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Distribution of cardiovascular related cells within the human thalamus
S M Oppenheimer1, N Kulshreshtha, F A Lenz
1Department of Neurology and Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
Insights
Researchers found specific thalamic cells in humans that respond to the cardiac cycle. These cells may play a role in cardiovascular regulation and processing cardiac pain signals.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Human Electrophysiology
Background:
- Cardiovascular representation in the human thalamus remains uninvestigated.
- In rats, cardiovascular representation is primarily in the insular cortex, with inputs from the thalamic nucleus ventralis posterolateralis-parvicellular portion (VPLpc).
Purpose of the Study:
- To investigate the presence and characteristics of cardiovascularly responsive cells within the human thalamus.
- To determine the location and functional properties of these thalamic cells.
Main Methods:
- Extracellular recording techniques were used to evaluate 4481 thalamic cells in 60 unanesthetized patients during neurosurgery.
- Phasic cardiovascular activity related to the cardiac cycle was identified.
Main Results:
- Twenty-six cells exhibiting phasic activity synchronized with the cardiac cycle were identified in 10 patients.
- These cells were located in the ventrocaudal nucleus of the thalamus, with equal distribution on both sides.
- A majority of these cells (17/26) peaked neuronal activity within 50 ms of systolic pressure, and 35% had cutaneous receptive fields in areas associated with referred cardiac pain.
Conclusions:
- The identified thalamic cells may integrate afferent baroreceptor information.
- These cells could be involved in the generation or processing of central cardiac pain in humans.
- Dysfunction of these cells might contribute to cardiovascular disturbances, such as those seen in fatal familial insomnia.
Abstract:
Representation of cardiovascular function has not been investigated in the human thalamus. In the rat, the insular cortex is the principal forebrain site of cardiovascular representation whose afferents originate from a circumscribed thalamic area (nucleus ventralis posterolateralis-parvicellular portion, VPLpc). We therefore evaluated 4481 thalamic cells for phasic cardiovascular activity using extracellular recording techniques in 60 unanesthetized patients undergoing neurosurgical procedures. We identified 26 cells with phasic activity strongly related to the cardiac cycle in 10 patients. These cells clustered within the ventrocaudal nucleus of the thalamus (the principal sensory nucleus analogous to the ventral posterior thalamic group in the rat and monkey) and were equally distributed between the right and left sides. The majority of these cells (17/26) showed peaks of phasic neuronal activity within 50 ms of the peak systolic pressure; 35% had peripheral cutaneous fields in areas to which cardiac pain is often referred. We suggest that these cells may be involved in the integration of afferent baroreceptor information; may possibly be concerned with the generation and/or processing of central cardiac pain in humans; and that their derangement may possibly contribute to the lethal cardiovascular disturbances which occur in fatal familial insomnia.