Bisphenol A Exposure Induces Sensory Processing Deficits in Larval Zebrafish during Neurodevelopment

Because of their ex utero development, relatively simple nervous system, translucency, and availability of tools to investigate neural function, larval zebrafish are an exceptional model for understanding neurodevelopmental disorders and the consequences of environmental toxins. Furthermore, early in development, zebrafish larvae easily absorb chemicals from water, a significant advantage over methods required to expose developing organisms to chemical agents in utero Bisphenol A (BPA) and BPA analogs are ubiquitous environmental toxins with known molecular consequences. All humans have measurable quantities of BPA in their bodies. Most concerning, the level of BPA exposure is correlated with neurodevelopmental difficulties in people. Given the importance of understanding the health-related effects of this common toxin, we have exploited the experimental advantages of the larval zebrafish model system to investigate the behavioral and anatomic effects of BPA exposure. We discovered that BPA exposure early in development leads to deficits in the processing of sensory information, as indicated by BPA's effects on prepulse inhibition (PPI) and short-term habituation (STH) of the C-start reflex. We observed no changes in locomotion, thigmotaxis, and repetitive behaviors (circling). Despite changes in sensory processing, we detected no regional or whole-brain volume changes. Our results show that early BPA exposure can induce sensory processing deficits, as revealed by alterations in simple behaviors that are mediated by a well-defined neural circuit.

The importance of air quality for underground spaces: An international survey of public attitudes

Space is a resource that is constantly being depleted, especially in mega-cities. Underground workspaces (UGS) are increasingly being included in urban plans and have emerged as an essential component of vertical cities. While progress had been made on the engineering aspects associated with the development of high-quality UGS, public attitudes toward UGS as work environments (ie, the public's design concerns with UGS) are relatively unknown. Here, we present the first large-scale study examining preferences and attitudes toward UGS, surveying close to 2000 participants from four cities in three continents (Singapore, Shanghai, London, and Montreal). Contrary to previous beliefs, air quality (and not lack of windows) is the major concern of prospective occupants. Windows, temperature, and lighting emerged as additional important building performance aspects for UGS. Early adopters (ie, individuals more willing to accept UGS and thus more likely to be the first occupants) across all cities prioritized air quality. Present results suggest that (perceived) air quality is a key building performance aspect for UGS that needs to be communicated to prospective occupants as this will improve their attitudes and views toward UGS. This study highlights the importance of indoor air quality for the public.

Flexible versus Fixed Spatial Self-Ordered Response Sequencing: Effects of Inactivation and Neurochemical Modulation of Ventrolateral Prefrontal Cortex

Previously, studies using human neuroimaging and excitotoxic lesions in non-human primate have demonstrated an important role of ventrolateral prefrontal cortex (vlPFC) in higher order cognitive functions such as cognitive flexibility and the planning of behavioral sequences. In the present experiments, we tested effects on performance of temporary inactivation (using GABA receptor agonists) and dopamine (DA) D2 and 5-HT2A-receptor (R) blockade of vlPFC via local intracerebral infusions in the marmoset. We trained common marmosets to perform spatial self-ordered sequencing tasks in which one cohort of animals performed two and three response sequences on a continuously varying spatial array of response options on a touch-sensitive screen. Inactivation of vlPFC produced a marked disruption of accuracy of sequencing which also exhibited significant error perseveration. There were somewhat contrasting effects of D2 and 5-HT2A-R blockade, with the former producing error perseveration on incorrect trials, though not significantly impairing accuracy overall, and the latter significantly impairing accuracy but not error perseveration. A second cohort of marmosets were directly compared on performance of fixed versus variable spatial arrays. Inactivation of vlPFC again impaired self-ordered sequencing, but only with varying, and not fixed spatial arrays, the latter leading to the consistent use of fewer, preferred sequences. These findings add to evidence that vlPFC is implicated in goal-directed behavior that requires higher-order response heuristics that can be applied flexibly over different (variable), as compared with fixed stimulus exemplars. They also show that dopaminergic and serotonergic chemomodulation has distinctive effects on such performance.SIGNIFICANCE STATEMENT This investigation employing local intracerebral infusions to inactivate the lateral prefrontal cortex (PFC) of the New World marmoset reveals the important role of this region in self-ordered response sequencing in variable but not fixed spatial arrays. These novel findings emphasize the higher order functions of this region, contributing to cognitive flexibility and planning of goal directed behavior. The investigation also reports for the first time somewhat contrasting neuromodulatory deficits produced by infusions of dopamine (DA) D2 and 5-HT2A receptor (R) antagonists into the same region, of possible significance for understanding cognitive deficits produced by anti-psychotic drugs.

0632 The Correlation Between Severity of Obstructive Sleep Apnea and Patient Compliance

Introduction

Obstructive sleep apnea (OSA) is a prevalent disorder affecting 9-38% of the global population and is linked to multiple health complications. Continuous Positive Airway Pressure (CPAP) is regarded as the gold standard treatment for OSA, but its efficacy is limited by poor patient compliance. Studies have linked many clinical and lifestyle factors to CPAP adherence, but have produced conflicting outcomes. Based on the current literature, it is assumed patients diagnosed with severe OSA are more likely to be compliant with CPAP due to a greater improvement in quality of life. The goal of this study is to compare the compliance rate of CPAP for patients with mild, moderate, and severe OSA, as well as identify other potential predictors of CPAP compliance.

Methods

This study is a retrospective chart review of 100 patients who were newly diagnosed with OSA and started on CPAP between January 1, 2017 and January 1, 2018. Baseline demographic data, past medical history, OSA severity, Epworth sleepiness scale, and compliance to CPAP therapy were recorded. Compliance was defined as CPAP usage greater than four hours per night for at least 21 days per month.

Results

Mean follow-up time after CPAP initiation was 3.19 months. Overall 77% of patients were compliant to CPAP therapy, of which 48% were males and 52% were females (P=0.48). CPAP compliance rates for mild OSA (79.3%), moderate OSA (73.7%), and severe OSA (78.8%) showed no significant difference for independence (P=0.83) or correlation with compliance (P=0.99). Only seasonal allergic rhinitis showed a positive association with CPAP adherence (P=0.031) and depression showed a negative association (P=0.027).

Conclusion

The level of OSA severity is not a significant predictor of short-term CPAP compliance among newly diagnosed patients.

Support

Parkview Physicians Group, Indiana School of Medicine - Fort Wayne, and the Dr. Luis and Anne B Schneider Foundation.

