Seminar Series
The Neuroscience Seminar Series was initiated to foster interdepartmental research by sponsoring lectures with an opportunity to share findings with colleagues on and off campus. Chat and refreshments are served in the First Floor Rotunda following the formal presentation providing an opportunity to discuss research interests.
Our current series covers a wide range of topics. For an overview flier of the Fall 2012 series see HERE (pdf).
October 8, 2012. 3:00pm, Morris Library Guyon Auditorium, Atrium Conference Room
Role of Sleep in Learning, Memory, and Cognitive Performance
Dr. Linda Larson-Prior, Dept of Radiological Sciences, Washington University School of Medicine
Both scalp-recorded electrophysiological (EEG and MEG) and blood-oxygen level dependent (BOLD)-magnetic resonance imaging (MRI) techniques have provided critical insights into the mechanisms by which the human brain develops, interacts with the environment, shifts state from alertness through drowsiness into sleep, and changes due to neuropathology. As the field currently stands, these data center on temporally static views of brain function that fail to take into account the signal non-stationarity inherent even in the slow temporal dynamics of functional MRI (fMRI) imaging. In addition, a confound of current resting-state fMRI network studies is that subjects change their neural state during the course of the scan period, going from alert wakefulness to drowsiness and even overt sleep. The recent development of technologies that allow electrophysiological (EEG) signals to be acquired in an MRI scanner enables imaging scientists to determine the presence of neural state changes and their consequences and provides a new method for examining the neural changes that accompany the transition from wake to sleep. However, the true promise of these techniques lies in their potential for enabling the study of brain dynamics in human subjects in ‘real time’ with the millimeter spatial resolution provided by MRI imaging techniques. While new analysis techniques, aided by advances in current image acquisition protocols and parameters, are needed to fulfill the promise of multi-modal imaging, substantial progress has already been made and will be the topic of this seminar.
Please see HERE for a flyer for this event (pdf). This event will be videoconferenced to the Atrium Conference Room on our Springfield campus.
October 22, 2012. 3:00pm. Morris Library Guyon Auditorium, Atrium Conference Room
Traumatic Brain Injury
Dr. David Brody, Dept of Neurology, Washington University School of Medicine
Blast-related traumatic brain injury (TBI) has been common in the wars in Iraq and Afghanistan, but fundamental questions about these injuries remain unanswered. We tested the hypothesis that blast-related TBI causes traumatic axonal injury using Diffusion Tensor Imaging (DTI), an advanced MRI method sensitive to axonal injury. Participants were 63 US military personnel evacuated to Landstuhl Regional Medical Center, clinically diagnosed with mild uncomplicated TBI, and scanned 1-90 days after injury. All had primary blast exposure plus another blast-related mechanism of injury (e.g. struck by a blunt object, fall, motor vehicle crash). Controls were 21 similar personnel with blast exposure and other injuries but no clinical diagnosis of TBI. DTI revealed abnormalities consistent with traumatic axonal injury in many TBI subjects. None had detectible intracranial injury on CT. DTI was markedly abnormal in the middle cerebellar peduncles (p=<0.001), cingulum bundles (p=0.002), and right orbitofrontal white matter (p=0.007). In 18/63 individual TBI subjects, there were significantly more DTI abnormalities than expected by chance (p<0.001). Follow-up scans performed 6-12 months later in 47 TBI subjects demonstrated persistent DTI abnormalities consistent with evolving injuries. In summary, DTI findings in US military personnel support the hypothesis that blast-related mild TBI can involve axonal injury.
This event was videoconferenced to the Atrium Conference Room on our Springfield campus.
October 29, 2012. 3:00pm. Morris Library Guyon Auditorium, Atrium Conference Room
An Amygdala – Prefrontal System for Attentional Bias to Subliminal Threat: Evidence from Functional and Structural MRI
Dr. Joshua Carlson, Dept of Biomedical Engineering, State University of New York at Stony Brook
Humans have evolved to preferentially allocate attentional resources to potential threats within their environment. This threat bias is so strong that attention can be elicited by subliminal cues. However, not all individuals show the same degree of attentional bias to threat and those with the highest levels of bias tend to suffer from anxiety. In this talk I described my research, which has used functional magnetic resonance imaging (fMRI), structural MRI, and diffusion tensor-weighted MRI to identify an amygdala–anterior cingulate cortex based network underlying attentional bias to subliminal threat. Additionally, research that has identified underlying genetic bases (5-HTTLPR & BDNF-Val66Met) for this behavior was discussed. A proposal that plasticity in the amygdala–anterior cingulate system mediates attention bias modification treatment outcome and that tracking structural change in this system with MRI may lead to more successful treatment concluded this talk.
This event was videoconferenced to the Atrium Conference Room on our Springfield campus.
