Neuroscience and Neurobiology Commons^™

Regulation Of System Xc- And Its Contribution To Cell Death, Xiaoqian Liu

Dissertations (1934 -)

The main focus of the studies in this thesis involves examining the role of cystine/glutamate exchange (system xC-) in neuronal death in primary cortical cell culture, with an emphasis on how glial function affects neuronal cell death. System xC- is a sodium-independent transporter that mediates cystine uptake and glutamate release. It accounts for most of the cystine uptake in astrocytes in mature cultures, providing the rate limiting substrate for synthesis of the main endogenous antioxidant glutathione. The glutamate released by system xC- may lead to excessive extracellular glutamate and cause excitotoxicity.

β-N-methylamino-L-alanine (BMAA) is a non-protein amino acid that may …

Corticosterone-Induced Potentiation Of Cocaine Seeking: A Potential Role For Organic Cation Transporter 3, Evan N. Graf

Dissertations (1934 -)

While it is known that stress plays a role in the relapse of cocaine-seeking behavior, recent studies demonstrate that stress may be acting as a "stage setter" rather than directly triggering further cocaine use. This model suggests stimuli that do not normally evoke relapse under stress-free conditions may result in drug seeking when the exposure occurs under stressful conditions. In this study, we examined the corticosterone-dependent potentiation of cocaine-induced reinstatement by a stressor, electric footshock (EFS), in rats following cocaine self-administration and extinction. We found that in rats with a history of drug exposure under low intake conditions, footshock alone …

The Human Brain Intracerebral Microvascular System: Development And Structure, Miguel Marín-Padilla

Dartmouth Scholarship

The capillary from the meningeal inner pial lamella play a crucial role in the development and structural organization of the cerebral cortex extrinsic and intrinsic microvascular compartments. Only pial capillaries are capable of perforating through the cortex external glial limiting membrane (EGLM) to enter into the nervous tissue, although incapable of perforating the membrane to exit the brain. Circulatory dynamics and functional demands determine which capillaries become arterial and which capillaries become venous. The perforation of the cortex EGLM by pial capillaries is a complex process characterized by three fundamental stages: (1) pial capillary contact with the EGLM with fusion …

Development Of Scn Connectivity And The Circadian Control Of Arousal: A Diminishing Role For Humoral Factors?, Andrew J. Gall, William D. Todd, Mark S. Blumberg

Faculty Publications

The suprachiasmatic nucleus (SCN) is part of a wake-promoting circuit comprising the dorsomedial hypothalamus (DMH) and locus coeruleus (LC). Although widely considered a "master clock," the SCN of adult rats is also sensitive to feedback regarding an animal's behavioral state. Interestingly, in rats at postnatal day (P)2, repeated arousing stimulation does not increase neural activation in the SCN, despite doing so in the LC and DMH. Here we show that, by P8, the SCN is activated by arousing stimulation and that selective destruction of LC terminals with DSP-4 blocks this activational effect. We next show that bidirectional projections among the …

Mcnamara 20120831fri-20120904tue Cosmic Ray Particles By Ccd Imaging, George Mcnamara

George McNamara

McNamara 20120831Fri-20120904Tue Cosmic Ray Particles by CCD imaging.zip contains image files in support of a Microscopy Today article - please see

http://www.microscopy-today.com/

Time-Dependent Statistical And Correlation Properties Of Neural Signals During Handwriting, Valery I. Rupasov, Mikhail A. Lebedev, Joseph S. Erlichman, Stephen L. Lee, James C. Leiter, Michael Linderman

Dartmouth Scholarship

To elucidate the cortical control of handwriting, we examined time-dependent statistical and correlational properties of simultaneously recorded 64-channel electroencephalograms (EEGs) and electromyograms (EMGs) of intrinsic hand muscles. We introduced a statistical method, which offered advantages compared to conventional coherence methods. In contrast to coherence methods, which operate in the frequency domain, our method enabled us to study the functional association between different neural regions in the time domain. In our experiments, subjects performed about 400 stereotypical trials during which they wrote a single character. These trials provided time-dependent EMG and EEG data capturing different handwriting epochs. The set of trials …

Brainstorm: Head Injuries And The Nfl, Part 7: What Mops Have To Do With The Nfl, John J. Medina Ph.D.

Brainstorm

In the last few installments, we discussed some vulnerable regions of neurological real estate that suffer damage in afflicted athletes, and their association with changes in outwardly observable behavior. Unfortunately, this is only a partial list. Enough is now known that I could create three or four more installments of this blog and still not cover everything that is being researched.