Trajectories and Milestones of Cortical and Subcortical Development of the Marmoset Brain From Infancy to Adulthood

With increasing attention on the developmental causes of neuropsychiatric disorders, appropriate animal models are crucial to identifying causes and assessing potential interventions. The common marmoset is an ideal model as it has sophisticated social/emotional behavior, reaching adulthood within 2 years of birth. Magnetic resonance imaging was used in an accelerated longitudinal cohort (n = 41; aged 3–27 months; scanned 2–7 times over 2 years). Splines were used to model nonlinear trajectories of grey matter volume development in 53 cortical areas and 16 subcortical nuclei. Generally, volumes increased before puberty, peaked, and declined into adulthood. We identified 3 milestones of grey matter development: I) age at peak volume; II) age at onset of volume decline; and III) age at maximum rate of volume decline. These milestones differentiated growth trajectories of primary sensory/motor cortical areas from those of association cortex but also revealed distinct trajectories between association cortices. Cluster analysis of trajectories showed that prefrontal cortex was the most heterogenous of association regions, comprising areas with distinct milestones and developmental trajectories. These results highlight the potential of high-field structural MRI to define the dynamics of primate brain development and importantly to identify when specific prefrontal circuits may be most vulnerable to environmental impact.

Health Effects of Underground Workspaces cohort: study design and baseline characteristics

The development of underground workspaces is a strategic effort towards healthy urban growth in cities with ever-increasing land scarcity. Despite the growth in underground workspaces, there is limited information regarding the impact of this environment on workers' health. The Health Effects of Underground Workspaces (HEUW) study is a cohort study that was set up to examine the health effects of working in underground workspaces. In this paper, we describe the rationale for the study, study design, data collection, and baseline characteristics of participants. The HEUW study recruited 464 participants at baseline, of whom 424 (91.4%) were followed-up at 3 months and 334 (72.0%) at 12 months from baseline. We used standardized and validated questionnaires to collect information on socio-demographic and lifestyle characteristics, medical history, family history of chronic diseases, sleep quality, health-related quality of life, chronotype, psychological distress, occupational factors, and comfort levels with indoor environmental quality parameters. Clinical and anthropometric parameters including blood pressure, spirometry, height, weight, and waist and hip circumference were also measured. Biochemical tests of participants' blood and urine samples were conducted to measure levels of glucose, lipids, and melatonin. We also conducted objective measurements of individuals' workplace environment, assessing air quality, light intensity, temperature, thermal comfort, and bacterial and fungal counts. The findings this study will help to identify modifiable lifestyle and environmental parameters that are negatively affecting workers' health. The findings may be used to guide the development of more health-promoting workspaces that attempt to negate any potential deleterious health effects from working in underground workspaces.

Rapid habituation of a touch-induced escape response in Zebrafish (Danio rerio) Larvae

Zebrafish larvae have several biological features that make them useful for cellular investigations of the mechanisms underlying learning and memory. Of particular interest in this regard is a rapid escape, or startle, reflex possessed by zebrafish larvae; this reflex, the C-start, is mediated by a relatively simple neuronal circuit and exhibits habituation, a non-associative form of learning. Here we demonstrate a rapid form of habituation of the C-start to touch that resembles the previously reported rapid habituation induced by auditory or vibrational stimuli. We also show that touch-induced habituation exhibits input specificity. This work sets the stage for in vivo optical investigations of the cellular sites of plasticity that mediate habituation of the C-start in the larval zebrafish.

A Psychosocial Approach to Understanding Underground Spaces

With a growing need for usable land in urban areas, subterranean development has been gaining attention. While construction of large underground complexes is not a new concept, our understanding of various socio-cultural aspects of staying underground is still at a premature stage. With projected emergence of underground built environments, future populations may spend much more of their working, transit, and recreational time in underground spaces. Therefore, it is essential to understand the challenges and advantages that such environments have to improve the future welfare of users of underground spaces. The current paper discusses various psycho-social aspects of underground spaces, the impact they can have on the culture shared among the occupants, and possible solutions to overcome some of these challenges.

Role of protein synthesis and DNA methylation in the consolidation and maintenance of long-term memory in Aplysia

Previously, we reported that long-term memory (LTM) in Aplysia can be reinstated by truncated (partial) training following its disruption by reconsolidation blockade and inhibition of PKM (Chen et al., 2014). Here, we report that LTM can be induced by partial training after disruption of original consolidation by protein synthesis inhibition (PSI) begun shortly after training. But when PSI occurs during training, partial training cannot subsequently establish LTM. Furthermore, we find that inhibition of DNA methyltransferase (DNMT), whether during training or shortly afterwards, blocks consolidation of LTM and prevents its subsequent induction by truncated training; moreover, later inhibition of DNMT eliminates consolidated LTM. Thus, the consolidation of LTM depends on two functionally distinct phases of protein synthesis: an early phase that appears to prime LTM; and a later phase whose successful completion is necessary for the normal expression of LTM. Both the consolidation and maintenance of LTM depend on DNA methylation.

Long-term habituation of the C-start escape response in zebrafish larvae

The cellular and molecular basis of long-term memory in vertebrates remains poorly understood. Knowledge regarding long-term memory has been impeded by the enormous complexity of the vertebrate brain, particularly the mammalian brain, as well as by the relative complexity of the behavioral alterations examined in most studies of long-term memory in vertebrates. Here, we demonstrate a long-term form of nonassociative learning-specifically, long-term habituation (LTH)-of a simple reflexive escape response, the C-start, in zebrafish larvae. The C-start is triggered by the activation of one of a pair of giant neurons in the zebrafish's hindbrain, the Mauthner cells. We show that LTH of the C-start requires the activity of NMDA receptors and involves macromolecular synthesis. We further show that the long-term habituated reflex can by rapidly dishabituated by a brief tactile stimulus. Our results set the stage for rigorous, mechanistic investigations of the long-term memory for habituation of a reflexive behavioral response, one that is mediated by a relatively simple, neurobiologically tractable, neural circuit. Moreover, the demonstration of NMDAR and transcriptionally dependent LTH in a translucent vertebrate organism should facilitate the use of optical recording, and optogenetic manipulation, of neuronal activity to elucidate the cellular basis of a long-term vertebrate memory.

