Process, as I said, is quite unknown.
However, removal of parts of the brain remove memory. We know what, but not how.
Yes I know all that.
So obviously these stimulation studies do not tell us anything about how the brain stores or creates the experience of a memory.
But my question is the same as: How does the mind move the arm? How does the mind get the brain to access a memory?
Beginning with the fundamentals of Cognition.
1) ''Neurons [/url]are nerve cells (neurocytes), which, together with neuroglial cells, comprise the nervous tissue making up the nervous system. The neuron is the integral element of our five senses and of countless other physical, regulatory, and mental faculties, including memory and consciousness. A neuron consists of a nerve cell body (or soma), an elongated projection (axon), and short branching fibers (called dendrites). Neurons receive nerve signals (action potentials), integrate action potentials, and transmit these signals to other neurons or effector organs, such as muscles and glands. The structure and function of neurons is essentially the same in all animals, although the human nervous system is much more specialized and complicated than that of lower animals.''
''At the axon hillock, chemical signals received by the dendrites may reach a threshold level to cause a wave of electrical depolarization and hyperpolarization of the axon cell membrane. The net movements of ions across the cell membrane are responsible for these changes that move down the axon to the axon terminus as an action potential. At the axon terminus, neurotransmitters are released into the synaptic gap. Through synaptic gaps, a typical neuron may interconnect with thousands and tens of thousands of other neurons. Axon terminals have knob-like swellings at the very end called synaptic knobs or end buttons. Each synaptic knob communicates with a dendrite or cell body of another neuron, the point of contact being a synapse.''
Memory is physically formed within neurons and neural pathways, shapes of proteins and - ''during the habitution of a repeated action, excitatory synapses from the sensory neurons onto motor neurons and interneurons undergo depression''' (well worn neural pathways facilitate a quick and well 'learnt' response) and sensory impulses travelling along pathways are modified by these memory 'markers' - which in turn stimulate the neural cell to respond in a particular way, signaling the production of seratonin, glandular secretions, and motor neuron functions, consciously perceived as feelings, etc...neurons do not make conscious choices, yet a response is achieved according to the stimulus that is applied to the neuron by the kind of input it receives, which means the response may, as mentioned above, entail a release of neurochemicals and a motor responses. Again, according to the nature of the stimulus that is applied by input to the cells, networks and structures and not by an action of 'conscious will'
''Among the brain's modular processors, some do not extract and process signals from the environment, but rather from the subject's own body and brain. Each brain thus contains multiple representations of itself and its body at several levels''
(Damasio,1999).
''The physical location of our body is encoded in continuously updated somatic, kinesthetic, and motor maps. Its biochemical homeostasis is represented in various subcortical and cortical circuits controlling our drives and emotions. We also represent ourselves as a person with an identity (presumably involving face and person-processing circuits of the inferior and anterior temporal lobes) and an autobiography encoded in episodic memory. Finally, at a higher cognitive level, the action perception, verbal reasoning, and `theory of mind' modules that we apply to interpret and predict other people's actions may also help us make sense of our own behavior
Once mobilized into the conscious workspace, the activity of those `self-coding' circuits would be available for inspection by many other processes, thus providing a putative basis for reflexive or higher-order consciousness.''
(Fletcher et al., 1995; Gallese, Fadiga, Fogassi, & Rizzolatti, 1996; Weiskrantz, 1997)''.
'When chemicals contact the surface of a neuron, they change the balance of ions (electrically charged atoms) between the inside and outside of the cell membrane. When this change reaches a threshold level, this effect runs across the cell's membrane to the axon. When it reaches the axon, it initiates the action potential, which is a rapidly moving exchange of ions.''