A: Functional Correlations (from (); with permission, Drug Discovery Research). The figure shows the thermal response of rats and humans to a 46°C stimulus applied to the dorsum of the foot. Note that the activation patterns in the regions of interest (primary somatosensory cortex (SI), thalamus (Th), insula (I), anterior cingulate cortex (aCG) and amygdala (A)) is similar in each species. Furthermore, the signal sign (i.e., increase or decrease in BOLD signal) is similar in both species).
B: Morphological Correlations: B1: The Figure shows cortical gray matter volume loss (gray matter density) in the dorsolateral prefrontal cortex (DLPF) in patients with chronic back pain (From (); with permission, Journal of Neuroscience). B2: Data from a rat neuropathic pain model (SNI) showing cortical volume loss in the prefrontal cortex (From (); with permission, Neuroimage).
C: Analgesic Correlations (from (); with permission, Drug Discovery Research). Effects of Drugs on Thermal Stressor in Humans. C1: Sample axial slices depicting activation maps for two drugs (imipramine and clonazepam) and placebo. Visual inspections indicate that there is an overall decrease in activation for imipramine vs. placebo and an overall increase in activation for clonazepam vs. placebo. C2: Voxel count for 5 drugs vs. placebo for whole brain (WHB) activation. Note that for imipramine (I) and gabapentin (G) more voxels are activated in drug vs. placebo while for clonazepam (C), rofecoxib (R) and ketorolac (K) more voxels are activated in the drug vs. placebo. Topiramate (T) has an intermediate or mixed effect. C3: Voxel count for pathway activation (PB). Note a similar pattern is present when compared with whole brain activation.
Effects of Drugs on Thermal Stressor in and Rats. C4: Sample axial slices depicting activation maps for two drugs (imipramine and clonazepam) and placebo. Visual inspection indicates that there is an overall decrease in activation for imipramine vs. placebo and an overall increase in activation for clonazepam (C) vs. placebo. C5: Voxel count for 4 drugs vs. placebo for rat whole brain (RWHB) activation. Note that for imipramine (I) more voxels are activated in placebo vs. drug while for clonazepam (C), rofecoxib (R) and ketorolac (K) more voxels are activated in the drug vs. placebo. C6: Voxel count for pathway (RPB) activation in rats, showing a similar pattern to that for RWHB. Key: Red bar = voxels activated in drug > placebo; blue bar = drugs < placebo.