Recognition memory performance reflects two distinct memory processes: a conscious process of recollection, which allows remembering specific details of a previous event, and familiarity, which emerges in the absence of any conscious information about the context in which the event occurred. Slow wave sleep and rapid eye movement sleep are differentially involved in the consolidation of different types of memory. The study assessed the effects of SWS and REM sleep on recollection, by means of the “remember”/”know” paradigm. Subjects studied (...) three blocks of 12 words before a 3-h retention interval filled with SWS, REM sleep or wakefulness, placed between 3 a.m. and 6 a.m. Afterwards, recognition and recollection were tested. Recollection was higher after a retention interval rich in SWS than after a retention interval rich in REM sleep or filled with wakefulness. The results suggest that SWS facilitates the process of recollection in recognition memory. (shrink)

IntroductionBrain tumours frequently cause language impairments and are also likely to co-occur with localised abnormal slow-wave brain activity. However, it is unclear whether this applies specifically to low-grade brain tumours. We investigate slow-wave activity in resting-state electroencephalography in low-grade glioma and meningioma patients, and its relation to pre- and postoperative language functioning.MethodPatients with a glioma infiltrating the language-dominant hemisphere and patients with a meningioma with mass effect on this hemisphere underwent extensive language testing before and 1 year after (...) surgery. EEG was registered preoperatively, postoperatively, and once in healthy individuals. Slow-wave activity in delta- and theta- frequency bands was evaluated visually and quantitatively by spectral power at three levels over the scalp: the whole brain, the affected hemisphere, and the affected region.ResultsGlioma patients had increased delta activity and increased theta activity before and after surgery. In these patients, increased preoperative theta activity was related to the presence of language impairment, especially to poor word retrieval and grammatical performance. Preoperative slow-wave activity was also related to postoperative language outcomes. Meningioma patients showed no significant increase in EEG slow-wave activity compared to healthy individuals, but they presented with word retrieval, grammatical, and writing problems preoperatively, as well as with writing impairments postoperatively.DiscussionAlthough the brain-tumour pathology in low-grade gliomas and meningiomas has a different effect on resting-state brain activity, patients with low-grade gliomas and meningiomas both suffer from language impairments. Increased theta activity in glioma patients can be considered as a language-impairment marker, with prognostic value for language outcome after surgery. (shrink)

We propose that rapid eye movement (REM) and slow-wave sleep contribute differently to the formation of episodic memories. REM sleep is important for building up invariant object representations that eventually recur to gamma-band oscillations in the neocortex. In contrast, slow-wave sleep is more directly involved in the consolidation of episodic memories through replay of sequential neural activity in hippocampal place cells.

Objective: To clarify whether long time constant is useful for detecting the after-slow activity of epileptiform discharges : sharp waves and spikes and for differentiating EDs from sharp transients.Methods: We employed 68 after-slow activities preceded by 32 EDs and 36 Sts from 52 patients with partial and generalized epilepsy defined by visual inspection. High-frequency activity associated with the apical component of EDs and Sts was also investigated to endorse two groups. After separating nine Sts that were labeled (...) by visual inspection but did not fulfill the amplitude criteria for after-slow of Sts, 59 activities were analyzed about the total area of after-slow under three TCs.Results: Compared to Sts, HFA was found significantly more with the apical component of EDs. The total area of after-slow in all 32 EDs under TC 2 s was significantly larger than those under TC 0.3 s and 0.1 s. Conversely, no significant differences were observed in the same parameter of 27 Sts among the three different TCs. Regarding separated nine Sts, the total area of after-slow showed a similar tendency to that of 27 Sts under three different TCs.Significance: These results suggest that long TC could be useful for selectively endorsing after-slow of EDs and differentiating EDs from Sts. These findings are concordant with the results of the HFA analysis. Visual inspection is also equally good as the total area of after-slow analysis. (shrink)

When Einstein formulated his special relativity, he developed his dynamics for point particles. Of course, many valiant efforts have been made to extend his relativity to rigid bodies, but this subject is forgotten in history. This is largely because of the emergence of quantum mechanics with wave-particle duality. Instead of Lorentz-boosting rigid bodies, we now boost waves and have to deal with Lorentz transformations of waves. We now have some nderstanding of plane waves or running waves (...) in the covariant picture, but we do not yet have a clear picture of standing waves. In this report, we show that there is one set of standing waves which can be Lorentz-transformed while being consistent with all physical principle of quantum mechanics and relativity. It is possible to construct a representation of the Poincaré group using harmonic oscillator wave functions satisfying space-time boundary conditions. This set of wave functions is capable of explaining the quantum bound state for both slow and fast hadrons. In particular it can explain the quark model for hadrons at rest, and Feynman’s parton model hadrons moving with a speed close to that of light. (shrink)

