Contrast and Strength of Visual Memory and Imagery Differentially Affect Visual Perception

Visual short-term memory (VSTM) and visual imagery have been shown to modulate visual perception. However, how the subjective experience of VSTM/imagery and its contrast modulate this process has not been investigated. We addressed this issue by asking participants to detect brief masked targets while they were engaged either in VSTM or visual imagery. Subjective experience of memory/imagery (strength scale), and the visual contrast of the memory/mental image (contrast scale) were assessed on a trial-by-trial basis. For both VSTM and imagery, contrast of the memory/mental image was positively associated with reporting target presence. Consequently, at the sensory level, both VSTM and imagery facilitated visual perception. However, subjective strength of VSTM was positively associated with visual detection whereas the opposite pattern was found for imagery. Thus the relationship between subjective strength of memory/imagery and visual detection are qualitatively different for VSTM and visual imagery, although their impact at the sensory level appears similar. Our results furthermore demonstrate that imagery and VSTM are partly dissociable processes.     

Interoceptive Focus Shapes the Experience of Time

The perception of time is a fundamental part of human experience. Recent research suggests that the experience of time emerges from emotional and interoceptive (bodily) states as processed in the insular cortex. Whether there is an interaction between the conscious awareness of interoceptive states and time distortions induced by emotions has rarely been investigated so far. We aimed to address this question by the use of a retrospective time estimation task comparing two groups of participants. One group had a focus on interoceptive states and one had a focus on exteroceptive information while watching film clips depicting fear, amusement and neutral content. Main results were that attention to interoceptive processes significantly affected subjective time experience. Fear was accompanied with subjective time dilation that was more pronounced in the group with interoceptive focus, while amusement led to a quicker passage of time which was also increased by interoceptive focus. We conclude that retrospective temporal distortions are directly influenced by attention to bodily responses. These effects might crucially interact with arousal levels. Sympathetic nervous system activation affecting memory build-up might be the decisive factor influencing retrospective time judgments. Our data substantially extend former research findings underscoring the relevance of interoception for the effects of emotional states on subjective time experience.     

Continuous Theta Burst Stimulation of Angular Gyrus Reduces Subjective Recollection

The contribution of lateral parietal regions such as the angular gyrus to human episodic memory has been the subject of much debate following widespread observations of left parietal activity in healthy volunteers during functional neuroimaging studies of memory retrieval. Patients with lateral parietal lesions are not amnesic, but recent evidence indicates that their memory abilities may not be entirely preserved. Whereas recollection appears intact when objective measures such as source accuracy are used, patients often exhibit reduced subjective confidence in their accurate recollections. When asked to recall autobiographical memories, they may produce spontaneous narratives that lack richness and specificity, but can remember specific details when prompted. Two distinct theoretical accounts have been proposed to explain these results: that the patients have a deficit in the bottom-up capturing of attention by retrieval output, or that they have an impairment in the subjective experience of recollection. The present study aimed to differentiate between these accounts using continuous theta burst stimulation (cTBS) in healthy participants to disrupt function of specific left parietal subregions, including angular gyrus. Inconsistent with predictions of the attentional theory, angular gyrus cTBS did not result in greater impairment of free recall than cued recall. Supporting predictions of the subjective recollection account, temporary disruption of angular gyrus was associated with highly accurate source recollection accuracy but a selective reduction in participants’ rated source confidence. The findings are consistent with a role for angular gyrus in the integration of memory features into a conscious representation that enables the subjective experience of remembering.     

The hippocampus supports both the recollection and the familiarity components of recognition memory

The receiver operating characteristic (ROC) has been used to investigate the component processes of recognition memory. Some studies with this technique have been taken to indicate that the hippocampus selectively supports the process of recollection, whereas adjacent cortex in the parahippocampal gyrus supports the process of familiarity. We analyzed ROC data from young adults, memory-impaired patients with limited hippocampal lesions, and age-matched controls. The shape of the ROC changed in similar ways from asymmetric to symmetric, as a function of the strength of memory (strong to weak) in both the young adults and the patients. Moreover, once overall memory strength was similar, the shape of the patient ROC was asymmetric and matched the control ROC. These results suggest that the component processes that determine the shape of the ROC are operative in the absence of the hippocampus, and they argue against the idea that the hippocampus selectively supports the recollection process.     

