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Biomedical subjects

Ruth M Benca

Publications and source records attributed to Ruth M Benca.

13 recordsLinked to original sources
PubMed2006

Event-related functional magnetic resonance imaging measures of neural activity to positive social stimuli in pre- and post-treatment depression.

BACKGROUND: Relationships between aberrant social functioning and depression have been explored via behavioral, clinical, and survey methodologies, highlighting their importance in the etiology of depression. The neural underpinnings of these relationships, however, have not been explored. METHODS: Nine depressed participants and 14 never-depressed control subjects viewed emotional and neutral pictures at two functional magnetic resonance imaging (fMRI) scanning sessions approximately 22 weeks apart. In the interim, depressed patients received the antidepressant Venlafaxine. Positively rated images were parsed into three separate comparisons: social interaction, human faces, and sexual images; across scanning session, activation to these images was compared with other positively rated images. RESULTS: For each of the three social stimulus types (social interaction, faces, sexual images), a distinguishable circuitry was activated equally in non-depressed control subjects and post-treatment depressed subjects but showed a hypo-response in the depressed group pre-treatment. These structures include regions of prefrontal, temporal, and parietal cortices, insula, basal ganglia, and the hippocampus. CONCLUSIONS: The neural hypo-response to positively valenced social stimuli that is observed in depression remits as response to antidepressant medication occurs, suggesting a state-dependent deficiency in response to positive social incentives. These findings underscore the importance of addressing social dysfunction in research and treatment of depression.

Adult↗
PubMed2006

Sleep in mood disorders.

Sleep disturbances are among the most common symptoms in patients who have acute episodes of mood disorders, and patients who have mood disorders exhibit higher rates of sleep disturbances than the general population, even during periods of remission. Insomnia and hypersomnia are associated with an increased risk for the development or recurrence of mood disorders and increased severity of psychiatric symptoms. Sleep electroencephalogram recordings have identified objective abnormalities associated with mood disorders, providing insight into the neurobiologic relationships between mood and sleep. Future studies will continue to investigate this association and potentially improve treatment of sleep and mood disorders.

Brain-Derived Neurotrophic Factor↗
PubMed2005

The effect of REM sleep deprivation on motivation for food reward.

Prolonged sleep deprivation in rats produces a characteristic syndrome consisting of an increase in food intake yet a decrease in weight. Moreover, the increase in food intake generally precedes the weight loss, suggesting that sleep deprivation may affect appetitive behaviors. Using the multiple platform method to produce rapid eye movement (REM) sleep deprivation, we investigated the effect of REM sleep deprivation (REMSD) on motivation for food reward utilizing food-reinforced operant tasks. In acquisition or maintenance of an operant task, REM sleep-deprived rats, with or without simultaneous food restriction, decreased responding for sucrose pellet reward in comparison to controls, despite the fact that all REM sleep-deprived rats lost weight. Furthermore, the overall response deficit of the REM sleep-deprived rats was due to a within-session decline in responding. REM sleep-deprived rats showed evidence of understanding the contingency of the task comparable to controls throughout deprivation period, suggesting that the decrements in responding were not primarily related to deficits in learning or memory. Rather, REM sleep deprivation appears to alter systems involved in motivational processes, reward, and/or attention.

Animals↗
PubMed2005

Acute effects of light and darkness on sleep in the pigeon (Columba livia).

In addition to entraining circadian rhythms, light has acute effects on sleep and wakefulness in mammals. To determine whether light and darkness have similar effects in birds, the only non-mammalian group that displays sleep patterns comparable to mammals, we examined the effects of lighting changes on sleep and wakefulness in the pigeon. We quantified sleep behavior (i.e., bilateral or unilateral eye closure) in pigeons maintained under a 12:12 LD cycle, and immediately following a change from a 12:12 to a 3:3 LD cycle. During both LD cycles, sleep was most prevalent during dark periods. During the 3:3 LD cycle, darkness had the greatest sleep promoting effect during the hours corresponding to the subjective night of the preceding 12:12 LD cycle, whereas light suppressed sleep across circadian phases. As previously suggested, the light-induced decrease in sleep in the subjective night might be partly mediated by the suppression of melatonin by light. Although the sleep promoting effect of darkness was modulated by the circadian rhythm, sleep in darkness occurred during all circadian phases, suggesting that darkness per se may play a direct role in inducing sleep. In addition to the effects of lighting on behavioral state, we observed an overall bias toward more right eye closure under all lighting conditions, possibly reflecting a response to the novel testing environment.

