WEBVTT 00:00:00.683 --> 00:00:05.287 Memory is such an everyday thing that we almost take it for granted. 00:00:05.668 --> 00:00:08.285 We all remember what we had for breakfast this morning 00:00:08.309 --> 00:00:09.891 or what we did last weekend. 00:00:09.915 --> 00:00:11.968 It's only when memory starts to fail 00:00:11.992 --> 00:00:14.657 that we appreciate just how amazing it is 00:00:14.681 --> 00:00:18.140 and how much we allow our past experiences to define us. NOTE Paragraph 00:00:19.600 --> 00:00:22.449 But memory is not always a good thing. 00:00:23.084 --> 00:00:26.851 As the American poet and clergyman John Lancaster Spalding once said, 00:00:26.875 --> 00:00:30.032 "As memory may be a paradise from which we cannot be driven, 00:00:30.056 --> 00:00:33.479 it may also be a hell from which we cannot escape." 00:00:34.817 --> 00:00:37.486 Many of us experience chapters of our lives 00:00:37.510 --> 00:00:39.952 that we would prefer to never have happened. 00:00:40.362 --> 00:00:42.904 It is estimated that nearly 90 percent of us 00:00:42.928 --> 00:00:46.803 will experience some sort of traumatic event during our lifetimes. 00:00:47.699 --> 00:00:52.530 Many of us will suffer acutely following these events and then recover, 00:00:52.554 --> 00:00:56.005 maybe even become better people because of those experiences. 00:00:56.881 --> 00:01:01.015 But some events are so extreme that many -- 00:01:01.039 --> 00:01:04.801 up to half of those who survive sexual violence, for example -- 00:01:04.825 --> 00:01:07.916 will go on to develop post-traumatic stress disorder, 00:01:07.940 --> 00:01:09.303 or PTSD. NOTE Paragraph 00:01:10.674 --> 00:01:13.956 PTSD is a debilitating mental health condition 00:01:13.980 --> 00:01:18.298 characterized by symptoms such as intense fear and anxiety 00:01:18.322 --> 00:01:20.901 and flashbacks of the traumatic event. 00:01:21.808 --> 00:01:26.045 These symptoms have a huge impact on a person's quality of life 00:01:26.069 --> 00:01:28.903 and are often triggered by particular situations 00:01:28.927 --> 00:01:31.708 or cues in that person's environment. 00:01:32.623 --> 00:01:37.594 The responses to those cues may have been adaptive when they were first learned -- 00:01:37.618 --> 00:01:41.259 fear and diving for cover in a war zone, for example -- 00:01:41.283 --> 00:01:42.446 but in PTSD, 00:01:42.470 --> 00:01:45.985 they continue to control behavior when it's no longer appropriate. 00:01:46.759 --> 00:01:50.096 If a combat veteran returns home and is diving for cover 00:01:50.120 --> 00:01:52.233 when he or she hears a car backfiring 00:01:52.257 --> 00:01:56.172 or can't leave their own home because of intense anxiety, 00:01:56.196 --> 00:02:00.121 then the responses to those cues, those memories, 00:02:00.145 --> 00:02:03.924 have become what we would refer to as maladaptive. 00:02:04.574 --> 00:02:10.739 In this way, we can think of PTSD as being a disorder of maladaptive memory. NOTE Paragraph 00:02:12.606 --> 00:02:14.182 Now, I should stop myself here, 00:02:14.206 --> 00:02:17.430 because I'm talking about memory as if it's a single thing. 00:02:17.454 --> 00:02:18.637 It isn't. 00:02:19.145 --> 00:02:21.115 There are many different types of memory, 00:02:21.139 --> 00:02:25.236 and these depend upon different circuits and regions within the brain. 00:02:26.181 --> 00:02:31.108 As you can see, there are two major distinctions in our types of memory. 00:02:31.618 --> 00:02:34.342 There are those memories that we're consciously aware of, 00:02:34.366 --> 00:02:35.530 where we know we know 00:02:35.554 --> 00:02:37.301 and that we can pass on in words. 00:02:37.686 --> 00:02:40.349 This would include memories for facts and events. 00:02:40.898 --> 00:02:43.115 Because we can declare these memories, 00:02:43.139 --> 00:02:45.690 we refer to these as declarative memories. NOTE Paragraph 00:02:46.972 --> 00:02:49.879 The other type of memory is non-declarative. 