Comparison of neck dislocation and percussion of the head on visual evoked responses in the chicken's brain.

The effect of neck dislocation, by stretching or by crushing, on the ability of the chicken's brain to sustain visual evoked responses was compared with the effect of a percussive blow. Less than 10 per cent of the birds whose necks were dislocated showed signs of concussion. It was concluded that neck dislocation may not concuss chickens, and that it is therefore uncertain whether it induces instantaneous unconsciousness.