Consciousness CLEARS the Mind

A full understanding of consciouness requires that we identify the brain processes from which conscious experiences emerge. What are these processes, and what is their utility in supporting successful adaptive behaviors? Adaptive Resonance Theory (ART) predicted a functional link between processes of Consciousness, Learning, Expectation, Attention, Resonance, and Synchrony (CLEARS), includes the prediction that "all conscious states are resonant states." This connection clarifies how brain dynamics enable a behaving individual to autonomously adapt in real time to a rapidly changing world. The present article reviews theoretical considerations that predicted these functional links, how they work, and some of the rapidly growing body of behavioral and brain data that have provided support for these predictions. The article also summarizes ART models that predict functional roles for identified cells in laminar thalamocortical circuits, including the six layered neocortical circuits and their interactions with specific primary and higher-order specific thalamic nuclei and nonspecific nuclei. These prediction include explanations of how slow perceptual learning can occur more frequently in superficial cortical layers. ART traces these properties to the existence of intracortical feedback loops, and to reset mechanisms whereby thalamocortical mismatches use circuits such as the one from specific thalamic nuclei to nonspecific thalamic nuclei and then to layer 4 of neocortical areas via layers 1-to-5-to-6-to-4.

Synchronized Oscillations During Cooperative Feature Lining in a Cortical Model of Visual Perception

A neural network model of synchronized oscillations in visual cortex is presented to account for recent neurophysiological findings that such synchronization may reflect global properties of the stimulus. In these experiments, synchronization of oscillatory firing responses to moving bar stimuli occurred not only for nearby neurons, but also occurred between neurons separated by several cortical columns (several mm of cortex) when these neurons shared some receptive field preferences specific to the stimuli. These results were obtained for single bar stimuli and also across two disconnected, but colinear, bars moving in the same direction. Our model and computer simulations obtain these synchrony results across both single and double bar stimuli using different, but formally related, models of preattentive visual boundary segmentation and attentive visual object recognition, as well as nearest-neighbor and randomly coupled models.

Synchronized Oscillations During Cooperative Feature Linking in a Cortical Model of Visual Perception

A neural network model of synchronized oscillator activity in visual cortex is presented in order to account for recent neurophysiological findings that such synchronization may reflect global properties of the stimulus. In these recent experiments, it was reported that synchronization of oscillatory firing responses to moving bar stimuli occurred not only for nearby neurons, but also occurred between neurons separated by several cortical columns (several mm of cortex) when these neurons shared some receptive field preferences specific to the stimuli. These results were obtained not only for single bar stimuli but also across two disconnected, but colinear, bars moving in the same direction. Our model and computer simulations obtain these synchrony results across both single and double bar stimuli. For the double bar case, synchronous oscillations are induced in the region between the bars, but no oscillations are induced in the regions beyond the stimuli. These results were achieved with cellular units that exhibit limit cycle oscillations for a robust range of input values, but which approach an equilibrium state when undriven. Single and double bar synchronization of these oscillators was achieved by different, but formally related, models of preattentive visual boundary segmentation and attentive visual object recognition, as well as nearest-neighbor and randomly coupled models. In preattentive visual segmentation, synchronous oscillations may reflect the binding of local feature detectors into a globally coherent grouping. In object recognition, synchronous oscillations may occur during an attentive resonant state that triggers new learning. These modelling results support earlier theoretical predictions of synchronous visual cortical oscillations and demonstrate the robustness of the mechanisms capable of generating synchrony.

Grooming and hygienic behaviours of the honey bee (Apis mellifera) toward the parasitic mite Varroa destructor

