Theta activity (~ 6-10 Hz) has been associated with transitions between different frames of consciousness, as studied using binocular rivalry (Dwarakanath, Logothetis 2023). This rhythm is modulated by neurons in the septal area by way of the hippocampus (Buzsáki 2006; Stewart and Fox 1990). A travelling theta wave occupies the posterior-anterior length of the hippocampus during locomotion along a track (Lubenov and Siapas 2009; Zhang and Jacobs 2015). Both excitatory (cholinergic) and inhibitory (GABAergic) neurons located within the septum are important for maintaining this rhythm (Stewart and Fox 1990). These neurons not only innervate the hippocampus, but they also affect the neocortex (Beaman et al. 2017; Bjordahl et al. 1998; Engel et al. 2016; Goard and Dan 2009; McLin et al. 2002; Miasnikov et al. 2009; Pinto et al. 2013; Tamamaki and Tomioka 2010; Vanderwolf 1969, 1990) so that the two regions can exhibit synchronized activations when tasks such as running along a track, playing a musical instrument, or delivering a speech are being executed. These behaviors require transitions between different frames of consciousness, as stored declaratively within the neocortex (Corkin 2002; Dwarakanath, Logothetis 2023; James 1890; Sacks 1976, 2012; Squire et al. 2001). Having both excitatory and inhibitory inputs to the neocortex (Stewart and Fox 1990; some 2/3 of neocortical neurons are excitatory and the remainder are inhibitory, Bekker 2011) allows for specific strings of consciousness to be concatenated, but only after overtraining which diminishes the roll of the cerebellar cortex (e.g., Lisberger 1984; Miles and Lisberger 1981). Thus, the concatenated items of the neocortex would need to have ready access to the brain stem and spinal cord nuclei to produce a sequence of behaviors (Kumura 1993; Vanderwolf 2007). For this to be accomplished there needs to be a fine interplay between the inhibitory and excitatory fibres of the neocortex. Exactly how this happens sequentially remains to be deduced by careful experimentation, but we now have the technology to study this globally in the brain (e.g., Hasanbegović 2024).
The travelling wave via the hippocampus (Lubenov and Siapas 2009; Zhang and Jacobs 2015) must be paired with specific neocortical neurons to deliver a declarative expression, such as—"I want to be a scientist”—which is generated by the muscles controlled by the brain stem vocal apparatus (see Footnote 1). Each cycle of a travelling wave would sample a particular sequence of activations within the neocortex and across one cycle a specific collection of neurons would be sequenced, and items stored within each neuron delivered verbally. This process would be repeated—the repetition of unique strings of consciousness—until the completion of a speech. The cerebellar cortex would only be engaged while delivering a speech, if alterations needed to be made to the executable code, which would happen, for example, if someone from the audience asked a question. Such an alteration would require a volitional intervention by the speaker (i.e., by the neocortex) to interrupt the automatic running of the executable code as memorized.
Footnote 1: The reason humans have been endowed with speech is because the M1 pyramidal fibres innervate the vocal apparatus directly which is composed of the following cranial nerves: V, VII, X, and XII (Aboitiz 2018; Kimura 1993; Ojemann 1991; Penfield and Roberts 1966; Simonyan and Horwitz 2011; Vanderwolf 2007). This allows for maximal control over the speech muscles. It is known that most speech, irrespective of language type, can be transferred at about 40 bits per second (Coupé et al. 2019; Reed and Durlach 1998; Tehovnik and Chen 2015). One will need to investigate whether this limit is set by the number of pyramidal fibres dedicated to the production of speech [note that a brain-machine interface for speech was found to transfer 2.1 bits per second for neural recordings made in the speech area of M1 (Willett, Shenoy et al. 2023), which falls well short of the 40 bits per second needed for normal performance]. Some 100 of the 700 skeletal muscles of the human body are involved in the delivery of a speech to operate the vocal apparatus (Simonyan and Horwitz 2011).
If we agree that the spoken sentence: "I want to be a scientist”, encompasses the exact same perception processes as writing the sentence: "I want to be a scientist”, then all the functional c.q. behavioral (conscious) perception processes can be found in the attached articles. (They show, only apart from the explanation of the cortcial streams, that the functional side doesn't have a relationship whatsoever with the physiological side of the matter.)
Chapter Writing with the other hand unequivocally exposes the presen...
Chapter Within writing the essence of the task is solely executed by...
Chapter The external primary focus within writing solely encompasses...
Chapter The execution of an external action trajectory shape over wh...
Chapter Writing - From random motor activity to the execution of del...
I think we agree. We had a scientist from Japan who could not speak a word of English, but was able to read and write in English. It was as though that pathway between the neocortex and the vocal apparatus did not exist but for Japanese he was obviously fluent and had no problem using his vocal apparatus.
That is one of the most amazing sequential descriptions inhave ever seen put together!! very enjoyable and informative reading!!!!
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