Animals↗
PubMed2005

Diagnosis and treatment of chronic insomnia: a review.

OBJECTIVE: Insomnia has high prevalence rates and is associated with significant personal and socioeconomic burden, yet it remains largely underrecognized and inadequately treated. METHODS: A PubMed search for English-language articles covering randomized controlled trials published between 1970 and 2004 was conducted. Search terms used were "insomnia," "behavioral therapy," and the generic names of agents commonly used to treat insomnia (the Food and Drug Administration-approved benzodiazepines and nonbenzodiazepines, trazodone, and over-the-counter agents). RESULTS: Evidence from epidemiologic studies, physician surveys, and clinical studies suggests that numerous patient and physician factors contribute to the fact that the needs of patients with insomnia remain unmet, including low reporting of insomnia by patients, limited physician training, and office-based time constraints, as well as misconceptions about the seriousness of insomnia, the advantages of treatment, and the risks associated with hypnotic use. Nonpharmacologic therapies produce long-lasting and reliable changes among people with chronic insomnia and have minimal side effects. Pharmacologic therapies have proven effective with improving wake time after sleep onset and sleep maintenance and reducing the number of nighttime awakenings. However, pharmacologic therapy has a greater chance of producing side effects. No conclusive evidence exists to favor either pharmacologic therapy or behavioral therapy. CONCLUSIONS: Insomnia is particularly challenging for clinicians because of the lack of guidelines and the small number of studies conducted in patient populations with behavioral and pharmacologic therapies. Current treatment options do not address the needs of difficult-to-treat patients with chronic insomnia, such as the elderly, and those with comorbid medical and psychiatric conditions. More research is necessary to determine the long-term effects of insomnia treatments.

Acetamides↗
PubMed2004

Migratory sleeplessness in the white-crowned sparrow (Zonotrichia leucophrys gambelii).

Twice a year, normally diurnal songbirds engage in long-distance nocturnal migrations between their wintering and breeding grounds. If and how songbirds sleep during these periods of increased activity has remained a mystery. We used a combination of electrophysiological recording and neurobehavioral testing to characterize seasonal changes in sleep and cognition in captive white-crowned sparrows (Zonotrichia leucophrys gambelii) across nonmigratory and migratory seasons. Compared to sparrows in a nonmigratory state, migratory sparrows spent approximately two-thirds less time sleeping. Despite reducing sleep during migration, accuracy and responding on a repeated-acquisition task remained at a high level in sparrows in a migratory state. This resistance to sleep loss during the prolonged migratory season is in direct contrast to the decline in accuracy and responding observed following as little as one night of experimenter-induced sleep restriction in the same birds during the nonmigratory season. Our results suggest that despite being adversely affected by sleep loss during the nonmigratory season, songbirds exhibit an unprecedented capacity to reduce sleep during migration for long periods of time without associated deficits in cognitive function. Understanding the mechanisms that mediate migratory sleeplessness may provide insights into the etiology of changes in sleep and behavior in seasonal mood disorders, as well as into the functions of sleep itself.

Animal Migration↗
PubMed2004

REM sleep deprivation induces changes in coping responses that are not reversed by amphetamine.

STUDY OBJECTIVE: Although sleep deprivation often occurs during stressful or threatening situations, the effects of sleep loss on defensive and coping behaviors are not well known. The purpose of the present study was to measure the effects of selective rapid eye movement (REM) sleep deprivation (RSD) on responses elicited by threatening situations and to assess the extent to which RSD-induced changes are reversed by amphetamine. DESIGN: Animals were divided into 3 groups; home-cage control, apparatus control, and REM sleep-deprived groups. The flowerpot method was used to produce RSD for up to 5 days. One set of rats was tested in the elevated plus maze, open field, shock-induced freezing, and analgesia tests. A second set of rats was evaluated for locomotor activity. A third set of animals was assessed in the defensive burying test. For the amphetamine studies, groups of home-cage control and REM sleep-deprived rats received an intraperitoneal injection of amphetamine prior to administration of the shock-induced freezing test or the defensive burying test. SETTING: Sleep Research Laboratory at UW-Madison. PARTICIPANTS AND INTERVENTIONS: 186 male Long-Evans rats approximately 3 months old. MEASUREMENTS AND RESULTS: RSD increased the proportion of time spent in open arms of the elevated plus maze and center of the open field, decreased freezing time, and reduced defensive burying. Amphetamine did not reverse RSD-induced changes in freezing or burying responses. CONCLUSIONS: RSD causes widespread abnormalities in coping and defensive responses in threatening situations; these deficits are not reversed and, in some cases, may be exacerbated by amphetamine.

