"Blue" Photonics: Optics in the Sea

The oceans and coastal zones of the world are vitally important resources for many aspects of human life. Their exploitation as sources of food dates back to the beginnings of civilisation, but in relatively more recent times, by comparison, our oceans have become valuable sources of energy. The oil and gas industries are well known examples of how the oceans can be exploited to provide us with our fossil fuel needs. More recently, wind, tidal and wave power are coming to the fore as we look more towards renewable sources of energy. We should also not forget the extraction of other mineral resources. However, the gathering and farming of food is still the most significant treasure that the oceans hold for us; and its control, management and sustainability are vital aspects of sea utilisation. There are many significant challenges which still face us in our drive to understand and utilise this unique environment and to exploit the natural resources contained within it. New techniques and instruments are continually being developed to help us explore and enhance our appreciation of the sea and how we depend upon it. Foremost amongst these is the increased use of optical techniques or photonics that help to us to extract information about the nature of the oceans, its constituents and its behaviour. In this special issue of the Journal of the European Optical Society we focus on what we term “Blue” Photonics: in other words, the use and understanding of optics in the sea (and also in rivers and lakes). Such a title embraces a wide range of aspects of optics and light in the oceans from basic optical propagation through water to the design of complex instruments which enable us to measure its properties and behaviour. The chosen papers highlight major topics in photonics applied to marine science and engineering from fundamental science through marine optics, optical metrology, biological optics, environmental optics to technology and instrumentation. A number of papers are related to the measurement of ocean water properties like the transparency measurements using the Secchi Disc (Wernand) or the colour evaluation with the Forel-Ule comparator (Wernand) and its change as a function of time (Wernand) caused by pollution or the presence of micro-organism. Another two papers deal with the development of new measurement methods and their influencing parameters. An interesting method in this area is the measurement of reflectance scattering with the application to the measurement of waves on the ocean surface (Creanor et al) as well as to the determination of solutes in the water. A complementary method is the measurement of light fluctuations in different depths under the surface giving an excellent approach to the wave evaluation (Hieronymi). The detection of micro-bubbles in the subsea environment is discussed by Zielinski et al. A new measurement method too is the Laser Line Scan method in the CW mode as well as in pulsed mode (Caimi and Dalgleish). This method increases the resolution and is robust against environmental influences and scans a larger volume. Imaging methods are another area of underwater metrology systems. Systems like the LOKI system (Schulz et al) are used to image Plankton. The papers here act only as a primer for the vast amount of work now being undertaken in Blue Photonics and we hope that they will serve as a catalyst for increased use of optics in the sea

Neuroimaging evidence implicating cerebellum in support of sensory/cognitive processes associated with thirst.

Recent studies implicate the cerebellum, long considered strictly a motor control structure, in cognitive, sensory, and affective phenomenon. The cerebellum, a phylogenetically ancient structure, has reciprocal ancient connections to the hypothalamus, a structure important in vegetative functions. The present study investigated whether the cerebellum was involved in vegetative functions and the primal emotions engendered by them. Using positron emission tomography, we examined the effects on the cerebellum of the rise of plasma sodium concentration and the emergence of thirst in 10 healthy adults. The correlation of regional cerebral blood flow with subjects' ratings of thirst showed major activation in the vermal central lobule. During the development of thirst, the anterior and posterior quadrangular lobule, lingula, and the vermis were activated. At maximum thirst and then during irrigation of the mouth with water to alleviate dryness, the cerebellum was less activated. However, 3 min after drinking to satiation, the anterior quadrangular lobule and posterior cerebellum were highly activated. The increased cerebellar activity was not related to motor behavior as this did not occur. Instead, responses in ancient cerebellar regions (vermis, fastigal nucleus, archicerebellum) may be more directly related to vegetative and affective aspects of thirst experiences, whereas activity in neocerebellar (posterior) regions may be related to sensory and cognitive aspects. Moreover, the cerebellum is apparently not involved in the computation of thirst per se but rather is activated during changes in thirst/satiation state when the brain is "vigilant" and is monitoring its sensory systems. Some neocerebellar activity may also reflect an intentionality for gratification by drinking inherent in the consciousness of thirst

