Two neural correlates of consciousness

For many years, since Baars (1988) explicitly formulated it, contrastive analysis has been the key methodological approach in experimental studies of consciousness. When certain properly chosen psychological experimental setups (allowing an invariant target stimulus either to be consciusly experienced or not) were combined with brain-imaging methods, contrastive analysis became a quite powerful tool of research (Crick, 1994; Koch, 2004). By subtracting markers of brain processes recorded in the conditions without conscious experience of the target from the markers recorded in the conditions where the same target is consciously experienced it was believed that the markers of neural correlates of consciousness (NCC) can be obtained. However, as it turned out in the subsequent theoretical and experimental analysis, the picture is not so clear and simple (Bachmann, 2000, 2009; Miller, 2007; Aru et al., 2012; de Graaf et al., 2012). For example, when in the invariant conditions of independent variables a masked visual stimulus was consciously perceived or not (consciousness of the target standed as a dependent variable), NCC which were measured as a spectral perturbation of EEG was present already before stimulus presentation (Aru and Bachmann, 2009). Thus, the neural correlate of consciousness of a stimulus was present earlier than the stimulus itself was presented. Now, a reader must not get excited here because instead of some paranormal explanations brain-science based explanations can be comfortably used. In order to overcome the conceptual crisis hitting the traditional contrastive analysis based NCC research it was suggested that unconscious prerequisite processes (NCCpr) emerging as a result of contrastive analysis of brain-process markers of consciousness and similarly unconscious consequent processes (NCCco) must be differentiated from the constitutive processes directly associated with conscious experience (Aru et al., 2012; de Graaf et al., 2012). Thus, new experimental approaches were in need to avoid the trap of distilling prerequisite, direct, and consequent processes as mutually confounded and empirically inseparable. Despite some first attempts in this direction (Aru and Bachmann, 2015), the specialist landscape in this domain has remained obscure and no breakthrough solutions have been in sight. Moreover, there seems to be a number of additional uncertainties when we try to disentangle the various sub-types of NCC. Even NCCpr and NCCco are not unitary in terms of their theoretical meaning and associated neural processes. First, as the contents on which the perceptual report is founded can be selective, the markers of unused conscious contents may be erroneously neglected as markers of unconscious processes. They actually belong to consciousness level processes, but related to contents of consciousness qualitatively different from the ones specified by NCC. Second, in measuring NCC we must be able to disentangle contributions of the general consciousness enabling mechanisms and the selective contents representing mechanisms because their markers can be different and thus confused. In what follows I will substantiate these two issues.

Purpose– This paper aims to link recent findings in cognitive neuroscience to better understand how andragogically informed instructional practices impact cognition and learning.Design/methodology/approach– The research questions guiding the study is in what ways can the recent findings in cognitive neuroscience help to inform adult education theory, including andragogy in particular, to deepen our understanding of how andragogical instructional principles and practices can improve learning? We adopted Torraco’s (2005) integrative literature review approach of providing enough details regarding the selection of the literature and the identification and verification of emerged themes of main ideas.Findings– The core assumptions of andragogy (self-direction, prior experience, readiness to learn and immediacy of application) have a connection to the neural networks related to memory and cognition.Research limitations/implications– First, this study provides fundamental foundations for combining cognitive neuroscience and adult learning to illuminate how cognitive neuroscience contributes physiologically to adult learning. Second, the findings in cognitive neuroscience related to the four assumptions for andragogy help to provide scientific explanations and interpretations for adult learning theories influencing human resource development (HRD), such as self-directed learning, experiential learning and role theory.Practical implications– First, HRD practitioners could use the integrative approach between andragogy and the cognitive neuroscience to reduce the issues of learning activities in generation differences. In addition, cognitive neuroscience research may contribute to improving teaching and instructional techniques.Originality/value– The contributions of this study is that it provides an integrative review about why and how anagogical principles work through the lens of cognitive neuroscience. Based on the findings, we suggested a model of adaptive cognitive neuroscience-adult learning structures.

