The 2010 Julius H. Comroe, Jr., Lecture of the American Physiological Society focuses on evolving ideas in chemoreception for CO₂/pH in terms of what is "sensed," where it is sensed, and how the sensed information is used physiologically. Chemoreception is viewed as involving neurons (and glia) at many sites within the hindbrain, including, but not limited to, the retrotrapezoid nucleus, the me...

TOPICALITIES IN THE SUDDEN UNEXPECTED DEATH SYNDROME IN INFANTS (Abstract): Sudden Infant Death Syndrome (SIDS) represents the third cause in postnatal mortality. The pathogenesis is multifactorial. SIDS victims can present sign of preexisting chronic asphyxia, persistent increase in dendritic spine and delayed maturation of synapses in medullary respiratory centers, if a decreased reactivity o...

The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of sudden infant death syndrome (SIDS). This seems to persist in human beings as an inheritance from diver birds and amphibians. It has been reported that washing the face with cold water or plunging into cold water can provoke cardiac deceleration through the intervention of the ambiguus and the vagal d...

The song system of songbirds consists of an interconnected set of forebrain nuclei that has traditionally been regarded as dedicated to the learning and production of song. Here, however, we suggest that the song system could also influence muscles used in reproductive behaviour, such as the cloacal sphincter muscle. We show that the same medullary nucleus, retroambigualis (RAm), that projects ...

Spontaneous vestibular syndrome in mice, characterized clinically by head tilt, circling or rolling, can be caused by otitis media, arteritis or central nervous system lesions. Postmortem examination of eleven non-inbred Swiss mice submitted for necropsy due to acute onset of vestibular signs revealed lesions consistent with brainstem infarction. The lesions were characterized by unilateral, we...

The expression of the proto-oncogene c-fos was used as a cellular marker of spinal cord neurons activated by microinjection of kainic acid into the medullary nucleus raphe magnus of awake and drug-free Sprague-Dawley rats. The c-FOS protein was detected by immunocytochemistry. We found increased immunoreactivity bilaterally in laminae I-VI of the dorsal horn. The strongest c-FOS expression was ...

The vagus, the 10th cranial nerve, contains pathways that contribute to the regulation of the internal viscera, including the heart. Vagal efferent fibers do not originate in a common brainstem structure. The Polyvagal Theory is introduced to explain the different functions of the two primary medullary source nuclei of the vagus: the nucleus ambiguus (NA) and the dorsal motor nucleus (DMNX). Al...

The ventilatory CO2 chemoreflex is inherently low in inbred Brown Norway (BN) rats compared with other strains, including inbred Dahl salt-sensitive (SS) rats. Since the brain stem expression of various pH-sensitive ion channels may be determinants of the CO2 chemoreflex, we tested the hypothesis that there would be fewer pH-sensitive K(+) channel-expressing cells in BN relative to SS rats with...

Mormyrid fish generate weak electric organ discharges (EODs) used for communication and navigation. EODs are initiated in the medullary command nucleus (CN), which receives dense projections from the mesencephalic precommand nucleus (PCN) and the adjacent thalamic dorsal posterior nucleus (DP), plus a minor projection from the ventral edge of the toral ventroposterior nucleus (VPv). The dorsal ...

In the bullfrog (Rana catesbeiana), the process of metamorphosis culminates in the appearance of new visual and visuomotor behaviors reflective of the emergence of binocular vision and visually-guided prey capture behaviors as the animal transitions to life on land. Using several different neuroanatomical tracers, we examined the substrates that may underlie these behavioral changes by tracing ...