While recording electrical activity from the prefrontal cortex of primates it has been found that a 1-9 Hz burst of activity (i.e., theta activity) occurs immediately before a perceptual transition during binocular rivalry (Dwarakanath, Logothetis et al. 2020). It is noteworthy that such transitions can be facilitated by changes in the scanning pattern of eye movements (Tehovnik, Hasanbegović, Chen 2024), a behavior accompanied by theta discharges (Tehovnik 2017; Vanderwolf 1969). Even in the absence of visual input (i.e., during resting state), the prefrontal cortex was found to undergo similar transitions punctuated by 1-9 Hz burst activity. A ‘conscious’ state typically lasted from 1 to 1.6 seconds both in the presence or absence of a rivalrous stimulus, which agrees with previous estimates (Varela 1999ab). Dwarakanath, Logothetis et al. (2020) have suggested that the state transitions are mediated by a pre-conscious process, which is much like the readiness potential generated in the frontal lobes that precedes conscious awareness of an up-and-coming motor act by many hundreds of milliseconds (Libet 1985).
The speed of a transition in consciousness is mediated by dopamine: low doses of dopamine have been associated with a reduced flow of consciousness/ mobility (a type of depression, causing the interruption of thinking and movement) (Sacks 2012; Varela 1999ab), whereas high doses of dopamine have been associated with an accelerated consciousness that if in excess concentrations can induce hallucinations and other distortions of reality, characteristic of schizophrenia (Varela 1999ab; also see Footnote 1). Wall Street executives are known to ingest cocaine (a dopamine potentiator) to accelerate their stream of consciousness. And some have speculated that the reason the industrial revolution started in England rather that in Germany is that while the English were caffeinating their consciousness, the Germans were drowning their wits in beer (Pendergrast 2010; see Footnote 2). Wilder Penfield believed that activation of the cerebral cortex prior to a volitional act is dependent on activity emanating from the brainstem (Penfield 1954; also see Vanderwolf 2007). We now know that neocortical-cerebellar loops are central to all behavioral programs (Hasanbegović 2024) and state transitions of consciousness, and it is the cerebellum that optimizes the timing of these transitions [Fig. 1 illustrates the scheme for the execution of saccadic eye movements, the best studied operant behavior on record as it applies to brain function, Schiller and Tehovnik 2015]. Theta activity is omnipresent throughout the brain for the synchronization of state transitions via the hippocampus, neocortex, and cerebellum (Asaka et al. 2005; Berry and Thompson 1978; Bohbot et al. 2017; Canto, De Zeeuw et al. 2023; Dwarakanath, Logothetis et al. 2020; Hoffman and Berry 2009; Lubenov and Siapas 2009; Nokia et al. 2012b; Vanderwolf 1969; Wikgren et al. 2010; Zhang and Jacobs 2015).
Footnote 1: If one electrically stimulates the lateral thalamus using high currents and long pulse durations (i.e., cathodal pulses of ~ 6,000 μA at 1 ms delivered for 60 Hz for 9 seconds), which would activate the unmyelinated dopaminergic axons (en route to the left cerebral hemisphere) 2.5 mm from the electrode tip, the speed of verbal utterances and the rate of counting are increased, but at suprathreshold currents these behaviors are interrupted (Hebb and Ojemann 2013). The current-spread estimate is based on the following formula: Current = Current-Distance Constant x Radial Distance^2, with a Constant of 1,000 μA/mm^2 for dopamine axons adjusted for 1-ms duration cathodal pulses (Yeomans et al. 1988).
Footnote 2: In combination with universal record keeping (care of the printing press, Clark 1998) and the peer-review process set in place by the Royal Society starting in 1660, the industrial revolution eventually lifted much of the world out of ignorance and poverty to bring us to the present day of global prosperity. Note, in the absence of a written language, the Pirahã people of Brazil (Everett 2005) would not have been able to accomplish this global transformation—even though we have much to learn from them about economic sustainability and respect for the planet.
Figure 1: The neocortex of primates mediates the ‘what’ characteristics of a visual target and the superior colliculus mediates the ‘where’ or location characteristics of a visual target. Symbols ‘A’ and ‘B’ are stored in the temporal cortex declaratively after learning. To communicate the ‘what’ and ‘where’ properties of the symbols to the cerebellum, the mossy fibres carry the pattern of the symbols to the cerebellar cortex (Marr 1969) and the climbing fibres carry the location signal to the cerebellar cortex (Soetedjo, Fuchs and colleagues 2019). The two signals are merged during learning so that once associated a saccadic eye movement is generated to a symbol at the appropriate time, i.e., ‘when’. To drive the saccadic behavior, i.e., the ‘why’, a reward signal is transmitted from the ventral tegmental area (VTA) to the cerebellar cortex via the climbing fibres. Other labels are as follows: visual cortex (V1), motor cortex (M1), and superior colliculus (SC). From Tehovnik, Hasanbegović, Chen (2024).
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