1 Beyond the cortex
It is common to come across statements like the following when trying to
characterize what makes human cognition special: “the enlargement and species-
specific elaboration of the cerebral neocortex during evolution holds the secret
to the mental abilities of humans” ( Rakic 2009: 724). The belief that the
neocortex holds the key to “humaniqueness”, as Hauser (2009) calls it, is deeply
rooted indeed. The same was true 50 years ago, which is why Lenneberg (1967)
could write: “Traditionally, all intellectual functions including speech and lan-
guage have been thought to be located in the cerebral cortex, and more specu-
lations have been directed to this thin sheet of tissue than toward any other
cerebral component” (p. 62).
But Lenneberg knew better, as he stressed that “there are many other struc-
tures that are demonstrably connected with the cortex and with each other
(often only by circuitous routes). Every structure of the brain is physiologically
active and at least some of the structures have been hypothesized to play a part
in the same intellectual functions that are more frequently imputed to the cor-
tex.” (p. 62) As an example, he cited Campion and Elliott-Smith (1934), who
proposed that “thought consisted of cortico-thalamic circulation of impulses”
(emphasis ours). Lenneberg also discussed Penfield’s idea of a “centrencephalic
integrating center”, a “central system within the brain stem which is responsible
for integration of varied specific functions from different parts of the hemi-
spheres.” Penfield too was aware of the explanatory potential of thalamic
involvement. “It is proposed,” he wrote (P enfield and Robert, 1959, p. 207)
“as a speech hypothesis, that the function of all three cortical speech areas (that
is, Broca’s, Wernicke’s, and the supplementary motor speech area) in man are
coordinated by projections of each to parts of the thalamus, and that by means
of these circuits, the elaboration of speech is somehow carried out.”
Unfortunately, Lenneberg’s remarks, which came not long after Lash ley’s
(1950) conclusion opposing localization and in favor of distribution in brain
studies, have not figured prominently in studies on language and human cogni-
tion more generally. As Staud igl et al. (2012) observe: “Human cognitive
neuroscience currently has a strong cortico-centric focus when it comes to