Introduction: Cerebral metabolic rate of oxygen (CMRO2) can be obtained with magnetic resonance imaging (MRI) by calibrating BOLD using hypercapnia. CO2 administration influences BOLD by increasing and eventually stabilizing blood flow and volume respectively. This leaves blood oxygenation as the predominating factor affecting the magnitude of BOLD. Obviously, the above assortment implies that increased CO2 acts exclusively as vasoactive agent, without affecting neuronal activity and hence oxygen metabolism. Amongst others, the latter assumption was strengthened by the results of Schmidt and Kety in the late 1940s. Most of the fMRI studies report coupling of cerebral blood flow (CBF) and oxygen metabolism of n = 2 (n being the ratio of fractional changes in CBF and CMRO2). In this study we investigated the dependence of neural activity on enhanced CO2 concentration by means of simultaneous intracortical recordings and BOLD imaging in the anesthetized macaque monkey. Methods: Combined electrophysiology and ...

Alzheimer's disease (AD) and vascular dementia (VaD) are two of the common dementias in the elderly. Imaging studies have demonstrated white matter changes of vascular etiology to occur in both disorders. While there have increased efforts to differentiate the white matter pathology by quantitative magnetic resonance imaging (MRI) methods in these disorders there is no clear concensus. We assessed white matter pathology in brains of prospectively assessed dementia patients who came to autopsy at our Institute. We examined the extent of white matter pathology by conventional and immunocytochemical methods including luxol fast blue for myelin, and amyloid beta precursor protein (APP) immunocytochemistry with 22C11 antibody. APP has recently been used to examine axonal injury in head trauma. Our results indicated APP reactive accumulation in the centrum semiovale region and along white matter tracts in the temporal lobe involving the hippocampal formation to be common. The highest reactivity was evident in ti...

OBJECTIVE: Intercortical communication is disrupted in patients with focal epilepsy, affecting the functions of anatomically remote brain areas. In the adult brain, pathologic oscillatory coupling between interictal epileptiform discharges (IEDs) and sl...

Using a cross-form priming paradigm we have previously shown the extraction of semantic information from pictures, both with and without awareness. We manipulated awareness by using extended presentations (5 sec), as well as brief (approx 50 msec), masked presentations designed to halt conscious processing. Subsequent recognition judgments revealed that information was extracted both with and without awareness. We have now adapted this cross-form paradigm for fMRI. Using the same briefly-presented, masked pictures we demonstrated activation associated with the extraction and encoding of semantic information. Further, by comparing block and event-related designs, we show activation differences for successful and unsuccessful encoding. Results are generally consistent with previous fMRI investigations of encoding. That is, we demonstrate activation in ventral visual cortex, medial frontal cortex, and hippocampal regions. However, key differences also are evident. For example, we did not observe primary visua...

Latent vertical eye position imbalances are physiologically compensated by vertical fusional vergence to prevent diplopia. In some people, such imbalances develop early in life and increase gradually so that enhanced vertical fusional vergence can inter...

Introduction: Chronically paralyzed spinal cord injured (SCI) patients have shown the ability to generate voluntary step-like movements via electrical spinal stimulation. Intraspinal microstimulation (ISMS) is a technique which has shown promise in rest...

The majority of people over the age of 80 are affected by sarcopenia, or loss of muscle mass and strength, resulting in impaired physical function and increased risk of mortality. Interestingly, after the age of 80 humans may lose up to 50% of their mot...

Successful memory formation and retrieval crucially depends on the ability to distinguish between overlapping memory representations. The CA3 and dentate gyrus (DG) subfields of the hippocampus (HC) have been implicated in the orthogonalization of mnemo...

Previous research investigating cortical plasticity in age-related hearing loss provides evidence for cross-modal reorganization in the auditory cortex, additional recruitment of the frontal lobe and increased coupling of visual and auditory cortex for ...

Research provides compelling evidence that non-Hispanic Blacks (NHB) engage in pain catastrophizing (a maladaptive tendency to negatively evaluate one’s ability to cope with pain) more often than non-Hispanic Whites (NHW), while NHWs more often use othe...