features of the so-called “default mode” network of the brain, of which the
thalamus is recognized as a key node. The default mode network refers to a set
of cortical and subcortical regions that are among the highest energy-consuming
brain regions and that have undergone the highest degree of expansion in our
lineage. The default mode network is typically involved in tasks such as mind
wandering, self-reference, recollecting one’s past and imagining one’s personal
future, internal mentation, and autobiographical plans. Buckner et al. ( 2008)
take the network to underlie “stimulus-independent thought”, and cite older
sources referring to this type of activity as “contribut[ing] a great deal to the
style and flavor of being human.”
Interestingly, once the combinatorial potential of language is seen as contrib-
uting to a particular mode of structuring and generating thought, capable of
linking conceptual domains, the language faculty can be brought closer to
standard descriptions of consciousness, working memory or the central executive
role. As Miller (2013) pu ts it, “working memory is, essentially, what we think
of as thought” (p. 411). Thanks to this, connections between the literature on
language and the literature on working memory become more transparent.
Indeed, the possibility that psychologists appealing to the central executive
function of working memory (Coolidge and Wyn n 2005, Wynn and Cooli dge
2007, Coolidge and Wyn n 2007, Aboitiz 1995, Ab oitiz et al. 2 006), or related
systems (Garofoli and Hai dle 2013), to account for the origins of human-specific
cognitive behavior were in fact attributing this transformative role to language
strikes us as very high.
An additional consideration leading to the thalamus arises in the context of
evolutionary discussions (Boeckx 2013a, Bo eckx and Ben ítez-Burraco 2014).
It is now well-established that Homo sapiens has a more globular braincase
compared to our closest relatives (both extant and extinct). Paleoneurological
studies based on endocranial geometry suggested that a spatial dilation of the
deep parietal areas was the major morphological difference between modern
and non modern human brains (Bruner et al. 20 03, Bruner 2004, 201 0). In
our sp ecies, the morphogenetic change associated with this parietal bulging was
then localized in a very early postnatal period, in a stage which is absent in
chimpanzees or in Neandertals (Gunz et al. 2012 , 2010, Neubauer et al. 2010).
Boeckx (2013a), and, in a much more articulated fashion, Boeckx and Benít ez-
Burraco (2014) suggested that the developmental changes expressed at the levels
of brain morphology and neural connectivity that occurred in our species after
the split from Neanderthals-Denisovans and that gave rise to a more globular
braincase configuration entailed significant changes not only at the cortical level,
but also, and equally importantly, at the subcortical level. Specifically, it is likely
that the thalamus benefited from this more globular environment given its
strategic, central position.
Sitting right at the center of the brain, the thalamus is in an ideal position to
modulate the activity of distant cortical (and subcortical) structures and render
them equidistant. In addition, by the logic of co-evolution and correlated growth,
parietal expansion is likely to lead to a similar expansion of thalamic nuclei
The central role of the thalamus 233