To study whether the distinction between introspective and non-introspective states of mind is an empirical reality or merely a conceptual distinction, we measured event-related potentials elicited in introspective and non-introspective instruction conditions while the observers were trying to detect the presence of a masked stimulus. The ERPs indicated measurable differences related to introspection in both preconscious and conscious processes. Our data support the hypothesis that introspective states empirically differ from non-introspective states.
Empirical work is reviewed which correlates the presence or absence of various parts of the auditory evoked potential with the disappearance and reemergence of auditory sensation during induction of and recovery from anesthesia. As a result, the hypothesis is generated that the electrophysiological correlate of auditory sensation is whatever neural activity generates the middle latency waves of the auditory evoked potential. This activity occurs from 20 to 80 ms poststimulus in the primary and secondary areas of the auditory cortex. Evidence (...) is presented suggesting that earlier or later waves in the auditory evoked potential do not covary with auditory sensation (as opposed to auditory perception) and it is therefore suggested that they are possibly not the electrophysiological correlates of sensation. (shrink)
This splendid volume reviews a productive period of research aimed at connecting brain and mind through the use of scalp- recorded brain potentials to chart the temporal course of information processing in the human brain.... The book that Rugg, Coles, and their collaborators have produced can serve both as a summary of where we have been and as a pointer of the way ahead." M Posner Event-related potential methodology has long been used in neuroscience to measure electrical activity in the (...) brain. It has become clear, however, that it can be a powerful took in studying and illuminating central psychological issues relating to attention, information, processing, dynamics, memory, and language. Linking this technology to newer imaging techniques such as positron emission tomography and functional magnetic resonance imaging, it becomes possible to build up a spatial and temporal picture of the brain during the performance of high-level skills. This volume provides strong evidence that cognitive psychology can benefit from the use of brain electrical activity, and will be of great interest to neuroscientists and psychologists alike. (shrink)
This paper employs a case study from the history of neuroscience—brain reward function—to scrutinize the inductive argument for the so-called ‘Heuristic Identity Theory’ (HIT). The case fails to support HIT, illustrating why other case studies previously thought to provide empirical support for HIT also fold under scrutiny. After distinguishing two different ways of understanding the types of identity claims presupposed by HIT and considering other conceptual problems, we conclude that HIT is not an alternative to the traditional identity theory so (...) much as a relabeling of previously discussed strategies for mechanistic discovery. (shrink)
David Marr's three-level method for completely understanding a cognitive system and the importance he attaches to the computational level are so familiar as to scarcely need repeating. Fewer seem to recognize that Marr defends his famous method by criticizing the “reductionistic approach.” This sets up a more interesting relationship between Marr and reductionism than is usually acknowledged. I argue that Marr was correct in his criticism of the reductionists of his time—they were only describing, not explaining. But a careful metascientific (...) account of reductionistic neuroscience over the past two decades reveals that Marr's criticisms no longer have force. Contemporary neuroscience now explains cognition directly, although in a fashion—causal-mechanistically—quite different than Marr recommended. So while Marr was correct to reject the reductionism of his day and offer an alternative method for genuinely explaining cognition, contemporary cognitive scientists now owe us a new defense of Marr's famous method and the advantages of its explanations over the type now pursued successfully in current reductionist neuroscience. There are familiar reasons for thinking that this debt will not be paid easily. (shrink)
Brain processes and social processes are not as separated as many of our Social Psychology and Neuroscience departments. This paper discusses the potential contribution of social neuroscience to the development of a multi-level, dynamic, and context-sensitive approach to prejudice. Specifically, the authors review research on event related potentials during social bias, stereotypes, and social attitudes measurements, showing that electrophysiological methods are powerful tools for analyzing the temporal fine-dynamics of psychological processes involved in implicit and explicit prejudice. Meta-theoretical implications are drawn (...) regarding the social psychological modeling of social attitudes, and for the integration of social neuroscience into a multi-level account of cultural behavior. (shrink)
The sense of being stared at is the basis of evil eye beliefs, which are regarded as superstitions because the emission of any form of energy from the human eye has been rejected by Western science. However, brainwaves in the 1–40 Hertz, 1–10 microvolt range emitted through the eye can be detected using a high-impedance electrode housed inside electromagnetically insulated goggles. This signal, which the author calls “human ocular extramission,” is physiologically active and has distinct electrophysiological properties from simultaneous brainwave (...) recordings over the forehead. Western science's rejection of evil eye beliefs may be based on an erroneous rejection of a widespread component of human consciousness, the sense of being stared at, which may in turn be based on a real electrophysiological signal. The author proposes a series of future studies designed to determine whether human ocular extramission is the basis of evil eye beliefs. (shrink)