Quantum formalism to describe binocular rivalry

On the basis of the general character and operation of the process of perception, a formalism is sought to mathematically describe the subjective or abstract/mental process of perception. It is shown that the formalism of orthodox quantum theory of measurement, where the observer plays a key role, is a broader mathematical foundation which can be adopted to describe the dynamics of the subjective experience. The mathematical formalism describes the psychophysical dynamics of the subjective or cognitive experience as communicated to us by the subject. Subsequently, the formalism is used to describe simple perception processes and, in particular, to describe the probability distribution of dominance duration obtained from the testimony of subjects experiencing binocular rivalry. Using this theory and parameters based on known values of neuronal oscillation frequencies and firing rates, the calculated probability distribution of dominance duration of rival states in binocular rivalry under various conditions is found to be in good agreement with available experimental data. This theory naturally explains an observed marked increase in dominance duration in binocular rivalry upon periodic interruption of stimulus and yields testable predictions for the distribution of perceptual alteration in time.     

Attention modulates spinal cord responses to pain

Reduced pain perception while being distracted from pain is an everyday example of how cognitive processes can interfere with pain perception. Previous neuroimaging studies showed distraction-related modulations of pain-driven activations in various cortical and subcortical brain regions, but the precise neuronal mechanism underlying this phenomenon is unclear. Using high-resolution functional magnetic resonance imaging of the human cervical spinal cord in combination with thermal pain stimulation and a well-established working memory task, we demonstrate that this phenomenon relies on an inhibition of incoming pain signals in the spinal cord. Neuronal responses to painful stimulation in the dorsal horn of the corresponding spinal segment were significantly reduced under high working memory load compared to low working memory load. At the individual level, reductions of neuronal responses in the spinal cord predicted behavioral pain reductions. In a subsequent behavioral experiment, using the opioid antagonist naloxone in a double-blind crossover design with the same paradigm, we demonstrate a substantial contribution of endogenous opioids to this mechanism. Taken together, our results show that the reduced pain experience during mental distraction is related to a spinal process and involves opioid neurotransmission.     

The functional impact of mental imagery on conscious perception

Mental imagery has been proposed to contribute to a variety of high-level cognitive functions, including memory encoding and retrieval, navigation, spatial planning, and even social communication and language comprehension. However, it is debated whether mental imagery relies on the same sensory representations as perception, and if so, what functional consequences such an overlap might have on perception itself. We report novel evidence that single instances of imagery can have a pronounced facilitatory influence on subsequent conscious perception. Either seeing or imagining a specific pattern could strongly bias which of two competing stimuli reach awareness during binocular rivalry. Effects of imagery and perception were location and orientation specific, accumulated in strength over time, and survived an intervening visual task lasting several seconds prior to presentation of the rivalry display. Interestingly, effects of imagery differed from those of feature-based attention. The results demonstrate that imagery, in the absence of any incoming visual signals, leads to the formation of a short-term sensory trace that can bias future perception, suggesting a means by which high-level processes that support imagination and memory retrieval may shape low-level sensory representations.     

Speech perception at the interface of neurobiology and linguistics

Speech perception consists of a set of computations that take continuously varying acoustic waveforms as input and generate discrete representations that make contact with the lexical representations stored in long-term memory as output. Because the perceptual objects that are recognized by the speech perception enter into subsequent linguistic computation, the format that is used for lexical representation and processing fundamentally constrains the speech perceptual processes. Consequently, theories of speech perception must, at some level, be tightly linked to theories of lexical representation. Minimally, speech perception must yield representations that smoothly and rapidly interface with stored lexical items. Adopting the perspective of Marr, we argue and provide neurobiological and psychophysical evidence for the following research programme. First, at the implementational level, speech perception is a multi-time resolution process, with perceptual analyses occurring concurrently on at least two time scales (approx. 20-80 ms, approx. 150-300 ms), commensurate with (sub)segmental and syllabic analyses, respectively. Second, at the algorithmic level, we suggest that perception proceeds on the basis of internal forward models, or uses an 'analysis-by-synthesis' approach. Third, at the computational level (in the sense of Marr), the theory of lexical representation that we adopt is principally informed by phonological research and assumes that words are represented in the mental lexicon in terms of sequences of discrete segments composed of distinctive features. One important goal of the research programme is to develop linking hypotheses between putative neurobiological primitives (e.g. temporal primitives) and those primitives derived from linguistic inquiry, to arrive ultimately at a biologically sensible and theoretically satisfying model of representation and computation in speech.     