Benefits and pitfalls of scientific research during undergraduate medical education

Objective: The integration of scientific research into medical education is a widely discussed topic. Most research training programs are offered on a voluntary basis. In Germany, it is mandatory to complete a doctoral thesis to obtain the academic title “doctor”. The reasons why students start a dissertation project and the influence of this project on their undergraduate studies and later career choices are not well known

Association between cognitive performance and cortical glucose metabolism in patients with mild Alzheimer's disease

Background: Neuronal and synaptic function in Alzheimer's disease (AD) is measured in vivo by glucose metabolism using positron emission tomography (PET). Objective: We hypothesized that neuronal activation as measured by PET is a more sensitive index of neuronal dysfunction than activity during rest. We investigated if the correlations between dementia severity as measured with the Mini Mental State Examination (MMSE) and glucose metabolism are an artifact of brain atrophy. Method: Glucose metabolism was measured using {[}F-18]fluorodeoxyglucose PET during rest and activation due to audiovisual stimulation in 13 mild to moderate AD patients (MMSE score >= 17). PET data were corrected for brain atrophy. Results: In the rest condition, glucose metabolism was correlated with the MMSE score primarily within the posterior cingulate and parietal lobes. For the activation condition, additional correlations were within the primary and association audiovisual areas. Most local maxima remained significant after correcting for brain atrophy. Conclusion: PET activity measured during audiovisual stimulation was more sensitive to functional alterations in glucose metabolism in AD patients compared to the resting PET. The association between glucose metabolism and MMSE score was not dependent on brain atrophy. Copyright (C) 2005 S. Karger AG, Basel

Attentive Learning of Sequential Handwriting Movements: A Neural Network Model

Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)

Neurobiology of functional (psychogenic) movement disorders.

PURPOSE OF REVIEW: This review explores recent developments in understanding the neurobiological mechanism of functional (psychogenic) movement disorders (FMDs). This is particularly relevant given the resurgence of academic and clinical interest in patients with functional neurological symptoms and the clear shift in diagnostic and treatment approaches away from a pure psychological model of functional symptoms. RECENT FINDINGS: Recent research findings implicate three key processes in the neurobiology of FMD (and by extension other functional neurological symptoms): abnormal attentional focus, abnormal beliefs and expectations, and abnormalities in sense of agency. These three processes have been combined in recent neurobiological models of FMD in which abnormal predictions related to movement are triggered by self-focused attention, and the resulting movement is generated without the normal sense of agency that accompanies voluntary movement. SUMMARY: New understanding of the neurobiology of FMD forms an important part of reappraising the way that patients with FMD (and other functional disorders) are characterized and treated. It also provides a testable framework for further exploring the pathophysiology of these common causes of ill health

The Flip Side of Distractibility-Executive Dysfunction in Functional Movement Disorders.

Attention plays a crucial role in functional neurological disorders. Attention to the symptoms leads to their exacerbation and distraction to their improvement or even transitory disappearance. Objective: The aim was to test if the alerting, orienting and particularly the executive aspect of attention are affected in functional movement disorders. Methods: Thirty patients with a functional movement disorder, 30 patients with an organic movement disorder and 30 healthy controls performed the attention network test. Results: The alerting and orienting effects were normal, but executive control of attention under conflict was abnormal in patients with functional movement disorders, compared to patients with an organic movement disorder and healthy controls. Conclusion: Executive dysfunction seems to be an important secondary feature of functional movement disorders, due to the overutilization of attentional resources for explicit movement control. Furthermore, it provides an explanation for seemingly unrelated symptoms commonly associated with functional movement disorders, such as concentration difficulties and fatigue

Cerebral activations related to ballistic, stepwise interrupted and gradually modulated movements in parkinson patients