Despite a multitude of environmental stressors, the Varroa mite is still regarded as the greatest cause of honey bee mortality in its invaded range. Breeding honey bees that are resistant to the mite is an important area of research. This thesis aimed to gain a better understanding of the grooming and hygienic behaviours of Russian honey bees (RHB). The effect of a break in the synchrony of a mite’s life cycle on reproductive success was tested through brood inoculation experiments. Mites released by hygienic behaviour and forced to enter a new cell are less likely to lay male offspring. Through laboratory cage assays it was found that daughter mites are more susceptible to grooming behaviour. A new method of marking Varroa mites was developed which would enable a single cohort of mites to be followed after inoculation. A strong brood removal trait was noticed in RHB colonies, therefore they were tested for Varroa sensitive hygienic (VSH) behaviour. RHB demonstrated levels of VSH as high as the USDA line bred specifically for this behaviour. In addition the same QTL found to be responsible for the trait in VSH bees, was associated with VSH in RHB stock. Previous work showed that the ratio of older mites to total trapped mites (O/T) in the debris of honey bee colonies demonstrated the strongest association with colony infestation. This research showed that O/T is associated with VSH and brood removal behaviour. In addition, bees that displayed high levels of VSH in this study were also more likely to spend a longer amount of time grooming in laboratory assays. This indicates that both grooming and hygienic behaviours play important roles in the resistance of RHB stock. Their likelihood to be expressed by other stocks is discussed and recommendations for further research are provided.

Spatial and temporal scales of neuronal correlation in visual area V4.

The spiking activity of nearby cortical neurons is correlated on both short and long time scales. Understanding this shared variability in firing patterns is critical for appreciating the representation of sensory stimuli in ensembles of neurons, the coincident influences of neurons on common targets, and the functional implications of microcircuitry. Our knowledge about neuronal correlations, however, derives largely from experiments that used different recording methods, analysis techniques, and cortical regions. Here we studied the structure of neuronal correlation in area V4 of alert macaques using recording and analysis procedures designed to match those used previously in primary visual cortex (V1), the major input to V4. We found that the spatial and temporal properties of correlations in V4 were remarkably similar to those of V1, with two notable differences: correlated variability in V4 was approximately one-third the magnitude of that in V1 and synchrony in V4 was less temporally precise than in V1. In both areas, spontaneous activity (measured during fixation while viewing a blank screen) was approximately twice as correlated as visual-evoked activity. The results provide a foundation for understanding how the structure of neuronal correlation differs among brain regions and stages in cortical processing and suggest that it is likely governed by features of neuronal circuits that are shared across the visual cortex.

Effects Of Oil On Digestive Cells In Mussels - Quantitative Alterations In Cellular And Lysosomal Structure

Structural changes were observed in the digestive tubule epithelial cells of Mytilus edulis following long-term exposure to the water accommodated fraction (WAF) of North Sea crude oil (30 μg · l−1 total oil derived aromatic hydrocarbons). The changes observed involved a reduction in the height of the digestive cells beyond that demonstrated in a normal feeding cycle. In addition there was a loss of the normal synchrony of the digestive cells to a point where nearly all the tubules exhibited an appearance similar to that which is usually termed ‘reconstituting’. These alterations were quantified using an image analysis technique and the mean height of the digestive cells used as an index of digestive function or state. Long-term exposure also induced a radical alteration of the structure of secondary lysosomes within the digestive cells, resulting in the formation of large lysosomes, believed to be autolysosomes. Stereological analyses showed that these lysosomes are reduced in numbers and greatly increased in volume in comparison with controls. There is a concomitant increase in surface area of lysosomes per unit volume of digestive cell compared with control conditions. These alterations are indicative of fundamental changes in secondary lysosomal function involving an autophagic response to oil derived hydrocarbons. which would contribute to the reduction of digestive cell cytoplasm. These cellular alterations are discussed in terms of their use as indices of cell injury, in response to oil.

Marine plankton phenology and life history in a changing climate: current research and future directions

Increasing availability and extent of biological ocean time series (from both in situ and satellite data) have helped reveal significant phenological variability of marine plankton. The extent to which the range of this variability is modified as a result of climate change is of obvious importance. Here we summarize recent research results on phenology of both phytoplankton and zooplankton. We suggest directions to better quantify and monitor future plankton phenology shifts, including (i) examining the main mode of expected future changes (ecological shifts in timing and spatial distribution to accommodate fixed environmental niches vs. evolutionary adaptation of timing controls to maintain fixed biogeography and seasonality), (ii) broader understanding of phenology at the species and community level (e.g. for zooplankton beyond Calanus and for phytoplankton beyond chlorophyll), (iii) improving and diversifying statistical metrics for indexing timing and trophic synchrony and (iv) improved consideration of spatio-temporal scales and the Lagrangian nature of plankton assemblages to separate time from space changes.

