6.3 Long Term Memory 1

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Del curso dictado por Tel Aviv University

Understanding Plants - Part I: What a Plant Knows

549 calificaciones

Tel Aviv University

Understanding Plants - Part I: What a Plant Knows

549 calificaciones

For centuries we have collectively marveled at plant diversity and form—from Charles Darwin’s early fascination with stems and flowers to Seymour Krelborn’s distorted doting in Little Shop of Horrors. This course intends to present an intriguing and scientifically valid look at how plants themselves experience the world—from the colors they see to the sensations they feel. Highlighting the latest research in genetics and more, we will delve into the inner lives of plants and draw parallels with the human senses to reveal that we have much more in common with sunflowers and oak trees than we may realize. We’ll learn how plants know up from down, how they know when a neighbor has been infested by a group of hungry beetles, and whether they appreciate the music you’ve been playing for them or if they’re just deaf to the sounds around them. We’ll explore definitions of memory and consciousness as they relate to plants in asking whether we can say that plants might even be aware of their surroundings. This highly interdisciplinary course meshes historical studies with cutting edge modern research and will be relevant to all humans who seek their place in nature. This class has three main goals: 1. To introduce you to basic plant biology by exploring plant senses (sight, smell, hearing, touch, taste, balance). 2. To introduce you to biological research and the scientific method. 3. To get the student to question life in general and what defines us as humans. Once you've taken this course, if you are interested in a more in-depth study of plants, check out my follow-up course, Fundamentals of Plant Biology (https://www.coursera.org/learn/plant-biology/home/welcome). In order to receive academic credit for this course you must successfully pass the academic exam on campus. For information on how to register for the academic exam – https://tauonline.tau.ac.il/registration Additionally, you can apply to certain degrees using the grades you received on the courses. Read more on this here – https://go.tau.ac.il/b.a/mooc-acceptance Teachers interested in teaching this course in their class rooms are invited to explore our Academic High school program here – https://tauonline.tau.ac.il/online-highschool

De la lección

What a Plant Remembers?

This week we move beyond survey of a plant's sensory systems, and explore how plants retain, store and recall sensory information. In other words, we ask the questions, What do plants remember? We'll try to define what we mean by "memory" and briefly review different types of human memory. The we'll look at the short-term memory found in the Venus fly trap, and the long term morphogenic memory first described 50 years ago by the Czech scientist Rudolf Dostal. We'll have a guest lecture from Prof. Nir Ohad about epigenetics and the long-term memory of winter, and even the role of epigenetics in trans-generational memory.

6.1 What a Plant Remembers?5:55

6.2 Short Term Memory5:31

6.3 Long Term Memory 15:59

6.4 Long Term Memory 2 (with Prof. Nir Ohad)10:07

6.5 Epigenetic Heredity1:56

6.6 Intelligent Memory?3:03

Conoce a los instructores

Professor Daniel Chamovitz, Ph.D.
Dean, George S. Wise Faculty of Life Sciences
Director, Manna Center for Plant Biosciences

Now that I hope I've convinced you that plants have a form of short-term memory,

let's move on to explore the possibility of long-term memory.

Not the memory of seconds or even hours, but days, weeks, even months.

Before I describe some experiments that demonstrate long term memory in plants,

I want to introduce another concept in plant biology that will be necessary for

us to understand these experiments.

This is a concept called apical dominance.

This is a concept that it intuitively known by the gardeners among you, and

relace and releasing apical dominance is the basis of pruning.

At the tip of the plant is the apical meristem as we've learned in

previous lectures.

We could also call this the apical bud,

and it's from here that all the new plant tissues grow.

At the base of each leaf going down the stem, there's also lateral buds.

Now, these lateral buds that are closest to the top don't grow, they're inhibited.

But further down the stem, some of the lateral buds have started to develop, and

these will form branches.

If we cut off the apical bud,

we release the inhibition on the lateral buds to grow.

In other words, the apical meristem, the apical bud,

the bud that's at the top of plant or

at the end of the branch, inhibits the development of the lateral buds.

When we cut it off, then the lateral buds immediately start growing, and

this is what you see when you prune a plant.

When we prune a plant, we get bushiness because of more lateral buds,

more lateral branches have started to grow.

So now that we have understood apical dominance,

I wanted to describe a few rather obscure experiments.

These were carried out first in the middle of the 20th century by a Czech botanist

named Rudolph Dostal, who studied what he termed morphogenetic memory in plants.

The morphogenetic memory is a type of memory that later influences the shape or

the form of the plant, in other words.

The plant can experience an external stimulus at some point,

like a rip in it's leaf or a fracture of its branch, and be unaffected by it first.

But when the environmental conditions change, the plant can remember

the past experience and respond by changing its growth.

Let me give you an example of the experiment that he did.

So under normal conditions, with apical dominance,

if the apical buds is pruned off, both lateral buds will grow evenly.

But what Dostal noticed is that if you removed one of the cut leaves,

one of the embryonic leaves prior to removing of the apical bud,

prior to decapitation of the apical bud.

Then only the lateral bud that would grow

was the one that was near the remaining leaf.

In other words, when Dostal removed one the plant remembered

this mutilation and only developed in the direction of the remaining one.

So are you convinced that this is memory?

Well Dosal's research was picked up by a French scientist named Michel Thellier.

He's a member of the French Academy of Sciences.

And what he noticed after decapitating the apocal bud on his plant of choice,

which is called bedin's pilosa.

Both lateral buds started to grow more or less evenly.

But if you simply wounded one of the cotyledons, didn't remove it, then

in this case, again, only the lateral bud closest to the healthy leaf would grow.

He didn't have to completely mangle the cotyledon leaf.

He didn't have to remove it to get the response.

It was enough that he pricked the leaf with a pin four or

five times with a needle, at the same time that he took off the apical bud.

And this minor wound was enough to get the asymmetrical growth of

the lateral buds So where does memory come into this?

Isn't this just another classic stimulus response phenomena?

Well during these experiments, when Thellier extended the amount of time

between the wounding of the leaf, and the decapitating of the apical bud,

even up to two weeks, and low and behold the lateral bud

furthest from the cotyledon would grow out, and not both lateral buds.

Thellier knew that there had to be some way that the plant stored

this traumatic experience of being pricked.

And had a mechanism for recalling it, once the central bud was removed,

even if that happened many days, or even weeks later.

The following experiment really sealed the idea that the bud of the plant

remembers which of its neighboring leaves had been damaged.

This time, Thellier stabbed one of the cotyledons as he did before.

But then he removed both cotyledons, the stabbed one and

the untreated, several minutes later.

And then, only then did he remove the apical meristem.

He found that the plant retained the memory of the stabbing.

Once the apocal bud is removed, the lateral bud

opposite the original wounded cotyledon, that means the lateral bud

next to the untreated cotteline grew more than the one on the other side.

The one that was next to the stabbed cotyledon.

The jury though, is still out on how this information is stored in the apical bud.

One promising option is that the signal is somehow connected

to the phytal hormone oxin.

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