Boundaries of specific gyri are often ambiguous, even on postmortem examination. This study addressed the reliability of MRI measurement between two labs using different methodologies for one frequently studied region, the planum temporale (PT). Scans were obtained for 40 normal men, aged 18-35 yr, who also had cognitive testing. The whole brain was scanned in 1.3 mm contiguous slices using a 1.5T MR imager (GE). The length of the horizontal segment of PT (HPT) was measured, extending from Heschl's main transverse sulcus (point H) to the point of posterior bifurcation of the Sylvian fissure (SF) or the end of the SF (point B). Both labs studied the same set of 40 scans and used the same definition of HPT (Witelson & Kigar, JCN, 1992). Lab 1 used all relevant slices in 3 planes, to locate the x, y, and z coordinates of points H and B and obtained the distance of HB. Lab 2 obtained the length of the tracing of the exposed surface of HB on sagittal slices (as in Leonard et al., Arch Neurol, 1993). Both labs o...

The relay of visceral sensory information through the brainstem to cortical structures has been determined primarily in animals using neuroanatomical and/or electrophysiological techniques. Visceral sensation, including gustatory, cardiopulmonary and gastric, is relayed within the medulla, in the nucleus of the solitary tract (NTS) to the ventrolateral medulla (VLM) for autonomic reflexes or to the parabrachial (PB) nucleus of the pons for relay to the forebrain. This representation of visceral information within the brainstem has not yet been demonstrated conclusively in humans. Functional magnetic resonance imaging (fMRI) was used to demonstrate that the NTS, VLM and PB are the critical brain stem sites mediating autonomic control in the human. The Valsalva's maneuver, isometric hand grip and maximal inspiration were used to stimulate cardiopulmonary receptors and cause changes in heart rate and blood pressure. Ten subjects were scanned in a 4T functional MRI while performing these tasks. High resolution...

Our eyes are constantly in motion and the various kinds of eye movements are closely linked to many aspects of human cognitive processing. Measuring all possible eye movements unobtrusively is not achievable with current methods. Video-based eye-trackers only measure rotational but not translational motion of the eye, require a calibration process relying on the participant’s self-report of accurate fixation, and do not work if vision of the eyeball is blocked. Scleral search coils attach physical weight on the eyeball and also do not measure translation. Here we describe a novel and fully automated method to use real-time Magnetic Resonance Imaging (MRI) for eye tracking. We achieved a temporal resolution sufficient to measure eye rotations and translations as short as those that occur within a blink and behind a closed eyelid. To demonstrate this method we measured the full extent of the blink-related eye movement for two individuals, suggesting that the eye approaches a holding position during lid closu...

Resting state networks (RSNs) are increasingly forwarded as candidate biomarkers for neuropsychiatric disorders. Such biomarkers may provide objective measures for evaluating novel therapeutic interventions in nonhuman primates often used in translational neuroimaging research. This study aimed to characterize the RSNs of awake squirrel monkeys and compare the characteristics of those networks in adolescent and adult subjects. Twenty-seven squirrel monkeys ( n =12 adolescents [6 male/6 female] ∼2.5 years and n =15 adults [7 male/8 female] ∼9.5 years) were gradually acclimated to awake scanning procedures; whole-brain fMRI images were acquired with a 9.4 Tesla scanner. Group level independent component (ICA) analysis (30 ICs) with dual regression was used to detect and compare RSNs. Twenty ICs corresponding to physiologically meaningful networks representing a range of neural functions, including motor, sensory, reward, and cognitive processes were identified in both adolescent and adult monkeys. The reprod...

Converging evidence from electrophysiological, neuropsychological, and brain imaging studies has implicated a frontal-parietal network of brain regions involved in controlling how attention is allocated in space. What remains to be understood is which portions of this network support specific mental operations that are under the broad umbrella of “attention control”. The present study used functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs) to identify which subregions of the attentional control network are involved in high-level interpretation of cue information by systematically varying discriminability of attention-directing cues while holding the shifting of attention signaled by the cues constant. The cues consisted of a line located on either side of fixation; the longer line indicated to which field attention should be directed. Discriminability of the cues was manipulated by varying the difference in length of the two lines. After 1500ms, bilateral targets briefly appea...

