综述: 人脑视觉意识的神经机制

意识的存在决定了人类生命的意义.意识问题被认为是21世纪科学要回答的一个最重要问题.意识科学正在成为认知和心理科学的皇冠,成为基础科学的顶峰.近20年来,随着认知科学、心理科学、神经科学和脑成像技术的发展,人们开始通过实验科学地研究意识问题,特别是与视觉意识相关的研究工作取得了很多重要进展.在这篇综述中,我们对以往的视觉意识研究工作进行了总结,并对未来的研究方向进行了展望.     

Direct and feedback temporary connections between unfamiliar visual stimuli]

Recording of averaged evoked potentials to two successive visual stimuli shows that associations, temporary connections, direct and feedback, can be elaborated in man between two unrecognized stimuli. The magnitude of cortical late response to the first stimulus in the complex diminishes as a result of action of the inhibitory feedback temporary connection. This inhibitory effect is more pronounced when the second stimulus is emotionally significant for the subject. The evoked potential to the second stimulus in the association between unrecognized visual stimuli is considerably facilitated. The role is discussed of direct and feedback temporary connections between unrecognized stimuli in some unconscious psychic phenomena in man.     

The Marriage of Psychoanalytic Methodology with the Biosemiotic Agenda

An overview of core phenomena and processes leading to Freud’s establishing his psycho-analytic method and early metatheoretical concepts is followed by the author’s revision of his topographical model into a seamless biosemiotic theory of mind and human communication. A careful methodological analysis of the semantic/referential scope; speech/listening processes, and semiotic features, of a dialogue designed to make the unconscious conscious, reveals an epistemological bridge between psychoanalytic methodology and the biosemiotic agenda within a unifying inter-penetrative paradigm.     

Brain mechanisms of the semantic analysis of words-homonyms

The brain mechanisms of semantic comprehension of a word were comparatively studied in three experimental conditions: simple perception of the nuclear value of a word-homonym determined by the preceding context, perception of its circumferential value, and during active semantic analysis of these values. It was shown that the amplitude of the evoked potential component P200 was correlated with complexity of the semantic analysis. A decrease in this amplitude under conditions of complication of semantic problem was associated with an increase in the activities of the caudate nucleus and hippocampus and a parallel slight decrease in the activity of cortical areas.     

Ethnographic surreality,possession and the unconscious

In the Second Manifesto of Surrealism, issued by André Breton in 1929, surrealism was described as “a total recuperation of our psychic strength by a means of none other than vertiginous descent into ourselves, systematic illumination of the hidden places and progressive darkening of the other places, a perpetual walk in the forbidden zone”. Surrealism sought to represent the unconscious and forbidden zones of the psyche, of the body, of the noumenal world within, which offered access, for surrealists, to energies and intuitions repressed by “civilized” modes of perception. For Jean Rouch, the significance of surrealism, of automatic writing and ciné‐transe, rested in the potential escape they offered from the formal constraints of conventional film and of conventional perception and observation. In his celebration of ciné‐transe, and of the technological apparatus that makes it possible, it is possible to detect his desire for a freeing‐up of the constraints of consciousness—a desire to “write with the body”, to dream, to tap the unexplored power of the unconscious in its overturning of “reality”, of system, and of convention. As a phaneroscopic “wide‐angle lens”, surreality aimed to document the scientifically unexplainable, the immense experiential overload of ritual possession. It attempted to make visible, in the movement between observation and participation and across disjunctive points of view; the crossings‐over into the unconscious world by which possessed Songhay dancers gained access to powers of phaneroscopic perception. By adopting filmic techniques which follow the surrealist practice of creating “verbal and visual collage”, in which randomly‐generated images, emerging out of a trance‐like state (of “automatic writing” or "ciné‐transe"), are juxtaposed in indeterminate and polyphonic relations with each other in an attempt to disturb or destroy patterns of perception which are confining, rationalistic, linear, or restricted to conscious phenomena, Rouch believed he could create powerful representations of the unknowable. This paper relates the phaneroscopic practice of ethnographic surrealism to psychoanalytic models of the unconscious. In a discussion of Rouch's interpretation of the Hauka spirit cult in his film Les Maîtres Fous, the paper argues that the neo‐Freudian paradigm which allowed him to depict the Sohghay's weekend Hauka rites as a parodic reversion to “savagery” (which both reversed the hierarchy of colonizer/colonized and enabled participants to experience a therapeutic release from the traumas of colonization) has been challenged by Lacanian and post‐Lacanian “re‐readings” of Freud that call into question the extent to which the unconscious can be equated with a pre‐linguistic state characterized by disjunctive “primitive” and “instinctive” energies. The surrealist longing for a rupture of the symbolic order of Western rationalism and a return to the “imaginary order” of the unconscious is confounded in the Lacanian conception of the unconscious as a zone inhabited by the “discourse of the Other”. However, the work of Gillès Deleuze and Félix Guanari [1977] provides a means of conceptualizing the unconscious in terms that avoid simplistic binary logic (phenomenon/noumenon; signifier/signified; subject/object; conscious/unconscious; civilization/savagery). The unconscious is not the “unrepresentable” Other of consciousness; it is a schizophrenic phaneron, a signifying “machine”, a transgressive producer of “group fantasy”. Rejecting both Freud's Oedipal model (the unconscious as primal imagery or “ghostly signifieds"), and the Lacanian notion of the unconscious (as a play of “empty signifiers"). Deleuze and Guattari argue that the unconscious cannot be accounted for in terms of the individual child and its entry into language any more than it can be conceived of as the domain of the primitive. On the contrary, the unconscious is constituted as “group fantasy”, as collective public memory which need not be reduced to elemental (Oedipal) signifiers: “all delirium possesses a world‐historical, political and racial content”. The schizophrenic embodies the public nature of unconscious meaning, since schizophrenia is primarily a communication disorder in which an individual never sees himself in terms of a linguistically‐generated “selfhood”, and fails to adopt the “false” identity which is offered to him in the language of the Other. Schizophrenia is characterized by a refusal to treat some meanings as superior to others, to remain within the bounds of a stable identity, or to distinguish between material (noumenal) things and actions and their (phenomenal) meanings. The schizophrenic unconscious treats all experience as signs, registering language in the same way as the body registers physical stimuli. Thus “meanings in the unconscious are simply meanings as workings of the body” [Harland 1987:174–175]. The schizophrenic as a model for the unconscious holds several implications for those interested in representing the experiential power of public rituals, for the public meanings in circulation during such rituals are material and noumenal, and are registered on the bodies of the dancers as they transgress boundaries and pass beyond consciousness. Rouch's surreality attempted to inscribe this unconscious production of public meaning as it was manifested in the movements of the ritual and in the movements of the camera‐body.     