00:02:50.466 --> 00:02:53.881 These are memories where we often don't have conscious access 00:02:53.905 --> 00:02:55.609 to the content of those memories 00:02:55.633 --> 00:02:57.567 and that we can't pass on in words. 00:02:58.598 --> 00:03:01.200 The classic example of a non-declarative memory 00:03:01.224 --> 00:03:03.700 is the motor skill for riding a bike. 00:03:04.296 --> 00:03:07.606 Now, this being Cambridge, the odds are that you can ride a bike. 00:03:07.630 --> 00:03:09.681 You know what you're doing on two wheels. 00:03:10.378 --> 00:03:13.403 But if I asked you to write me a list of instructions 00:03:13.427 --> 00:03:15.663 that would teach me how to ride a bike, 00:03:15.687 --> 00:03:18.251 as my four-year-old son did when we bought him a bike 00:03:18.275 --> 00:03:19.803 for his last birthday, 00:03:19.827 --> 00:03:22.321 you would really struggle to do that. 00:03:23.140 --> 00:03:25.640 How should you sit on the bike so you're balanced? 00:03:25.664 --> 00:03:28.142 How fast do you need to pedal so you're stable? 00:03:28.519 --> 00:03:30.563 If a gust of wind comes at you, 00:03:30.587 --> 00:03:33.372 which muscles should you tense and by how much 00:03:33.396 --> 00:03:35.421 so that you don't get blown off? 00:03:36.451 --> 00:03:39.649 I'll be staggered if you can give the answers to those questions. 00:03:39.673 --> 00:03:43.352 But if you can ride a bike, you do have the answers, 00:03:43.376 --> 00:03:45.762 you're just not consciously aware of them. NOTE Paragraph 00:03:48.894 --> 00:03:50.422 Getting back to PTSD, 00:03:50.446 --> 00:03:53.113 another type of non-declarative memory 00:03:53.137 --> 00:03:55.101 is emotional memory. 00:03:55.125 --> 00:03:57.534 Now, this has a specific meaning in psychology 00:03:57.558 --> 00:04:01.039 and refers to our ability to learn about cues in our environment 00:04:01.063 --> 00:04:04.012 and their emotional and motivational significance. 00:04:04.671 --> 00:04:05.954 What do I mean by that? 00:04:06.373 --> 00:04:10.733 Well, think of a cue like the smell of baking bread, 00:04:10.757 --> 00:04:13.497 or a more abstract cue like a 20-pound note. 00:04:13.964 --> 00:04:17.246 Because these cues have been pegged with good things in the past, 00:04:17.270 --> 00:04:19.190 we like them and we approach them. 00:04:19.931 --> 00:04:24.813 Other cues, like the buzzing of a wasp, elicit very negative emotions 00:04:24.837 --> 00:04:28.629 and quite dramatic avoidance behavior in some people. NOTE Paragraph 00:04:29.620 --> 00:04:32.267 Now, I hate wasps. 00:04:32.291 --> 00:04:33.802 I can tell you that fact. 00:04:33.826 --> 00:04:37.406 But what I can't give you are the non-declarative emotional memories 00:04:37.430 --> 00:04:39.711 for how I react when there's a wasp nearby. 00:04:40.174 --> 00:04:42.333 I can't give you the racing heart, 00:04:42.357 --> 00:04:45.869 the sweaty palms, that sense of rising panic. 00:04:45.893 --> 00:04:48.056 I can describe them to you, 00:04:48.080 --> 00:04:50.355 but I can't give them to you. 00:04:52.363 --> 00:04:55.270 Now, importantly, from the perspective of PTSD, 00:04:55.294 --> 00:05:00.056 stress has very different effects on declarative and non-declarative memories 00:05:00.080 --> 00:05:02.806 and the brain circuits and regions supporting them. 00:05:03.463 --> 00:05:06.840 Emotional memory is supported by a small almond-shaped structure 00:05:06.864 --> 00:05:08.022 called the amygdala 00:05:08.046 --> 00:05:09.280 and its connections. 00:05:09.883 --> 00:05:14.376 Declarative memory, especially the what, where and when of event memory, 00:05:14.400 --> 00:05:16.976 is supported by a seahorse-shaped region of the brain 00:05:17.000 --> 00:05:18.494 called the hippocampus. NOTE Paragraph 00:05:19.348 --> 00:05:22.489 The extreme levels of stress experienced during trauma 00:05:22.513 --> 00:05:25.848 have very different effects on these two structures. 