J. Neurosci. -- eLetters for Baliki et al., 28 (6) 1398-1403

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Brief Communications:
Marwan N. Baliki, Paul Y. Geha, A. Vania Apkarian, and Dante R. Chialvo
Beyond Feeling: Chronic Pain Hurts the Brain, Disrupting the Default-Mode Network Dynamics
J. Neurosci. 2008; 28: 1398-1403 [Abstract] [Full text] [PDF]

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The pain is mainly in the brain (once again)
Patrick B. Wood (11 February 2008)

The pain is mainly in the brain (once again) 11 February 2008

Patrick B. Wood,
Chief Medical Officer
Angler Biomedical Technologies, LLC. Rockville, MD 20852
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Re: The pain is mainly in the brain (once again)

pwood{at}anglerbiomedical.com Patrick B. Wood

I have read with great interest the report by Baliki and colleagues describing increased prefrontal activity (“decreased deactivation”) during a cognitive paradigm in patients with chronic low back pain (Baliki et al., 2008). While the authors suggest their findings indicate that chronic pain alters brain function, by their own admission, study design disallows definitive mechanistic explanations. Excitatory prefrontal afferents preferentially target interneurons that inhibit mesolimbic projections (Carr & Sesack, 2000), while attenuated dopaminergic activity within the striatum augments nociceptive behavior (Altier & Stewart, 1999; Saadé et al, 1997). One would therefore anticipate that a predisposition towards increased prefrontal activity (i.e. “hyperfrontality”) would produce a proportional decrease in mesolimbic activity thereby augmenting nociception and, ostensibly, placing one at increased risk for developing chronic pain. Indeed, relative increases in prefrontal activity among healthy subjects correlate with increased subjective pain ratings (Coghill et al., 2003), and clinical pain states are likewise associated with prefrontal hyperactivity (Apkarian et al, 2001; Cook et al., 2004). Conversely, the inverse relationship between prefrontal activation and mesolimbic reactivity may underlie the observation that schizophrenia, which is associated with both hypofrontality (Andreasen et al., 1997) and mesolimbic hyperactivity (Bertolino et al., 1999), is also associated with hypoalgesia (Potvin & Marchand, 2007). Thus, chronic pain might be the result of increased prefrontal activity rather than its cause.
References
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