Interannual variability of marine zooplankton and their environments: Within- and between-region comparisons

The work highlights the first Global Comparison of Zooplankton Time Series. ► Variation of the peak in abundance is affected by annual temperature anomalies. ► Results show no global-scale synchrony in zooplankton time-series. ► There are spatial autocorrelations over substantial distances (1000–3000 km). ► There remains considerable uncertainty about the relative causes of shifts in distributions.

Role of peripheral afference during acquisition of a complex coordination task

It has long been supposed that the interference observed in certain patterns of coordination is mediated, at least in part, by peripheral afference from the moving limbs. We manipulated the level of afferent input, arising from movement of the opposite limb, during the acquisition of a complex coordination task. Participants learned to generate flexion and extension movements of the right wrist, of 75degrees amplitude, that were a quarter cycle out of phase with a 1-Hz sinusoidal visual reference signal. On separate trials, the left wrist either was at rest, or was moved passively by a torque motor through 50degrees, 75degrees or 100degrees, in synchrony with the reference signal. Five acquisition sessions were conducted on successive days. A retention session was conducted I week later. Performance was initially superior when the opposite limb was moved passively than when it was static. The amplitude and frequency of active movement were lower in the static condition than in the driven conditions and the variation in the relative phase relation across trials was greater than in the driven conditions. In addition, the variability of amplitude, frequency and the relative phase relation during each trial was greater when the opposite limb was static than when driven. Similar effects were expressed in electromyograms. The most marked and consistent differences in the accuracy and consistency of performance (defined in terms of relative phase) were between the static condition and the condition in which the left wrist was moved through 50degrees. These outcomes were exhibited most prominently during initial exposure to the task. Increases in task performance during the acquisition period, as assessed by a number of kinematic variables, were generally well described by power functions. In addition, the recruitment of extensor carpi radialis (ECR), and the degree of co-contraction of flexor carpi radialis and ECR, decreased during acquisition. Our results indicate that, in an appropriate task context, afferent feedback from the opposite limb, even when out of phase with the focal movement, may have a positive influence upon the stability of coordination.

Let your feet do the walking: constraints on the stability of bipedal coordination

In this paper we consider whether the behaviour of the neural circuitry that controls lower limb movements in humans is shaped primarily by the spatiotemporal characteristics of bipedal gait patterns, or by selective pressures that are sensitive to considerations of balance and energetics. During the course of normal locomotion, the full dynamics of the neural circuitry are masked by the inertial properties of the limbs. In the present study, participants executed bipedal movements in conditions in which their feet were either unloaded or subject to additional inertial loads. Two patterns of rhythmic coordination were examined. In the in-phase mode, participants were required to flex their ankles and extend their ankles in synchrony. In the out-of-phase mode, the participants flexed one ankle while extending the other and vice versa. The frequency of movement was increased systematically throughout each experimental trial. All participants were able to maintain both the in-phase and the out-of-phase mode of coordination, to the point at which they could no longer increase their frequency of movement. Transitions between the two modes were not observed, and the stability of the out-of-phase and in-phase modes of coordination was equivalent at all movement frequencies. These findings indicate that, in humans, the behaviour of the neural circuitry underlying coordinated movements of the lower limbs is not constrained strongly by the spatiotemporal symmetries of bipedal gait patterns.

A Cross-modal Approach for Karaoke Artifacts Correction

Karaoke singing is a popular form of entertainment in several parts of the world. Since this genre of performance attracts amateurs, the singing often has artifacts related to scale, tempo, and synchrony. We have developed an approach to correct these artifacts using cross-modal multimedia streams information. We first perform adaptive sampling on the user's rendition and then use the original singer's rendition as well as the video caption highlighting information in order to correct the pitch, tempo and the loudness. A method of analogies has been employed to perform this correction. The basic idea is to manipulate the user's rendition in a manner to make it as similar as possible to the original singing. A pre-processing step of noise removal due to feedback and huffing also helps improve the quality of the user's audio. The results are described in the paper which shows the effectiveness of this multimedia approach.