Processing of Phonemic Consonant Length: Semantic and Fragment Priming Evidence from Bengali

Six cross-modal lexical decision tasks with priming probed listeners' processing of the geminate-singleton contrast in Bengali, where duration alone leads to phonemic contrast ([pata] 'leaf' vs. [pat:a] 'whereabouts'), in order to investigate the phonological representation of consonantal duration in the lexicon. Four form-priming experiments (auditory fragment primes and visual targets) were designed to investigate listeners' sensitivity to segments of conflicting duration. Each prime derived from a real word ([k(h)[symbol: see text]m]/[g(h)en:]) was matched with a mispronunciation of the opposite duration (*[k(h)[symbol: see text]m:]/*[g(h)en]) and both were used to prime the full words [k(h)[symbol: see text]ma] ('forgiveness') and [g(h)en:a] ('disgust') respectively. Although all fragments led to priming, the results showed an asymmetric pattern. The fragments of words with singletons mispronounced as geminates led to equal priming, while those with geminates mispronounced as singletons showed a difference. The priming effect of the real-word geminate fragment was significantly greater than that of its corresponding nonword singleton fragment. In two subsequent semantic priming tasks with full-word primes a stronger asymmetry was found: nonword geminates (*[k(h)[symbol: see text]m:a]) primed semantically related words ([marjona] 'forgiveness') but singleton nonword primes (*[ghena]) did not show priming. This overall asymmetry in the tolerance of geminate nonwords in place of singleton words is attributed to a representational mismatch and points towards a moraic representation of duration. While geminates require a mora which cannot be derived from singleton input, the additional information in geminate nonwords does not create a similar mismatch.

Reinstatement of long-term memory following erasure of its behavioral and synaptic expression in Aplysia

Long-term memory (LTM) is believed to be stored in the brain as changes in synaptic connections. Here, we show that LTM storage and synaptic change can be dissociated. Cocultures of Aplysia sensory and motor neurons were trained with spaced pulses of serotonin, which induces long-term facilitation. Serotonin (5HT) triggered growth of new presynaptic varicosities, a synaptic mechanism of long-term sensitization. Following 5HT training, two antimnemonic treatments-reconsolidation blockade and inhibition of PKM--caused the number of presynaptic varicosities to revert to the original, pretraining value. Surprisingly, the final synaptic structure was not achieved by targeted retraction of the 5HT-induced varicosities but, rather, by an apparently arbitrary retraction of both 5HT-induced and original synapses. In addition, we find evidence that the LTM for sensitization persists covertly after its apparent elimination by the same antimnemonic treatments that erase learning-related synaptic growth. These results challenge the idea that stable synapses store long-term memories.

Learning and memory in zebrafish larvae

Larval zebrafish possess several experimental advantages for investigating the molecular and neural bases of learning and memory. Despite this, neuroscientists have only recently begun to use these animals to study memory. However, in a relatively short period of time a number of forms of learning have been described in zebrafish larvae, and significant progress has been made toward their understanding. Here we provide a comprehensive review of this progress; we also describe several promising new experimental technologies currently being used in larval zebrafish that are likely to contribute major insights into the processes that underlie learning and memory.

Habituation of the C-start response in larval zebrafish exhibits several distinct phases and sensitivity to NMDA receptor blockade

The zebrafish larva has been a valuable model system for genetic and molecular studies of development. More recently, biologists have begun to exploit the surprisingly rich behavioral repertoire of zebrafish larvae to investigate behavior. One prominent behavior exhibited by zebrafish early in development is a rapid escape reflex (the C-start). This reflex is mediated by a relatively simple neural circuit, and is therefore an attractive model behavior for neurobiological investigations of simple forms of learning and memory. Here, we describe two forms of short-lived habituation of the C-start in response to brief pulses of auditory stimuli. A rapid form, persisting for ≥1 min but <15 min, was induced by 120 pulses delivered at 0.5–2.0 Hz. A more extended form (termed “short-term habituation” here), which persisted for ≥25 min but <1 h, was induced by spaced training. The spaced training consisted of 10 blocks of auditory pulses delivered at 1 Hz (5 min interblock interval, 900 pulses per block). We found that these two temporally distinguishable forms of habituation are mediated by different cellular mechanisms. The short-term form depends on activation of N-methyl-d-aspartate receptors (NMDARs), whereas the rapid form does not.

Synaptic dysfunction and abnormal behaviors in mice lacking major isoforms of Shank3

SHANK3 is a synaptic scaffolding protein enriched in the postsynaptic density (PSD) of excitatory synapses. Small microdeletions and point mutations in SHANK3 have been identified in a small subgroup of individuals with autism spectrum disorder (ASD) and intellectual disability. SHANK3 also plays a key role in the chromosome 22q13.3 microdeletion syndrome (Phelan-McDermid syndrome), which includes ASD and cognitive dysfunction as major clinical features. To evaluate the role of Shank3 in vivo, we disrupted major isoforms of the gene in mice by deleting exons 4-9. Isoform-specific Shank3(e4-9) homozygous mutant mice display abnormal social behaviors, communication patterns, repetitive behaviors and learning and memory. Shank3(e4-9) male mice display more severe impairments than females in motor coordination. Shank3(e4-9) mice have reduced levels of Homer1b/c, GKAP and GluA1 at the PSD, and show attenuated activity-dependent redistribution of GluA1-containing AMPA receptors. Subtle morphological alterations in dendritic spines are also observed. Although synaptic transmission is normal in CA1 hippocampus, long-term potentiation is deficient in Shank3(e4-9) mice. We conclude that loss of major Shank3 species produces biochemical, cellular and morphological changes, leading to behavioral abnormalities in mice that bear similarities to human ASD patients with SHANK3 mutations.

Influence of the NR3A subunit on NMDA receptor functions

Various combinations of subunits assemble to form the NMDA-type glutamate receptor (NMDAR), generating diversity in its functions. Here we review roles of the unique NMDAR subunit, NR3A, which acts in a dominant-negative manner to suppress receptor activity. NR3A-containing NMDARs display striking regional and temporal expression specificity, and, unlike most other NMDAR subtypes, they have a low conductance, are only modestly permeable to Ca(2+), and pass current at hyperpolarized potentials in the presence of magnesium. While glutamate activates triheteromeric NMDARs composed of NR1/NR2/NR3A subunits, glycine is sufficient to activate diheteromeric NR1/NR3A-containing receptors. NR3A dysfunction may contribute to neurological disorders involving NMDARs, and the subunit offers an attractive therapeutic target given its distinct pharmacological and structural properties.