Thickness of the cerebral cortex was measured in 88 healthy nondemented volunteers with an age range of 48–75 years (Mean=65). 56 participants were classified as APOE ε4- (no ε4 allele) and 32 as ε4+ (1 or 2 ε4 alleles). The genotype groups had similar age, sex (72/28% f/m) and IQ (Mean/SD=117/11). Two T1-weighted MP-RAGE sequences were averaged for each participant to yield images with high signal-to-noise ratio. Images were analyzed semi-automatically as described by Salat et al (2004). We first analyzed general age effects in all 88 participants. Preliminary results indicate significant global white matter volume loss with increasing age whereas gray matter loss showed a similar, but non-significant trend. Regionally specific cortical thinning was evident with increasing age, especially in occipital areas, insula, parts of the temporal lobes, central sulcus, precentral gyrus and a subset of prefrontal areas. The sample’s age range precludes any direct comparison with previous research but the results ar...

BACKGROUND: The brain has not traditionally been considered a target organ for complications of diabetes, however recent research suggests a duration dependent effect of diabetes on the central nervous system. Impaired neuronal function and decreased neuronal density in the hippocampus correlate with performance on behavioral tests in diabetic rats. Hippocampal cerebral blood volume (CBV), measured using MRI, has been correlated with neuronal function, neuronal glucose metabolism, and neuronal density in mice and humans. Using high field strength MRI, CBV maps of mouse hippocampal subregions can be created, providing unique insight into neuronal function. OBJECTIVE: To create a CBV map characteristic of the early diabetic mouse brain. The noninvasive nature of this modality will allow us to follow the progression of neuronal dysfunction throughout the course of disease. METHODS: Six week old mice are rendered diabetic by a 5 day treatment with Streptozotocin. Using a 9.4 Tesla vertical Bruker magnet, image...

The development of the corpus callosum (CC) in rhesus monkeys was investigated using non-invasive magnetic resonance imaging (MRI) techniques. Eleven infant and juvenile monkeys (6 males, 5 females) were scanned in the coronal and sagittal planes using a T-1 weighted imaging sequence from 5 to 115 weeks of age. Also, five adult male monkeys (3-7 years) were scanned using identical procedures. The midsagittal image was used to identify the CC. The CC was segmented into seven subregions (rostrum, genu, rostral body, anterior midbody, posterior midbody, isthmus, and splenium) as described by Witelson, et al. (Brain, 1989, 112:799). Using the Image J software, the surface area of each segment was measured and summed to provide total midsagittal CC surface. Total brain volume (TBV) was also calculated by measuring the surface area of coronal sections at 5mm intervals through the entire brain. CC data, either uncorrected or corrected for TBV, were analyzed for linear maturational trends for both males and female...

This study examined the relation of fronto-limbic functional abnormalities to particular components of PTSD symptomology, in this case the symptoms of psychological and physiological distress. Subjects with DSM-IV diagnosis of PTSD, associated with sexual/physical assault, were studied using two complementary fMRI activation probes, an emotional word paradigm, and an instructed fear conditioning paradigm. Symptoms were evaluated by the Clinician-Administered PTSD Scale (CAPS). Significant activations at p<0.05 (SVC) in a priori regions of interest are reported. As expected, activity changes in mesotemporal and ventro-medial prefrontal brain regions correlated more closely with the relevant combinations of probes and clinical symptoms. With the linguistic, top-down emotional word paradigm, the CAPS score for psychological distress (B4) was positively correlated with right more than left amygdala activity, and negatively with left posterior OFC, left ventral striatum and anterior insula activity. With the no...

Numerous studies have investigated how information about the position of a target object perceived through the senses is converted into motor commands, so that an effector can act toward this target. One of the challenges the brain faces in solving this task is the conversion of spatial coordinates