"What-Where-Which" Episodic Retrieval Requires Conscious Recollection and Is Promoted by Semantic Knowledge

Episodic memory is defined as the conscious retrieval of specific past events. Whether accurate episodic retrieval requires a recollective experience or if a feeling of knowing is sufficient remains unresolved. We recently devised an ecological approach to investigate the controlled cued-retrieval of episodes composed of unnamable odors (What) located spatially (Where) within a visual context (Which context). By combining the Remember/Know procedure with our laboratory-ecological approach in an original way, the present study demonstrated that the accurate odor-evoked retrieval of complex and multimodal episodes overwhelmingly required conscious recollection. A feeling of knowing, even when associated with a high level of confidence, was not sufficient to generate accurate episodic retrieval. Interestingly, we demonstrated that the recollection of accurate episodic memories was promoted by odor retrieval-cue familiarity and describability. In conclusion, our study suggested that semantic knowledge about retrieval-cues increased the recollection which is the state of awareness required for the accurate retrieval of complex episodic memories.     

Components of episodic memory: the contribution of recollection and familiarity

The examination of recognition memory confidence judgements indicates that there are two separate components or processes underlying episodic memory. A model that accounts for these results is described in which a recollection process and a familiarity process are assumed to contribute to recognition memory performance. Recollection is assumed to reflect a threshold process whereby qualitative information about the study event is retrieved, whereas familiarity reflects a classical signal-detection process whereby items exceeding a familiarity response criterion are accepted as having been studied. Evidence from cognitive, neuropsychological and neuroimaging studies indicate that the model is in agreement with the existing recognition results, and indicate that recollection and familiarity are behaviourally, neurally and phenomenologically distinct memory retrieval processes.     

Cultural symbolism of fish and the psychotropic properties of omega-3 fatty acids

Fish is a food with unique psychotropic properties. Consumption of long-chain omega-3 fatty acids, rich in seafood, reduces depression, aggression and anger while improving mental well-being. We posit that symbols of fish have become linked to the emotional states induced by long-chain fatty acid by associative pairings, both conscious and unconscious. The limbic and hippocampal activity necessary for memory formation containing emotional content and the labeling of social context by cortical processes appears to be optimized by diets rich in long-chain omega-3 fatty acid. In this critical literature survey, we find that fish have been culturally labeled as symbols of emotional well-being and social healing in religious and medical practices among independent cultures, for at least six millennia. This understanding of the perception of fish as a symbolically healing or purifying food can assist current messages improving public health.     

Recognition memory: can you teach an old dogma new tricks?

Familiarity and recollection are components of recognition memory. Whether these underlie two separate processes or a single process differing only in memory strength is a matter of continued debate. In this issue of Neuron, Haskins et al. provide further evidence in support of a dual-process perspective, whereas Shrager et al. provide evidence supporting a single-process viewpoint.     

An integrative and functional framework for the study of animal emotion and mood

A better understanding of animal emotion is an important goal in disciplines ranging from neuroscience to animal welfare science. The conscious experience of emotion cannot be assessed directly, but neural, behavioural and physiological indicators of emotion can be measured. Researchers have used these measures to characterize how animals respond to situations assumed to induce discrete emotional states (e.g. fear). While advancing our understanding of specific emotions, this discrete emotion approach lacks an overarching framework that can incorporate and integrate the wide range of possible emotional states. Dimensional approaches that conceptualize emotions in terms of universal core affective characteristics (e.g. valence (positivity versus negativity) and arousal) can provide such a framework. Here, we bring together discrete and dimensional approaches to: (i) offer a structure for integrating different discrete emotions that provides a functional perspective on the adaptive value of emotional states, (ii) suggest how long-term mood states arise from short-term discrete emotions, how they also influence these discrete emotions through a bi-directional relationship and how they may function to guide decision-making, and (iii) generate novel hypothesis-driven measures of animal emotion and mood.     

Intra- and inter-item associations doubly dissociate the electrophysiological correlates of familiarity and recollection

Single-process models of recognition memory posit that recognizing is based on a unidimensional value of global memory strength. By contrast, dual-process models propose the existence of two independent processes subserving the explicit recognition of previously encountered episodes, namely "familiarity" and "recollection." Familiarity represents a noncontextual form of recognition that may only support the retrieval of associative information when the to-be-associated information can be unitized, such as when two photographs depicting the same person are memorized (intra-item associations). Conversely, recollection enables retrieving associations between arbitrarily linked information, such as associations between photographs of different persons (inter-item associations). By measuring event-related brain potentials (ERPs), we obtained a double dissociation of familiarity and recollection that strongly favors dual-process accounts of recognition memory: the electrophysiological correlate of familiarity was significantly larger for intra- than for inter-item associations. Conversely, the electrophysiological correlate of recollection was significantly larger for inter- than for intra-item associations.     

The cognitive neuroscience of memory: perspectives from neuroimaging research.

