Encoding of environmental illumination by primate melanopsin neurons.

Light regulates physiology, mood, and behavior through signals sent to the brain by intrinsically photosensitive retinal ganglion cells (ipRGCs). How primate ipRGCs sense light is unclear, as they are rare and challenging to target for electrophysiological recording. We developed a method of acute identification within the live, ex vivo retina.

Ion Homeostasis in Rhythmogenesis: The Interplay Between Neurons and Astroglia.

Proper function of all excitable cells depends on ion homeostasis. Nowhere is this more critical than in the brain where the extracellular concentration of some ions determines neurons' firing pattern and ability to encode information. Several neuronal functions depend on the ability of neurons to change their firing pattern to a rhythmic bursting pattern, whereas, in some circuits, rhythmic firing is, on the contrary, associated to pathologies like epilepsy or Parkinson's disease.

An astrocyte-dependent mechanism for neuronal rhythmogenesis.

Communication between neurons rests on their capacity to change their firing pattern to encode different messages. For several vital functions, such as respiration and mastication, neurons need to generate a rhythmic firing pattern. Here we show in the rat trigeminal sensori-motor circuit for mastication that this ability depends on regulation of the extracellular Ca(2+) concentration ([Ca(2+)]e) by astrocytes.

How do we walk and chew gum at the same time?

A genetic approach has been used to map the neural circuits that control and coordinate the tongue and jaw muscles.

Generation of the masticatory central pattern and its modulation by sensory feedback.

The basic pattern of rhythmic jaw movements produced during mastication is generated by a neuronal network located in the brainstem and referred to as the masticatory central pattern generator (CPG). This network composed of neurons mostly associated to the trigeminal system is found between the rostral borders of the trigeminal motor nucleus and facial nucleus. This review summarizes current knowledge on the anatomical organization, the development, the connectivity and the cellular properties of these trigeminal circuits in relation to mastication.

Modulation of rhythmogenic properties of trigeminal neurons contributing to the masticatory CPG.

Increasing evidence suggests that the dorsal part of the principal sensory nucleus of the trigeminal nerve (NVsnpr) contains a significant core of the central pattern generator (CPG) circuitry required for mastication (Tsuboi et al., 2003). Like many trigeminal brainstem neurons, those of NVsnpr are rhythmically active in phase with fictive mastication in vivo (Tsuboi et al.