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Autonomic responses and efferent pathways from the insular cortex in the rat
Y Yasui1, C D Breder, C B Saper
1Department of Pharmacology and Physiology, University of Chicago.
The Journal of Comparative Neurology
|January 15, 1991
Summary
The insular cortex controls autonomic functions, with distinct regions triggering either increased blood pressure and heart rate or decreased blood pressure and heart rate. These regions connect differently to brain areas, influencing specific cardiovascular responses.
Area of Science:
- Neuroscience
- Autonomic Nervous System Research
- Cardiovascular Physiology
Background:
- The insular cortex plays a crucial role in integrating visceral sensory information and regulating autonomic functions.
- Understanding the specific neural pathways originating from the insular cortex is essential for comprehending autonomic control.
Purpose of the Study:
- To map the anatomical distribution of autonomic, particularly cardiovascular, responses originating in the insular cortex.
- To investigate the efferent connectivity of cardiovascular-responsive sites within the insular cortex.
Main Methods:
- Systematic electrical microstimulation of the insular cortex.
- Microinjection of D,L-homocysteic acid to localize response origins.
- Anterograde tracing using Phaseoleus vulgaris leucoagglutinin (PHA-L) to map efferent pathways.
Main Results:
- Two distinct cardiovascular response patterns were identified: pressor (increased arterial pressure and tachycardia) from the rostral posterior insula, and depressor (decreased arterial pressure and bradycardia) from the caudal posterior insula.
- Pressor sites showed stronger connections to limbic regions (infralimbic cortex, amygdala, bed nucleus of the stria terminalis, thalamic nuclei).
- Depressor sites projected more heavily to sensory areas (somatosensory cortex, thalamus, spinal trigeminal nucleus) and showed topographical differences in projections to the lateral hypothalamus.
Conclusions:
- Distinct anatomical regions within the insular cortex mediate specific cardiovascular responses (pressor vs. depressor).
- Differential connectivity patterns of pressor and depressor sites to limbic and sensory areas provide an anatomical basis for integrated cardiovascular control.
- These findings elucidate the neural circuitry underlying autonomic regulation within the insular cortex.