Adaptation, Psychological↗
PubMed2004

Comparison of hypocretin/orexin and melanin-concentrating hormone neurons and axonal projections in the embryonic and postnatal rat brain.

Hypocretin/orexin (H/O) and melanin-concentrating hormone (MCH) are peptide neuromodulators found in separate populations of neurons located within the lateral and perifornical hypothalamic regions. H/O has been linked to sleep-wakefulness regulation and to the sleep disorder narcolepsy, and both systems have been implicated in energy homeostasis, including the regulation of food intake. In the present study we compared the development of H/O and MCH-expressing neuronal populations with in situ hybridization and immunohistochemistry on adjacent sections in the embryonic and postnatal rat brain. We found that MCH mRNA and protein were present in developing neurons of the hypothalamus by embryonic day 16 (E16), whereas H/O mRNA and protein were not detected until E18. We also identified previously undescribed populations of MCH-immunoreactive cells in the lateral septum, paraventricular hypothalamic nucleus, lateral zona incerta, and ventral lateral geniculate nucleus that may play a specific role in the development of these regions. MCH immunoreactive axonal processes were also evident earlier than H/O stained fibers and at the time H/O immunoreactive processes were first identified in the hypothalamus at E20, extensive MCH axonal fiber systems were already present in many brain regions. Interestingly, however, the density of axonal fibers immunoreactive for H/O in the locus coeruleus reached peak levels at the same developmental age (P21) as MCH immunoreactive axons in the diagonal band of Broca (DBB). The peak of axon density coincided with the developmental stage at which adult patterns of feeding and sleep-waking activity become established. The present results demonstrate developmental differences and similarities between the MCH and H/O systems that may relate to their respective roles in feeding and sleep regulation.

Animals↗
PubMed2004

Sleep responses to light and dark are shaped by early experience.

Light regulates sleep timing through circadian entrapment and by eliciting acute changes in behavior. These behaviors are mediated by the subcortical visual system, retinorecipient nuclei distinct from the geniculocortical system. To test the hypothesis that early visual experience shapes light regulation of behavior, the authors recorded sleep in albino rats reared in continuous dark, continuous light, or a 12-hr light-dark cycle. Dark rearing strengthened and light rearing weakened acute responses to light, including light modulation of REM sleep, a marker for pretectal function in albino rats. However, neither dark nor light rearing altered daily amounts of wakefulness, non-REM sleep, or REM sleep. Thus, light and dark rearing might differentially affect the balance between acute and circadian responses to light that, in concert, govern sleep timing.

Animals↗
PubMed2004

Special considerations in insomnia diagnosis and management: depressed, elderly, and chronic pain populations.

Patients with insomnia who also have chronic pain or depression or who are elderly represent segments of the population that are particularly difficult to treat. These populations tend to be at higher risk for experiencing difficulty sleeping and are more likely to experience chronic insomnia, sleep maintenance problems, and/or nonrestorative sleep. Worsening insomnia may exacerbate other somatic and psychological symptoms and vice versa. Conversely, there is evidence that appropriate recognition and management of the sleep complaint may alleviate other symptoms related to the associated condition and help interrupt this vicious cycle.

Adult↗
PubMed2002

Brain electrical tomography in depression: the importance of symptom severity, anxiety, and melancholic features.

BACKGROUND: The frontal lobe has been crucially involved in the neurobiology of major depression, but inconsistencies among studies exist, in part due to a failure of considering modulatory variables such as symptom severity, comorbidity with anxiety, and distinct subtypes, as codeterminants for patterns of brain activation in depression. METHODS: Resting electroencephalogram was recorded in 38 unmedicated subjects with major depressive disorder and 18 normal comparison subjects, and analyzed with a tomographic source localization method that computes the cortical three-dimensional distribution of current density for standard electroencephalogram frequency bands. Symptom severity and anxiety were measured via self-report and melancholic features via clinical interview. RESULTS: Depressed subjects showed more excitatory (beta3, 21.5-30.0 Hz) activity in the right superior and inferior frontal lobe (Brodmann's area 9/10/11) than comparison subjects. In melancholic subjects, this effect was particularly pronounced for severe depression, and right frontal activity correlated positively with anxiety. Depressed subjects showed posterior cingulate and precuneus hypoactivity. CONCLUSIONS: While confirming prior results implicating right frontal and posterior cingulate regions, this study highlights the importance of depression severity, anxiety, and melancholic features in patterns of brain activity accompanying depression.

Adult↗