The entorhinal cortex (EC) and hippocampal formation (HF) are pathologically affected very early in Alzheimer’s disease (AD). Therefore, the in vivo quantitation of changes in these regions is of great interest for identifying those at risk for developing AD. In the present study we used proportional odds models to assess the relationship between EC and HF size and risk of incident AD among 58 non-demented elderly people. All participants were followed with yearly clinical evaluations and high resolution MRI scans for up to 6 years. 23/58 people received a diagnosis of amnestic mild cognitive impairment (MCI) during the baseline evaluation and 35/58 had no cognitive impairment (NCI). EC and HF volumes were derived from 1.6 mm gapless T1 weighted coronal images reformatted to be perpendicular to the long axis of the HF. The Analyze software was used for volumetric determinations and the coregistration of sequential scans. Of the 58 non-demented subjects, 14 developed AD during the follow-up period. Results ...

Mouse models provide useful tools to examine the genetic basis of disease. The Tennessee Mouse Genome Consortium screen for clinically relevant mouse models identified one mutant (178TNC) with reduced brain weight that was 3-5 standard deviations below the mean. We sought to validate this preliminary result and precisely quantify differences in brain size between mutant and wild-type animals using anatomical MRI scans with volumetric analysis. Freshly fixed age-matched mouse heads were secured within a custom-built T/R TEM RF coil using a locking mouth bar unit, ensuring reproducible head orientation and stabilization. Images were acquired using a proton density-weighted spin echo pulse sequence (TR=5000, TE=8.6, bandwidth=30K, voxel size=100x100x350 microns) on a Magnex 7 Tesla MRI scanner driven by a Varian console running VNMRJ. “Whole brain” regions for analysis were traced in coded data sets using XVOXTRACE. These regions included the olfactory bulbs and cerebellum and were demarcated at the level of ...

We have embarked on a series of studies lesioning the amygdala in rhesus monkeys to understand its involvement in mediating fear-related psychopathology. Ibotenic acid lesions are preferable because they allow for selective damage and spare fibers of passage. Since these experiments are long term, relying on traditional histopathological verification of lesion extent is problematic. Therefore, we have been exploring noninvasive methods to determine the accuracy and extent of lesions. To assess the validity of using MRI to verify lesions, T2-weighted images were obtained from 5 monkeys at 1,2, and 3 weeks after lesioning. Approximately 9-12 months after surgery, 40 micron thick histological brain sections were obtained, and the extent of histopathological damage was compared with the one week post-surgery MRI data. A Region-of-Interest (ROI) was drawn around the bright signal region on the T2-weighted MRI (indicative of edema). Then the region of actual tissue loss based on each individual's histological da...

It is well documented that gray matter (GM) and white matter (WM) volumes decrease with age, while CSF increases. Statistical Parametric Mapping (SPM) is a widely used method for automated segmentation of brain tissue on MRI images. SPM uses a material mixture model of the distribution of image intensities with initial estimates provided by apriori probablility maps. Tissue volumes are expressed relative to Intra-Cranial Cavity Volume (ICCV) to normalize across different sized brains. Whole brain images of 24 elderly subjects (81.8 +/-6.3 years, 12 men) were acquired with a Siemens 1.5T Magnetom Vision scanner using a 3D MPRAGE sequence (TR/TE1= 11.4s/4.4) with 160-192 sagittal slices yielding 1mm3 voxels. SPM segmentation estimated normalized tissue volume (%ICCV). Individual subject tissue volume results (GM, WM and CSF) and ICCV were correlated with age. Average tissue volumes were 39.3 GM, 30.0 WM and 30.6 CSF %ICCV, though individual results varied substantially. Visual inspection demonstrated that GM...

Objective. Behavioral exposure, a first-line treatment for spider phobia (SP), is conceptionally based on fear-inhibitory learning during fear extinction. Although showing large effect sizes, a significant proportion of patients does not benefit suffici...

Neurodevelopmental impairment is an important challenge for survivors after pediatric cardiac surgery. Cardiopulmonary bypass (CPB) can cause substantial systemic inflammation and trigger prolonged microglial activation in the brain. Mesenchymal stromal...

The human primary auditory cortex (PAC) occupies major parts of the Heschl’s gyrus (HG). The macro-anatomical geometry of HG, however, is highly variable across individuals and provides only rough indication of the position and extent of PAC.In the curr...

Multiple Sclerosis (MS) is an immune-mediated, demyelinating disease of the central nervous system. Motor cortex (MC) dysfunction occurs in MS patients and is associated with muscular impairment, weakness, and fatigue, the prevailing symptoms of MS. Pre...

It has been argued that the longer lasting effects of low-frequency rTMS trains rely on post-synaptic inhibitory GABAergic synapses, but there remains some uncertainty whether an additional pathophysiological mechanism might support this post-synaptic inhibition. In this study, we investigated whether rTMS at 1 Hz administered for 12 minutes at 90% of motor threshold to the primary motor cortex would lead to any changes in cortical diffusivity of water protons by comparing a series of diffusion weighted MRI (DWI) scans acquired before and after the rTMS train. Impairments of water diffusivity can typically be seen in the acute stage of an ischemic insult or focal status epilepticus, and their reversibility has been shown. Preliminary analysis of the diffusion images shows only a minimally increased signal within the motor region in half of the subjects (3 out of 6). This minimal signal change was no longer present 15 minutes after the end of the rTMS train. The initial signal change in some subjects is not...

Minisymposia focus on advances or present conflicting views in rapidly developing areas of neuroscience. Speakers are typically junior investigators, and researchers at all career levels are encouraged to attend. Minisymposia will take place on October 5–9 in McCormick Place. Minisymposia taking place during Neuroscience 2024 are listed below.