Anatomical studies of the visual cortex have identified massive back-projecting pathways. Theoretical studies suggest how such pathways may play important roles in vision by mediating 'top-down' processing, in which information from a relatively high level is fed back to early visual stages.

During visually guided movements both vision and proprioception inform the brain about the position of the hand, so interaction between these two modalities is presumed. Current theories suggest that this interaction occurs by sensory information from both sources being fused into a more reliable, multimodal, percept of hand location. In the literature on perception, however, there is evidence ...

We present a fast and accurate non-invasive brain-machine interface (BMI) based on demodulating steady-state visual evoked potentials (SSVEPs) in electroencephalography (EEG). Our study reports an SSVEP-BMI that, for the first time, decodes primarily based on top-down and not bottom-up visual information processing. The experimental setup presents a grid-shaped flickering line array that the pa...

Unmethylated CpG motifs in bacterial DNA or short oligodeoxynucleotides (ODN) stimulate cells of the immune system and provide adjuvant activity. CpG DNA directly activates macrophages to secrete IL-12 and TNF-alpha and increases transcription of various genes, but its effects on macrophage Ag processing remain uncertain. The effects of CpG ODN on class II MHC (MHC-II) Ag processing and present...

Traditional views of visual processing suggest that early visual neurons are static spatiotemporal filters that extract local features by feedforward computation. The extracted information is then fed forward through a chain of modules to successively higher visual areas for further analysis. Recording from early visual neurons in awake behaving monkeys, we revealed there are many levels of com...

Processing speed, or the rate at which tasks can be performed, is a robust predictor of age-related cognitive decline and an indicator of independence among older adults. This review examines evidence for neurobiological predictors of age-related changes in processing speed, which is guided in part by our source based morphometry findings that unique patterns of frontal and cerebellar gray matt...

All cortical and thalamic levels of sensory processing are subject to powerful top-down influences, the shaping of lower-level processes by more complex information. New findings on the diversity of top-down interactions show that cortical areas function as adaptive processors, being subject to attention, expectation, and perceptual task. Brain states are determined by the interactions between ...

Speech perception is formed based on both the acoustic signal and listeners' knowledge of the world and semantic context. Access to semantic information can facilitate interpretation of degraded speech, such as speech in background noise or the speech signal transmitted via cochlear implants (CIs). This paper focuses on the latter, and investigates the time course of understanding words, and ho...

In this issue of Neuron, Hamilton et al. (2013) stimulate identified inhibitory interneurons with optogenetics, revealing powerful control of the flow of sensory responses across cortical layers. During natural behavior, these influences may mediate the rapid adaptive abilities necessary for detection and perception of sensory signals in noisy environments.