It is for this reason that many of the disorders discussed so far are called “neu-
rodevelopmental disconnection syndromes” (Shi et al. 2013).
5 Thalamus-generated oscillations and oscillopathies
Perhaps the best way to understand the crucial connecting, regulatory function
of the thalamus is in terms of brain oscillations. When it comes to brain func-
tioning, anatomical connections are not enough. Rather, dynamic, functional
connectivity between anatomically connected regions is key. Reinhart and Wood-
man (2013) put it this way: “Oscillatory synchronizat ion has been proposed to
dynamically establish large-scale networks among brain areas; the network rel-
evant to each cognitive operation should form and dissolve through dynamically
regulating the strength of functional connectivity between brain areas via oscil-
latory synchronization or coupling.”
As reviewed in Akam and Kullmann (2010), task-dependent increases in
strength and int erregion coherence of network oscillations have been reported
in numerous brain systems, with strong, coherent, synchronized oscillation
between sending and receiving regions during communication. Uhlhaas and
Singer (2006) review evidence that certain brain disorders , such as schizophrenia,
epilepsy, autism, Alzheimer’s disease, and Parkinson’s are associated with abnor-
mal neural synchronization. This is not surprising, considering that these deficits
concern functions, such as working memory, attention, and perceptual organiza-
tion, that have been argued to involve synchronization of oscillatory activity in
specific frequency bands.
Interestingly, local and long-distance synchrony appear to take place at dif-
ferent frequencies, and so Uhlhaas and Singer (2006) suggest that selective
deficiencies in the abi lity of cortico-thalamocortical loops to engage in precisely
synchronized oscillations at particular frequencies may provide the right level
of explanation for the disorders at issue. In particular, we think that this pos-
sibility may provide us with a deeper understanding of what the thalamus does,
and how language is implemented in the brain, taking us from the connectome
to the dynome. This is the topic of this section.
Uhlhaas and Singer (2006) point out that “cognitive dysfunctions were pa r-
ticularly pronounced for tasks requiring interactions between widely distributed
brain areas, such as integration of polymodal stimulus attributes, dynamic per-
ceptual grouping, working memory, and executive processes.” If we are correct,
the thalamus plays a key role establishing and maintaining large-scale integration
of activity. In other words, we expect many of the disorders reviewed above to
be accounted for in terms of thalamic dysrhythmia.
Daitch et al. (2013) pursue this very idea, starting with the claim that “dif-
ferent attention processes (holding vs. shifting attention)” are associated with
synchrony at different frequencies, and crucially appeal to the role of the thalamus
in this context. As they observe, “the pulvinar nucleus of the thalamus, for
example, has broadly distributed cortical connections and exhibits both attention-
modulated spike rate and synchrony with visual areas. The inhibitory thalamic
The central role of the thalamus 241