Digital Commons Network^™

Field Effects And Ictal Synchronization: Insights From In Homine Observations, Shennan A. Weiss, Guy Mckhann Jr., Robert Goodman, Ronald G. Emerson, Andrew Trevelyan, Marom Bikson, Catherine A. Schevon

Publications and Research

It has been well established in animal models that electrical fields generated during inter-ictal and ictal discharges are strong enough in intensity to influence action potential firing threshold and synchronization. We discuss recently published data from microelectrode array recordings of human neocortical seizures and speculate about the possible role of field effects in neuronal synchronization. We have identified two distinct seizure territories that cannot be easily distinguished by traditional EEG analysis. The ictal core exhibits synchronized neuronal burst firing, while the surrounding ictal penumbra exhibits asynchronous and relatively sparse neuronal activity. In the ictal core large amplitude rhythmic ictal discharges …

Cervicothoracic Multisegmental Transpinal Evoked Potentials In Humans, Jonathan Einhorn, Alan Li, Royi Hazan, Maria Knikou

Publications and Research

The objectives of this study were to establish the neurophysiological properties of the transpinal evoked potentials (TEPs) following transcutaneous electric stimulation of the spine (tsESS) over the cervicothoracic region, changes in the amplitude of the TEPs preceded by median nerve stimulation at group I threshold, and the effects of tsESS on the flexor carpi radialis (FCR) H-reflex in thirteen healthy human subjects while seated. Two re-usable self-adhering electrodes, connected to function as one electrode (cathode), were placed bilaterally on the clavicles. A re-usable electrode (anode) was placed on the cervicothoracic region covering from Cervical 4 – Thoracic 2 and held …

Differential Joint-Specific Corticospinal Tract Projections Within The Cervical Enlargement, Curtis O. Asante, John H. Martin

Publications and Research

The motor cortex represents muscle and joint control and projects to spinal cord interneurons and–in many primates, including humans–motoneurons, via the corticospinal tract (CST). To examine these spinal CST anatomical mechanisms, we determined if motor cortex sites controlling individual forelimb joints project differentially to distinct cervical spinal cord territories, defined regionally and by the locations of putative last-order interneurons that were transneuronally labeled by intramuscular injection of pseudorabies virus. Motor cortex joint-specific sites were identified using intracorticalmicrostimulation. CST segmental termination fields from joint-specific sites, determined using anterograde tracers, comprised a high density core of terminations that was consistent between animals …

Cholinergic Enhancement Of Brain Activation In Mild Cognitive Impairment During Episodic Memory Encoding, Shannon L. Risacher, Yang Wang, Heather A. Wishart, Laura A. Rabin, Laura A. Flashman, Brenna C. Mcdonald, John D. West, Robert B. Santulli, Andrew J. Saykin

Publications and Research

Objective: To determine the physiological impact of treatment with donepezil (Aricept) on neural circuitry supporting episodic memory encoding in patients with amnestic mild cognitive impairment (MCI) using functional magnetic resonance imaging (fMRI).

Methods: Eighteen patients with MCI and 20 age-matched healthy controls (HC) were scanned twice while performing an event-related verbal episodic encoding task. MCI participants were scanned before treatment and after approximately 3 months on donepezil; HCwere untreated but rescanned at the same interval.Voxel-level analyses assessed treatment effects on activation profiles in MCI patients relative to retest changes in non-treated HC. Changes in task-related connectivity in medial temporal circuitry …

Unconscious Priming Requires Early Visual Cortex At Specific Temporal Phases Of Processing, Marjan Persuh, Tony Ro

Publications and Research

Although examples of unconscious shape priming have been well documented, whether such priming requires early visual cortex (V1/V2) has not been established. In the current study, we used TMS of V1/V2 at varying temporal intervals to suppress the visibility of preceding shape primes while the interval between primes and targets was kept constant. Our results show that, although conscious perception requires V1/V2, unconscious priming can occur without V1/V2 at an intermediate temporal interval but not at early (5–25 msec) or later (65–125 msec) stages of processing. Because the later time window of unconscious priming suppression has been proposed to interfere …

Explorations Of Object And Location Memory Using Fmri, Andrew D. Passaro, L. Caitlin Elmore, Timothy M. Ellmore, Kenneth J. Leising, Andrew C. Papanicolaou, Anthony A. Wright

Publications and Research

Content-specific sub-systems of visual working memory (VWM) have been explored in many neuroimaging studies with inconsistent findings and procedures across experiments. The present study employed functional magnetic resonance imaging (fMRI) and a change detection task using a high number of trials and matched stimulus displays across object and location change (what vs. where) conditions. Furthermore, individual task periods were studied independently across conditions to identify differences corresponding to each task period. Importantly, this combination of task controls has not previously been described in the fMRI literature. Composite results revealed differential frontoparietal activation during each task period. A separation of object …

Effortless Awareness: Using Real Time Neurofeedback To Investigate Correlates Of Posterior Cingulate Cortex Activity In Meditators' Self-Report, Kathleen A. Garrison, Juan F. Santoyo, Jake H. Davis, Thomas A. Thomhill Iv, Catherine E. Kerr, Judson A. Brewer

Publications and Research

Neurophenomenological studies seek to utilize first-person self-report to elucidate cognitive processes related to physiological data. Grounded theory offers an approach to the qualitative analysis of self-report, whereby theoretical constructs are derived from empirical data. Here we used grounded theory methodology (GTM) to assess how the first-person experience of meditation relates to neural activity in a core region of the default mode network—the posterior cingulate cortex (PCC). We analyzed first-person data consisting of meditators' accounts of their subjective experience during runs of a real time fMRI neurofeedback study of meditation, and third-person data consisting of corresponding feedback graphs of PCC activity …