Studies based on the Rankine-Hugoniot relations have classified MHO shock waves as fast, switch-on, intermediate, switch-off, and slow. Any waves found in nature must also: possess steady-state structures and be stable in the presence of small-flow disturbances. In this monograph, Dr. Anderson examines these criteria in relation to plane shocks for which the collision frequency is large compared with cyclotron frequency. It contains a three-dimensional graphic representation of shock end states and presents an exact solution for the (...) shock adiabatic curve in a convenient form. An MIT Press Research Monograph. (shrink)

In standard Wheeler-Feynman electrodynamics advanced waves from any source are absolutely canceled by the advanced waves from the absorber responding to that source. The present work shows this cancellation fails over cosmic distances in a steady-state universe. A test of the view proposed earlier, in a paper which assumed failure of cancellation and hoc, that zero-point fluctuations of the electromagnetic field are such emergent advanced waves, is posed. The view entails anomalous slowing of spontaneous transition rates at (...) longer emission wavelengths; available data go against this, furnishing additional argument against the suspect assumption that the universe is steady-state. (shrink)

We suggest scattering experiments which implement the concept of “protective measurements” allowing the measurement of the complete wave function even when only one quantum system (rather than an ensemble) is available. Such scattering experiments require massive, slow, projectiles with kinetic energies lower than the first excitation of the system in question. The results of such experiments can have a (probabilistic) distribution (as is the case when the Born approximation for the scattering is valid) or be deterministic (in a semiclassical (...) limit). (shrink)

We propose that sleep is linked to synaptic homeostasis. Specifically, we propose that: (1) Wakefulness is associated with synaptic potentiation in cortical circuits; (2) synaptic potentiation is tied to the homeostatic regulation of slow wave activity; (3) slow wave activity is associated with synaptic downscaling; and (4) synaptic downscaling is tied to several beneficial effects of sleep, including performance enhancement.

It is traditionally believed that cerebral activation (the presence of low voltage fast electrical activity in the neocortex and rhythmical slow activity in the hippocampus) is correlated with arousal, while deactivation (the presence of large amplitude irregular slow waves or spindles in both the neocortex and the hippocampus) is correlated with sleep or coma. However, since there are many exceptions, these generalizations have only limited validity. Activated patterns occur in normal sleep (active or paradoxical sleep) and during (...) states of anesthesia and coma. Deactivated patterns occur, at times, during normal waking, or during behavior in awake animals treated with atropinic drugs. Also, the fact that patterns characteristic of sleep, arousal, and waking behavior continue in decorticate animals indicates that reticulo-cortical mechanisms are not essential for these aspects of behavior. (shrink)

Despite the ubiquity of knowledge attribution in human social cognition, its associated neural and cognitive mechanisms are poorly documented. A wealth of converging evidence in cognitive neuroscience has identified independent perspective-taking and inhibitory processes for belief attribution, but the extent to which these processes are shared by knowledge attribution isn't presently understood. Here, we present the findings of an EEG study designed to directly address this shortcoming. These findings suggest that belief attribution is not a component process in knowledge attribution, (...) contra a standard attitude taken by philosophers. Instead, observed differences in P3b amplitude indicate that knowledge attribution doesn't recruit the strong self-perspective inhibition characteristic of belief attribution. However, both belief and knowledge attribution were observed to display a late slow wave widely associated with mental state attribution, indicating that knowledge attribution also shares in more general processing of others' mental states. These results provide a new perspective both on how we think about knowledge attribution, as well as Theory of Mind processes generally. (shrink)

Theories of superior collicular and hippocampal function have remarkable similarities. Both structures have been repeatedly implicated in spatial and attentional behaviour and in inhibitory control of locomotion. Moreover, they share certain electrophysiological properties in their single unit responses and in the synchronous appearance and disappearance of slow wave activity. Both are phylogenetically old and the colliculus projects strongly to brainstem nuclei instrumental in the generation of theta rhythm in the hippocampal EECOn the other hand, close inspection of behavioural and (...) electrophysiological data reveals disparities. In particular, hippocampal processing mainly concerns stimulus ambiguity, contextual significance, and spatial relations or other subtle, higher order characteristics. This requires the use of largely preprocessed sensory information and mediation of poststimulus investigation. Although collicular activity must also be integrated with that of “higher” centres, its primary role in attention is more “peripheral” and specific in controlling orienting/localisation via eye and body movements toward egocentrically labelled spatial positions. In addition, the colliculus may exert a nonspecific influence in alerting higher centres to the imminence of information potentially worthy of focal attention. Nevertheless, it is noteworthy that collicular and hippocampal lesions produce deficits on similar tasks, although the type of deficit is usually different in each case. Functional overlap between hippocampus and colliculus is virtually certain vis-à-vis stimulus sampling, for example in the acquisition of information via vibrissal movements and visual scanning. In addition, insofar as stimulus significance is a factor in collicular orienting mechanisms, the hippocampus — cingulate – cortex — colliculus pathway may play a significant role, modulating collicular responsiveness and thus ensuring an attentional strategy appropriate to current requirements. A tentative “reciprocal loop” model is proposed which bridges physiological and behavioural levels of analysis and which would account for the observed degree and nature of functional overlap between the superior colliculus and hippocampus. (shrink)