00:05:26.793 --> 00:05:30.036 As you can see, as you increase a person's level of stress 00:05:30.060 --> 00:05:32.105 from not stressful to slightly stressful, 00:05:32.129 --> 00:05:33.381 the hippocampus, 00:05:33.405 --> 00:05:35.605 acting to support the event memory, 00:05:35.629 --> 00:05:37.289 increases in its activity 00:05:37.313 --> 00:05:40.593 and works better to support the storage of that declarative memory. 00:05:41.371 --> 00:05:45.001 But as you increase to moderately stressful, intensely stressful 00:05:45.025 --> 00:05:48.620 and then extremely stressful, as would be found in trauma, 00:05:48.644 --> 00:05:52.323 the hippocampus effectively shuts down. 00:05:53.361 --> 00:05:56.147 This means that under the high levels of stress hormones 00:05:56.171 --> 00:05:58.194 that are experienced during trauma, 00:05:58.218 --> 00:06:00.241 we are not storing the details, 00:06:00.265 --> 00:06:03.987 the specific details of what, where and when. NOTE Paragraph 00:06:05.374 --> 00:06:07.785 Now, while stress is doing that to the hippocampus, 00:06:07.809 --> 00:06:09.640 look at what it does to the amygdala, 00:06:09.664 --> 00:06:13.080 that structure important for the emotional, non-declarative memory. 00:06:13.104 --> 00:06:16.289 Its activity gets stronger and stronger. 00:06:17.670 --> 00:06:20.206 So what this leaves us with in PTSD 00:06:20.230 --> 00:06:24.172 is an overly strong emotional -- in this case fear -- memory 00:06:24.196 --> 00:06:27.112 that is not tied to a specific time or place, 00:06:27.136 --> 00:06:31.798 because the hippocampus is not storing what, where and when. 00:06:32.437 --> 00:06:35.541 In this way, these cues can control behavior 00:06:35.565 --> 00:06:37.670 when it's no longer appropriate, 00:06:37.694 --> 00:06:40.377 and that's how they become maladaptive. 00:06:40.808 --> 00:06:46.617 So if we know that PTSD is due to maladaptive memories, 00:06:46.641 --> 00:06:49.883 can we use that knowledge to improve treatment outcomes 00:06:49.907 --> 00:06:51.658 for patients with PTSD? NOTE Paragraph 00:06:53.508 --> 00:06:58.312 A radical new approach being developed to treat post-traumatic stress disorder 00:06:58.336 --> 00:07:01.898 aims to destroy those maladaptive emotional memories 00:07:01.922 --> 00:07:03.639 that underlie the disorder. 00:07:04.338 --> 00:07:07.014 This approach has only been considered a possibility 00:07:07.038 --> 00:07:10.320 because of the profound changes in our understanding of memory 00:07:10.344 --> 00:07:11.759 in recent years. 00:07:12.575 --> 00:07:15.030 Traditionally, it was thought that making a memory 00:07:15.054 --> 00:07:17.694 was like writing in a notebook in pen: 00:07:17.718 --> 00:07:21.200 once the ink had dried, you couldn't change the information. 00:07:21.659 --> 00:07:23.949 It was thought that all those structural changes 00:07:23.973 --> 00:07:26.675 that happen in the brain to support the storage of memory 00:07:26.699 --> 00:07:28.554 were finished within about six hours, 00:07:28.578 --> 00:07:30.639 and after that, they were permanent. 00:07:31.061 --> 00:07:33.779 This is known as the consolidation view. NOTE Paragraph 00:07:35.081 --> 00:07:38.111 However, more recent research suggests that making a memory 00:07:38.135 --> 00:07:41.412 is actually more like writing in a word processor. 00:07:41.894 --> 00:07:45.518 We initially make the memory and then we save it or store it. 00:07:45.542 --> 00:07:49.300 But under the right conditions, we can edit that memory. 