Opposing effects of 5,7-DHT infusions into the orbitofrontal cortex and amygdala on flexible responding

Central serotonin is implicated in a variety of emotional and behavioral control processes. Serotonin depletion can lead to exaggerated aversive processing and deficient response inhibition, effects that have been linked to serotonin's actions in the amygdala and orbitofrontal cortex (OFC), respectively. However, a direct comparison of serotonin manipulations within the OFC and amygdala in the same experimental context has not been undertaken. This study compared the effects of infusing the serotonin neurotoxin, 5,7-dihydroxytryptamine into the OFC and amygdala of marmosets performing an appetitive test of response inhibition. Marmosets had to learn to inhibit a prepotent response tendency to choose a box containing high-incentive food and instead choose a box containing low-incentive food, to obtain reward. OFC infusions caused long-lasting reductions in serotonin tissue levels, as revealed at postmortem, and exaggerated prepotent responses. In contrast, the significantly reduced prepotent responses following amygdala infusions occurred at a time when serotonin tissue levels had undergone considerable recovery, but there remained residual reductions in extracellular serotonin, in vivo. These opposing behavioral effects of serotonin manipulations in the same experimental context may be understood in terms of the top-down regulatory control of the amygdala by the OFC.

Sensitivity of candidate markers of psychophysiological strain to cyclical changes in manual control load during simulated process control

Complex systems are vulnerable to unpredictable breakdowns in operator performance. Although primary task goals are typically protected by compensatory effort, such protection may break down under fatigue and high strain. Detection of strain states would enable prediction of increased operational risk through adaptive automation, triggering a switch of control from human to computer. A simulated process control task was used to identify markers of strain under a cyclic loading procedure, which forced performance breakdown through stepwise changes in control load. Four trained participants provided data on control performance and a range of candidate psychophysiological markers of strain (two EEG power ratios and HRV). Within-individual analyses showed the strongest sensitivity for 'task load index' (TLI), an EEG measure based on executive control activity in frontal brain areas, though all measures were sensitive for some participants. The implications of such findings for the development of a closed loop system for adaptive automation are discussed.

Downregulation of NR3A-containing NMDARs is required for synapse maturation and memory consolidation

NR3A is the only NMDA receptor (NMDAR) subunit that downregulates sharply prior to the onset of sensitive periods for plasticity, yet the functional importance of this transient expression remains unknown. To investigate whether removal/replacement of juvenile NR3A-containing NMDARs is involved in experience-driven synapse maturation, we used a reversible transgenic system that prolonged NR3A expression in the forebrain. We found that removal of NR3A is required to develop strong NMDAR currents, full expression of long-term synaptic plasticity, a mature synaptic organization characterized by more synapses and larger postsynaptic densities, and the ability to form long-term memories. Deficits associated with prolonged NR3A were reversible, as late-onset suppression of transgene expression rescued both synaptic and memory impairments. Our results suggest that NR3A behaves as a molecular brake to prevent the premature strengthening and stabilization of excitatory synapses and that NR3A removal might thereby initiate critical stages of synapse maturation during early postnatal neural development.

COERCION AND DRUG TREATMENT FOR POSTPARTUM WOMEN

This research examined the extent to which various indicators of coercion were related to treatment retention in a gender-specific treatment program and a traditional outpatient program for pregnant and postpartum women who were mandated to enter treatment. Women who were given custody of their infant stayed in treatment longer than women who did not have custody. There was an interaction effect with women who had custody and were in the intensive day treatment program completing treatment at a much higher rate than those in the traditional program. Implications for social work professionals and policy makers are discussed.

Ube3a is required for experience-dependent maturation of the neocortex

Experience-dependent maturation of neocortical circuits is required for normal sensory and cognitive abilities, which are distorted in neurodevelopmental disorders. We tested whether experience-dependent neocortical modifications require Ube3a, an E3 ubiquitin ligase whose dysregulation has been implicated in autism and Angelman syndrome. Using visual cortex as a model, we found that experience-dependent maturation of excitatory cortical circuits was severely impaired in Angelman syndrome model mice deficient in Ube3a. This developmental defect was associated with profound impairments in neocortical plasticity. Normal plasticity was preserved under conditions of sensory deprivation, but was rapidly lost by sensory experiences. The loss of neocortical plasticity is reversible, as late-onset visual deprivation restored normal synaptic plasticity. Furthermore, Ube3a-deficient mice lacked ocular dominance plasticity in vivo when challenged with monocular deprivation. We conclude that Ube3a is necessary for maintaining plasticity during experience-dependent neocortical development and suggest that the loss of neocortical plasticity contributes to deficits associated with Angelman syndrome.

Differential contributions of dopamine and serotonin to orbitofrontal cortex function in the marmoset

We have shown previously that the inhibitory control functions of the orbitofrontal cortex (OFC) are disrupted by serotonin, but not dopamine depletions. However, both dopamine and serotonin terminals and receptors are present within the OFC and thus the aim of the present study was to determine the differential contributions of these neurotransmitters to orbitofrontal function. OFC and dopamine are involved in the process by which neutral stimuli take on reinforcing properties, by virtue of their prior association with reward, and guide behavior. Thus, we compared the performance of marmosets with dopaminergic or serotoninergic OFC depletions on a test of conditioned reinforcement. To further our understanding of serotonin in behavioral flexibility, the effect of these depletions was also compared on the extinction of a visual discrimination. Monkeys with serotonin depletions of the OFC displayed stimulus-bound responding on both tests of conditioned reinforcement and discrimination extinction suggesting that orbitofrontal serotonin plays a specific role in preventing competing, task irrelevant, salient stimuli from biasing responding. In contrast, monkeys with dopamine depletion were insensitive to conditioned reinforcers and displayed persistent responding in the absence of reward in extinction, a pattern of deficits that may reflect basic deficits in the associative processing of reward.

The role of the orbitofrontal cortex and medial striatum in the regulation of prepotent responses to food rewards

An impairment in learning to inhibit prepotent responses to positive stimuli is associated with damage to the orbitofrontal cortex (OFC) in rats, monkeys, and humans performing discrimination reversal, extinction, and detour reaching tasks. In contrast, a recent study showed that OFC-lesioned rhesus monkeys could learn to select the smaller of 2 quantities of food reward in order to receive the larger reward, at an equivalent rate to controls, despite the requirement to inhibit a prepotent response. Given this result, the aim of the present study was to further specify the contexts under which the OFC regulates responding and to identify additional components of limbic circuitry that contribute to such regulation. Marmosets with lesions of the OFC and medial striatum (MS), but not the amygdala, made more prepotent responses to a clear Perspex box containing high incentive food before learning to choose the box containing low incentive food, to obtain reward. However, having learned the incongruent incentive discrimination OFC- and MS-lesioned monkeys were impaired upon reversal of the reward contingencies, repeatedly selecting the previously rewarded low incentive object. These findings identify the critical contribution of the OFC and MS in the regulation of responding by affective cues.