Clinical Physiological Significance of Intraoperative Evoked Potential Monitoring

Modern approaches to intraoperative evoked potential (EP) monitoring in cerebral and spinal cord pathology are reviewed. The criteria of physiological permissibility of neurosurgery based on EP data and the possibilities of studying the neurophysiological mechanisms of somatosensory, auditory, and visual perception in unconscious patients are discussed.     

Individual differences in trait anxiety predict the response of the basolateral amygdala to unconsciously processed fearful faces

Responses to threat-related stimuli are influenced by conscious and unconscious processes, but the neural systems underlying these processes and their relationship to anxiety have not been clearly delineated. Using fMRI, we investigated the neural responses associated with the conscious and unconscious (backwardly masked) perception of fearful faces in healthy volunteers who varied in threat sensitivity (Spielberger trait anxiety scale). Unconscious processing modulated activity only in the basolateral subregion of the amygdala, while conscious processing modulated activity only in the dorsal amygdala (containing the central nucleus). Whereas activation of the dorsal amygdala by conscious stimuli was consistent across subjects and independent of trait anxiety, activity in the basolateral amygdala to unconscious stimuli, and subjects' reaction times, were predicted by individual differences in trait anxiety. These findings provide a biological basis for the unconscious emotional vigilance characteristic of anxiety and a means for investigating the mechanisms and efficacy of treatments for anxiety.     

The scope and limits of top-down attention in unconscious visual processing

Attentional selection plays a critical role in conscious perception. When attention is diverted, even salient stimuli fail to reach visual awareness. Attention can be voluntarily directed to a spatial location or a visual feature for facilitating the processing of information relevant to current goals. In everyday situations, attention and awareness are tightly coupled. This has led some to suggest that attention and awareness might be based on a common neural foundation, whereas others argue that they are mediated by distinct mechanisms. A body of evidence shows that visual stimuli can be processed at multiple stages of the visual-processing streams without evoking visual awareness. To illuminate the relationship between visual attention and conscious perception, we investigated whether top-down attention can target and modulate the neural representations of unconsciously processed visual stimuli. Our experiments show that spatial attention can target only consciously perceived stimuli, whereas feature-based attention can modulate the processing of invisible stimuli. The attentional modulation of unconscious signals implies that attention and awareness can be dissociated, challenging a simplistic view of the boundary between conscious and unconscious visual processing.     