Clinical and experimental evidence suggests that hippocampal damage causes more severe disruption of episodic memories if those memories were encoded in the recent rather than the more distant past. This decrease in sensitivity to damage over time might reflect the formation of multiple traces within the hippocampus itself, or the formation of additional associative links in entorhinal and association cortices. Physiological evidence also supports a two-stage model of the encoding process in which the initial encoding occurs during active waking and (...) deeper consolidation occurs via the formation of additional memory traces during quiet waking or slow-wave sleep. In this article I will describe the changes in cholinergic tone within the hippocampus in different stages of the sleep-wake cycle and will propose that these changes modulate different stages of memory formation. In particular, I will suggest that the high levels of acetylcholine that are present during active waking might set the appropriate dynamics for encoding new information in the hippocampus, by partially suppressing excitatory feedback connections and so facilitating encoding without interference from previously stored information. By contrast, the lower levels of acetylcholine that are present during quiet waking and slow-wave sleep might release this suppression and thereby allow a stronger spread of activity within the hippocampus itself and from the hippocampus to the entorhinal cortex, thus facilitating the process of consolidation of separate memory traces. (shrink)

Over the last decade, attention has crawled from out of the shadows into the philosophical limelight with several important books and widely read articles. Carolyn Dicey Jennings has been a key player in the attention revolution, actively publishing in the area and promoting awareness. This book was much anticipated by insiders and does not disappoint. It is in no way redundant with respect to other recent monographs, covering both a different range of material and developing novel positions throughout. The book (...) might have been called The Attending Self, since Jennings defines attention as mental prioritization controlled by the self. This invocation of the self is among her central innovations, and may prove to be the main source of controversy. I will highlight points of contention here, but want to emphasize at the outset that the book is essential reading for anyone interested in attention. Jennings also contributes to a range of other debates, which will help a broader audience appreciate the importance this topic.After a brief introduction, Jennings provides “a philosophical landscape” of attention (chap. 2), tracing the concept through history. This is an invaluable achievement that will be welcomed by both newcomers and veterans. Jennings exhibits enormous breadth, covering areas that contemporary philosophers of mind tend to neglect: medieval philosophy, Buddhist thought, and phenomenology, to name a few. We also get perspectives on attention from core figures in the Western canon, such as Descartes, Locke, and Kant, as well as thinkers who gave the topic a more political inflection: Mary Wollstonecraft and W. E. B. DuBois. Jennings surveys contemporary literature as well, locating recent work in these older lineages. Some authors get more treatment later in the book (e.g., William James and Wayne Wu). Overall, Jennings provides the best overview of this history I have seen. She proves that attention is not a new topic, but one with deep roots and one that can inform current debates; Jennings draws on these roots throughout. I would love to see a companion piece surveying scientific theories, including “gain control” and “biased competition,” which get little airtime in the book. Some recent philosophical theories are under-explored as well, including Chris Mole’s concept of cognitive unison (Jennings discusses other aspects of his view), Carlos Montemayor and Harry Haladjian’s exploration of attention’s diversity (we get a touch of this), and my own proposal that attention is a gateway to working memory (not mentioned here). That said, no extant survey is more complete.Chapter 3 begins with the empirical claim that attention is regulated by slow brainwaves, and then takes up two issues. The first is mental causation. Endorsing moderate emergentism, Jennings argues that slow brain waves are causally efficacious even though they are not reducible to lower-level processes. (The metaphysics and neuroscience are presented accessibly, aided by three appendixes.) Second, Jennings argues that these slow brain waves indicate that attention is controlled by the self. As someone who was never moved by the mental causation problem—I don’t think overdetermination threatens efficacy—I would have welcomed more development of this second issue. For one thing, in linking attention to subjective control, Jennings eschews the idea that there can be purely “bottom-up” attention driven by stimulus features alone. This goes against the orthodoxy in attention science, and makes it hard for her to accommodate phenomena such as “pop-out,” or the commonsense idea that attention can be “captured” by a sudden flash or loud sound. For another thing, I wanted to hear more on why Jennings relates slow brain waves to the self. Does this include the slow waves that occur during deep sleep? Is there even such a thing as the self? Is there one self or many? How do slow brain waves reflect our interests, projects, values, self-conceptions, autobiographical narratives, or social identities? Does the social self invoked by Wollstonecraft and DuBois gain a foothold here? The whole chapter campaigns against metaphysical reductionism, but arrives at a perspective on the self that will strike some readers as highly reductive.In the fourth chapter, Jennings sheds further light on her conjecture that attention involves the self by advancing the thesis that attention endows sensory information with meaning. On the face of it, this may sound implausible. Object recognition, reading, and many other meaning-involving processes can take place outside of attention and outside of consciousness. But Jennings has a richer notion of “meaning” in mind. She develops the idea of “subject unity,” which is imposition of structure on perception