We assess the relationship of age-related losses in striatal D1 receptor densities to age-related reductions in functional connectivity between spatially distinct cortical regions in healthy human participants. Previous neuroimaging studies have reported age-related differences in functional connectivity of the frontoparietal working memory network and the default mode network during task performance. We used functional magnetic resonance imaging and seed-based connectivity (right dorsolateral and medial prefrontal cortex) to extend these findings: Anterior–posterior connectivity of both these functional networks was reduced in older (65–75 years, n = 18) compared with younger (20–30 years, n = 19) adults, whereas bilateral connectivity in prefrontal cortex was increased in older adults. Positron emission tomography with the D1 receptor ligand [11C]SCH23390 was used to assess caudate D1 receptor density in the same sample. Older adults showed significantly reduced caudate D1 receptor density compared to th...

Considering the close phylogenetic relationship between humans and chimpanzees, it is of particular interest to characterize the age-related changes of the chimpanzee brain that correspond to key foci of pathologic brain aging in humans such as hippocampus, entorhinal cortex, and basal ganglia. Recently, we reported that, unlike aged humans with neurodegenerative pathology, aged great apes have preserved neuron number and cellular volume in layer II neurons of the entorhinal cortex. In the present study, we measured the volume of the hippocampus, caudate nucleus, and putamen from magnetic resonance images (MRIs) of a cross-sectional age-graded sample of postmortem chimpanzee brains. Volumes of interest (VOIs) were measured from either axial T1 weighted or coronal T2 weighted scans, using MRIcro software. VOI measurements were normalized for whole brain volume. Whole brain, raw VOI, and normalized VOI volumes were not correlated with age. ANOVA found no differences in any VOI between age cohorts (19-27 and ...

Converging lines of evidence suggest that the Human Immunodeficiency Virus (HIV) can cause frontal-subcortical damage and cognitive dysfunction. Neuropsychological studies have demonstrated sensitivity of the Stroop Interference Task to HIV-related cognitive dysfunction, but the underlying pathophysiology is poorly understood. In this study, fMRI (1.5T Siemens, TR=2, 21 slices of 5 mm, blocked design, SPM '99) was used to compare patterns of brain activity in 9 HIV-positive (HIV+) and 8 HIV-negative (HIV-) males during performance of two Stroop-variant tasks. In the Counting Stroop (Bush '98), subjects used a button-press to indicate the number of animal names (neutral) or incongruent number words (interference) presented on a screen. HIV+ subjects were slower and more susceptible to interference than HIV- subjects. FMRI analysis (interference vs. neutral) showed that HIV+ subjects also recruited more regions of motor and parietal cortex compared to HIV- subjects. In the Oddball Stroop (Bush, personal comm...

It is still unclear to what extent cortical areas are involved in non-conscious processing of tactile stimuli. However, from subdural recordings of somatosensory evoked potentials in awake humans there is evidence for excitation of areas in the postcentral gyrus in response to peripheral subliminal electrical stimulation without any associated conscious sensation (Libet et al. 1967). For further investigation an fMRI study (6 subjects, mean age±S.D.=27.7±2.3 yrs) was performed with an 1.5 T scanner using echoplanar sequences (TR=2 s, FOV=256 mm, voxel size=4×4×5 mm, 16 slices). Blocks (10 scans) of subthreshold and suprathreshold electrical stimuli (pulse frequency=7 Hz, pulse duration=0.2 ms), at least 15% below (2.2±0.42 mA) and 15% above (3.1±0.62 mA) sensory threshold for conscious perception (2.7±0.52 mA), respectively, were scan triggered and delivered in a randomized order to the left index finger via ring electrodes. Parametrical maps were calculated using BrainVoyager. In the group analysis, subth...