The significance of unrecognized feedback stimuli in cognitive activity

In adult emotionally excitable persons the role was studied of unrecognized reinforcement forms in the function of differentiation of time microintervals. As feedback stimuli the word "good" (positive reinforcement) and a word connected with negative emotions of the subject (negative reinforcement) were applied. Experimental confirmation was obtained of the hypothesis that unrecognized phenomena of environment can influence conscious psychic activity, the process of man learning. Unrecognized semantic stimuli can function as a reinforcing factor and in this way participate in the process of learning of cognitive activity realized at conscious level.     

Breakthrough to awareness: a preliminary neural network model of conscious and unconscious perception in word processing

 A neural network model is constructed to mimic the processing involved in semantic and working memory when subliminal effects are involved. These effects involve modifications of reaction time to later inputs, according to whether or not there has been conscious or unconscious processing of the earlier input. The model is constructed of two separate modules: one (a semantic memory module) allowing for processing at a semantic, but unconscious, level, and the other (a working memory module) for conscious experience. The latter module, although a replica of the earlier one, has different lateral connectivity and output function from the former. The model is shown to give a good fit to Marcel’s data on the processing of polysemous words. Further tests are suggested for the model, and a possible cortical implementation suggested. The relevance of the model to recent approaches to consciousness is also explored. Received: 7 February 1995/Accepted in revised form: 14 November 1995     

BEHAVIORAL CHARACTERISTICS OF DANGEROUS DRIVERS—Importance of Correction

Studies of accident-prone drivers emphasize the frequency of unstable, aggressive or antisocial personalities expressing themselves through the automobile as a real and a symbolic weapon. Such expressions may be voluntary or unconscious and may also lead a driver to injure himself or seek injury from others.Because of the great public danger from such drivers, it is urgent that judges and enforcers of the law recognize the psychic motivation in habitual violation and withhold driving privileges from violators until a psychic adjustment has been made. Physicians can contribute in gaining acceptance for this attitude of enforcement, and in setting up adequate psychiatric procedures for correction of violators.     

Computational models of spatial updating in peri-saccadic perception

Perceptual phenomena that occur around the time of a saccade, such as peri-saccadic mislocalization or saccadic suppression of displacement, have often been linked to mechanisms of spatial stability. These phenomena are usually regarded as errors in processes of trans-saccadic spatial transformations and they provide important tools to study these processes. However, a true understanding of the underlying brain processes that participate in the preparation for a saccade and in the transfer of information across it requires a closer, more quantitative approach that links different perceptual phenomena with each other and with the functional requirements of ensuring spatial stability. We review a number of computational models of peri-saccadic spatial perception that provide steps in that direction. Although most models are concerned with only specific phenomena, some generalization and interconnection between them can be obtained from a comparison. Our analysis shows how different perceptual effects can coherently be brought together and linked back to neuronal mechanisms on the way to explaining vision across saccades.     

Conditioned switching-over and cognitive set

The importance of Asratyan's conditioned switching-over phenomenon as an experimental model for investigation of the control function of the inner states (sets) in behavior is discussed. It is argued that experimental investigation of the animal conditioned switching-over phenomenon at the novel cognitive stage of exploration of neural mechanisms of behavior using the modern conceptual models of brain operation and conceptual apparatus can be a promising approach to understanding of the physiological basis of human unconscious cognitive sets and their role in perception of external signals and organization of voluntary behavior.     

Estimation of the involvement of subconsciousness in heartbeat perception in healthy volunteers

The results of analysis of heartbeat parameters and characteristics of its self-monitoring by 25 healthy volunteers have been used as the basis for original estimation of the involvement of subconsciousness in heartbeat perception. The first objective index for such estimation is proposed. It is calculated as the individual fragmentation coefficient of heartbeat perception. The discreteness of heartbeat perception is related to changes in the degree (weight) of involvement of subconsciousness in the perception of cardiac signals. A conclusion is drawn on the relationship between the efficiency of perception of one’s own heartbeat and the degree of involvement of subconsciousness in this process. The practical implication of the study is the possibility of using a similar approach to estimating the weight of unconscious processes in perception of stimuli of different types, including those used in psychodiagnostic studies.     

Mechanisms of the Early Phases of Plant Gravitropism

Gravitropism is directed growth of a plant or plant organ in response to gravity and can be divided into the following temporal sequence: perception, transduction, and response. This article is a review of the research on the early events of gravitropism (i.e., phenomena associated with the perception and transduction phases). The two major hypotheses for graviperception are the protoplast-pressure and starch-statolith models. While most researchers support the concept of statoliths, there are suggestions that plants have multiple mechanisms of perception. Evidence supports the hypothesis that the actin cytoskeleton is involved in graviperception/ transduction, but the details of these mechanisms remain elusive. A number of recent developments, such as increased use of the molecular genetic approach, magnetophoresis, and laser ablation, have facilitated research in graviperception and have allowed for refinement of the current models. In addition, the entire continuum of acceleration forces from hypo- to hyper-gravity have been useful in studying perception mechanisms. Future interdisciplinary molecular approaches and the availability of sophisticated laboratories on the International Space Station should help to develop new insights into mechanisms of gravitropism in plants.     

