Central pathways relaying cardiovascular afferent information to amygdala.

Area of Science:

• Neuroscience
• Cardiovascular Physiology

Background:

• Cardiovascular information influences amygdala function.
• The paraventricular nucleus of the hypothalamus (PVH) and parabrachial nucleus (PB) are hypothesized relay sites.

Purpose of the Study:

• To investigate the role of PVH and PB in relaying cardiovascular information to the amygdala.
• To determine the specific contributions of baroreceptor and chemoreceptor activation.

Main Methods:

• Recorded amygdala unit activity during PVH and PB stimulation in anesthetized cats.
• Tested responses to baroreceptor (BA) and chemoreceptor (CA) activation.
• Assessed effects of neuronal block (procaine) and lesions (electrolytic, kainic acid) in PVH and PB on evoked potentials from buffer nerve stimulation.

Main Results:

• PB stimulation activated more amygdala units than PVH stimulation.
• PB-activated units showed responses to CA and some to BA.
• Neuronal block and lesions in the PB significantly attenuated evoked amygdala potentials.
• PVH block did not alter evoked potentials.

Conclusions:

• The parabrachial nucleus (PB) is a critical relay site for cardiovascular information, specifically chemoreceptor and some baroreceptor inputs, to the amygdala.
• The paraventricular nucleus of the hypothalamus (PVH) is unlikely to be a primary relay for this information.