NMDA receptor antagonists reveal age-dependent differences in the properties of visual cortical plasticity

The suggestion that NMDA receptor (NMDAR)-dependent plasticity is subunit specific, with NR2B-types required for long-term depression (LTD) and NR2A-types critical for the induction of long-term potentiation (LTP), has generated much attention and considerable debate. By investigating the suggested subunit-specific roles of NMDARs in the mouse primary visual cortex over development, we report several important findings that clarify the roles of NMDAR subtypes in synaptic plasticity. We observed that LTD was not attenuated by application of ifenprodil, an NR2B-type antagonist, or NVP-AAM007, a less selective NR2A-type antagonist. However, we were surprised that NVP-AAM007 completely blocked adult LTP (postnatal day (P) 45-90), while only modestly affecting juvenile LTP (P21-28). To assess whether this developmental transition reflected an increasing role for NR2A-type receptors with maturity, we characterized the specificity of NVP-AAM007. We found not only that NVP-AAM007 lacks discernable subunit specificity but also that the effects of NVP-AAM077 on LTP could be mimicked using subsaturating concentrations of APV, a global NMDAR antagonist. These results indicate that the effects of NVP-AAM077 on synaptic plasticity are largely explained by nonspecific blockade of NMDARs. Moreover our findings are the first to reveal a developmental increase in the sensitivity of LTP to NMDAR antagonism. We suggest that discrepant reports describing the effect of NVP-AAM077 on LTP may be partially explained by this developmental shift in the properties of LTP. These results indicate that the degree of NMDAR activation required for LTP increases with development, providing insight into a novel underlying mechanism governing the properties of synaptic plasticity.

Melatonin and the brain in photoperiodic mammals

The reproductive cycle of photoperiodic species is driven by seasonal changes in daylength. The pineal gland transduces photic information into an endocrine signal. The duration of the nocturnal bout of melatonin secretion is a direct indicator of night-length. The circadian rhythm of melatonin production is driven by a multisynaptic pathway from the suprachiasmatic nuclei (SCN), via the parvocellular portion of the paraventricular nucleus to the preganglionic sympathetic neurons of the thoracic spinal cord. The melatonin signal acts as an interval timer. The cellular basis of the detection of the signal is unknown. The site of detection is possibly within the anterior hypothalamus. The SCN are not essential components of the system that responds to the pineal interval timer. Photoperiod and the pineal melatonin signal have pronounced effects on the function of endogenous opioids, which are probably related to changes in the neuroendocrine mechanisms that regulate gonadotropin release.

Developmental regulation of the NMDA receptor subunits, NR3A and NR1, in human prefrontal cortex

Subunit composition of N-methyl-D-aspartate-type glutamate receptors (NMDARs) dictates their function, yet the ontogenic profiles of human NMDAR subunits from gestation to adulthood have not been determined. We examined NMDAR mRNA and protein development in human dorsolateral prefrontal cortex (DLPFC), an area in which NMDARs are critical for higher cognitive processing and NMDAR hypofunction is hypothesized in schizophrenia. Using quantitative reverse transcriptase-polymerase chain reaction and western blotting, we found NR1 expression begins low prenatally, peaks in adolescence, yet remains high throughout life, suggesting lifelong importance of NMDAR function. In contrast, NR3A levels are low during gestation, surge soon after birth, and decline progressively through adolescence and into adulthood. Because NR3A subunits uniquely attenuate NMDAR-mediated currents, limit calcium influx, and suppress dendritic spine formation, high levels during early childhood may be important for regulating neuroprotection and activity-dependent sculpting of synapses. We also examined whether subunit changes underlie reduced NMDAR activity in schizophrenia. Our results reveal normal NR1 and NR3A protein levels in DLPFC from schizophrenic patients, indicating that NMDAR hypofunction is unlikely to be maintained by gross changes in NR3A-containing NMDARs or overall NMDAR numbers. These data provide insights into NMDAR functions in the developing CNS and will contribute to designing pharmacotherapies for neurological disorders.

Synergistic and Regulatory Effects of Orbitofrontal Cortex on Amygdala-Dependent Appetitive Behavior

This paper will review two avenues of our research in marmosets that have focused on the role of the orbitofrontal cortex (OFC) in amygdala-dependent appetitive behavior. The first demonstrates the important contribution of both the OFC and the amygdala to conditioned reinforcement (CRF). The second reveals the regulatory effects of the OFC on amygdala-dependent autonomic and behavioral arousal in appetitive conditioning. The process of CRF is one way in which an environmental cue can guide emotional behavior. As a consequence of its previous relationship with reward, a cue can take on affective value and reinforce behavior. Lesion studies in marmosets are described that show that CRF is dependent upon both the amygdala and OFC. The synergistic interactions between these structures that have been shown to underlie other aspects of reward processing are then considered with respect to CRF. The results are contrasted with those that show the importance of the OFC in suppressing positive affective responses elicited by the amygdala in response to a conditioned stimulus (CS). Specifically, it will be shown that the OFC is involved in the rapid suppression of conditioned autonomic arousal upon CS withdrawal and in the co-ordination of conditioned autonomic and behavioral responses when adapting to changing reward contingencies. It will be argued that, overall, the OFC plays a critical role in the context-dependent regulation of positive affective responding governed by external cues, in keeping with a role in executive control.

Differential Regulation of Fronto-Executive Function by the Monoamines and Acetylcholine

The prefrontal cortex (PFC) is innervated by the monoamines, dopamine (DA), noradrenaline (NA), and serotonin, as well as acetylcholine, and the marked influence of these neurochemical systems on prefrontal working memory processes has been widely described. However, their potentially, differential contribution to prefrontal functioning is less well understood. This paper reviews evidence to support the hypothesis that these neurochemical systems recruit distinct fronto-executive operations. Direct comparison of the effects of manipulations of these neuromodulators within PFC on performance of an attentional set-shifting paradigm reveals their differential contribution to distinct task stages. Depletion of prefrontal serotonin selectively disrupts reversal learning but not attentional set formation or set shifting. In contrast, depletion of prefrontal DA disrupts set formation but not reversal learning. NA depletion on the other hand specifically impairs set-shifting, whereas its effects on reversal learning remain unclear. Finally, depletion of prefrontal acetylcholine has no effect on either set formation or set shifting but impairs serial reversal learning. Because these neurochemical systems are known to represent distinct states of stress, arousal, attention, and affect, it is postulated that they augment the different types of executive operation that are recruited and performed within these states via a synergistic interaction with the PFC.

