Is there a region of the brain that mediates pain in a manner reminiscent of the mesolimbic pathway?

Question

The mesolimbic dopamine pathway is a common neural pathway upon which rewards converge AKA the pleasure pathway.

So I am trying to find a comparable pathway in the brain for pain -- is there such a thing? Ideally, one where a probe could be inserted and stimulated to induce intractable pain in the victim. Is there anything reminiscent of the mesolimbic pathway but for pain, perhaps with some sort of somatosensory mapping?

What you never thought about using Deep Brain Stimulation to torture someone before?

Answer 1

Based on the most recent (all post-2009) research, it seems to be the same general pathway, just with different gradients in the same areas of the brain. From Taylor et al. (2016):

Recent studies suggest that dopamine neurons in the VTA [ventral tegmental area] and SN [substantia nigra] form a heterogeneous population tuned to either (or both) aversive or rewarding stimuli.

The heterogeneity of dopamine neurons in response to aversive and rewarding stimuli suggests that they serve unique functional roles. Cells activated by reward and inhibited by punishment are well suited to code motivational valence, whereas neurons activated by both rewarding and punishing stimuli are likely to code motivational salience [stimulus awareness]. Neurons coding motivational valence [whether the stimulus is positive or negative in value] would provide a signal for reward seeking, evaluation, and value learning, in line with current theories on the role of dopamine in reward processing. In contrast, neurons coding motivational salience would provide a signal for detection and prediction of highly important events independent of valence, pursuant to dopamine's role in salience processing. These distinct aspects of dopamine neurotransmission might be neuroanatomically separate: dopaminergic neurons coding motivational valence have been found more commonly in the ventromedial SN and lateral VTA with projections to nucleus accumbens [NAc] shell, whereas neurons coding motivational salience are more often reported in the dorsolateral SN with projections to the nucleus accumbens core.

The primary evidence for this updated view seems mostly based (in order of the number of citations) on 3 papers:

• Matsumoto and Hikosaka, "Two types of dopamine neuron distinctly convey positive and negative motivational signals", Nature 2009;
• Brischoux et al., "Phasic excitation of dopamine neurons in ventral VTA by noxious stimuli", PNAS 2009
• Lammel et al., "Projection-specific modulation of dopamine neuron synapses by aversive and rewarding stimuli", Neuron 2011

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The part of your question that probably confused Alice and also confuses me a little is that you also ask (in your final paragraph) about somatosensory mapping. The latter doesn't generally involve tracing any pathways beyond the sensory areas of the brain, e.g. for macaques

Also such maps are not totally fixed as there is some use-dependent plasticity.