that reflects the interests of the perceiving subject. This, she claims, is what brings perception into the space of reasons. Along the way, she has interesting observations about binding, feature integration, and demonstrative reference. The material is highly original, and Jennings’s postulation of interest-based perceptual organization is compelling. At the same time, one might wonder whether interests are really relegated to the ambit of attentional control. Consider the cocktail party effect, wherein one’s own name captures attention. This implies a preattentive filter that reflects our interests. Emotionally charged words, facial expressions, and dangerous objects also work this way, and social biases can operate preattentively as well. If these reflect our interests, then meaning may arise outside attention.Jennings’s fifth chapter explores the relationship between attention and consciousness. Some authors have argued that attention is necessary and sufficient for consciousness. Jennings focuses primarily on the necessity claim. She does not systematically review the empirical literature here, but she addresses some of the key findings, and effectively rebuts studies that allege to find consciousness outside attention. She does not rest her case there, however. Instead, she identifies a new class of examples that purport to establish the possibility of consciousness without attention. Her central example she calls “conscious entrainment,” which is what we experience when engaged in habitual or skilled activities. Other possible examples touched on in the chapter include hypervigilance in individuals with attention deficit hyperactivity disorder (ADHD), passive movie watching, dreaming, and “attentional neglect.” These states all involve intense focus, Jennings admits, but not attention. To some readers this may sound contradictory. Isn’t focus a kind of attention? Don’t these states of absorption involve stimulus selection and enhancement of relevant features, suppression of distractors, and other hallmarks of attention? Jennings says none of this is tantamount to attention. Recall that she thinks attention is controlled by the self. In these cases, we are invited to imagine that the self takes a passive role: control is either ceded to the world (movie watching) or to previously mastered routines (skills and habits). Thus, Jennings’s claim that there is no attention in these cases hangs on her contentious thesis that attention requires a controlling self. One might also push back by arguing that, in some of Jennings’s allegedly selfless examples, the self remains involved. Skilled activities and hypervigilance, for example, can reflect personal interests.Skills and hypervigilance get more airtime in chapter 6. There, Jennings turns to questions of responsibility—a neglected topic in attention research. The chapter begins with a manslaughter trial in which the teenage plaintiff was given a light sentence because the judge evidently believed that the teen’s ADHD compromised his ability to control his actions. The example may be a bit triggering for people who have a personal relationship with this diagnosis, but, putting that aside, Jennings uses it to introduce the important concept of attention-based control. With reduced control, Jennings argues, comes reduced responsibility. I am inclined to see ADHD as involving dysregulation of attention (difficulty disengaging and dividing attention, for example) rather than diminished attention, but that can still be characterized as an issue with control of attention; therefore ADHD still illustrates Jennings’s point that there is a link between responsibility and control of attention. This, it turns out, is only half of her story. Having argued for this link, one might expect Jennings to follow Wayne Wu, who contends that attention is necessary for action, and hence for responsibility. She does not. Instead, she says argues that responsibility can also arise in cases of “strategic automaticity.” This brings us back to skills. When skills are deployed, action is governed by learned pairings between stimuli and responses. The choice to exercise a skill requires attention, so attention is needed for being a responsible agent, but once a skill kicks in, attention is no longer required, and one can be held responsible for actions performed skillfully—thus attention is not required for responsibility tout court. Jennings addresses an opposing view (defended by Wu, Ellen Fridland, and Barbara Montero), according to which skills involve “automatic attention” rather than no attention. Jennings worries that this move will collapse the distinction between attention and other kinds of selection and filtering that occur throughout the nervous system, including the retina. She says that the attentional interpretation of skilled action is at odds with the lack of top-down reweighing of sensory inputs, regulated by lateral frontal cortex. These objections to automatic attention warrant response. My own view is that attention involves broadcasting to working memory, so retinal filtering is ruled out. Jennings’s insistence on top-down reweighing will not move those who believe attention can be purely bottom-up. For all that, I side with Jennings in wanting to allow for responsibility without attentional control. I think we can be responsible for implicit biases, for example. I also think attentional control is insufficient for responsibility, as when we act under duress.Jennings offers fresh perspective on the nature of attention, and its role in meaningful perception, consciousness, action, and responsibility. Each chapter can be read separately, but they hang together well, and each reflects her thesis that attention is essentially linked to the self. Though I am skeptical of that strong claim, we would do well to follow Jennings in regarding attention as interest-laden interface between mind and world. I look forward to a sequel in which attention is related to richer conceptions of identity, and where the political consequences of this link are actively explored. Meanwhile, one can hardly fault Jennings for covering too little. She tackles a remarkable range of topics, from metaphysics to ethics. Her arguments throughout demand response, repay careful study, and propel the field forward. (shrink)