Selective prefrontal serotonin depletion impairs acquisition of a detour-reaching task

We have recently shown that serotonin in the primate orbitofrontal cortex (OFC) contributes to the flexible control of behaviour. 5,7-dihydroxytryptamine-induced 5-HT depletions of OFC impair performance on a serial reversal discrimination task [Clarke et al. (2004)Science, 304, 878-880]. The deficit is characterized by perseverative responding to the previously rewarded stimulus, a deficit similar to that seen following lesions of the intrinsic neurones of the OFC [Dias et al. (1996)Nature, 380, 69-72]. The effect is neurochemically selective as dopaminergic lesions of the OFC, induced by 6-hydroxydopamine, have no effect [Clarke et al. (2006)Cerebral Cortex]. In order to test for the generality of the effect of serotonin on orbitofrontal processing and, in particular, its effects on flexible behaviour, the present study investigated the effects of serotonin depletions of OFC on performance of another task dependent upon an intact OFC, the detour-reaching task [Wallis et al. (2001)European Journal of Neuroscience, 13, 1797-1808]. Successful performance of this task requires inhibition of the animal's prepotent response tendency to reach directly along its line of sight to the reward. Compared with sham-operated controls, we found that lesioned monkeys made significantly more barrier reaches directly along their line of sight to the visible reward during task acquisition. This finding provides further support for the role of prefrontal serotonin in inhibitory control processes specifically in tasks sensitive to OFC dysfunction.

Synaptic facilitation and behavioral dishabituation in Aplysia: dependence on release of Ca2+ from postsynaptic intracellular stores, postsynaptic exocytosis, and modulation of postsynaptic AMPA receptor efficacy

Sensitization and dishabituation of the defensive withdrawal reflex in Aplysia have been ascribed to presynaptic mechanisms, particularly presynaptic facilitation of transmission at sensorimotor synapses in the CNS of Aplysia. Here, we show that facilitation of sensorimotor synapses in cell culture during and after serotonin (5-HT) exposure depends on a rise in postsynaptic intracellular Ca(2+) and release of Ca(2+) from postsynaptic stores. We also provide support for the idea that postsynaptic AMPA receptor insertion mediates a component of synaptic facilitation by showing that facilitation after 5-HT offset is blocked by injecting botulinum toxin, an exocytotic inhibitor, into motor neurons before application of 5-HT. Using a reduced preparation, we extend our results to synaptic facilitation in the abdominal ganglion. We show that tail nerve shock-induced facilitation of siphon sensorimotor synapses also depends on elevated postsynaptic Ca(2+) and release of Ca(2+) from postsynaptic stores and recruits a late phase of facilitation that involves selective enhancement of the AMPA receptor-mediated synaptic response. To examine the potential role of postsynaptic exocytosis of AMPA receptors in learning in Aplysia, we test the effect of injecting botulinum toxin into siphon motor neurons on dishabituation of the siphon-withdrawal reflex. We find that postsynaptic injections of the toxin block dishabituation resulting from tail shock. Our results indicate that postsynaptic mechanisms, particularly Ca(2+)-dependent modulation of AMPA receptor trafficking, play a critical role in synaptic facilitation as well as in dishabituation and sensitization in Aplysia.

Cognitive Inflexibility after Prefrontal Serotonin Depletion Is Behaviorally and Neurochemically Specific

We have previously demonstrated that prefrontal serotonin depletion impairs orbitofrontal cortex (OFC)-mediated serial discrimination reversal (SDR) learning but not lateral prefrontal cortex (PFC)-mediated attentional set shifting. To address the neurochemical specificity of this reversal deficit, Experiment 1 compared the effects of selective serotonin and selective dopamine depletions of the OFC on performance of the SDR task. Whereas serotonin depletions markedly impaired performance, OFC dopamine depletions were without effect. The behavioral specificity of this reversal impairment was investigated in Experiment 2 by examining the effect of OFC serotonin depletion on performance of a modified SDR task designed to distinguish between 3 possible causes of the impairment. The results showed that the reversal deficit induced by prefrontal serotonin depletion was not due to a failure to approach a previously unrewarded stimulus (enhanced learned avoidance) or reduced proactive interference. Instead, it was due specifically to a failure to inhibit responding to the previously rewarded stimulus. The neurochemical and behavioral specificity of this particular form of cognitive inflexibility is of particular relevance to our understanding of the aetiology and treatment of inflexible behavior apparent in many neuropsychiatric and neurodegenerative disorders involving the PFC.

Primate orbitofrontal cortex and adaptive behaviour

Orbitofrontal cortex contributes to behavioural adaptation in response to changes in the contingent relationship and incentive value of positive affective stimuli in the environment. This article integrates early descriptions of the effects of orbitofrontal ablation in monkeys, on object discrimination reversal and extinction, with contemporary theories of animal learning. Studies of incentive devaluation, conditioned reinforcement and changes in reward contingency are reviewed, highlighting the role of the orbitofrontal cortex in processing the affective and non-affective properties of rewarding stimuli, in reward expectation, and in goal selection. It is argued that future studies should focus on the interaction of the orbitofrontal cortex with peripheral arousal systems and the ascending monoamine systems in order to understand fully the role of the orbitofrontal cortex in behavioural adaptation.

Prefrontal serotonin depletion affects reversal learning but not attentional set shifting

Recently, we have shown that serotonin (5-HT) depletion from the prefrontal cortex (PFC) of the marmoset monkey impairs performance on a serial discrimination reversal (SDR) task, resulting in perseverative responding to the previously correct stimulus (Clarke et al., 2004). This pattern of impairment is just one example of inflexible responding seen after damage to the PFC, with performance on the SDR task being dependent on the integrity of the orbitofrontal cortex. However, the contribution of 5-HT to other forms of flexible responding, such as attentional set shifting, an ability dependent on lateral PFC (Dias et al., 1996a), is unknown. The present study addresses this issue by examining the effects of 5,7-dihydroxytryptamine-induced PFC 5-HT depletions on the ability to shift attention between two perceptual dimensions of a compound visual stimulus (extradimensional shift). Monkeys with selective PFC 5-HT lesions, despite being impaired in their ability to reverse a stimulus-reward association, were unimpaired in their ability to make an extradimensional shift when compared with sham-operated controls. These findings suggest that 5-HT is critical for flexible responding at the level of changing stimulus-reward contingencies but is not essential for the higher-order shifting of attentional set. Thus, psychological functions dependent on different loci within the PFC are differentially sensitive to serotonergic modulation, a finding of relevance to our understanding of cognitive inflexibility apparent in disorders such as obsessive-compulsive disorder and schizophrenia.