Pain, suffering and positive emotions in patients in vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious states (MCS) pose clinical and ethical challenges. Clinically, we evaluate behavioural responses after painful stimulation and also emotionally-contingent behaviours (e.g., smiling). Using stimuli with emotional valence, neuroimaging and electrophysiology technologies can detect subclinical remnants of preserved capacities for pain which might influence decisions about treatment limitation. To date, no data exist as to how healthcare providers think about end-of-life options (e.g., withdrawal of artificial nutrition (...) and hydration) in the presence or absence of pain in non-communicative patients. Here, we aimed to better clarify this issue by re-analyzing previously published data on pain perception (Prog Brain Res 2009 177, 329–38) and end-of-life decisions (J Neurol 2010 258, 1058–65) in patients with disorders of consciousness. In a sample of 2259 European healthcare professionals we found that, for VS/UWS more respondents agreed with treatment withdrawal when they considered that VS/UWS patients did not feel pain (77%) as compared to those who thought VS/UWS did feel pain (59%). This interaction was influenced by religiosity and professional background. For MCS, end-of-life attitudes were not influenced by opinions on pain perception. Within a contemporary ethical context we discuss (1) the evolving scientific understandings of pain perception and their relationship to existing clinical and ethical guidelines; (2) the discrepancies of attitudes within (and between) healthcare providers and their consequences for treatment approaches, and (3) the implicit but complex relationship between pain perception and attitudes toward life-sustaining treatments. (shrink)
Creating focal lesions in primary visual cortex (V1) provides an opportunity to study the role of extra-geniculo-striate pathways for activating extrastriate visual cortex. Previous studies have shown that more than 95% of neurons in macaque area V2 and V3 stop firing after reversibly cooling V1 [1,2,3]. However, no studies on long term recovery in areas V2, V3 following permanent V1 lesions have been reported in the macaque. Here we use macaque fMRI to study area V2, V3 activity patterns from 1 (...) to 22 months after lesioning area V1. We find that visually driven BOLD responses persist inside the V1-lesion projection zones (LPZ) of areas V2 and V3, but are reduced in strength by ,70%, on average, compared to prelesion levels. Monitoring the LPZ activity over time starting one month following the V1 lesion did not reveal systematic changes in BOLD signal amplitude. Surprisingly, the retinotopic organization inside the LPZ of areas V2, V3 remained similar to that of the non-lesioned hemisphere, suggesting that LPZ activation in V2, V3 is not the result of input arising from nearby (non-lesioned) V1 cortex. Electrophysiology recordings of multi-unit activity corroborated the BOLD observations: visually driven multi-unit responses could be elicited inside the V2 LPZ, even when the visual stimulus was entirely contained within the scotoma induced by the V1 lesion. Restricting the stimulus to the intact visual hemi-field produced no significant BOLD modulation inside the V2, V3 LPZs. We conclude that the observed activity patterns are largely mediated by parallel, V1-bypassing, subcortical pathways that can activate areas V2 and V3 in the absence of V1 input. Such pathways may contribute to the behavioral phenomenon of blindsight. (shrink)
fMRI is a tool to study brain function noninvasively that can reliably identify sites of neural involvement for a given task. However, to what extent can fMRI signals be related to measures obtained in electrophysiology? Can the blood-oxygen-level-dependent signal be interpreted as spatially pooled spiking activity? Here we combine knowledge from neurovascular coupling, functional imaging and neurophysiology to discuss whether fMRI has succeeded in demonstrating one of the most established functional properties in the visual brain, namely directional selectivity in the (...) motion-processing region V5/ MT+. We also discuss differences of fMRI and electrophysiology in their sensitivity to distinct physiological processes. We conclude that fMRI constitutes a complement, not a poor-resolution substitute, to invasive techniques, and that it deserves interpretations that acknowledge its stand as a separate signal. (shrink)
In the history of science, the alterations of laboratorial working conditions during a defined period of time and the processes leading to substitution of one instrument by another are not well reconstructed. With respect to electrophysiology between 1845 and 1910, the present article attempts to call attention to the relationship between the use of instruments in a laboratory, the change in these instruments and the change of local environments in which the laboratory was situated.
This article examines the science of electrophysiology developed by Emil du Bois-Reymond in Berlin in the 1840s. In it I recount his major findings, the most significant being his proof of the electrical nature of nerve signals. Du Bois-Reymond also went on to detect this same ‘negative variation’, or action current, in live human subjects. In 1850 he travelled to Paris to defend this startling claim. The essay concludes with a discussion of why his demonstration failed to convince his hosts (...) at the French Academy of Sciences. (shrink)