Alzheimer's disease (AD) has a slow onset, so it is challenging to distinguish brain changes in healthy elderly persons from incipient AD. One-year brain changes with a distinct frontotemporal pattern have been shown in older adults. However, it is not clear to what extent these changes may have been affected by undetected, early AD. To address this, we estimated 1-year atrophy by magnetic resonance imaging (MRI) in 132 healthy elderly persons who had remained free of diagnosed mild cognitive impairment or AD for at least 3 years. We found significant volumetric reductions throughout the brain. The sample was further divided into low-risk groups based on clinical, biomarker, genetic, or cognitive criteria. Although sample sizes varied, significant reductions were observed in all groups, with rates and topographical distribution of atrophy comparable to that of the full sample. Volume reductions were especially pronounced in the default mode network, closely matching the previously described frontotemporal ...

Introduction: Primary progressive aphasia (PPA) is a class of neurological disorders characterized by progressive speech and language deficits, and are associated with different pathologies. As treatment trials are developed, finding reliable methods of...

The cytokine interleukin-1β (IL-1β) is implicated in a broad spectrum of CNS pathologies, in which it is thought to exacerbate neuronal loss. Here, the effects of injecting recombinant rat IL-1β into the striatum of 3-week-old rats were followed noninvasively from 2 to 123 hr using magnetic resonance imaging and spectroscopy. Four hours after injection of IL-1β (1 ng in 1 μl), cerebral blood volume was significantly increased, the blood–brain barrier (BBB) became permeable to intravenously administered contrast agent between 4.5 and 5 hr, and the apparent diffusion coefficient (ADC) of brain water fell by 6 hr (5.42 ± 0.35 × 10−4 mm2/sec treated, 7.35 ± 0.77 × 10−4 mm2/sec control; p < 0.001). At 24 hr the BBB was again intact, but the ADC, although partially recovered, remained depressed at both 24 and 123 hr ( p < 0.03). Depleting the animals of neutrophils before IL-1β injection prevented the BBB permeability at all time points, but the ADC was still depressed at 6 hr (6.64 ± 0.34 × 10−4 mm2/sec treated...

Manganese-enhanced MRI (MEMRI) is a neuroimaging technique with the potential to differentiate neuronal connectivity and assess temporal responses to stimuli controlling food intake in vivo. It offers many advantages over c-fos expression analysis, generating a real time representation of hypothalamic neuronal activity. Here we employ MEMRI analysis in conjunction with a murine model of appetite stimulation using the orexigenic gut hormone, ghrelin. T1 weighted scans were performed on male C57BL/6 mice in a 9.4T horizontal-bore MR scanner, before and after intravenous (IV) infusion of 100mM MnCl2 and intraperitoneal (IP) administration of ghrelin (0.06 and 0.3 nmol/g body weight) or saline (n = 4-5 /group). The signal intensities (SI) of various hypothalamic nuclei, incuding the arcuate nucleus (ARC), periventricular nucleus (PE) and paraventricular nucleus (PVN), aswell as the ventromedial hypothalamus (VMH), anterior pituitary gland (AP) and 4th ventricle were measured by drawing regions of interest (ROI...

Understanding the anatomy of brain microvasculature is an important step in learning about nutrient and gas transport and has direct applications in understanding cancer and stroke. Currently, techniques used to image brain vasculature on a broad scale,...

Competing cognitive theories of categorical representation are feature-based theory (FT) and structured-representation theory (ST). FT suggests that superordinate categories are represented by a subset of features of basic level categories. In contrast, ST suggests that superordinate representations contain variables not represented in basic level categories. In the present study, we used functional MRI to study neural substrates underlying categorization at basic and superordinate levels. Participants viewed easily-nameable objects and judged whether these objects (e.g. poodle) fit into either basic (e.g. dog) or superordinate (e.g. animal) categories. FT predicts that superordinate categorization should activate a subset of areas activated by basic level categorization, or the same areas at a lower level. ST predicts superordinate categorization should active areas outside those activated by basic level categorization. Preliminary data and analyses are consistent with ST: contrasting different levels of ...

The rabbit is an ideal animal for fMRI imaging research. It is uniquely tolerant of restraint for prolonged time periods without the need for any anaesthetic to immobilize the animal. The visual pathways and central mechanisms of both pattern and movement vision are well explored. In addition the associative conditioning of the rabbit nictitating membrane has long been a major animal model for studying neural mechanisms of associative learning. The purpose of the present study is to determine the concordance between MRI assessment of the extent of experimentally induced brain lesions with postmortem histological reconstruction of the lesions. Using sterile procedure discrete sections of the corpus callosum were made in the rabbit brain. Assessment of tissue damage was undertaken both after 1 hour and 72 hours following surgery. Magnetic field images (6 Tesla) of lesion damage are described and compared with detailed histological reconstruction for both fiber and cellular damage.

The ability to noninvasively activate, silence, and provide receptor subtype specific neuromodulation with high temporal resolution and spatial specificity would greatly advance our ability to study brain circuits in vivo. Optogenetics, the genetic inco...

The posterior insula/retroinsular cortex including the lateral sulcus has been associated with self-motion perception, gravity-related processing and the integration of vestibular, optokinetic, proprioceptive and tactile signals. Two areas, referred to ...

Major depressive disorder (MDD) has been associated with disruptions in the topological organization of brain structural and functional networks. However, it remains unclear whether such disruptions was modulated by aging and if so whether the influence...