For a long time, congenital prosopagnosia has been described as a low incidence anecdotic entity. Only very recently, epidemiologic and genetic studies indicated that their prevalence may in fact amount to 2% of the population, and an autosomal-dominant inheritance pattern was proposed. In neuropsychologic terms, hereditary prosopagnosia is not part of a general visual agnosia but may extend to certain deficits in recognition of other, similarly complex visual stimuli. Here we performed a functional MRI study on a group of 18 hereditary prosopagnosics as compared to 18 matched controls. Neutral and emotional faces as well as houses and visual control stimuli were presented in a blocked design. Our behavioural data show that recognition memory for both faces and houses was significantly reduced in prosopagnosics as compared to controls. This effect was most pronounced for faces with neutral expressions. However, the prosopagnosics showed no memory deficits for faces displaying negative emotions such as ange...

Visual perceptual learning is often specific for the region of the visual field where training is carried out, suggesting that learning-related plasticity occurs at a level of the visual cortical hierarchy where receptive fields are small. In an ongoing fMRI study, we are investigating the neural correlates of perceptual learning in a visual hyperacuity task. Subjects reported the direction of lateral offset of the center dot of a linear, vertically oriented, 3-dot array, presented at 5 degrees of eccentricity in the lower left quadrant of the visual field. Psychophysical thresholds were expressed in terms of the magnitude of offset required for 75% correct discrimination. This threshold declined over a number of training sessions (~10). fMRI data and high-resolution anatomic scans were acquired during pre-training and post-training sessions using a Siemens 3T scanner, and analyzed using BrainVoyager QX. A block design was used for fMRI data acquisition, with alternating active and fixation blocks, each of...

Metabolic mapping studies in monkeys demonstrate that auditory inputs are processed throughout the entire superior temporal gyrus (STG), much of which remains unexplored except by anatomical methods. Establishing functional subdivisions within this unexplored territory might be facilitated by relating the targets of functional studies - lesion, single-unit recording, neuroimaging, etc. - to known architectonic divisions, particularly if these could be estimated in advance on MRI scans with the aid of anatomical landmarks. To provide such correlative evidence, we prepared three brains for architectonic analysis by sectioning each one in the coronal plane and staining adjacent series with thionin, myelin, acetylcholinesterase, cytochrome oxidase, and parvalbumin. We confirmed many of the subdivisions established by Seltzer and Pandya (1978), including areas TAa, TPO, PGa, IPa, and Ts1-3. The latter areas, however, did not appear to extend into the adjacent ventral bank of the lateral sulcus, an architectonic...

Previously we demonstrated that Mn-enhanced MRI (MEMRI) can be used to detect sound-evoked activity in the mouse auditory midbrain. To further investigate this noninvasive neuroimaging technique, we applied MEMRI to map tonotopic activity in the mouse inferior colliculus (IC). Our previous studies established that MEMRI signal enhancement is optimal at postnatal week 3, when an adult-like tonotopic map is already present. We therefore injected (IP) 3-week old mice with MnCl2 (0.4mmol/kg body weight) and exposed them to either of two different frequency band sound stimuli (High frequency (HF), 20-60kHz; Low frequency (LF), 2-6kHz) for 24-h prior to imaging. For the HF stimulated mouse group, signal enhancement was confined to the caudal-ventral part of central IC. In contrast, the signal enhancement in the LF stimulated mouse IC was found in the dorso-rostral region. To further confirm this result, we performed experiments to determine if the observed frequency-dependent enhancement patterns could be shifte...

‘The NIH MRI Study of Normal Brain Development’ is being carried out by the 'Brain Development Cooperative Group' and is the most comprehensive and rigorous study of human brain and behavioral development ever conducted. This is a multi-site research project using a combined longitudinal and cross-sectional design to map brain-behavioral development of normal/typical children from birth through 18 years of age. The project is funded by NIH (NINDS, NICHD, NIMH, and NIDA), and includes seven Medical Centers (Boston, Philadelphia, St. Louis, Cincinnati, Houston, Los Angeles, and Montreal). This abstract deals with Objective-2 of this project, which covers children from birth through 4.5 years of age. Children were recruited at hospitals and community organizations, and a demographically-representative sample of 50 children is available to date. Subject's received repeated brain scan + behavioral studies at 3 to 6 month intervals, for a minimum of 3 scans-tests per child at between birth through 4.5 years of a...