Long-Term Effects Of Estradiol Replacement In The Olfactory System, Britto P. Nathan, Michael Tonsor, Robert G. Struble

Britto P. Nathan

Olfactory dysfunction often precedes other clinical symptoms in chronic neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. Estrogen deficiency and apoE genotype are known risk factors in these diseases and these factors also affect olfaction. Therefore we examined the effects of estradiol replacement following ovariectomy on expression of apoE and markers of cell proliferation, neuronal maturation, synaptogenesis and reactive gliosis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Estradiol replacement increased apoE staining in the olfactory nerve and glomerular layers. Estradiol increased astrocyte density and olfactory epithelium (OE) thickness regardless of the genotype. In addition estradiol …

Long-Term Effects Of Estradiol Replacement In The Olfactory System, Britto P. Nathan, Michael Tonsor, Robert G. Struble

Faculty Research & Creative Activity

Olfactory dysfunction often precedes other clinical symptoms in chronic neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. Estrogen deficiency and apoE genotype are known risk factors in these diseases and these factors also affect olfaction. Therefore we examined the effects of estradiol replacement following ovariectomy on expression of apoE and markers of cell proliferation, neuronal maturation, synaptogenesis and reactive gliosis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Estradiol replacement increased apoE staining in the olfactory nerve and glomerular layers. Estradiol increased astrocyte density and olfactory epithelium (OE) thickness regardless of the genotype. In addition estradiol …

Long-Term Effects Of Estradiol Replacement In The Olfactory System, Britto Nathan, Michael Tonsor, Robert Struble

Faculty Research & Creative Activity

Olfactory dysfunction often precedes other clinical symptoms in chronic neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. Estrogen deficiency and apoE genotype are known risk factors in these diseases and these factors also affect olfaction. Therefore we examined the effects of estradiol replacement following ovariectomy on expression of apoE and markers of cell proliferation, neuronal maturation, synaptogenesis and reactive gliosis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Estradiol replacement increased apoE staining in the olfactory nerve and glomerular layers. Estradiol increased astrocyte density and olfactory epithelium (OE) thickness regardless of the genotype. In addition estradiol …

Adrenal Steroids Uniquely Influence Sexual Motivation Behavior In Male Rats, George Taylor, Joshua Dearborn, Susan Maloney

Psychology Faculty Works

The androgenic adrenal steroids dehydroepiandrosterone (DHEA) and 4α-androstenedione (4-A) have significant biological activity, but it is unclear if the behavioral effects are unique or only reflections of the effects of testosterone (TS). Gonadally intact male Long-Evans rats were assigned to groups to receive supplements of DHEA, 4-A, TS, corticosteroid (CORT), all at 400 µg steroid/kg of body weight, or vehicle only for 5 weeks. All males were tested in a paradigm for sexual motivation that measures time and urinary marks near an inaccessible receptive female. It was found that DHEA and 4-A supplements failed to influence time near the estrous …

Mental Reversal Of Imagined Melodies: A Role For The Posterior Parietal Cortex, R.J. Zatorre, Andrea Halpern, M. Bouffard

Andrea Halpern

Two fMRI experiments explored the neural substrates of a musical imagery task that required manipulation of the imagined sounds: temporal reversal of a melody. Musicians were presented with the first few notes of a familiar tune (Experiment 1) or its title (Experiment 2), followed by a string of notes that was either an exact or an inexact reversal. The task was to judge whether the second string was correct or not by mentally reversing all its notes, thus requiring both maintenance and manipulation of the represented string. Both experiments showed considerable activation of the superior parietal lobe (intraparietal sulcus) during …

Identification Of Speeded And Slowed Familiar Melodies By Younger, Middle-Aged, And Older Musicians And Nonmusicians, M.W. Andrews, W.J. Dowling, J.C. Bartlett, Andrea Halpern

Andrea Halpern

There is a range of tempos within which listeners can identify familiar tunes (around 0.8 to 6.0 notes/s). Faster and slower tunes are difficult to identify. The authors assessed fast and slow melody-identification thresholds for 80 listeners ages 17–79 years with expertise varying from musically untrained to professional. On fast-to-slow (FS) trials the tune started at a very fast tempo and slowed until the listener identified it. Slow-to-fast (SF) trials started slow and accelerated. Tunes either retained their natural rhythms or were stylized isochronous versions. Increased expertise led to better performance for both FS and SF thresholds (r = .45). …

Contextual Information And Memory For Unfamiliar Tunes In Older And Younger Adults, S.A. Deffler, Andrea Halpern

Andrea Halpern

We examined age differences in the effectiveness of multiple repetitions and providing associative facts on tune memory. For both tune and fact recognition, three presentations were beneficial. Age was irrelevant in fact recognition, but older adults were less successful than younger in tune recognition. The associative fact did not affect young adults' performance. Among older people, the neutral association harmed performance; the emotional fact mitigated performance back to baseline. Young adults seemed to rely solely on procedural memory, or repetition, to learn tunes. Older adults benefitted by using emotional associative information to counteract memory burdens imposed by neutral associative information.

