Language in shadow.

The recent finding that Broca's area, the motor center for speech, is activated during action observation lends support to the idea that human language may have evolved from neural substrates already involved in gesture recognition. Although fascinating, this hypothesis can be questioned because while observing actions of others we may evoke some internal, verbal description of the observed scene. Here we present fMRI evidence that the involvement of Broca's area during action observation is genuine.

Tonotopic control of auditory thalamus frequency tuning by reticular thalamic neurons.

GABAergic cells of the thalamic reticular nucleus (TRN) can potentially exert strong control over transmission of information through thalamus to the cerebral cortex. Anatomical studies have shown that the reticulo-thalamic connections are spatially organized in the visual, somatosensory, and auditory systems. However, the issue of how inhibitory input from TRN controls the functional properties of thalamic relay cells and whether this control follows topographic rules remains largely unknown.

Attentional modulation in the human visual cortex: the time-course of the BOLD response and its implications.

Throughout the visual areas of the brain, the sensory response to a stimulus is enhanced by attending to the stimulus. Neurophysiological studies in primates show that such enhancement is marked in posterior parietal cortex and some anterior occipital areas, but much more modest in the earliest processing stages, such as the primary visual cortex (V1). In contrast, human fMRI studies show large and robust attentional modulation in all visual areas, including V1.

Evoked oscillations in unit recordings from the thalamo-cortical auditory system: an aspect of temporal processing or the reflection of hyperpolarized brain states?

Since the beginning of the 90's several lines of research have brought new insights concerning the temporal aspects of sensory processing. Initial observations showing that sensory stimuli can trigger evoked, or induced, oscillations has generated a large number of studies where, explicitly or implicitly, the large-scale rhythmic activity of thalamo-cortical neurons was viewed as a key factor to synchronize neurons responding to different dimensions of a given stimulus, and therefore to solve the so-called "binding problem" (for reviews see Eckhorn 2000, Singer 1990, 1999). This line of research contrasts with the rate coding concept which has been used over the last 40 years to describe the functional properties of neurons in sensory systems and the plasticity of sensory systems both during development and in adulthood.

Evoked oscillations in the thalamo-cortical auditory system are present in anesthetized but not in unanesthetized rats.

Over the last decade, a large number of studies have characterized stimulus-evoked oscillations in the visual cortex of anesthetized and unanesthetized animals. Comparatively, only a few studies have been performed in auditory cortex. This study compared the tone-evoked oscillations detected from the same recording sites in the thalamo-cortical auditory system of unanesthetized and anesthetized rats.