The present ERP study investigated effects of subliminal emotional words on preference judgments about subsequent visual target stimuli . Each target was preceded by a masked 17-ms emotional adjective. Four classes of prime words were distinguished according to the combinations of positive/negative valence and high/low arousal. Targets were liked significantly more after positive-arousing primes , relative to negative-arousing , positive-nonarousing , and negative-nonarousing primes . In the target ERP, amplitude of right-hemisphere positive slow wave was increased after positive-arousing compared (...) to negative-arousing primes. Evaluative priming effects on judgments and ERPs were more pronounced in high state-anxious participants. The results suggest that there is indeed affective/semantic processing of unconscious words, evaluative priming operates relatively late during target processing, to be effective, prime words need to score high on the arousal dimension, and individual differences in state anxiety modulate the susceptibility to subliminal evaluative priming. (shrink)

Several decades of behavioral research have established that variations in socioeconomic status are related to differences in cognitive performance. Neuroimaging and psychophysiological techniques have recently emerged as a method of choice to better understand the neurobiological processes underlying this phenomenon. Here we present a systematic review of a particular sub-domain of this field. Specifically, we used the PICOS approach to review studies investigating potential relationships between SES and scalp event-related brain potentials. This review found evidence that SES is related to (...) amplitude variations in a diverse range of ERPs: P1, N1, N2, Error-Related Negativities, N400, auditory evoked potentials, negative difference waves, P3 and slow waves. These ERPs include early, mid-latency and late potentials that reflect a broad range of cognitive processes. In this review, all SES effects on ERPs appeared to reflect an impairment or a less efficient form of task-related neural activity for low-SES compared to high-SES individuals. Overall, these results confirm that a wide variety of distinct neural processes with different functional meanings are sensitive to SES differences. The findings of this review also suggest that the relationship between SES and some ERP components may depend on the developmental stage of study participants. Results are further discussed in terms of the current limitations of this field and future avenues of research. (shrink)

The neuroanatomical substrates controlling and regulating sleeping and waking, and thus consciousness, are located in the brain stem. Most crucial for bringing the brain into a state conducive for consciousness and information processing is the mesencephalic part of the brain stem. This part controls the state of waking, which is generally associated with a high degree of consciousness. Wakefulness is accompanied by a low-amplitude, high-frequency electroencephalogram, due to the fact that thalamocortical neurons fire in a state of tonic depolarization. Information (...) can easily pass the low-level threshold of these neurons, leading to a high transfer ratio. The complexity of the electroencephalogram during conscious waking is high, as expressed in a high correlation dimension. Accordingly, the level of information processing is high. Spindles, and alpha waves in humans, mark the transition from wakefulness to sleep. These phenomena are related to drowsiness, associated with a reduction in consciousness. Drowsiness occurs when cells undergo moderate hyperpolarizations. Increased inhibitions result in a reduction of afferent information, with a lowered transfer ratio. Information processing subsides, which is also expressed in a diminished correlation dimension. Consciousness is further decreased at the onset of slow wave sleep. This sleep is controlled by the medullar reticular formation and is characterized by a high-voltage, low-frequency electroencephalogram. Slow wave sleep becomes manifest when neurons undergo a further hyperpolarization. Inhibitory activities are so strong that the transfer ratio further drops, as does the correlation dimension. Thus, sensory information is largely blocked and information processing is on a low level. Finally, rapid eye movement sleep is regulated by the pontine reticular formation and is associated with a ''wake-like'' electroencephalographic pattern. Just as during wakefulness, this is the expression of a depolarization of thalamocortical neurons. The transfer ratio of rapid eye movement sleep has not yet been determined, but seems to vary. Evidence exists that this type of sleep, associated with dreaming, with some kind of perception and consciousness, is involved in processing of ''internal'' information. In line with this, rapid eye movement sleep has higher correlation dimensions than slow-wave sleep and sometimes even higher than wakefulness. It is assumed that the ''near-the-threshold'' depolarized state of neurons in the thalamus and cerebral cortex is a necessary condition for perceptual processes and consciousness, such as occurs during waking and in an altered form during rapid eye movement sleep. (shrink)

To define 'consciousness' is to describe its uses and deter-mine its boundaries, essential nature, and mechanisms. I distinguish between 'normal waking consciousness'; altered forms of waking consciousness underlying trance, absorption, hypnosis, dissociation, meditative states, drug states, and out of body experiences; and REM/dreaming and slow-wave/deep sleep - examining them by the basic characteristics and mechanisms of normal waking conscious-ness: cortical arousal, qualitative experiences, first-person subjectiv-ity, intentionality, knowing objects and self, interaction with external and inner world, united field, and reflective (...) consciousness. (shrink)