Absolute Pitch And Planum Temporale, J.P. Keenan, V. Thangaraj, Andrea Halpern, G.S. Schlaug

Andrea Halpern

An increased leftward asymmetry of the planum temporale (PT) in absolute-pitch (AP) musicians has been previously reported, with speculation that early exposure to music influences the degree of PT asymmetry. To test this hypothesis and to determine whether a larger left PT or a smaller right PT actually accounts for the increased overall PT asymmetry in AP musicians, anatomical magnetic resonance images were taken from a right-handed group of 27 AP musicians, 27 nonmusicians, and 22 non-AP musicians. A significantly greater leftward PT asymmetry and a significantly smaller right absolute PT size for the AP musicians compared to the two …

Melody Recognition At Fast And Slow Tempos: Effects Of Age, Experience, And Familiarity, W.J. Dowling, J.C. Bartlett, Andrea Halpern, M.W. Andrews

Andrea Halpern

Eighty-one listeners defined by three age ranges (18–30, 31–59, and over 60 years) and three levels of musical experience performed an immediate recognition task requiring the detection of alterations in melodies. On each trial, a brief melody was presented, followed 5 sec later by a test stimulus that either was identical to the target or had two pitches changed, for a same–different judgment. Each melody pair was presented at 0.6 note/sec, 3.0 notes/sec, or 6.0 notes/sec. Performance was better with familiar melodies than with unfamiliar melodies. Overall performance declined slightly with age and improved substantially with increasing experience, in agreement …

Recognition Of Familiar And Unfamiliar Music In Normal Aging And Alzheimer's Disease, J.C. Bartlett, Andrea Halpern, W.J. Dowling

Andrea Halpern

We tested normal young and elderly adults and elderly Alzheimer’s disease (AD) patients on recognition memory for tunes. In Experiment 1, AD patients and age-matched controls received a study list and an old/new recognition test of highly familiar, traditional tunes, followed by a study list and test of novel tunes. The controls performed better than did the AD patients. The controls showed the “mirror effect” of increased hits and reduced false alarms for traditional versus novel tunes, whereas the patients false-alarmed as often to traditional tunes as to novel tunes. Experiment 2 compared young adults and healthy elderly persons using …

Hearing In The Mind's Ear: A Pet Investigation Of Musical Imagery And Perception, Robert J. Zatorre, Andrea R. Halpern, David W. Perry, Ernst Meyer, Alan C. Evans

Andrea Halpern

Neuropsychological studies have suggested that imagery processes may be mediated by neuronal mechanisms similar to those used in perception. To test this hypothesis, and to explore the neural basis for song imagery, 12 normal subjects were scanned using the water bolus method to measure cerebral blood flow (CBF) during the performance of three tasks. In the control condition subjects saw pairs of words on each trial and judged which word was longer. In the perceptual condition subjects also viewed pairs of words, this time drawn from a familiar song; simultaneously they heard the corresponding song, and their task was to …

Behavioral And Neural Correlates Of Perceived And Imagined Musical Timbre, Andrea Halpern, R.J. Zattore, M. Bouffard, J.A. Johnson

Andrea Halpern

The generality of findings implicating secondary auditory areas in auditory imagery was tested by using a timbre imagery task with fMRI. Another aim was to test whether activity in supplementary motor area (SMA) seen in prior studies might have been related to subvocalization. Participants with moderate musical background were scanned while making similarity judgments about the timbre of heard or imagined musical instrument sounds. The critical control condition was a visual imagery task. The pattern of judgments in perceived and imagined conditions was similar, suggesting that perception and imagery access similar cognitive representations of timbre. As expected, judgments of heard …

Prediction Accuracy Of Young And Middle-Aged Adults In Memory For Familiar And Unfamiliar Texts, S.K. Johnson, Andrea Halpern

Andrea Halpern

This study investigated the influence of age, familiarity, and level of exposure on the metamemorial skill of prediction accuracy on a future test. Young (17 to 23 years old) and middle-aged adults (35 to 50 years old) were asked to predict their memory for text material. Participants made predictions on a familiar text and an unfamiliar text, at three different levels of exposure to each. The middle-aged adults were superior to the younger adults at predicting performance. This finding indicates that metamemory may increase from youth to middle age. Other findings include superior prediction accuracy for unfamiliar compared to familiar …