Explicit and implicit sequence learning has been extensively studied, but explicit and implicit learning of visuo-motor transformations is less well understood. Gradual, implicit, rotation of visual feedback in a tracking task leads to greater learning than a sudden, explicit, rotation and may involve different neural circuits. We studied this task with whole brain fMRI at 3T. 5 right handed subjects (4 female, 1 male) followed alternating motion of a visual target with a cursor controlled by a joystick. In experiment 1, we used 5 conditions in a 30s block design: rest (eye movement only), normal tracking, adaptation to step (30° in 1 trial) or ramp rotation (1° per trial ramping to 30°) and re-adaptation to normal tracking. Comparison of adaptation vs. normal movement highlighted the main motor areas but also bilateral posterior parietal cortex BA39. Contrasting step and ramp adaptation showed activation of extrastiate visual areas and BA39. In experiment 2, we tested cued and uncued ramp rotation, with s...

Human working memory capacity develops during childhood and is a strong predictor of future academic performance, in particular, achievements in mathematics and reading. Predicting working memory development is important for the early identification of children at risk for poor cognitive and academic development. Here we show that structural and functional magnetic resonance imaging data explain variance in children's working memory capacity 2 years later, which was unique variance in addition to that predicted using cognitive tests. While current working memory capacity correlated with frontoparietal cortical activity, the future capacity could be inferred from structure and activity in basal ganglia and thalamus. This gives a novel insight into the neural mechanisms of childhood development and supports the idea that neuroimaging can have a unique role in predicting children's cognitive development.

The Enhanced-Deep-Super-Resolution (EDSR) model is a state-of-the-art convolutional neural network suitable for improving image spatial resolution. It was previously trained with general-purpose pictures and then, in this work, tested on biomedical magnetic resonance (MR) images, comparing the network outcomes with traditional up-sampling techniques. We explored possible changes in the model response when different MR sequences were analyzed. T1w and T2w MR brain images of 70 human healthy subjects (F:M, 40:30) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) repository were down-sampled and then up-sampled using EDSR model and BiCubic (BC) interpolation. Several reference metrics were used to quantitatively assess the performance of up-sampling operations (RMSE, pSNR, SSIM, and HFEN). Two-dimensional and three-dimensional reconstructions were evaluated. Different brain tissues were analyzed individually. The EDSR model was superior to BC interpolation on the selected metrics, both for two- ...

The quantity and quality of the language input that infants receive from their caregivers affects their future language abilities; however, it is unclear how variation in this input relates to preverbal brain circuitry. The current study investigated the relation between naturalistic language input and the functional connectivity (FC) of language networks in human infancy using resting-state functional magnetic resonance imaging (rsfMRI). We recorded the naturalistic language environments of five- to eight-month-old male and female infants using the Linguistic ENvironment Analysis (LENA) system and measured the quantity and consistency of their exposure to adult words (AWs) and adult–infant conversational turns (CTs). Infants completed an rsfMRI scan during natural sleep, and we examined FC among regions of interest (ROIs) previously implicated in language comprehension, including the auditory cortex, the left inferior frontal gyrus (IFG), and the bilateral superior temporal gyrus (STG). Consistent with th...

The idea that the medial temporal lobe (MTL), traditionally viewed as an exclusive memory system, may also subserve higher-order perception has been debated fiercely. To support this suggestion, monkey and human lesion studies have demonstrated that perirhinal cortex damage impairs complex object discrimination. The interpretation of these findings has, however, been disputed because these impairments may reflect a primary deficit in MTL-mediated working memory processes or, in the case of human patients, undetected damage to visual processing regions beyond the MTL. To address these issues, this study investigated object perception in two human amnesic patients who were chosen on the basis of their lesion locations and suitability for detailed neuroimaging investigation. A neuropsychological task with minimal working memory demands was administered in which participants assessed the structural coherency of single novel objects. Critically, only the patient with perirhinal atrophy was impaired. Moreover, v...

PIP2 Regulation of M-Type Potassium Channels Yang Li, Nikita Gamper, Donald W. Hilgemann, and Mark S. Shapiro (see pages [9825-9835][1]) Voltage-gated Kv7 (KCNQ) potassium channels that underlie the M current appear to be modulated by the membrane-bound molecule phosphatidylinositol (4,5)-