Neural Activations During Visual Sequence Learning Leave A Trace In Post-Training Spontaneous Eeg, Clara Moisello, Hadj Boumediene Meziane, Simon Kelly, Bernardo Perfetti, Svetlana Kvint, Nicholas Voutsinas, Daniella Blanco, Angelo Quartarone, Giulio Tononi, Maria Felice Ghilardi

Publications and Research

Recent EEG studies have shown that implicit learning involving specific cortical circuits results in an enduring local trace manifested as local changes in spectral power. Here we used a well characterized visual sequence learning task and high density-(hd-)EEG recording to determine whether also declarative learning leaves a post-task, local change in the resting state oscillatory activity in the areas involved in the learning process. Thus, we recorded hd-EEG in normal subjects before, during and after the acquisition of the order of a fixed spatial target sequence (VSEQ) and during the presentation of targets in random order (VRAN). We first determined …

Dominance Of Orientation Over Frequency In The Perception Of 3-D Slant And Shape, Danny M. Tam, Ji Shin, Andrea Li

Publications and Research

In images of textured three-dimensional surfaces, pattern changes can be characterized as changes in orientation and spatial frequency, features for which neurons in primary visual cortex are classically selective. Previously, we have demonstrated that correct 3-D shape perception is contingent on the visibility of orientation flows that run parallel to the surface curvature. We sought to determine the relative contributions of orientation modulations (OMs) and frequency modulations (FMs) for the detection of slant and shape from 3-D surfaces. Results show that 1) when OM and FM indicate inconsistent degrees of surface slant or curvature, observer responses were consistent with the …

Sex-Specific Brain Deficits In Auditory Processing In An Animal Model Of Cocaine-Related Schizophrenic Disorders, Patricia A. Broderick, Taylor Rosenbaum

Publications and Research

Cocaine is a psychostimulant in the pharmacological class of drugs called Local Anesthetics. Interestingly, cocaine is the only drug in this class that has a chemical formula comprised of a tropane ring and is, moreover, addictive. The correlation between tropane and addiction is well-studied. Another well-studied correlation is that between psychosis induced by cocaine and that psychosis endogenously present in the schizophrenic patient. Indeed, both of these psychoses exhibit much the same behavioral as well as neurochemical properties across species. Therefore, in order to study the link between schizophrenia and cocaine addiction, we used a behavioral paradigm called Acoustic Startle. …

Neural Processing Of Facial Identity And Emotion In Infants At High-Risk For Autism Spectrum Disorders, Sharon E. Fox, Jennifer B. Wagner, Christine L. Shrock, Helen Tager-Flusberg, Charles A. Nelson

Publications and Research

Deficits in face processing and social impairment are core characteristics of autism spectrum disorder. The present work examined 7-month-old infants at high-risk for developing autism and typically developing controls at low-risk, using a face perception task designed to differentiate between the effects of face identity and facial emotions on neural response using functional Near-Infrared Spectroscopy. In addition, we employed independent component analysis, as well as a novel method of condition-related component selection and classification to identify group differences in hemodynamic wave forms and response distributions associated with face and emotion processing.The results indicate similarities of waveforms, but differences in the …

Unconscious Processing Of Unattended Features In Human Visual Cortex, Tatiana Aloi Emmanouil, Philip Burton, Tony Ro

Publications and Research

Unconscious processing has been convincingly demonstrated for task-relevant feature dimensions. However, it is possible that the visual system is capable of more complex unconscious operations, extracting visual features even when they are unattended and task irrelevant. In the current study, we addressed this question by measuring unconscious priming using a task in which human participants attended to a target object's shape while ignoring its color. We measured both behavioral priming effects and priming-related fMRI activations from primes that were unconsciously presented using metacontrast masking. The results showed faster RTs and decreases in fMRI activation only when the primes were identical …

A Naturally-Occurring Histone Acetyltransferase Inhibitor Derived From Garcinia Indica Impairs Newly Acquired And Reactivated Fear Memories, Stephanie A. Maddox, Casey S. Watts, Valerie Doyere, Glenn E. Schafe

Publications and Research

The study of the cellular and molecular mechanisms underlying the consolidation and reconsolidation of traumatic fear memories has progressed rapidly in recent years, yet few compounds have emerged that are readily useful in a clinical setting for the treatment of anxiety disorders such as post-traumatic stress disorder (PTSD). Here, we use a combination of biochemical, behavioral, and neurophysiological methods to systematically investigate the ability of garcinol, a naturallyoccurring histone acetyltransferase (HAT) inhibitor derived from the rind of the fruit of the Kokum tree (Garcina indica), to disrupt the consolidation and reconsolidation of Pavlovian fear conditioning, a widely studied rodent model …

Peripheral Nerve Injury Is Associated With Chronic, Reversible Changes In Global Dna Methylation In The Mouse Prefrontal Cortex, Maral Tajerian, Sebastian Alvarado, Magali Millecamps, Pascal Vachon, Cecilia Crosby, M. Catherine Bushnell, Moshe Szyf, Laura S. Stone

Publications and Research

Changes in brain structure and cortical function are associated with many chronic pain conditions including low back pain and fibromyalgia. The magnitude of these changes correlates with the duration and/or the intensity of chronic pain. Most studies report changes in common areas involved in pain modulation, including the prefrontal cortex (PFC), and pain-related pathological changes in the PFC can be reversed with effective treatment. While the mechanisms underlying these changes are unknown, they must be dynamically regulated. Epigenetic modulation of gene expression in response to experience and environment is reversible and dynamic. Epigenetic modulation by DNA methylation is associated with …