In their environment, plants are continuously submitted to natural stimuli such as wind, rain, temperature changes, wounding, etc. These signals induce a cascade of events which lead to metabolic and morphogenetic responses. In this paper the different steps are described and discussed starting from the reception of the signal by a plant organ to the final morphogenetic response. In our laboratory two plants are studied: Bryonia dioica for which rubbing the internode results in reduced elongation and enhanced radial expansion and (...) Bidens pilosa for which the response occurs at distance, hence pricking the cotyledon of a plantlet induces the growth inhibition of both the hypocotyl and the axillary bud of the pricked cotyledon. Reception of the signal and transmission of the message. In Bryonia the signal is received by epidermal cells while in Bidens they are the cells adjacent to the midrib of the cotyledon which receive the mechanical signal. In both plants the message is transmitted via a wave of electric depolarization. This latter is composed of an action potential associated with a slow wave whose transmission rates are respectively 1cm s−1 and 1 mm s−1. Recent results have shown the involvement of Ca2+ in the triggering of the slow wave and the role of the H+ pump during the slow wave. Transient and fast biochemical responses. An entry of extraceilular Ca2+ into the cells and a transient increase in IP3 occur within seconds following the mechanical stimulus. At the same time, the membrane becomes more fluid, correlated with qualitative changes in phospholipids. The rapid increase in the concentration of peroxidated lipids may be correlated with ethylene biosynthesis which is stimulated after rubbing. Other parameters such as cytoplasmic pH, relative water content, hydric potential, membrane potential and modifications of K+, Mg2+-ATPase and Ca2+-ATPase activities, play a key role in the early responses induced by the traumatisms. Irreversible-biochemical responses. The mechanical stimulus performed on a Bryonia internode induces an acceleration of: i) enzymatic activities related to the lignification, ii) esterification of phenolic acids in the cell wall. Consequently the lignification process is accelerated. Storage of the information. After being received by the target cells the information can be stored during several days before being expressed. At the level of cotyledonary bud, the first message, previously stored, can be expressed or not by a second treatment. Bidens thus behaves as if it was able to “store” and to “retrieve” morphogenetic messages, using a sort of rudimentary memory. The nuclei of the bud cells of the pricked cotyledon show that these cells, initially in G2 phase, divide and then remain in the G1 phase. In Bryonia, calli derived from young stimulated internodes, keep thigmomorphogenetic characteristics during several weeks. In the last part of this paper the particularity of our plant model which permits a study of the transmission and storage of the message, is underlined. The links between the different steps induced by the stimulus are discussed. Special attention is devoted to second messengers and to the amplification of the message. (shrink)

Humans preferentially remember information processed for their survival relevance, a memorial benefit known as the survival processing effect. Memory is also biased towards information associated with the prospect of reward. Given the adaptiveness of these effects, they may depend on similar mechanisms. We tested whether motivation drives both effects, with reward incentives that are known to boost extrinsic motivation and survival processing perhaps stimulating intrinsic motivation. Accordingly, we manipulated survival processing and reward incentive independently during an incidental-encoding task in which (...) participants chose between pairs of words concerning their relevance for a scenario, and examined the effects on encoding event-related potentials activity and later performance on a surprise recall test. We hypothesized that if survival processing fosters intrinsic motivation, it should reduce the beneficial effects of extrinsic motivation. In contrast to this prediction, we found that reward incentive and survival processing independently improved memory and that the P300, a measure of lower-level cognitive resource allocation, was increased by reward incentive independent of survival processing. Further, survival processing and reward incentive independently increased the frontal slow wave, a measure of higher-level elaboration. These findings suggest that while survival processing and reward incentive may both increase encoding elaboration, the memory-enhancing effect of survival processing does not depend on increased intrinsic motivation. Additionally, we replicated a recent finding whereby the survival processing effect generalizes to a choice-based encoding task and further showed that the beneficial effect of choice on memory likely does not interact with either survival processing or reward. (shrink)

The identity of working-memory and long-term memory representations follows from many lines of evidence. However, the data provided by Ruchkin et al. are hardly compelling, as they make unproved assumptions about hypothetical generators. We cite studies from our lab in which congruent slow-wave topographies were found for short-term and long-term memory tasks, strongly suggesting that both activate identical cell assemblies.

