The Cambridge Declaration on Consciousness*
On this day of July
7, 2012, a prominent international group of cognitive neuroscientists,
neuropharmacologists, neurophysiologists, neuroanatomists and computational
neuroscientists gathered at The University of Cambridge to reassess the
neurobiological substrates of conscious experience and related behaviors in
human and non-human animals. While comparative research on this topic is
naturally hampered by the inability of non-human animals, and often humans,
to clearly and readily communicate about their internal states, the
following observations can be stated unequivocally:
·The field of
Consciousness research is rapidly evolving. Abundant new techniques and
strategies for human and non-human animal research have been developed.
Consequently, more data is becoming readily available, and this calls for a
periodic reevaluation of previously held preconceptions in this field.
Studies of non-human animals have shown that homologous brain circuits
correlated with conscious experience and perception can be selectively
facilitated and disrupted to assess whether they are in fact necessary for
those experiences. Moreover, in humans, new non-invasive techniques are
readily available to survey the correlates of consciousness.
neural substrates of emotions do not appear to be confined to cortical
structures. In fact, subcortical neural networks aroused during affective
states in humans are also critically important for generating emotional
behaviors in animals. Artificial arousal of the same brain regions generates
corresponding behavior and feeling states in both humans and non-human
animals. Wherever in the brain one evokes instinctual emotional behaviors in
non-human animals, many of the ensuing behaviors are consistent with
experienced feeling states, including those internal states that are
rewarding and punishing. Deep brain stimulation of these systems in humans
can also generate similar affective states. Systems associated with affect
are concentrated in subcortical regions where neural homologies abound.
Young human and nonhuman animals without neocortices retain these brain-mind
functions. Furthermore, neural circuits supporting
behavioral/electrophysiological states of attentiveness, sleep and decision
making appear to have arisen in evolution as early as the invertebrate
radiation, being evident in insects and cephalopod mollusks (e.g., octopus).
·Birds appear to offer, in their behavior, neurophysiology, and
neuroanatomy a striking case of parallel evolution of consciousness.
Evidence of near human-like levels of consciousness has been most
dramatically observed in African grey parrots. Mammalian and avian emotional
networks and cognitive microcircuitries appear to be far more homologous
than previously thought. Moreover, certain species of birds have been found
to exhibit neural sleep patterns similar to those of mammals, including REM
sleep and, as was demonstrated in zebra finches, neurophysiological
patterns, previously thought to require a mammalian neocortex. Magpies in
particular have been shown to exhibit striking similarities to humans, great
apes, dolphins, and elephants in studies of mirror self-recognition.
·In humans, the effect of certain hallucinogens appears to be associated
with a disruption in cortical feedforward and feedback processing.
Pharmacological interventions in non-human animals with compounds known to
affect conscious behavior in humans can lead to similar perturbations in
behavior in non-human animals. In humans, there is evidence to suggest that
awareness is correlated with cortical activity, which does not exclude
possible contributions by subcortical or early cortical processing, as in
visual awareness. Evidence that human and nonhuman animal emotional feelings
arise from homologous subcortical brain networks provide compelling evidence
for evolutionarily shared primal affective qualia.
We declare the
following: “The absence of a neocortex does not appear to preclude an
organism from experiencing affective states. Convergent evidence indicates
that non-human animals have the neuroanatomical, neurochemical, and
neurophysiological substrates of conscious states along with the capacity to
exhibit intentional behaviors. Consequently, the weight of evidence
indicates that humans are not unique in possessing the neurological
substrates that generate consciousness. Nonhuman animals, including all
mammals and birds, and many other creatures, including octopuses, also
possess these neurological substrates.”
* The Cambridge
Declaration on Consciousness was written by Philip Low and edited by Jaak
Panksepp, Diana Reiss, David Edelman, Bruno Van Swinderen, Philip Low and
Christof Koch. The Declaration was publicly proclaimed in Cambridge, UK, on
July 7, 2012, at the Francis Crick Memorial Conference on Consciousness in
Human and non-Human Animals, at Churchill College, University of Cambridge,
by Low, Edelman and Koch. The Declaration was signed by the conference
participants that very evening, in the presence of Stephen Hawking, in the
Balfour Room at the Hotel du Vin in Cambridge, UK. The signing ceremony was
memorialized by CBS 60 Minutes.