Cognitive neuroscience approaches to memory attempt to elucidate the brain processes and systems that are involved in different forms of memory and learning. This paper examines recent research from brain-damaged patients and neuroimaging studies that bears on the distinction between explicit and implicit forms of memory. Explicit memory refers to conscious recollection of previous experiences, whereas implicit memory refers to the non-conscious effects of past experiences on subsequent performance and behaviour. Converging evidence suggests that an implicit form of memory known as priming is associated with changes in posterior cortical regions that are involved in perceptual processing; some of the same regions may contribute to explicit memory. The hippocampal formation and prefrontal cortex also play important roles in explicit memory. Evidence is presented from recent PET scanning studies that suggests that frontal regions are associated with intentional strategic efforts to retrieve recent experiences, whereas the hippocampal formation is associated with some aspect of the actual recollection of an event.     

Time Slices: What Is the Duration of a Percept?

We experience the world as a seamless stream of percepts. However, intriguing illusions and recent experiments suggest that the world is not continuously translated into conscious perception. Instead, perception seems to operate in a discrete manner, just like movies appear continuous although they consist of discrete images. To explain how the temporal resolution of human vision can be fast compared to sluggish conscious perception, we propose a novel conceptual framework in which features of objects, such as their color, are quasi-continuously and unconsciously analyzed with high temporal resolution. Like other features, temporal features, such as duration, are coded as quantitative labels. When unconscious processing is “completed,” all features are simultaneously rendered conscious at discrete moments in time, sometimes even hundreds of milliseconds after stimuli were presented.     

Remembering: functional organization of the declarative memory system

How do brain systems support our subjective experience of recollection and our senses of familiarity and novelty? A new functional imaging study concludes that each of these functions is accomplished by a distinct component of the medial temporal lobe, shedding new light on the functional organization of this memory system.     

社会认知神经科学的取向与研究进展

社会认知神经科学是社会心理学和认知神经科学相结合的新兴多学科研究领域,其强调在社会、认知与脑神经等三个层面的交互作用上去理解心理现象。前几年主要是对刻板印象、态度与态度改变、他人知觉、自我认知以及情绪与认知交互作用等方面进行了深入研究,其主要范式是应用认知神经科学的方法来验证社会心理学在这些范围内上的各种不同的理论观点,当前的研究主要集中在知觉和再认的社会标记、社会判断和归因、评价调节知觉和经验以及社会交互作用等传统的社会心理学方面,并取得了突破性进展。展望未来的研究,其将在系统准则研究发展的基础上,把当今的社会认知研究与认知神经科学在理论和方法论上整合起来,为揭示人类高级社会心理现象的神经基础,开辟一条崭新的研究道路。     

A small frog that makes a big difference: brain wave testing of TV advertisements

It is important for the marketing industry to better understand the role of the unconscious and emotions in advertising communication and shopping behavior. Yet, traditional consumer research is not enough for such a purpose. Conventional paper-and-pencil or verbal declarations favor conscious pragmatism and functionality as the principles underlying consumer decisions and motives. These approaches should be combined with an emerging discipline (consumer neuroscience or neuromarketing) to examine the brain and its functioning in the context of consumer choices. It has been widely acknowledged that patterns of brain activity are closely related to consumers cognition and behavior. Thus, the analysis of consumers neurophysiology may increase the understanding of how consumers process incoming information and how they use their memory and react emotionally (See "Three Types of Brain Wave Research on TV Advertisements"): Moreover, as the majority of consumer mental processes occur below the level of conscious awareness, observations of the brain reactions enable researchers to reach the very core (which is consciously inaccessible) foundations of consumer decisions, emotions, motivations, and preferences.     

Higher-order awareness, misrepresentation and function

Conscious mental states are states we are in some way aware of. I compare higher-order theories of consciousness, which explain consciousness by appeal to such higher-order awareness (HOA), and first-order theories, which do not, and I argue that higher-order theories have substantial explanatory advantages. The higher-order nature of our awareness of our conscious states suggests an analogy with the metacognition that figures?in the regulation of psychological processes and behaviour. I argue that, although both consciousness and metacognition involve higher-order psychological states, they have little more in common. One thing they do share is the possibility of misrepresentation; just as metacognitive processing can misrepresent one's cognitive states and abilities, so the HOA in virtue of which one's mental states are conscious can, and sometimes does, misdescribe those states. A striking difference between the two, however, has to do with utility for psychological processing. Metacognition has considerable benefit for psychological processing; in contrast, it is unlikely that there is much, if any, utility to mental states' being conscious over and above the utility those states have when they are not conscious.