Memory (cognitive ability, executive control, motor control, whatever) resides in a place(s). If we fix that (those) place(s), we fix memory (our failing faculties).
For MEMORY, as an example, most scientists focus on one of three places:
- the hippocampus, for ‘episodic’ or ‘long-term memory’;
- the inferior/medial temporal or lateral frontal cortex, for ‘immediate’ or ‘working memory’; or
- the frontal cortex, for ‘executive control’
It has been easy to show that your memory or your ‘executive control’ suffers – in fact, can be almost obliterated – by damage to, or the temporary, magnetic-stimulation-achieved shut-down of these key brain regions. It has been easy to show the machinery in the hippocampus or temporal/frontal cortex doesn’t work very well, as you struggle to remember, with your old brain. It has been relatively easy to pinpoint processes in these structures that seem to directly limit memory. It has even been relatively easy to show that the pharmacological manipulation of those processes measurably improves indices of memory as expressed by relatively simple behaviors in an old mouse or rat. So what could possibly be wrong with this picture?!
Two things, in fact.
First, you don’t possess any ‘memory box’ in your brain. The entire machine participates in remembering – and in an old brain, EVERY PART of that machine has altered its operations. A young brain represents information you are trying to remember in refined detail, with fidelity and power. An old brain represents information you are trying to remember in fuzzier detail, with a translation in neurological terms that is error-ridden, weaker, and much more poorly resolved in detail in ongoing time — and is very sensitive to distractors or noise. Tweaking a hypothetical ‘memory box’ just cannot overcome the widely-distributed changes that limit the operations of your older brain – and any REAL recovery will require that this more fundamental and more complete set of problems be addressed.
Second, while these brain regions/processes all represent useful therapeutic targets, who could choose between them? They’re ALL important – and there are scads of other ones that are arguably just as important. Moreover, nobody told the brain that these locations were the linchpins of recovering your cognitive abilities. They complexly feed one another, and in this kind of multivariate system, if you were to see that manipulating one variable provides the basis of a real cure, get down on your knees, because you’ve witnessed a miracle.
The real answer to the question “What is wrong with (isn’t working as well in) your older brain?”
Pretty much everything.
Or to put it another way, there are one helluva lot of processes (places) to fix!