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Spinothalamic lamina I neurons selectively sensitive to histamine: a central neural pathway for itch


We found a class of lamina I spinothalamic tract (STT) neurons selectively excited by iontophoretic histamine. The responses of this class of neurons parallel the pure itching sensation this stimulus elicits in humans, and match the responses of peripheral C-fibers that have similar selectivity. These neurons have distinct central conduction velocities and thalamic projections, indicating that they constitute a unique subset of STT neurons. These findings can explain why a lesion of the lateral STT disrupts itch along with pain and temperature sensations. Our findings provide strong evidence that itch is subserved by specific neural elements both peripherally and centrally.

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Figure 1: Responses from a histamine-sensitive lamina I STT neuron.
Figure 2: Histamine and vehicle evoked responses from histamine-sensitive lamina I STT neurons.
Figure 3: The effects of histamine and vehicle on a nociceptive lamina I STT neuron.
Figure 4: Distinguishing features of histamine-sensitive lamina I STT neurons.
Figure 5: Response properties of chemo-nociceptive lamina I STT neurons.


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This study was supported by the NIH (NS 25616) and the Atkinson Pain Research Fund administered by the Barrow Neurological Foundation. We thank M. Tatum for technical support.

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Correspondence to D. Andrew.

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Andrew, D., Craig, A. Spinothalamic lamina I neurons selectively sensitive to histamine: a central neural pathway for itch. Nat Neurosci 4, 72–77 (2001).

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