Patients with Parkinson's disease (PD) experience impaired initiation and inhibition of movements such as difficulty to start/stop walking. At single-joint level this is accompanied by reduced inhibition of antagonist muscle activity. While normal basal ganglia (BG) contributions to motor control include selecting appropriate muscles by inhibiting others, it is unclear how PD-related changes in BG function cause impaired movement initiation and inhibition at single-joint level. To further elucidate these changes we studied 4 right-hand movement tasks with fMRI, by dissociating activations related to abrupt movement initiation, inhibition and gradual movement modulation. Initiation and inhibition were inferred from ballistic and stepwise interrupted movement, respectively, while smooth wrist circumduction enabled the assessment of gradually modulated movement. Task-related activations were compared between PD patients (N = 12) and healthy subjects (N = 18). In healthy subjects, movement initiation was characterized by antero-ventral striatum, substantia nigra (SN) and premotor activations while inhibition was dominated by subthalamic nucleus (STN) and pallidal activations, in line with the known role of these areas in simple movement. Gradual movement mainly involved antero-dorsal putamen and pallidum. Compared to healthy subjects, patients showed reduced striatal/SN and increased pallidal activation for initiation, whereas for inhibition STN activation was reduced and striatal-thalamo-cortical activation increased. For gradual movement patients showed reduced pallidal and increased thalamo-cortical activation. We conclude that PD-related changes during movement initiation fit the (rather static) model of alterations in direct and indirect BG pathways. Reduced STN activation and regional cortical increased activation in PD during inhibition and gradual movement modulation are better explained by a dynamic model that also takes into account enhanced responsiveness to external stimuli in this disease and the effects of hyper-fluctuating cortical inputs to the striatum and STN in particular

Involvement of the subthalamic nucleus in engagement with behaviourally relevant stimuli

In this study we investigate how the basal ganglia (BG) may process the behavioural relevance of environmental cues by recording local field potentials (LFPs) in the subthalamic nucleus of patients with Parkinson’s disease who had undergone implantation of electrodes for deep brain stimulation. Fourteen patients were recorded as they performed a paradigm dissociating warning cue presentation from programming related to execution of specific tasks. Target and non-target warning cues of differing behavioural relevance were contrasted, and we evaluated if warning cue-evoked activities varied according to whether the eventual task to be performed was motor or cognitive and whether patients were receiving or withdrawn from dopaminergic therapy. Warning cues evoked a complex temporal sequence of activities with three epochs over the 760 ms following the onset of the warning cue. In contrast to the initial evoked LFP, evoked activities over two later periods were significantly influenced by behavioural relevance and by treatment state. The early activity was likely related to the initial orientating of attention induced by a novel target, while the delayed responses in our paradigm may reflect processing related to the non-motor resource implications of cues. The results suggest that the BG are intimately involved in the evaluation of changes in the environment and of their behavioural significance. The latter process is partly modulated by dopamine. Weakness in this function might contribute to the behavioural impairment that can follow BG lesions and surgery

Pain Intensity and Functional Outcomes for Activities of Daily Living, Gait and Balance in Older Adults Accessing Outpatient Rehabilitation Services: A Retrospective Study

Purpose: Older adults are referred for outpatient physical therapy to improve their functional capacities. The goal of the present study was to determine if pain had an influence on functional outcomes in older adults who took part in an outpatient physical rehabilitation program. Patients and Methods: A retrospective study was performed on the medical records of patients aged 65 and over referred for outpatient physical therapy to improve physical functioning (n=178). Pain intensity (11-point numeric pain scale) and results from functional outcome measures (Timed Up and Go [TUG], Berg Balance Scale [BBS], 10-meter walk test, 6-minute walk test and Functional Autonomy Measuring System [SMAF]) were extracted at initial (T1) and final (T2) consultations. Paired t-tests were performed to determine if there were differences in functional outcome measures between T1 and T2 in all the patients. Patients were stratified to those with pain (PAIN, n=136) and those without pain (NO PAIN, n=42). Differences in functional outcome measures between T1 and T2 (delta scores) were compared between groups with independent t-tests with Welch corrections for unequal variances. Pearson correlation coefficients between initial pain intensity and changes in functional outcome measures (T2-T1) were also performed. Correcting for multiple comparisons, a p-value of p≤ 0.01 was considered as statistically significant. Results: The TUG, BBS, 10-meter walk test, 6-minute walk test all demonstrated improvement between T1 and T2 (all p 0.10). Conclusion: These results suggest that pain is not an impediment to functional improvements in older individuals who participated in an outpatient physical rehabilitation program