People categorize objects slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT) theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger impoverishment effects for (...) real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a) word meaning in temporal cortex during the N400, (b) internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600), and (c) response related activity in posterior cingulate during an anterior slow wave (SW) after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition. (shrink)

The neuromodulatory effects of brain stimulation therapies notably involving repetitive transcranial magnetic stimulation on nocturnal sleep, which is critically disturbed in major depression and other neuropsychiatric disorders, remain largely undetermined. We have previously reported in major depression patients that prefrontal rTMS sessions enhanced their slow wave activity power, but not their sigma power which is related to sleep spindle activity, for electrodes located nearby the stimulation site. In the present study, we focused on measuring the spindle density to investigate (...) cumulative effects of prefrontal rTMS sessions on the sleep spindle activity. Fourteen male inpatients diagnosed with medication-resistant unipolar or bipolar depression were recruited and subjected to 10 daily rTMS sessions targeting the left dorsolateral prefrontal cortex. All-night polysomnography data was acquired at four time points: Adaptation, Baseline, Post-1, and Post-2. Clinical and cognitive evaluations were longitudinally performed at Baseline, Post-1, and Post-2 time points to explore associations with the spindle density changes. The PSG data from 12 of 14 patients was analyzed to identify sleep spindles across the sleep stages II–IV at four electrode sites: F3, F4, P3, and P4. Statistical analysis by two-way ANOVA revealed that spindle density at F3 increased at Post-1 but decreased at Post-2 time points. Moreover, the local and transient increase of spindle density at F3 was associated with the previously reported SWA power increase at F3, possibly reflecting a shared mechanism of thalamocortical synchronization locally enhanced by diurnal prefrontal rTMS sessions. Clinical and cognitive correlations were not observed in this dataset. These findings suggest that diurnal rTMS sessions transiently modulate nocturnal sleep spindle activity at the stimulation site, although clinical and cognitive effects of the local changes warrant further investigation. (shrink)

This paper approaches dreaming consciousness through an examination of the self-organizing properties of the sleeping brain. This view offers a step toward reconciliation between brain-based and content-based attempts to understand the nature of dreaming. Here it is argued that the brain can be understood as a complex self-organizing system that in dreaming responds to subtle influences such as residual feelings and memories. The hyper-responsiveness of the brain during dreaming is viewed in terms of the tendency of complex chaotic-like systems to (...) respond to small variations in initial conditions and to the amplification of subtle emotional and cognitive signals through the mechanism of stochastic resonance, all in combination with psychophysiological changes in the brain during both slow wave sleep and REM sleep dreaming. Such changes include the active inhibition of extroceptive stimulation and, especially in REM sleep, alterations in the brain's dominant neuromodulatory systems, bombardment of the visual cortex with bursts of PGO activity, increases in limbic system activity, and a reduction of activity in the prefrontal regions. (shrink)

Prior to the initiation of spontaneous movement, evoked potentials can be seen to precede awareness of the impending movement by several hundreds of milliseconds, meaning that this recorded neural activity is the result of unconscious processing. This study investigates the neural representations of impending movement with and without awareness. Specifically, the relationship between awareness and ‘idling’ cortical oscillations in the beta range was assessed. It was found that, in situations where there was awareness of the impending movement, pre-movement evoked potentials (...) were associated with a decrease in beta range oscillations. In contrast, when awareness of the impending movement was not present, the onset of the pre-movement potential was associated with tonic levels of beta range oscillations. A model is considered where by distributed neural activity remains outside of conscious awareness through the persistence of tonic slow wave cortical oscillations. (shrink)

It has long been thought that the central nervous system is able to influence the progression of disease. Furthermore, there is now overwhelming evidence that the communication pathways are bidirectional. A variety of immune system peptides are now known to be capable of transmitting information from the immune system to the central nervous system. These immunotransmitters include interleukins, interferons and thymosine peptides which have the capability of modulating slow‐wave sleep as well as the release of neuro‐ and pituitary peptides. (...) In some instances, release of these peptides during early development may have long lasting, if not permanent effects upon the normal development of neuro‐endocrine circuits. Collectively these various brain mediated events appear to contribute in various and diverse ways to defense against pathogens. It is becoming more and more apparent that certain abnormalities within the immune system may be the consequence of a neurological abnormality. The converse is also true. (shrink)

Nielsen's model presents a new isomorphic brain-mind viewpoint, according to which the sole dream generator is found in a REM-on (explicit or covert REM) mechanism. Such a model cannot explain the dreamlike activity during SWS (slow wave sleep), SO (sleep onset) and in the last period of sleep. Moreover the hypothesis contrasts with Solms's data, which show that dreaming is present also in case of destruction of the REM generator. [Nielsen; Solms].

In this chapter, we aimed at further characterizing the functional neuroanatomy of the human rapid eye movement (REM) sleep at the population level. We carried out a meta-analysis of a large dataset of positron emission tomography (PET) scans acquired during wakefulness, slow wave sleep and REM sleep, and focused especially on the brain areas in which the activity diminishes during REM sleep. Results show that quiescent regions are confined to the inferior and middle frontal cortex and to the inferior (...) parietal lobule. Providing a plausible explanation for some of the features of dream reports, these findings may help in refining the concepts, which try to account for human cognition during REM sleep. In particular, we discuss the significance of these results to explain the alteration in executive processes, episodic memory retrieval and self representation during REM sleep dreaming as well as the incorporation of external stimuli into the dream narrative. (shrink)

Reflective waking mentation is supported by cortical activating and inhibitory processes. The thought-like mental content of slow wave sleep appears with lower levels of both kinds of influence. During REM sleep, the equation: activation + disinhibition + dopamine may explain the often psychotic-like mode of psychological functioning. [Hobson et al.; Nielsen; Revonsuo; Solms; Vertes & Eastman].