Common input to different regions of biceps brachii long head

The purpose of the experiment was to compare the level of synchronization exhibited by pairs of motor units located within and between functionally distinct regions of the biceps brachii muscle. Pairs of single motor units were recorded from seven subjects using separate electrodes located in the lateral and medial aspects of the long head of biceps brachii. Participants were required to exert a combination of flexion and supination torques so that both motor units discharged at approximately 10 pps for a parts per thousand yen200 s and the level of motor unit synchronization could be quantified. When motor unit recordings were sufficiently stable at the completion of this synchrony task, a series of ramp contractions with multiple combinations of flexion and supination torques were performed to characterize the recruitment thresholds of the motor units. Common input strength (CIS) was significantly greater (P <0.01) for the within-region pairs of motor units (0.28 extra sync. imps/s, n = 26) than for the between-region pairs (0.13 extra sync. imps/s, n = 18), but did not differ significantly for the 12 within-region pairs from the lateral head and 14 from the medial head (0.27 vs. 0.29 extra sync. imps/s; P = 0.83). Recruitment thresholds were measured for 33 motor units, but there was only a weak association between CIS and the respective recruitment patterns for motor unit pairs (n = 9). The present investigation provides evidence of a differential distribution of synaptic input across the biceps brachii motor neuron pool, but this appears to have minimal association with the recruitment patterns for individual motor units.

Evidence for progressive Holocene aridification in southern Africa recorded in Namibian hyrax middens: Implications for African Monsoon dynamics and the

Presented here are stable nitrogen isotope data from a rock hyrax (Procavia capensis) middens from northwestern Namibia that record a series of rapid aridification events beginning at ca. 3800 cal yr BP, and which mark a progressive decrease in regional humidity across the Holocene. Strong correlations exist between this record and other terrestrial and marine archives from southern Africa, indicating that the observed pattern of climate change is regionally coherent. Combined, these data indicate hemispheric synchrony in tropical African climate change during the Holocene, with similar trends characterising the termination of the 'African Humid Period' (AHP) in both the northern and southern tropics. These findings run counter to the widely accepted model of direct low-latitude insolation forcing, which requires an antiphase relationship to exist between the hemispheres. The combined dataset highlights: 1) the importance of forcing mechanisms influencing the high northern latitudes in effecting low-latitude climate change in Africa, and 2) the potential importance of solar forcing and variations in the Earth's geomagnetic shield in determining both long-term and rapid centennial-scale climate changes, identifying a possible mechanism for the variations marking the AHP termination in both the southern and northern tropics. (C) 2010 University of Washington. Published by Elsevier Inc. All rights reserved.

Combining multisensory temporal information for movement synchronisation

The ability to synchronise actions with environmental events is a fundamental skill supporting a variety of group activities. In such situations, multiple sensory cues are usually available for synchronisation, yet previous studies have suggested that auditory cues dominate those from other modalities. We examine the control of rhythmic action on the basis of auditory and haptic cues and show that performance is sensitive to both sources of information for synchronisation. Participants were required to tap the dominant hand index finger in synchrony with a metronome defined by periodic auditory tones, imposed movements of the non-dominant index finger, or both cues together. Synchronisation was least variable with the bimodal metronome as predicted by a maximum likelihood estimation (MLE) model. However, increases in timing variability of the auditory cue resulted in some departures from the MLE model. Our findings indicate the need for further investigation of the MLE account of the integration of multisensory signals in the temporal control of action.

Asynchrony in key Holocene chronologies: Evidence from Irish bog pines

The Greenland Ice Core Chronology 2005 (GICC05) and the radiocarbon calibration curve (IntCal) are the foremost time scales used in paleoclimatic and paleoenvironmental studies of the most recent 10 k.y. Due to varying and often insufficient dating resolution, opportunities to test the synchrony of these two influential chronologies are rare. Here we present evidence for a phase of major pine recruitment on Irish bogs at ca. 8160 yr B.P. Dendrochronological dating of subfossil trees from three sites reveals synchronicity in germination across the study area, indicative of a regional forcing. The concurrent colonization of pine on peatland is interpreted in terms of drier surface conditions and provides the first substantive proxy data in support of a significant hydroclimatic change in the north of Ireland accompanying the 8.2 ka climate cooling event. The date of pine establishment does not overlap with the GICC05 age range for the event, and possible lags between responses are unlikely to explain the full difference. In light of recent studies highlighting a possible offset in GICC05 and IntCal dates, the Irish pine record supports the notion of ice core dates being too early during the period of study. If the suggested discrepancy in timing is an artifact of chronological error, it is likely to have affected interpretations of previous proxy comparisons and alignments.