Higher-order consciousness is based on semantic capability, the ability to refer to objects and
express feelings by symbolic means. The authors propose that in evolution, semantics developed
before language in the form of gestures and sounds conveying meaning. Subsequently,
verbal syntax may have emerged from a ”protosyntax” related to gestures and pointing actions.
The evolutionary development of symbolic gestures and speech has served expressive functions
as well as referential functions, and is closely linked to value systems. Fully developed higher-order
consciousness is strongly dependent on language and memory systems mediated by language (pp.
193-197).
6.2. Antonio Damasio: Self Comes to Mind. Constructing the Conscious Brain.
Similar to Edelman and Tononi, Damasio proposes a model of the working brain and its connections
on the cortical and subcortical levels. He characterizes his project as a framework of hypotheses.
Damasio’s understanding of conscious experience displays similarities with Edelman and Tononi’s
model, but also an important difference. Damasio includes the brain stem as an integrated basis of
consciousness. He proposes that the key brain structures crucial for consciousness are sectors of
the upper brain stem, nuclei in the thalamus, and widespread regions of the cortex.
Mapping
It is a fundamental concept in Damasio’s framework that the brain maps the surrounding world as
well as is own activity. Maps are momentary neural patterns which represent objects and events in
the external world and the body, or represent other patterns processed in the brain. These momen-
tary patterns are experienced as images in the mind. In Damasio’s terminology, an experienced im-
age may be auditory, tactile or visceral as well as visual (p. 18, 70-71).
The construction of maps of the outside world is closely connected to interaction with objects in
the world. Similar to Edelman and Tononi, Damasio underscores the connection between perception
and action, and states that perception involves both information from the senses and active contribu-
tions from inside the brain (pp. 63-65).
Contributions of the thalamus and the cortex to consciousness
Damasio agrees with Edelman and Tononi that reentrant connectivity between the thalamus and re-
gions of the cortex is a requirement for the processing of images in the conscious mind. He refers to
reentry as massive recursive cross-signalling amplified by corticothalamic interlocking. Furthermore,
he points out the cooperation between the primary sensory cortices, nuclei in the thalamus, and
large areas of associative cortices. Ensembles of neurons that work together appear to synchronize
their activity momentarily. This synchronization can be measured by EEG as oscillations in the gam-
ma range, approximately 40 Hz (pp. 75, 86-88, 248).