………making it very hard to remember the past and even harder to plan the future, affecting her ability to understand her present.
Mental imagery provides an essential simulation tool for remembering the past and planning the future, with its strength affecting both cognition and mental health. Research suggests that neural activity spanning prefrontal, parietal, temporal, and visual areas supports the generation of mental images. Exactly how this network controls the strength of visual imagery remains unknown. Here, brain imaging and transcranial magnetic phosphene data show that lower resting activity and excitability levels in early visual cortex (V1-V3) predict stronger sensory imagery. Further, electrically decreasing visual cortex excitability using tDCS increases imagery strength, demonstrating a causative role of visual cortex excitability in controlling visual imagery. Together, these data suggest a neurophysiological mechanism of cortical excitability involved in controlling the strength of mental images. Cortical excitability controls the strength of mental imagery Rebecca Keogh , Johanna Bergmann, Joel Pearson eLife 2020
Neuronal activity is very sensitive to internal changes to its acid base levels or intracellular pH.
The importance of pH regulation to the viability of cells, [including neurons], is widely recognized. The production of intracellular acid is a normal consequence of [cell] respiration and, if unchecked, can lead to a marked fall in intracellular pH, compromising vital functions. Regulation and Modulation of pH in the Brain MITCHELL CHESLER Department of Physiology and Neuroscience, Department of Neurosurgery, New York University School of Medicine, New York, New York Physiol Rev 83: 1183–1221, 2003; 10.1152/physrev.00010.2003.
And physiological vital functions include motor control of ventilation as well as other indicators of normal physiological function [blood pressure, heart rate, body temperature and function of mental imagery or thinking]. These vital functions are easily measured during periods of malfunction affecting the function of the mind.
As a general rule a rise in pH increases neuronal activity, whereas it is dampened by a fall of pH. Neuronal activity per se also challenges pH homeostasis by the increase of metabolic acid equivalents. Moreover, the negative membrane potential of neurons promotes the intracellular accumulation of protons. Synaptic key players such as glutamate receptors or voltage-gated calcium channels show strong pH dependence and effects of pH gradients on synaptic processes are well known. However, the processes and mechanisms that allow controlling the pH in synaptic structures and how these mechanisms contribute to normal synaptic function are only beginning to be resolved…. ……Conclusion: There is ample evidence that synaptic function critically depends on intracellular and extracellular pH gradients and that synaptic activity also causes local pH gradients. Minireview: pH and synaptic transmission Edited by Alexander Gabibov, Vladimir Skulachev, Felix Wieland and Wilhelm, AnneSinningabChristian A.Hübnera FEBS Letters Volume 587, Issue 13, 27 June 2013, Pages 1923-1928
The motor control of ventilation is an important feedback mechanism, linked to neuronal function and balance of intracellular neuronal pH, which, as we read above, will affect the generation of mental imagery and thought.
And this is important to understand when a patient experiences sudden changes to generate thinking.
And because these patients can no longer easily generate their thinking, their ability to communicate this will be lost and their doctors won’t have a clue that such a thing is even possible. Unless they understand the importance of normal motor control of ventilation to the intracellular pH of neurons.
This is what it really means to “lose your mind”.
And motor control of respiratory rate and ability to increase respiratory rate in response to rising respiratory acids produced by cell metabolism seems to play a key role in loss of mind.
And it is an easy hypothesis to test.
Because baseline ventilatory rate per minute is easy to count. If too slow or too fast, further investigations exist and are easy to do.
Abnormal resting baseline respiratory rate, with signs of internal mental confusion and loss of mental imagery will suggest that the motor control of breathing is impaired and the feedback system for rising carbon dioxide in the blood or cells or neurons has been overwhelmed and that supportive medical treatments are necessary to restore the patient’s baseline level of mind and normal mental imagery.
Please, dear reader, tell doctors and scientists interested in the workings of mind, mental imagery, memory, mood, behavior and consciousness, to read Paula’s story and to think about our discussions written out in this blog.