More conscious conundrums and connections
Interesting aspects of intuition and collective consciousness
My past newsletters delved into the nature of consciousness and how we slip into and out of it. Recent publications add intriguing details to the picture.
Anesthesia Actions
Isoflurane is a volatile anesthetic gas, and its mechanisms of action to cause loss of consciousness, are not fully understood. A recent report examined its effects on the neuronal cytoskeleton.
Volatile anesthetics are currently believed to cause unconsciousness by acting on one or more molecular targets including neural ion channels, receptors, mitochondria, synaptic proteins, and cytoskeletal proteins. Anesthetic gases including isoflurane bind to cytoskeletal microtubules (MTs) and dampen their quantum optical effects, potentially contributing to causing unconsciousness. This possibility is supported by the finding that taxane chemotherapy consisting of MT-stabilizing drugs reduces the effectiveness of anesthesia during surgery in human cancer patients. In order to experimentally assess the contribution of MTs as functionally relevant targets of volatile anesthetics, we measured latencies to loss of righting reflex (LORR) under 4% isoflurane in male rats injected subcutaneously with vehicle or 0.75 mg/kg of the brain-penetrant MT–stabilizing drug epothilone B (epoB). EpoB-treated rats took an average of 69 s longer to become unconscious as measured by latency to LORR. This was a statistically significant difference corresponding to a standardized mean difference (Cohen’s d) of 1.9, indicating a “large” normalized effect size. The effect could not be accounted for by tolerance from repeated exposure to isoflurane. Our results suggest that binding of the anesthetic gas isoflurane to MTs causes unconsciousness and loss of purposeful behavior in rats (and presumably humans and other animals). This finding is predicted by models that posit consciousness as a property of a quantum physical state of neural MT. - S Khan, et al.
Past literature detailed quantum chemical modeling of anesthetic and nonanesthetic molecules binding to the tubulin dimers that make up MTs, and found that anesthetic potency was predicted by the modeled disruption or failure to disrupt high-frequency vibrations inside MT protein subunits. Consciousness may be quantum in nature, and its brain basis is a collective quantum vibration of microtubule proteins inside neurons.
Just breathe, and you will see
Take a deep breath to get a clearer picture. Breathing can impact your visual perception. Yes indeed, these interoceptive stimuli can modulate the perception of external stimuli.
The experiment had volunteers observe gray squares which were cross-hatched diagonally. Subjects were queried as to whether they saw the patterns or not, and the diagonal orientation. The contrast of the crosshatching was calibrated so that participants consciously perceived it 50% of the time. Yet, despite only 50% conscious perception, the subject could correctly determine the orientation 85% of the time. So, the volunteers often processed the patterns without full consciousness.
Cardiac and respiratory rhythms reflect in baroreceptor activity fluctuations across the cycle. And apparently, they can shape awareness-related brain activity for visual threshold stimuli. When comparing the brain electrical activity between situations where the subjects had seen the crosshatching or not, neuronal markers of consciousness could be identified.
When correlating these neural markers to cardiac phase, if the image was displayed during heart relaxation, the markers of consciousness appeared 150 milliseconds earlier than if the image was displayed during heart contraction. Similarly, breathing impacted visual perception, with the same delay.
Visual information can follow two different routes. When in the presence of bodily signals, it passes through the parietal cortex. In their absence, it passes through the frontal cortex instead. Thus, pressure receptors in the arteries will determine the cerebral pathway for visual perception.
More Mind Melds
In the newsletter, Synchronicity and Cooperativity, I discussed experimental phenomena that were consistent with the concept of collective consciousness. When two people interact, their brain activity becomes synchronized. Now here comes another example of external mind coupling. How are the speaker’s and listener’s brains aligned during their conversation?
Highlights:
•We acquired intracranial recordings in five dyads during face-to-face conversations
•Large language models can serve as a shared linguistic space for communication
•Context-sensitive embeddings track the exchange of information from brain to brain
•Contextual embeddings outperform other models for speaker-listener coupling
SUMMARY Effective communication hinges on a mutual understanding of word meaning in different contexts. We recorded brain activity using electrocorticography during spontaneous, face-to-face conversations in five pairs of epilepsy patients. We developed a model-based coupling framework that aligns brain activity in both speaker and listener to a shared embedding space from a large language model (LLM). The context-sensitive LLM embeddings allow us to track the exchange of linguistic information, word by word, from one brain to another in natural conversations. Linguistic content emerges in the speaker’s brain before word articulation and rapidly re-emerges in the listener’s brain after word articulation. The contextual embeddings better capture word-by-word neural alignment between speaker and listener than syntactic and articulatory models. Our findings indicate that the contextual embeddings learned by LLMs can serve as an explicit numerical model of the shared, context-rich meaning space humans use to communicate their thoughts to one another. - Z Zada, et al.
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Your mind to my mind... your thoughts to my thoughts...
Live long and prosper!
REFERENCES
S Khan, et al. Microtubule-Stabilizer Epothilone B Delays Anesthetic-Induced Unconsciousness in Rats. eNeuro (2024). DOI: 10.1523/ENEURO.0291-24.2024
V Leupin, et al. Interoceptive signals shape the earliest markers and neural pathway to awareness at the visual threshold, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2311953121
Z Zada, et al. A shared model-based linguistic space for transmitting our thoughts from brain to brain in natural conversations. Neuron (2024). DOI: 10.1016/j.neuron.2024.06.025. www.cell.com/neuron/fulltext/S0896-6273(24)00460-4
Kathleen A. Martin et al,
Vagus nerve stimulation recruits the central cholinergic system to enhance perceptual learning, Nature Neuroscience (2024).
DOI: 10.1038/s41593-024-01767-4
"in mice VNS activates the central cholinergic system, a neural network that utilizes the neurotransmitter acetylcholine to communicate with other neurons and supports various brain functions. The activation of this neural network was found to in turn enhance the performance of mice in the perceptual learning task they developed."