RELATIONSHIPS BETWEEN HIPPOCAMPAL ACTIVITY AND BREATHING PATTERNS

Single cell discharge, EEG activity, and optical changes accompanying alterations in breathing patterns, as well as the knowledge that respi ratory musculature is heavily involved in movement and other behaviora l acts, implicate hippocampal regions in some aspects of breathing con trol. The control is unlikely to reside in oscillatory breathing movem ents, because such patterns emerge in preparations retaining only the medulla land perhaps only the spinal cord). However, momentary changes in breathing patterns induced by affect, startle, whole-body movement changes, or compensatory ventilatory changes mediated by rostral brai n regions likely depend on hippocampal action in aspects of control. H ippocampal activity was enhanced prior to sighs, and this enhancement was accompanied by increased slow theta activity. Theta frequency incr eased during apnea. prior to return of breathing. Consideration of hip pocampal contributions to breathing control should be viewed in the co ntext that significant interactions exist between blood pressure chang es and ventilation, and that modest breathing challenges, such as expo sure to hypercapnia or to increased resistive loads, bring into action a vast array of brain regions involving nearly every level of the neu raxis. (C) 1998 Elsevier Science Ltd. All rights reserved.