When the anteromedial frontal "escape" system is damaged, involuntary but purposive movements of an exploratory reach-and-grasp nature—what Denny-Brown referred to as a "positive" cortical tropism—are released in the contralateral limb. This is referred to as a "positive" cortical tropism because eliciting sensory stimuli, such as would result from tactile contact on the volar aspect of the fingers and palm of the hand, are linked to the activation of movement that increases or enhances the eliciting stimulation through a positive feedback connection (see discussion above in section entitled "Parietal and Occipital Lobes").