Fig. 1.

Behavioral assessment of thermal hyperalgesia and mechanical allodynia. Rats rested comfortably in a restrainer with a covering over the head and face that exposed the chin. The covering was sufficiently loose to allow limited upward and lateral head movements. The restrainer was angled so that the chin rested on a warmed glass surface and could be stimulated with radiant heat to elicit head withdrawals. This also allowed mechanical von Frey stimulation to record head withdrawal thresholds.