00:07:50.229 --> 00:07:53.914 This reconsolidation view suggests that those structural changes 00:07:53.938 --> 00:07:56.334 that happen in the brain to support memory 00:07:56.358 --> 00:07:57.989 can be undone, 00:07:58.013 --> 00:08:00.451 even for old memories. NOTE Paragraph 00:08:02.304 --> 00:08:05.690 Now, this editing process isn't happening all the time. 00:08:05.714 --> 00:08:08.704 It only happens under very specific conditions 00:08:08.728 --> 00:08:10.432 of memory retrieval. 00:08:11.230 --> 00:08:14.866 So let's consider memory retrieval as being recalling the memory 00:08:14.890 --> 00:08:17.044 or, like, opening the file. 00:08:18.076 --> 00:08:20.613 Quite often, we are simply retrieving the memory. 00:08:20.637 --> 00:08:23.158 We're opening the file as read-only. 00:08:23.833 --> 00:08:25.733 But under the right conditions, 00:08:25.757 --> 00:08:28.068 we can open that file in edit mode, 00:08:28.092 --> 00:08:30.310 and then we can change the information. 00:08:30.334 --> 00:08:34.298 In theory, we could delete the content of that file, 00:08:34.322 --> 00:08:36.038 and when we press save, 00:08:36.062 --> 00:08:39.875 that is how the file -- the memory -- 00:08:39.899 --> 00:08:41.150 persists. 00:08:43.134 --> 00:08:45.379 Not only does this reconsolidation view 00:08:45.403 --> 00:08:48.509 allow us to account for some of the quirks of memory, 00:08:48.533 --> 00:08:51.716 like how we all sometimes misremember the past, 00:08:51.740 --> 00:08:56.074 it also gives us a way to destroy those maladaptive fear memories 00:08:56.098 --> 00:08:57.920 that underlie PTSD. 00:08:58.488 --> 00:09:01.120 All we would need would be two things: 00:09:01.144 --> 00:09:06.187 a way of making the memory unstable -- opening that file in edit mode -- 00:09:06.211 --> 00:09:08.573 and a way to delete the information. NOTE Paragraph 00:09:09.330 --> 00:09:10.876 We've made the most progress 00:09:10.900 --> 00:09:13.442 with working out how to delete the information. 00:09:13.862 --> 00:09:15.650 It was found fairly early on 00:09:15.674 --> 00:09:19.514 that a drug widely prescribed to control blood pressure in humans -- 00:09:19.538 --> 00:09:21.651 a beta-blocker called Propranolol -- 00:09:21.675 --> 00:09:24.358 could be used to prevent the reconsolidation 00:09:24.382 --> 00:09:26.092 of fear memories in rats. 00:09:27.004 --> 00:09:30.773 If Propranolol was given while the memory was in edit mode, 00:09:30.797 --> 00:09:35.141 rats behaved as if they were no longer afraid of a frightening trigger cue. 00:09:35.563 --> 00:09:39.919 It was as if they had never learned to be afraid of that cue. 00:09:40.261 --> 00:09:43.920 And this was with a drug that was safe for use in humans. 00:09:44.955 --> 00:09:46.259 Now, not long after that, 00:09:46.283 --> 00:09:50.308 it was shown that Propranolol could destroy fear memories in humans as well, 00:09:50.332 --> 00:09:54.993 but critically, it only works if the memory is in edit mode. NOTE Paragraph 00:09:56.170 --> 00:09:58.583 Now, that study was with healthy human volunteers, 00:09:58.607 --> 00:10:01.834 but it's important because it shows that the rat findings 00:10:01.858 --> 00:10:06.088 can be extended to humans and ultimately, to human patients. 00:10:07.334 --> 00:10:09.278 And with humans, 00:10:09.302 --> 00:10:13.959 you can test whether destroying the non-declarative emotional memory 00:10:13.983 --> 00:10:16.897 does anything to the declarative event memory. 00:10:17.561 --> 00:10:19.941 And this is really interesting. 00:10:19.965 --> 00:10:22.586 Even though people who were given Propranolol 00:10:22.610 --> 00:10:24.217 while the memory was in edit mode 00:10:24.241 --> 00:10:27.968 were no longer afraid of that frightening trigger cue, 00:10:27.992 --> 00:10:30.473 they could still describe the relationship 00:10:30.497 --> 00:10:34.205 between the cue and the frightening outcome. 