of human peripheral nervous system which includes both somatic nervous system and autonomic nervous system?Q2: Can the concept HUNGER(which is related to the visceral stimuli)be used to understand the relevant abstract concept DESIRE in the same way the concept SEEING(which is related to the sensory stimuli)has been demonstrated to be used to understand the relevant abstract concept UNDERSTANDING?Q3: Which brain areas will be activated by the concept HUNGER and DESIRE respectively? What are the neural connections between these two concepts? That is to say,how do we understand the primary metaphor DESIRE IS HUNGER at the neural level?To answer these questions,the current study proposes a neural model of the primary metaphor DESIRE IS HUNGER on the basis of the physiological and neural features of hunger sensation,and conducts an fMRI study of the concept DESIRE and HUNGER respectively.The findings of the present empirical study are as follows:(1)The neural mechanisms of certain concrete concepts such as HUNGER,which involve the autonomic nervous system,are responsible for understanding and reasoning about the relevant abstract concepts such as DESIRE.(2)The previous cognitive linguistic and neuroscientific studies have shown that concrete concepts derived from the sensory stimuli are used to understand the relevant abstract concepts,e.g.,the primary conceptual metaphor UNDERSTANDING IS SEEING does have an empirical grounding.The present empirical study resonates with the previous ones in that it uncovers the neural fact that the concrete concepts arising from the visceral stimuli can also be used tounderstand the relevant abstract concepts,e.g.,the primary conceptual metaphor DESIRE IS HUNGER also has an empirical grounding.(3)The results of the present fMRI study reveal that the neural correlates of hunger-related mechanisms include the left and right supplementary motor areas,right superior cerebellum,right fusiform gyrus,left inferior orbitofrontal cortex,left and right middle occipital gyri,right cuneus,left precentral gyrus,and right lingual gyrus,while the general desire activates such brain regions as the left superior medial frontal gyrus,left superior dorsolateral frontal gyrus,left gyrus rectus,right medial orbitofrontal cortex(right mOFC),left anterior cingulate gyrus,and left and right median cingulate gyri.Among the different brain areas being activated by the concepts of HUNGER and DESIRE respectively,the OFC—an essential part of the central reward network—is activated by both concepts.This finding is consistent with what we propose in the neural model of DESIRE IS HUNGER.Therefore,we come to a conclusion that the OFC is the functional neural circuitry involved in the understanding of the primary metaphor DESIRE IS HUNGER,which means that the visceral concept HUNGER can be used to understand the relevant abstract concept DESIRE.The findings of the present empirical study of the primary metaphor DESIRE IS HUNGER demonstrate that the conceptual metaphor theory is not a kind of theoretical hypothesis,but essentially represents the thinking mode of our thought.Furthermore,it has empirical and neural foundations.This study provides convincing evidences for the validity of the neural theory of conceptual metaphor.What's more,the methodological innovation of the present study can have some implications for the future empirical study of conceptual metaphor theory.