Implications for Meditation and for Kensho
Kensho and satori are brief, transforming moments. Fresh ongoing perceptions are registered accurately, and they often remain indelible. In contrast, old maladaptive memory associations drop out instantly. So do all prior personal constructs and concepts of the self. This psychophysiological pattern is very distinctive. It does not suggest that one's hippocampal CA1 cells per se are malfunctioning. Nor does it imply that one's usual stream of messages must have stopped on their way to CA1 cells from CA3 cells [Z:182-184].
Normally, we start to encode new memories with the aid of our hippocampus and adjacent temporal cortex. Next, we engage a widely distributed network in order to lay down, store, and retrieve memories.13 The term consolidation describes the way memory traces soon pass beyond, then gradually become independent of, the first steps in this processing chain, both in the hippocampus and its nearby entorhinal, perirhinal, and parahippocampal cortex. In chapter 27, we observed that the amygdala also responds quickly, and then disperses its information elsewhere.
We consolidate memories mostly when we are either at rest or asleep, because these are the quieter times when we are not processing any new external events. What evidence suggests that such consolidation does occur at rest? Electrodes implanted widely throughout cortex have monitored monkeys' brain functions for many hours. The firing patterns are distinctive. They confirm that those same nerve cells which had previously fired together cooperatively during tasks, later reenacted their responsivities. When? During the next rest period. Yet at this time, no such task was being overtly performed. Without moving, the resting monkeys appeared to be "replaying" their previous task activity spontaneously.
Are such replaying data relevant to a period of open, relaxed meditation, an interval of quiet that seems reasonably close to an actual state of rest? This plausible hypothesis remains to be tested. If so, then perhaps actual "no-thought" mediation periods do offer a meditator the chance to consolidate—spontaneously and subconsciously—what had just been learned during the course of some experience that had immediately preceded it. For example, such an event could be in the form of information heard during a lecture or encountered while reading.
Spontaneous replaying tendencies at rest have a second set of implications. Both our ordinary leaps of creative intuition and extraordinary peak experiences usually occur during pauses. Each requires an extra, dynamic ingredient, not just the mere replaying of a problem long incubated but still unsolved. Novel closures often mean that some new item or motive source of energy has closed the information gap. Instantly, large networks shift into brand-new configurations.
What about the usual processes that enable us to recall ordinary memories? Functional brain imaging studies identify three left frontal regions that become coactivated when we retrieve memories: the polar cortex, the mid ventrolateral cortex, and the mid dorsolateral cortex. All contribute, whether the kinds of memory being tested involve events of personal experience (episodic memory), working memory, or factual items (semantic memory). The dorsal anterior cingulate cortex also shares in these coactivations.14
One basic function of Zen meditation is to calm the habit energies that drive these four sources of memory retrieval into endless strings of discursive thoughts. In short, the regular practice of zazen helps to dampen the ordinary "leaps" of one's monkey mind (see chapter 13). It is rare for kensho to occur while a person is actually seated and engaged in zazen meditation.
The self that will drop out during kensho had a very long prior autobiographical history. It was fearful. It had major impulses and motivations to do things. It possessed an acute sense of time. To the degree that these older memory formations had long since "passed through the hippocampus'' and been represented beyond it, then kensho might seem to have dissolved their functional representations, at hierarchical levels above and beyond the hippocampus. Yet we still need to explain kensho's influence on immediate memory mechanisms, for these hippocampal functions might seem to be registering ongoing events clearly and at considerable speed. Does any recent research support such a process?
Recent fMRI studies confirm that patients who have medial temporal lobe damage don't need their hippocampus to recall their older, well-consolidated, personal memories.15 Indeed, they accurately recall such prior experiences when prompted by such simple cue words as "river" or "nail." However, other patients had damage to their frontal lobes and to the lateral aspects of their temporal lobes. They did lose their remote autobiographical memories for time and place. These findings suggest that kensho blocks the links of early egocentric functions at frontotemporal levels beyond the hippocampus.
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