Experimental and theoretical approaches aiming at the establishment of neural correlates of higher cognitive functions and awareness have been extensively studied in the past decade. Information-theoretical indices are useful tools in establishing quantitative metrics when analyzing data of cognitive experiments. In this work we report a systematic statistical analysis of multiple runs of ECoG measurements over the rabbit visual cortex. The results are interpreted invoking the concept of Pragmatic Information, which is complementary to the Shannon Entropy Index. We interpret these finding based on a dynamical system approach to brains and cognition. We identify large-scale synchronization across broad frequency band as potential manifestation of the `aha' effect, indicating the construction of knowledge and meaning from input sensory data and leading to awareness experience.

Dissociation, cognitive conflict and nonlinear patterns of heart rate dynamics in patients with unipolar depression

EDITORIAL article Front. Psychol., 01 September 2011 | https://doi.org/10.3389/fpsyg.2011.00191

An accurate reflux-symptom relationship analysis method is an unmet need in gastroesophageal reflux disease (GERD) diagnosis. The aim of this study was to adapt signal detection theory (SDT) approach to reflux-symptom relationship analysis to develop a new diagnosis method. Patients with predominant symptoms of heartburn and regurgitation were enrolled. Proton pump inhibitor (PPI)-responsive and PPI-unresponsive groups were created via interview and PPI trial. Patients then underwent stationary esophageal manometry and 24-hour multichannel intraluminal impedance-pH monitoring. SDT measurement parameters (discriminability: d' and criterion: c) were calculated using empirically selected time windows (0.5, 1, 2, 3, 4 and 5 minutes). The time window that provided the highest d' value was selected as the optimal time window. A cut-off d' value that optimally separates two groups was found using receiver operating characteristics analysis. Sixty-three patients completed the study (45 PPI responsive). Optimal time window and cut-off d' value were found as 1 and 0.767 minute, respectively. Symptom association probability (SAP) index values showed good correlation (rS = 0.7182, P < 0.0001) with d' values. SDT approach to reflux-symptom relationship analysis showed sensitivity (89% vs. 78%) and negative predictive values (75% vs. 60%) favorable over SAP index analysis. SDT approach using 1-minute time window and 0.767 cut-off d' value provides us a new and more accurate measure of reflux-symptom relationship than SAP index analysis.

The evolutionary claim that the function of self-awareness lies, at least in part, in the benefits of theory of mind (TOM) regained attention in light of current findings in cognitive neuroscience, including mirror neuron research. Although certain non-human primates most likely possess mirror self-recognition skills, we claim that they lack the introspective abilities that are crucial for human-like TOM. Primate research on TOM skills such as emotional recognition, seeing versus knowing and ignorance versus knowing are discussed. Based upon current findings in cognitive neuroscience, we provide evidence in favor of an introspection-based simulation theory account of human mindreading.

Consciousness: converging insights from connectionist modeling and neuroscience

EDITORIAL article Front. Hum. Neurosci., 01 February 2013Sec. Cognitive Neuroscience Volume 7 - 2013 | https://doi.org/10.3389/fnhum.2013.00022

A few decades ago the search for the neuronal correlates of consciousness was considered both technically intractable and philosophically questionable. Searching for a material substrate of phenomena accessible only from the first-person perspective appeared to be epistemically problematic. But the development of non-invasive imaging technologies and the availability of intracranial recordings from patients alleviated the imminent technical problems. Progress in the analysis of the connectome of the brain, and the introduction of multisite recordings from the cerebral cortex of animals led to a revision of concepts in the field of cognitive neuroscience, emphasizing principles of distributed processing in recurrent networks with non-linear dynamics, self-organization, and coding in high-dimensional-state space. These advances, together with the growing evidence for epigenetic shaping of brain functions by socio-cultural influences, pave the way for novel theories that attempt to bridge the gap between neuronal processes and subjective states.