Neuroscience research has followed two distinct paths in investigating central neural mechanisms of pain and emotion. Theories of emotion and pain processing predict an interaction between pain and emotion, such that emotional states may serve to both increase or decrease pain. Theories of emotion view emotions as interpretations of bodily states and imply neuroanotomic relations between emotion and pain in the brain. Similarly pain neuromatrix theory predicts an affective dimension of pain experience that has been defined in terms of both pain unpleasantness and secondary affect, emphasizing the role of emotion in pain experience. In the present study, painful heat stimulation was applied to the face while simultaneously conducting whole brain imaging using functional magnetic resonance imaging (fMRI). In addition, personal episodes involving anger, fear, and neutral emotion were recalled during fMRI both with, and without, painful heat stimulation. The frontal cortex, cingulate cortex, and insula were sh...

The majority of neurophysiological studies in conscious primates use craniotomies and recording chambers to access the same cortical territory for up to several years. In this technique, stereotaxic references are adequate for coarse positioning of the recording chamber relative to the brain area under study. However, individual anatomical variations, chamber placement errors, and changes over time degrade our ability to localize recording sites using conventional methods, particularly in regions of brain with complex anatomy such as the cerebral cortex. As a result, labs increasingly rely on functional criteria to characterize recording sites. Since functional criteria are rarely standardized, this strategy can make it difficult for the neuroscience community at large to reconcile results obtained from different labs. We have developed a robust, practical method to localize single unit recordings to within 1mm using magnetic resonance imaging (MRI). After chamber placement, a high-resolution (0.5-0.8 mm³)...

High cardiovascular reactivity due to stress has been established as a risk factor for the development of cardiovascular disease. Animal and human studies indicate a role of forebrain regions, specifically the medial prefrontal cortex, the insular cortex and the amygdala, in mediating autonomic control of the cardiovascular system. However, the specific regions of the forebrain involved in the cardiovascular control during the stress response in humans are unknown. The purpose of this study is to investigate what proportion of a young healthy population demonstrates cardiovascular reactivity to a laboratory mental stress task, and to determine the forebrain regions involved in the stress response in high cardiovascular reactors (reactors) and low cardiovascular reactors (non reactors). Methods: In a prescreening trial, 50 volunteer subjects (mean age 24) performed 2 mental stress tasks: mental arithmetic (MA) and the Stroop Color Word Task (SCWT). Heart rate (HR) and Mean Arterial Pressure (MAP) were conti...

Introduction: Parcellation of the cerebellar cortex allows for detailed functional and structural imaging studies of the cerebellum. Volumetric changes during normal development and aging, or related to pathology, emphasize the relevance of morphometric analysis of cerebellar cortex. Previously, we described a parcellation system of the human cerebellar cortex based upon neuroanatomy [1]. In the present study morphometric analysis was performed on five normal humans, as well as intra- and inter-rater reliability measurements. Methods: The cerebellar cortex of five normal human subjects was parcellated using T1-weighted anatomic MR images. The method of parcellation applied here was based on our previous study, which delineated 20 parcellation units (PUs) in each cerebellar hemisphere and 12 PUs in each hemivermis [1]. Reliability measurements were performed on the resulting parcellations. Results and Discussion: Volumetric analysis and trials for intra- and inter-rater reliability were performed in a blind...

Objective: The stem of the superior longitudinal fascicle (SLF) was characterized volumetrically and biophysically (in terms of fractional (FI) and lattice anisotropy (LI) indices) in vivo in four patients with left perisylvian ischemic stroke lesions, and in four healthy adult human subjects using DT-MRI. Quantitative analysis was performed anterior to the site of the lesion to assess the integrity and size of SLF, allowing for the identification of potential secondary degeneration changes of this association fiber pathway. Methods: A Siemens Sonata 1.5 Tesla scanner was used. Scans included MP-RAGE T1 scans and echo-planar diffusion tensor-MRI (DT-MRI). The echo-planar based protocol included diffusion tensor imaging to sample the diffusion tensor, D, using a seven-shot EPI technique with TR=200ms, TE=89ms, 36 averages, image matrix=128x128, voxel size=2x2x2mm3, b=1000s/mm2, 60 contiguous coronal slices for a total acquisition time of approx. 13 min, and a SNR of approx. 40. Custom made software and semi...