The position, surface area and visual field representation of human areas V1, V2 V3 were measured using fMRI in 7 subjects (14 hemispheres). Cortical maps the central 12 deg rotating wedge expanding ring stimuli. boundaries between identified an automated procedure to fit atlas expected map data. All position measurements made along boundary white matter gray matter. 2 V2, hV4 spans about 2100 mm2 is centered on lateral-ventral aspect occipital lobes at Talairach coordinates -29, -78, -11...

Human colour vision originates in the cone photoreceptors, whose spatial density peaks fovea and declines rapidly into periphery. For this reason, one expects to find a large representation of cone–rich those cortical locations that support perception. occipital cortex contains several distinct foveal representations including at least two extend onto ventral surface: region thought be critical for vision. To learn more about these signals, we used functional magnetic resonance imaging...

We describe the first systematic functional magnetic resonance imaging (fMRI) measurements of visual field maps in macaque cortex. The boundaries areas V1, V2, V3, V3A, V4, MT/V5, and TEO/V4A were identified using stimuli that create traveling waves activity retinotopically organized Furthermore, these used to measure dimensions representations central 11° V1–V3, quantitative eccentricity functions for V1–V3 MT, distribution foveal peripheral signals within occipital lobe. Within portions...

Diffusion tensor imaging (DTI) and fiber tracking (FT) were used to measure the occipital lobe tracts connecting two hemispheres in individual human subjects. These are important for normal vision. Also, damage portions of these is associated with alexia. To assess reliability DTI-FT measurements, occipital-callosal projections estimated from each subject's left right independently. The estimates converged onto same positions within splenium. We further characterized properties by combining...

The functional organization of human auditory cortex has not yet been characterized beyond a rudimentary level detail. Here, we use MRI to measure the microstructure orthogonal tonotopic and periodotopic gradients forming complete field maps (AFMs) in core belt cortex. These AFMs show clear homologies subfields identified nonhuman primates cytoarchitectural studies. In addition, present measurements macrostructural these into “clover leaf” clusters, consistent with seen across visual As is...

Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in cortex during healthy aging. Two recent showed primary (V1) normal aging; however, no characterized the effects of aging on beyond V1, important measurements both for understanding process and comparison to diseases. Similarly, there almost information Alzheimer’s disease (AD), most common form dementia. Because...

<title>Abstract</title> As an avenue to explore the extent which human posterior parietal cortex (PPC) can undergo dynamic reorganization, we used fMRI investigate cortical effects of extreme alteration visual input. In Experiment-1, subjects adapted a complete left-right visual-field reversal for two weeks continuously. After 7-10 days, behaviorally, and, in tandem, fields their PPC shifted visuospatial representations from primarily contralateral ipsilateral field responses. When normal...

In 2000, monocular vision was restored to M. M., who had been blind between the ages of 3 and 46 years. Tests carried out over 2 years following surgery revealed impairments 3-D form, object, face processing an absence object- face-selective blood-oxygen-level-dependent responses in ventral visual cortex. present research, we reexamined test for experience-dependent recovery function. Behaviorally, remains impaired processing. Accordingly, found little no evidence category-selective...

Are silencing, ectopic shifts, and receptive field (RF) scaling in cortical scotoma projection zones (SPZs) the result of long-term reorganization (plasticity) or short-term adaptation? Electrophysiological studies SPZs after retinal lesions animal models remain controversial, because they are unable to conclusively answer this question limitations methodology. Here, we used functional MRI (fMRI) visual mapping through population RF (pRF) modeling with moving bar stimuli under photopic...

Aging often results in reduced visual acuity from changes both the eye and neural circuits [1-4]. In normally aging subjects, primary cortex has been shown to have responses stimulation [5]. It is not known, however, what extent affects field repre-sentations population receptive sizes human cortex. Here we use func-tional MRI (fMRI) (pRF) modeling [6] measure angular ec-centric retinotopic representations fields healthy subjects ages 57 - 70 young volunteers 24 36 (n = 9). Retinotopic...

Abstract Peatlands store more carbon than the world's forests combined, despite covering only 3% of Earth's surface. Governing sequestration are biogeochemical processes which controlled largely by hydrology, is influenced physical properties soils, such as bulk density, particle and porosity. Reliable values for these peat can be found in literature; however, Sphagnum litter, particularly often not measured or reported. The that do exist litter rarely report depth any spatial differences...

Game theory has been useful for understanding risk-taking and cooperative behavior. However, in studies of the neural basis decision-making during games conflict, subjects typically play against opponents with predetermined strategies. The present study introduces a neurobiologically plausible model action selection neuromodulation, which adapts to its opponent's strategy environmental conditions. is based on assumption that dopaminergic serotonergic systems track expected rewards costs,...

Abstract Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in brain, influencing neural development, plasticity, and repair (Chen et al., 2004; Thoenen, 1995). The BDNF gene contains a single-nucleotide polymorphism (SNP) called Val66Met. Met allele interferes with intracellular BDNF-trafficking, decreases activity-dependent secretion, consequently often associated shift from plasticity to stability circuits (Egan 2003). We investigated behavioral consequences of...

Visual working memory (VWM) is the ability to maintain visual information in a readily available and easily updated state. Converging evidence has revealed that VWM capacity limited by number of maintained objects, which about 3 - 4 for average human. Recent work suggests also resolution required tied objects' inherent complexity. Electroencephalogram (EEG) studies using Contralateral Delay Activity (CDA) paradigm have cortical representations are at minimum loosely organized like primary...