00:10:35.139 --> 00:10:38.715 It was as if they knew they should be afraid, 00:10:39.652 --> 00:10:41.065 and yet they weren't. 00:10:42.030 --> 00:10:45.424 This suggests that Propranolol can selectively target 00:10:45.448 --> 00:10:47.983 the non-declarative emotional memory 00:10:48.007 --> 00:10:51.693 but leave the declarative event memory intact. 00:10:52.053 --> 00:10:56.460 But critically, Propranolol can only have any effect on the memory 00:10:56.484 --> 00:10:58.318 if it's in edit mode. NOTE Paragraph 00:10:59.020 --> 00:11:01.089 So how do we make a memory unstable? 00:11:01.113 --> 00:11:03.191 How do we get it into edit mode? 00:11:03.643 --> 00:11:06.458 Well, my own lab has done quite a lot of work on this. 00:11:06.482 --> 00:11:11.283 We know that it depends on introducing some but not too much new information 00:11:11.307 --> 00:11:13.568 to be incorporated into the memory. 00:11:13.592 --> 00:11:16.124 We know about the different chemicals the brain uses 00:11:16.148 --> 00:11:18.644 to signal that a memory should be updated 00:11:18.668 --> 00:11:20.527 and the file edited. 00:11:21.307 --> 00:11:23.514 Now, our work is mostly in rats, 00:11:23.538 --> 00:11:28.280 but other labs have found the same factors allow memories to be edited in humans, 00:11:28.304 --> 00:11:32.898 even maladaptive memories like those underlying PTSD. 00:11:33.396 --> 00:11:36.159 In fact, a number of labs in several different countries 00:11:36.183 --> 00:11:40.663 have begun small-scale clinical trials of these memory-destroying treatments 00:11:40.687 --> 00:11:41.979 for PTSD 00:11:42.003 --> 00:11:44.679 and have found really promising results. NOTE Paragraph 00:11:45.830 --> 00:11:49.263 Now, these studies need replication on a larger scale, 00:11:49.287 --> 00:11:52.737 but they show the promise of these memory-destroying treatments 00:11:52.761 --> 00:11:54.743 for PTSD. 00:11:54.767 --> 00:12:00.321 Maybe trauma memories do not need to be the hell from which we cannot escape. NOTE Paragraph 00:12:02.619 --> 00:12:05.828 Now, although this memory-destroying approach holds great promise, 00:12:05.852 --> 00:12:08.403 that's not to say that it's straightforward 00:12:08.427 --> 00:12:10.514 or without controversy. 00:12:10.538 --> 00:12:12.728 Is it ethical to destroy memories? 00:12:12.752 --> 00:12:14.970 What about things like eyewitness testimony? 00:12:15.488 --> 00:12:17.674 What if you can't give someone Propranolol 00:12:17.698 --> 00:12:20.960 because it would interfere with other medicines that they're taking? NOTE Paragraph 00:12:21.801 --> 00:12:24.396 Well, with respect to ethics and eyewitness testimony, 00:12:24.420 --> 00:12:26.456 I would say the important point to remember 00:12:26.480 --> 00:12:28.777 is the finding from that human study. 00:12:29.896 --> 00:12:34.181 Because Propranolol is only acting on the non-declarative emotional memory, 00:12:34.205 --> 00:12:37.651 it seems unlikely that it would affect eyewitness testimony, 00:12:37.675 --> 00:12:40.074 which is based on declarative memory. 00:12:40.960 --> 00:12:43.443 Essentially, what these memory-destroying treatments 00:12:43.467 --> 00:12:44.645 are aiming to do 00:12:44.669 --> 00:12:46.769 is to reduce the emotional memory, 00:12:46.793 --> 00:12:49.671 not get rid of the trauma memory altogether. 00:12:50.437 --> 00:12:53.562 This should make the responses of those with PTSD 00:12:53.586 --> 00:12:55.914 more like those who have been through trauma 00:12:55.938 --> 00:12:58.130 and not developed PTSD 00:12:58.154 --> 00:13:01.643 than people who have never experienced trauma in the first place. 00:13:02.302 --> 00:13:05.678 I think that most people would find that more ethically acceptable 00:13:05.702 --> 00:13:09.522 than a treatment that aimed to create some sort of spotless mind. NOTE Paragraph 00:13:11.538 --> 00:13:13.053 What about Propranolol? 00:13:13.077 --> 00:13:15.139 You can't give Propranolol to everyone, 00:13:15.163 --> 00:13:18.708 and not everyone wants to take drugs to treat mental health conditions. 