To examine the interaction of working memory type with emotional interference in trait anxiety, event-related potentials were measured in a combined WM and emotional task. Participants completed a delayed matching-to-sample task of WM, and emotional pictures were presented during the maintenance interval. The results indicated that negative affect interfered with spatial WM; task-related changes in amplitude were observed in the late positive potential and slow waves in both the high and low anxiety groups. We also found an interaction (...) among WM type, emotion, and trait anxiety such that participants with high levels of trait anxiety showed an opposite neural response to verbal and spatial WM tasks compared with individuals with low trait anxiety during the sustained brain activity involved in processing negative or neutral pictures in the delay phase. Our results increase our understanding of the influence of emotions on recognition and the vulnerability of those with trait anxiety to emotional stimuli. (shrink)

Easy of learning judgments occur before active learning begins, and it is a prediction of how difficult it will be to learn new material in future learning. This study compared the amplitude of event-related potential components and brain activation regions between high and low EOL judgments by adopting ERPs with a classical EOL judgment paradigm, aiming to confirm the ease-of-processing hypothesis. The results showed that the magnitudes of EOL judgments are affected by encoding fluency cues, and the judgment magnitude increases (...) with encoding fluency; low EOL judgments are associated with higher N400 amplitude at the left superior frontal gyrus and left middle frontal gyrus. High EOL judgments showed enlarged slow-wave potentials than low EOL judgments at the left medial temporal lobe, right ventromedial prefrontal cortex, and dorsolateral prefrontal cortex. Our results support the ease-of-processing hypothesis, particularly, by affirming that EOL judgments are affected by encoding fluency in two processing stages. N400 reflects the process of acquiring encoding fluency cues, while slow-wave indicates that individuals use encoding fluency cues for metacognitive monitoring. (shrink)

BackgroundPrenatal and early postnatal choline supplementation reduces cognitive and behavioral deficits in animal models of Fetal Alcohol Spectrum Disorder. In a previously published 9-month clinical trial of choline supplementation in children with FASD, we reported that postnatal choline was associated with improved performance on a hippocampal-dependent recognition memory task. The current paper describes the neurophysiological correlates of that memory performance for trial completers.MethodsChildren with FASD who were enrolled in a clinical trial of choline supplementation were followed for 9 months. Delayed (...) recall on a 9-step elicited imitation task served as the behavioral measure of recognition memory. Neurophysiological correlates of memory were assessed via event-related potentials.ResultsDelayed recall on EI was correlated with two ERP components commonly associated with recognition memory in young children: middle latency negative component and positive slow wave. No significant ERP differences were observed between the choline and placebo groups at the conclusion of the trial.ConclusionAlthough the small sample size limits the ability to draw clear conclusions about the treatment effect of choline on ERP, the results suggest a relationship between memory performance and underlying neurophysiological status in FASD. This trial was registered.1. (shrink)

A complex brain network, centered on the hippocampus, supports episodic memories throughout their lifetimes. Classically, upon memory encoding during active behavior, hippocampal activity is dominated by theta oscillations (6-10Hz). During inactivity, hippocampal neurons burst synchronously, constituting sharp waves, which can propagate to other structures, theoretically supporting memory consolidation. This 'two-stage' model has been updated by new data from high-density electrophysiological recordings in animals that shed light on how information is encoded and exchanged between hippocampus, neocortex and subcortical structures such (...) as the striatum. Cell assemblies (tightly related groups of cells) discharge together and synchronize across brain structures orchestrated by theta, sharp waves and slow oscillations, to encode information. This evolving dynamical schema is key to extending our understanding of memory processes. (shrink)

In view of a resurgence of concern about the measurement problem, it is pointed out that the Relativistic Transactional Interpretation remedies issues previously considered as drawbacks or refutations of the original TI. Specifically, once one takes into account relativistic processes that are not representable at the non-relativistic level, absorption is quantitatively defined in unambiguous physical terms. RTI therefore provides a well-defined terminus to what appears to be a necessary infinite regress concerning ‘absorption’ when only the non-relativistic level is considered. In (...) addition, specifics of the relativistic transactional model demonstrate that the Maudlin ‘contingent absorber’ challenge to the original TI cannot even be mounted: basic features of established relativistic field theories dictate that the ‘slow-moving offer wave’ required for the challenge scenario cannot exist. It is concluded that issues previously considered obstacles for TI are no longer legitimately viewed as such, and that reconsideration of the transactional picture is warranted in connection with solving the measurement problem. (shrink)