Acquisition of instrumental conditioned reinforcement is resistant to the devaluation of the unconditioned stimulus

The associative mechanisms responsible for the efficacy of Pavlovian stimuli during first- and second-order conditioning have been extensively studied, but little is known about the representations underlying instrumental conditioned reinforcement. The present study investigated the associative structure underlying conditioned reinforcement, by employing an unconditioned stimulus (US) devaluation procedure on a commonly used instrumental task: the acquisition of a new response with conditioned reinforcement. Whilst US-directed behaviour was abolished following devaluation, the conditioned stimulus acting as a conditioned reinforcer supported the acquisition of instrumental responding. In this preparation then, the conditioned reinforcer appears to be impervious to devaluation of its associated US, suggesting that the underlying representation maintaining behaviour is independent of the current value of the US and may reflect the activation of a central appetitive motivational state.

Cognitive Inflexibility After Prefrontal Serotonin Depletion

Serotonergic dysregulation within the prefrontal cortex (PFC) is implicated in many neuropsychiatric disorders, but the precise role of serotonin within the PFC is poorly understood. Using a serial discrimination reversal paradigm, we showed that upon reversal, selective serotonin depletion of the marmoset PFC produced perseverative responding to the previously rewarded stimulus without any significant effects on either retention of a discrimination learned preoperatively or acquisition of a novel discrimination postoperatively. These results highlight the importance of prefrontal serotonin in behavioral flexibility and are highly relevant to obsessive-compulsive disorder, schizophrenia, and the cognitive sequelae of drug abuse in which perseveration is prominent.

Learning in Aplysia: looking at synaptic plasticity from both sides

Until recently, learning and memory in invertebrate organisms was believed to be mediated by relatively simple presynaptic mechanisms. By contrast, learning and memory in vertebrate organisms is generally thought to be mediated, at least in part, by postsynaptic mechanisms. But new experimental evidence from research using a model invertebrate organism, the marine snail Aplysia, indicates that this apparent distinction between invertebrate and vertebrate synaptic mechanisms of learning is invalid: learning in Aplysia cannot be explained in terms of exclusively presynaptic mechanisms. NMDA-receptor-dependent LTP appears to be necessary for classical conditioning in Aplysia. Furthermore, modulation of trafficking of postsynaptic ionotropic glutamate receptors underlies behavioral sensitization in this snail. Exclusively presynaptic processes appear to support only relatively brief memory in Aplysia. More persistent memory is likely to be mediated by postsynaptic processes, or by presynaptic processes whose expression depends upon retrograde signals.

Hematological and blood viscosity changes in tail-suspended rats

BACKGROUND

Fluid shifts during exposure to microgravity result in a decrease in plasma volume which can lead to a transient increase in hematocrit. This transient increase in hematocrit could result in an increased blood viscosity. Yet, hematocrit returns to near normal values within a matter of hours of microgravity exposure as a result of a reduction in red blood cell mass. Rat tail-suspension models mimic the fluid shifts and hematological changes associated with microgravity exposure.

METHODS

Tail-suspended rats were monitored for hematological and hemorheological changes over 4, 24, 72, and 168 h of tail suspension. Additionally, hematological and hemorheological changes were followed during recovery periods of 48, 120, and 192 h following 168 h of tail suspension.

RESULTS

Although hematocrit increased significantly by 4 h of suspension, blood viscosity did not differ from controls. However, blood viscosity was significantly greater in the 72-, 168-, and 168/48-h suspension groups relative to controls despite no significant differences in hematocrits between groups. Theoretical calculations of blood viscosity at hematocrits of 50 and 60% (values intended to mimic hematocrits that would occur if red blood cell mass did not decrease) show a significant increase relative to the blood viscosities determined for the actual hematocrits in the experimental groups.

CONCLUSIONS

The lowering of hematocrit associated with spaceflight may substantially reduce blood viscosity and thereby maintain the hematocrit at an optimal level for oxygen delivery to tissues.

Dissociable contributions of the orbitofrontal and lateral prefrontal cortex of the marmoset to performance on a detour reaching task

To gain insight into the nature and neural specificity of the relationship between simple problem solving, inhibitory control and prefrontal cortex, comparison of the effects of excitotoxic lesions of the orbitofrontal and lateral prefrontal cortex were examined on the performance of common marmosets on a detour reaching task. Monkeys were required to inhibit reaching directly for food reward in a transparent box and instead make a detour reach around to the side of the box either having had (i) no prior experience on the task (experiment 1) or (ii) previous experience in reaching around the sides of an opaque box (experiment 2). Whilst monkeys with orbitofrontal lesions had difficulty in inhibiting direct reaches to visible food reward (experiment 1), they could resist this prepotent response tendency following extensive prior experience of detour reaching with an opaque box (experiment 2). In marked contrast, monkeys with lateral prefrontal lesions exhibited no difficulty in inhibiting reaching to visible food reward or acquiring detour reaching per se (experiment 1). However, having been given the opportunity to acquire an efficient detour reaching strategy to hidden food reward these lateral prefrontal lesioned monkeys were impaired at transferring this strategy to the new context in which the food reward was made visible (experiment 2). This double dissociation between the effects of orbitofrontal and lateral prefrontal lesions on detour reaching provides evidence for a clear distinction in the level of control over responding exerted by the orbitofrontal and lateral prefrontal cortex, consistent with hierarchical ordering of response control processes within prefrontal cortex.

In-the-ear hearing aids within auricular prostheses

We report a child with bilateral congenital microtia in whom cosmetic and auditory rehabilitation has been effected using in-the-ear hearing aids within prostheses overlying the rudimentary external auditory meati after canaloplasty. This novel method of auditory rehabilitation has not been reported before and is suitable in selected cases. The prostheses themselves were successfully secured using a prosthetic contact adhesive we have developed that offers excellent retention, little if any skin reaction, and high patient acceptability.

Differential effects of 6-OHDA lesions of the frontal cortex and caudate nucleus on the ability to acquire an attentional set

Evidence from both human and animal studies indicates that catecholamine (dopamine and noradrenaline) imbalances in the fronto-striatal circuitry are associated with deficits in higher- order cognitive functions. The present study examined how catecholamines within this circuitry modulate attentional function, specifically the ability to develop, maintain, and shift an attentional set. Catecholamine depletions within the frontal cortex of the common marmoset impaired the ability to acquire an attentional set, and increased susceptibility to distraction from task-irrelevant stimuli. Analysis of set-shifting performance with stimulus dimensions of varying salience suggested that frontal catecholamine depletion selectively disrupts "top-down", but not "bottom-up" attentional processing. In contrast, the ability to acquire and shift an attentional set remained intact following dopaminergic depletion from the caudate nucleus. However, the reduced susceptibility to distraction from task-irrelevant stimuli displayed by monkeys with dopaminergic depletions of the caudate nucleus suggests that responding was under more rigid control by the currently rewarded stimulus. The results demonstrate opposite behavioural effects of 6-hydroxydopamine (6-OHDA) lesions in the frontal cortex and caudate nucleus in tasks requiring selective attention. Frontal catecholamine depletion caused an increase in distractibility while caudate dopamine loss induced greater focusing of responding.