November 5, 2012. 3:00pm. Morris Library Guyon Auditorium, Atrium Conference Room
Manatee Neurobiology
Dr. Roger Reep, Dept of Physiological Sciences, University of Florida
Manatees are unique among mammals in being obligate aquatic herbivores, and they possess correspondingly unusual neural traits. Manatees have low relative brain size whether compared to mammals generally (EQ ~ 0.27), to cetaceans (EQ ~ 0.25), or to pinnipeds (EQ ~ 0.50). The small relative brain size seen in all sirenia is perhaps better viewed as relatively large body size. Selection for large body size accommodates ingestion and processing of large quantities of food and a slow digesta passage rate, as well as providing thermal compensation for the resulting low metabolic rate. Manatee brains are strikingly lissencephalic for their size (~ 350 gm), but the cerebral cortex is robust in size and internal architecture. The timing of development of cortical connections may change the tensional dynamics that are thought to underlie gyration. Somatic sensation and audition are expanded in manatees whereas vision and chemosensation are reduced. Manatees possess vibrissae over the entire body; ~ 2000 on the face and head, innervated by ~ 110,000 axons, and ~ 3300 on the postcranial body, innervated by ~ 100,000 axons. Several types of vibrissal mechanoreceptors have been identified, including one novel to manatees. This extensive investment in the vibrissal system is reflected in large, elaborate trigeminal, gracile-cuneate, and lateral cervical nuclei. The somatosensory thalamus is exceedingly large, producing displacements of the medial and lateral geniculate nuclei. Behavioral studies have shown that the facial vibrissae are involved in tactile scanning and prehensile grasping of food, whereas the postcranial vibrissae are used to detect hydrodynamic stimuli that are likely used in navigation and to detect nearby features of the environment.
This event was videoconferenced to the Atrium Conference Room on our Springfield campus.
November 19, 2012. 3:00pm. Morris Library Guyon Auditorium, Atrium Conference Room
Exacerbation of Experimental Parkinson's Disease by Chronic Stress-Induced Depression
Dr. Kim Seroogy, Depts of Biology and Kinesioloy, Washington University School of Medicine
Major neuropsychiatric disorders, such as depression, often accompany Parkinson’s disease. Depression is a highly prevalent in Parkinson's disease and is often said to contribute more to the lowered quality of life than the debilitating motor symptoms. Although the etiology of depression in Parkinson’s is unknown, understanding the potential pathophysiological processes and harmful consequences of these co-morbidities is of high importance, and may lead to the development of novel treatment therapies. To determine the potential deleterious effects that depression may inflict on Parkinson’s disease symptoms and dopamine cell degeneration, we combined models of both experimental depression and experimental parkinsonism. We used the chronic variable stressor (CVS) regimen to produce behavioral and endocrine symptoms of depression in rats flanking progressive unilateral neurotoxin (6-OHDA) lesions of the nigrostriatal pathway. Analysis of behavioral data (forelimb use asymmetry) and stereological cell counting of tyrosine hydroxylase (TH)-positive cells in the substantia nigra pars compacta several weeks post-lesion revealed that CVS concomitant with the 6-OHDA lesion exacerbated both the motor deficits and loss of TH-positive neurons in the injured substantia nigra. Subjecting the rats to CVS prior to the lesion alone or following the lesion alone did not affect the typical course of nigral TH cell degeneration and associated motor dysfunction. These data are consistent with the notion that chronic stress-induced depression concurrent with, but not solely preceding or following, neurotoxin lesioning exacerbates the behavioral dysfunction and neurodegeneration of the dopaminergic nigrostriatal system.
This event was videoconferenced to the Atrium Conference Room on our Springfield campus. See HERE for a flier (pdf).
December 3, 2012. 3:00pm. Morris Library Guyon Auditorium, Atrium Conference Room
Slow and Fast Gamma Oscillations in the Hippocampus
Dr. Laura Colgin, Center for Learning and Memory, University of Texas at Austin
Brain rhythms reflect periodically synchronized electrical activity across groups of neurons and are thought to be important for neuronal communication across disparate brain regions. Gamma oscillations are a particular rhythm type that occurs throughout many regions of the brain and have been linked to functions such as sensory perception, attention, and memory. Gamma oscillations vary in frequency (from ~25 Hz to ~ 100 Hz) from one brain region to another and also within a given brain region from one moment to the next. The exact frequency of oscillations is important because different areas will communicate most effectively when their oscillatory timing is the same. In the hippocampus, a brain region critically involved in memory operations, two distinct subtypes of gamma oscillations, slow and fast gamma, occur at different times. During slow gamma (~40 Hz), hippocampal subfield CA1 is coupled with neighboring subfield CA3, an area involved in memory retrieval. During fast gamma (~80 Hz), CA1 is coupled with the entorhinal cortex, a region transmitting information about the current environment. In this lecture, I will present new results supporting the hypothesis that slow and fast gamma oscillations serve different functions, namely that slow gamma facilitates memory retrieval and fast gamma promotes memory encoding.
This event was videoconferenced to the Atrium Conference Room on our Springfield campus.