A variety of neural signals have been measured as correlates to consciousness. In particular, late current sinks in layer 1, distributed activity across the cortex, and feedback processing have all been implicated. What are the physiological underpinnings of these signals? What computational role do they play in the brain? Why do they correlate to consciousness? This thesis begins to answer these questions by focusing on the pyramidal neuron. As the primary communicator of long-range feedforward and feedback signals in the cortex, the pyramidal neuron is set up to play an important role in establishing distributed representations. Additionally, the dendritic extent, reaching layer 1, is well situated to receive feedback inputs and contribute to current sinks in the upper layers. An investigation of pyramidal neuron physiology is therefore necessary to understand how the brain creates, and potentially uses, the neural correlates of consciousness. An important part of this thesis will be in establishing the computational role that dendritic physiology plays. In order to do this, a combined experimental and modeling approach is used. This thesis beings with single-cell experiments in layer 5 and layer 2/3 pyramidal neurons. In both cases, dendritic nonlinearities are characterized and found to be integral regulators of neural output. Particular attention is paid to calcium spikes and NMDA spikes, which both exist in the apical dendrites, considerable distances from the spike initiation zone. These experiments are then used to create detailed multicompartmental models. These models are used to test hypothesis regarding spatial distribution of membrane channels, to quantify the effects of certain experimental manipulations, and to establish the computational properties of the single cell. We find that the pyramidal neuron physiology can carry out a coincidence detection mechanism. Further abstraction of these models reveals potential mechanisms for spike time control, frequency modulation, and tuning. Finally, a set of experiments are carried out to establish the effect of long-range feedback inputs onto the pyramidal neuron. A final discussion then explores a potential way in which the physiology of pyramidal neurons can establish distributed representations, and contribute to consciousness.

Recent findings in neuroscience strongly suggest that an object's features (e.g., its color, texture, shape, etc.) are represented in separate areas of the visual cortex. Although represented in separate neuronal areas, somehow the feature representations are brought together as a single, unified object of visual consciousness. This raises a question of binding: how do neural activities in separate areas of the visual cortex function to produce a feature-unified object of visual consciousness? Several prominent neuroscientists have adopted neural synchrony and attention-based approaches to explain object feature binding. I argue that although neural synchrony and/or attentional mechanisms might function to disambiguate an object's features, it is difficult to see how either of these mechanisms could fully explain the unity of an object's features at the level of visual consciousness. After presenting a detailed critique of neural synchrony and attention-based approaches to object feature binding, I propose interactive hierarchical structuralism (IHS) . This view suggests that a unified percept (i.e., a feature-unified object of visual consciousness) is not reducible to the activity of any cognitive capacity or to any localized neural area, but emerges out of the interaction of visual information organized by spatial structuring capacities correlated with lower, higher, and intermediate levels of the visual hierarchy. After clarifying different notions of emergence and elaborating evidence for IHS, I discuss how IHS can be tested through transcranial magnetic stimulation and masking. In the final section I present some further implications/advantages of IHS.

Intrusive memories hijack consciousness and their control may lead to forgetting. However, the contribution of reflexive attention to qualifying a memory signal as interfering is unknown. We used machine learning to decode the brain's electrical activity and pinpoint the otherwise hidden emergence of intrusive memories reported during a memory suppression task. Importantly, the algorithm was trained on an independent attentional model of visual activity, mimicking either the abrupt and interfering appearance of visual scenes into conscious awareness or their deliberate exploration. Intrusion of memories into conscious awareness were decoded above chance. The decoding accuracy increased when the algorithm was trained using a model of reflexive attention. Conscious detection of intrusive activity decoded from the brain signal was central to the future silencing of suppressed memories and laterforgetting. Unwanted memories require the reflexive orienting of attention and access to consciousness to be suppressed effectively by inhibitory control.

Byrnes and Fox present a sophisticated approach to the development of useful relations between cognitive neuroscience and education. Their approach, which is similar to approaches advocated by other educational psychologists, emphasizes the importance of findings in cognitive neuroscience to the building of educationally useful models of learning. In contrast to that defensible approach is a popular but simplistic approach that tries to relate the results of individual cognitive neuroscience studies directly to the improvement of teaching. The advantages of the sophisticated approach presented by Byrnes and Fox are discussed and supported for their important roles in the development of productive relations between cognitive neuroscience and education.

Bridging the big (data) gap: levels of control in small- and large-scale cognitive neuroscience research