Contribution of L. Ya. Balonov and V. L. Deglin to Study of Verbal-Thinking Activity from the Viewpoint of Functional Brain Asymmetry

This paper summarized experimental data on the role of the right and left brain hemispheres in performance of the verbal and thinking activity, which were obtained by Lev Yakovlevich Balonov and Vadim L'vovich Deglin and published in numerous articles and monographs. The interpretation of these results, the concepts of Balonov and Deglin on regularities underlying division of functions between two hemispheres and on mechanisms of the hemispheric interaction are presented. The original concept is exposed, which consists in that the functional brain asymmetry is based on different relation of the right and left hemispheres to the language sign, its different vision and perception by each hemisphere. The data of study on the functional brain asymmetry also helped the authors to find answers to the questions concerning general scientific and general human problems dealing with the conscious and the unconscious, speech development in child, evolution of psychic activity. The authors understood clearly that the answers to these questions ...by no means will be exhaustive... and that ...this is merely one of possible points of view.     

Hippocampus Is Place of Interaction between Unconscious and Conscious Memories

Recent evidence suggests that humans can form and later retrieve new semantic relations unconsciously by way of hippocampus—the key structure also recruited for conscious relational (episodic) memory. If the hippocampus subserves both conscious and unconscious relational encoding/retrieval, one would expect the hippocampus to be place of unconscious-conscious interactions during memory retrieval. We tested this hypothesis in an fMRI experiment probing the interaction between the unconscious and conscious retrieval of face-associated information. For the establishment of unconscious relational memories, we presented subliminal (masked) combinations of unfamiliar faces and written occupations (“actor” or “politician”). At test, we presented the former subliminal faces, but now supraliminally, as cues for the reactivation of the unconsciously associated occupations. We hypothesized that unconscious reactivation of the associated occupation—actor or politician—would facilitate or inhibit the subsequent conscious retrieval of a celebrity’s occupation, which was also actor or politician. Depending on whether the reactivated unconscious occupation was congruent or incongruent to the celebrity’s occupation, we expected either quicker or delayed conscious retrieval process. Conscious retrieval was quicker in the congruent relative to a neutral baseline condition but not delayed in the incongruent condition. fMRI data collected during subliminal face-occupation encoding confirmed previous evidence that the hippocampus was interacting with neocortical storage sites of semantic knowledge to support relational encoding. fMRI data collected at test revealed that the facilitated conscious retrieval was paralleled by deactivations in the hippocampus and neocortical storage sites of semantic knowledge. We assume that the unconscious reactivation has pre-activated overlapping relational representations in the hippocampus reducing the neural effort for conscious retrieval. This finding supports the notion of synergistic interactions between conscious and unconscious relational memories in a common, cohesive hippocampal-neocortical memory space.     

Neurophysiological Markers of Abnormal Development in Children with Mental Disorders

Longitudinal analysis of the spectral power of the main EEG bands was performed in the wakeful state with the eyes open and the eyes closed in children with mental disorders at various stages of correction by transcranial direct current stimulation (tDCS). A significant increase in the power of α-rhythm in the parietal-occipital areas and a significant decrease in the slow wave activity in the left frontotemporal areas were observed in the course of the correction process. The data obtained can be considered as the neurophysiological markers of the tDCS effects (formation of age-related EEG parameters in children with mental disorders). The data also prove the relations between the described phenomena and the cortical mechanisms of speech disorders and other psychic processes caused by perinatal CNS disorders.     

Temporal changes in conscious and unconscious trace phenomena in six to seven-year-old children]

Development in time of unconscious trace reactions as well as a change in the time of reproduction of verbal material in natural conditions was studied by the conditioned reflex to time method on 107 school children aged from six to seven years and on 35 subjects of the same age from a kindergarten. It has been found that in schoolchildren the transfer of trace reactions to long-term storage is completed faster, and their voluntary acts in the course of conscious reproduction of an interstimuli intervals are more adequate than in the kindergarten children of the same age. The trace phenomena formed in natural conditions and in the laboratory experiment develop in time in a similar way. The change in time of conscious trace phenomena is of a more complex nature than of the unconscious phenomena. The practical significance of the data obtained is noted.