00:13:19.237 --> 00:13:21.916 Well, here Tetris could be useful. 00:13:22.542 --> 00:13:23.976 Yes, Tetris. 00:13:25.430 --> 00:13:27.203 Working with clinical collaborators, 00:13:27.227 --> 00:13:30.025 we've been looking at whether behavioral interventions 00:13:30.049 --> 00:13:33.620 can also interfere with the reconsolidation of memories. 00:13:33.971 --> 00:13:35.600 Now, how would that work? NOTE Paragraph 00:13:35.624 --> 00:13:38.050 Well, we know that it's basically impossible 00:13:38.074 --> 00:13:40.022 to do two tasks at the same time 00:13:40.046 --> 00:13:43.471 if they both depend on the same brain region for processing. 00:13:43.826 --> 00:13:46.159 Think trying to sing along to the radio 00:13:46.183 --> 00:13:48.262 while you're trying to compose an email. 00:13:48.286 --> 00:13:51.545 The processing for one interferes with the other. 00:13:52.335 --> 00:13:54.611 Well, it's the same when you retrieve a memory, 00:13:54.635 --> 00:13:55.896 especially in edit mode. 00:13:55.920 --> 00:13:59.918 If we take a highly visual symptom like flashbacks in PTSD 00:13:59.942 --> 00:14:02.988 and get people to recall the memory in edit mode 00:14:03.012 --> 00:14:06.270 and then get them to do a highly engaging visual task 00:14:06.294 --> 00:14:08.088 like playing Tetris, 00:14:08.112 --> 00:14:12.412 it should be possible to introduce so much interfering information 00:14:12.436 --> 00:14:13.753 into that memory 00:14:13.777 --> 00:14:16.406 that it essentially becomes meaningless. 00:14:17.644 --> 00:14:18.828 That's the theory, 00:14:18.852 --> 00:14:22.323 and it's supported by data from healthy human volunteers. 00:14:22.823 --> 00:14:26.748 Now, our volunteers watched highly unpleasant films -- 00:14:26.772 --> 00:14:30.308 so, think eye surgery, road traffic safety adverts, 00:14:30.332 --> 00:14:32.076 Scorsese's "The Big Shave." 00:14:32.997 --> 00:14:36.933 These trauma films produce something like flashbacks 00:14:36.957 --> 00:14:40.694 in healthy volunteers for about a week after viewing them. 00:14:41.789 --> 00:14:45.110 We found that getting people to recall those memories, 00:14:45.134 --> 00:14:48.181 the worst moments of those unpleasant films, 00:14:48.205 --> 00:14:50.751 and playing Tetris at the same time, 00:14:50.775 --> 00:14:54.364 massively reduced the frequency of the flashbacks. 00:14:54.388 --> 00:14:58.565 And again: the memory had to be in edit mode for that to work. NOTE Paragraph 00:15:00.063 --> 00:15:03.769 Now, my collaborators have since taken this to clinical populations. 00:15:03.793 --> 00:15:06.813 They've tested this in survivors of road traffic accidents 00:15:06.837 --> 00:15:10.081 and mothers who've had emergency Caesarean sections, 00:15:10.105 --> 00:15:14.200 both types of trauma that frequently lead to PTSD, 00:15:14.224 --> 00:15:17.087 and they found really promising reductions in symptoms 00:15:17.111 --> 00:15:19.489 in both of those clinical cases. NOTE Paragraph 00:15:21.434 --> 00:15:25.682 So although there is still much to learn and procedures to optimize, 00:15:25.706 --> 00:15:28.841 these memory-destroying treatments hold great promise 00:15:28.865 --> 00:15:31.254 for the treatment of mental health disorders 00:15:31.278 --> 00:15:33.041 like PTSD. 00:15:33.065 --> 00:15:38.409 Maybe trauma memories do not need to be a hell from which we cannot escape. NOTE Paragraph 00:15:39.266 --> 00:15:41.034 I believe that this approach 00:15:41.058 --> 00:15:42.985 should allow those who want to 00:15:43.009 --> 00:15:45.079 to turn the page on chapters of their lives 00:15:45.103 --> 00:15:47.761 that they would prefer to never have experienced, 00:15:47.785 --> 00:15:50.484 and so improve our mental health. NOTE Paragraph 00:15:51.238 --> 00:15:52.430 Thank you. NOTE Paragraph 00:15:52.454 --> 00:15:53.492 (Applause)