Integral role of interventional radiology in the development of a pediatric liver transplantation program

The aim of this study was to examine the role of interventional radiology (IR) in the pretransplant evaluation of potential living-related liver transplantation (LRLT) donors and in the post-transplant management of pediatric liver transplant recipients. Medical records and procedural reports were reviewed of 12 potential donors and five recipients for left lateral segment liver transplants. Procedures performed by the IR Division, clinical indications, and complications were tabulated. Retrospective calculation of radiation exposure to the skin and gonads of the donors and recipients were made. Three-dimensional ultrasound (3D US) was used in all 12 potential donors to screen for the donor with the most appropriately sized left lateral segment. The four optimal donor candidates underwent contrast angiography in order to measure the diameter and screen for variant arterial supply to the left lateral segment. Pretransplantation, one recipient underwent mesenteric angiography with indirect portography to confirm thrombosis of the portal vein and to prove patency of the splenomesenteric venous confluence. Three children underwent LRLT and two children received split livers from cadaveric donors. Thirty-two IR procedures were performed after transplantation (Tx) in the four transplant survivors (one child died following Tx). These IR procedures included: ultrasound-guided percutaneous liver biopsy to evaluate the pathologic cause of liver dysfunction (seven); placement of nasal jejunal feeding tubes (three) or a peripherally inserted central catheter (four) for nutritional and pharmacologic support; large-volume diagnostic and therapeutic paracentesis (two) and thoracentesis (one); percutaneous catheter drainage of symptomatic large pleural effusions (two), large-volume chylous ascites (one) (with later drain removal [one]), and a large biloma (one); percutaneous biliary drain placement (three), biliary drain replacement (two), and balloon cholangioplasty (four) to relieve obstructive jaundice from biliary enteric anatomic strictures; and mesenteric arteriography (one) for suspected thrombosis of the hepatic artery. No complications occurred. Mean skin and gonadal radiation doses were 193 mGy and 27 mGy, respectively, for donors, and 164 mGy and 60 mGy, respectively, for recipients. Even in a program such as this, with a limited series of pediatric liver Txs, it is apparent that IR plays an integral role in optimizing the clinical outcome and use of resources. Specific benefits included: selection of optimal donors; accurate mapping of the donor and occasionally recipient hepatic vasculature; and, most importantly, providing relatively safe minimally invasive procedures for nutritional support and diagnosis and management of untoward events after Tx. When possible, ultrasound guidance should be used to avoid excessive cumulative fluoroscopic exposure to recipients.

The role of the primate amygdala in conditioned reinforcement

Conditioned reinforcement refers to the capacity of a conditioned stimulus to support instrumental behavior by acquiring affective properties of the primary reinforcer with which it is associated. Conditioned reinforcers maintain behavior over protracted periods of time in the absence of, and potentially in conflict with, primary reinforcers and as such may play a fundamental role in complex social behavior. A relatively large body of evidence supports the view that the amygdala (and in particular the basolateral area) contributes to conditioned reinforcement by maintaining a representation of the affective value of conditioned stimuli. However, a recent study in primates (Malkova et al., 1997), using a second-order visual discrimination task, suggests that the amygdala is not critical for the conditioned reinforcement process. In the present study, excitotoxic lesions of the amygdala in a new world primate, the common marmoset, resulted in a progressive impairment in responding under a second-order schedule of food reinforcement. In addition, the responding of amygdala-lesioned animals was insensitive to the omission of the conditioned reinforcer, unlike that of control animals, for which responding was markedly reduced. In contrast, lesioned animals were unimpaired when responding on a progression of fixed-ratio schedules of primary reinforcement. These data confirm that the amygdala is critical for the conditioned reinforcement process in primates, and taken together with other recent work in monkeys, these results suggest that the contribution of the amygdala is to provide the affective value of specific reinforcers as accessed by associated conditioned stimuli.

Transient ovarian failure: a complication of uterine artery embolization

OBJECTIVE

To report a case of transient ovarian failure shortly after arterial embolization for treatment of uterine fibroids, followed by recovery of ovarian function.

DESIGN

Case report.

SETTING

A university-based hospital.

PATIENT

A 49-year-old woman with menorrhagia and anemia secondary to uterine fibroids and refractory to medical management. The follicle-stimulating hormone (FSH) level on cycle day 3 before the procedure was 8.2 mIU/mL.

INTERVENTION(S)

Bilateral uterine artery embolization for treatment of menorrhagia.

MAIN OUTCOME MEASURE(S)

Serum FSH level.

RESULT(S)

The patient developed amenorrhea and hot flashes 3 months after uterine artery embolization. Her serum FSH level at that time was 140.1 mIU/mL. Four months later, uterine bleeding resumed; her serum FSH level was 2.1 mIU/mL.

CONCLUSION(S)

Uterine artery embolization may hasten ovarian failure. This procedure should be reserved for women who have completed their child-bearing or are poor candidates for myomectomy. Patients should be counseled appropriately about the risk of possible ovarian failure.

Blood viscosity and hematological changes during prolonged submergence in normoxic water of northern and southern musk turtles (Sternotherus odoratus)

Musk turtles (Sternotherus odoratus) can survive at least 150 days of submergence in normoxic water at 3 degreesC, during which time there are large increases in packed cell volume (PCV). We investigated the effects of submergence in normoxic water at 3 degreesC on the blood viscosity of musk turtles from northern (Massachusetts) and southern (Alabama) locales. Blood was collected from air-breathing turtles and after 20, 50, 100, and 150 days of submergence in normoxic water at 3 degreesC. Hematological responses to submergence were similar in the two groups, therefore the results were combined. Packed cell volume increased steadily above that of controls after 20, 50, 100, and 150 days of submergence. Hemoglobin concentration also progressively increased above that of controls after 20, 50, and 100 days of submergence but declined to near control values after 150 days. Blood viscosity increased with increasing PCV; however, blood viscosity of musk turtles appears less affected by PCV than is blood viscosity of mammalian species. As such, musk turtles appear to be able to maintain adequate blood flow to tissues while increasing the oxygen carrying capacity of the blood during prolonged submergence. However, after 150 days submergence, oxygen delivery should decrease due to a reduced oxygen carrying capacity of the blood and an increased resistance to blood flow, which may limit the length of time these turtles can remain viable during hibernation.