Transcriber: Ian Brown Reviewer: David DeRuwe
Today, I would like to talk to you about the biological basis for memory,
and in particular, I would like to impress upon you
that memory is really underpinned
by an amazing molecular orchestration deep within your brain
that actually allows you to remember.
And so in this way, on the cellular and molecular level,
memory is really a particular kind of information storage
that arises out of the genetic and environmental interface.
And we can come to appreciate this when we consider that the environment,
the very context of this room,
represents a particular kind of information.
And so with that thought in mind, I pose the following question rhetorically:
Could it be that our fondest memories are but the remnants of past information
codified within the molecular matrix of our brain?
And so to better understand this question,
I’ll ask you to reimagine the world around you, not as it appears,
but as a reservoir of information that whirls about in myriad form.
Importantly, as human beings, we’re biological organisms
that are completely immersed in this information,
and moreover, our survival is entirely dependent upon our ability
to successfully navigate our surroundings.
In particular, our survival is dependent upon our ability
to detect and distinguish energy forms.
Such information is readily converted
into sensations of sight, touch, taste, smell, and hearing,
so that we may successfully navigate the frontier of our surroundings,
and so to this end, the nervous system,
the biological apparatus that mediates these sensations,
must remain ever-responsive to changes in environmental information.
And so in order to accomplish this feat,
the cells of the nervous system, neurons,
are equipped and fitted with immense information-sensing capabilities
that capture, process, and represent environmental information
as a distinct bio-electric code called neural activity.
Neural activity is an intracellular language
by which environmental information
is coded and disseminated across the nervous system at rapid speeds.
When this information needs to be stored in the context of memory,
neural activity dynamically directs cellular gene expression,
which stably codifies this information inside neuronal cells,
but it does it in a peculiar way.
It does it by actually storing that information
in the morphology of the neuron, in the shape,
and it does so at distinct structures.
These structures are synaptic structure.
Now, synaptic structure is interesting and important
because it’s essentially a biological hallmark
of the vast and amazing potential that dwells within us all.
It’s particularly important, and this rings true in the context of memory,
when we consider, like I said, just to walk you through,
the environment is really a particular kind of information
that gets coded and represented in the nervous system as neural activity.
Neural activity dynamically directs gene expression to store that information
by modifying synaptic structure.
This is important for some reasons that we can all appreciate.
It’s important because it allows us to remember those experiences
that would otherwise wane into obscurity.
While this latter premise provides some molecular reconciliation
for the phenomenon that we call memory,
there are still so many great questions pending along this great frontier.
Now, importantly, as a neuroscientist
at Harvard Medical School, much of my research is devoted
to unveiling molecular details along this front.
Mechanistically, environmentally directed gene expression
requires a molecular link, and this is what enamors me,
a molecular link capable of dynamically altering gene expression in response
to neural activity.
Now importantly, the neuron has evolved a robust suite of regulatory sensors
for exactly this purpose, which include a special class of biomolecules
that I study called microRNAs.
Now, microRNAs are important
because they’re indispensable regulators of gene expression
within unique dimensions of cellular time and space.
This is interesting and important because, as I alluded to earlier,
the spatial character of the neuron
is stratified across the immense morphological polarity and complexity,
as you can see here.
This spatial dimensionality imposes unique time constraints
on cellular gene expression, primarily because gene expression,
or upstream modes of gene regulation rather,
occur within the nucleus, which in some neurons
can be millimeters to meters, vastly distant from synaptic structure.
These spatial and therefore temporal demands are in part
met through the regulatory action of microRNAs,
which are capable of regulating gene expression locally at the synapse,
which is critical for depositing that information
through modifying synaptic morphology,
and this is the basis for the process
or the information stores that we understand as memory.
So importantly, with that in mind,
what I’d like you to take home tonight is that memory on the cellular
and molecular level is a particular kind of information storage
that precipitates through the genetic and environmental interaction,
and moreover, the next time that you just so happen to reminisce
about the good old days or the formative days of your youth,
I hope that you will also marvel over the great molecular orchestration
deep within your brain that ever guides you back to the nostalgia of yesteryear.
And I hope that you’ve been inspired and enamored
by the vast biological potential that lives and breathes within us all.
Thank you.
(Applause)