Sarah-Jayne Blakemore: El misterioso funcionamiento del cerebro adolescente
Summary
TLDREl guion del video revela cómo los avances en neuroimagen, como la resonancia magnética funcional (fMRI), han cambiado nuestra comprensión del desarrollo cerebral humano. Se destaca que el cerebro no se desarrolla solo en la infancia, sino que continua su crecimiento durante la adolescencia y hasta los 20s y 30s. El estudio del cortex prefrontal, una región clave para funciones cognitivas avanzadas, muestra cambios significativos en la adolescencia, incluyendo un proceso de 'podar sináptico' que refuerza conexiones neuronales importantes. Además, se explora cómo la adolescencia afecta la toma de decisiones sociales y la capacidad de entender las perspectivas de otros, destacando la importancia de este periodo para el aprendizaje y el desarrollo social.
Takeaways
- 🧠 Hace 15 años, se pensaba que el desarrollo cerebral se completaba en los primeros años de vida, pero con avances en la tecnología de imagen cerebral, como la resonancia magnética (MRI), se ha podido observar que el cerebro continúa desarrollándose hasta la adolescencia y los 20s o 30s.
- 📈 El uso de la MRI estructural permite tomar fotografías de alta resolución del interior del cerebro y cuestionar cómo cambia la cantidad de materia gris con la edad.
- 🎥 La fMRI (funcional) permite grabar la actividad cerebral durante tareas, ofreciendo información sobre cómo el cerebro reacciona a diferentes situaciones.
- 🔍 Los estudios muestran que el desarrollo del cerebro no termina en la infancia temprana, sino que continúa hasta la adolescencia y más allá, lo que cambia nuestra comprensión de cómo evoluciona el cerebro humano.
- 🧒 La adolescencia se define como el período que comienza con los cambios hormonales y físicos de la pubertad y termina cuando una persona alcanza un rol estable e independiente en la sociedad.
- 🧠 El córtex prefrontal, una región del cerebro altamente desarrollada en humanos y responsable de funciones cognitivas complejas, experimenta cambios dramáticos durante la adolescencia.
- 📉 El volumen de materia gris en el córtex prefrontal disminuye significativamente durante la adolescencia, un proceso conocido como poda sináptica que es esencial para la maduración del cerebro.
- 🤔 La fMRI también revela que la actividad cerebral en áreas relacionadas con la toma de decisiones sociales varía con la edad, siendo más activa en adolescentes que en adultos.
- 👶 La capacidad de considerar la perspectiva de otros y guiar el comportamiento en consecuencia sigue desarrollándose en la adolescencia media hasta la adultez.
- 🌐 La adolescencia no es un fenómeno reciente; se han encontrado descripciones históricas similares a las de hoy, como la de Shakespeare hace casi 400 años.
- 🏫 Los cambios en el cerebro adolescente proporcionan una excelente oportunidad para el aprendizaje y el desarrollo social, y es crucial abordar adecuadamente estos años críticos de desarrollo.
Q & A
¿Cuál era la creencia general hace 15 años sobre el desarrollo del cerebro humano?
-Hace 15 años, se creía ampliamente que la mayoría del desarrollo cerebral ocurría en los primeros años de vida.
¿Qué ha permitido a los neurocientíficos observar el desarrollo cerebral a lo largo de la vida?
-Los avances en la tecnología de imágenes cerebrales, como la resonancia magnética (MRI), han permitido a los neurocientíficos observar el desarrollo cerebral en seres humanos de todas las edades.
¿Qué tipo de imágenes cerebrales se utilizan para estudiar la estructura y la actividad cerebral?
-Se utilizan imágenes estructurales (MRI) para capturar fotografías de alta resolución del interior del cerebro y fMRI (funcional) para registrar la actividad cerebral durante tareas específicas.
¿Cómo ha cambiado la comprensión del desarrollo cerebral humano en los últimos años?
-La comprensión ha cambiado drásticamente, revelando que el desarrollo cerebral no termina en la infancia temprana, sino que continúa durante la adolescencia y hasta los 20s y 30s.
¿Cuál es el período de la vida que se define como adolescencia?
-La adolescencia se define como el período que comienza con los cambios biológicos, hormonales y físicos de la pubertad y termina cuando una persona alcanza un rol estable e independiente en la sociedad.
¿Qué región cerebral cambia dramáticamente durante la adolescencia?
-La región cerebral que cambia más dramáticamente durante la adolescencia es el córtex prefrontal.
¿Qué funciones cognitivas están involucradas en el córtex prefrontal y cómo cambia durante la adolescencia?
-El córtex prefrontal está involucrado en funciones cognitivas altas como la toma de decisiones, la planificación, la inhibición de comportamientos inapropiados, la interacción social y la autoconciencia. Durante la adolescencia, experimenta un aumento en el volumen de la materia gris que luego disminuye, un proceso asociado a la poda sináptica.
¿Qué es la poda sináptica y cómo se relaciona con el desarrollo del córtex prefrontal en la adolescencia?
-La poda sináptica es el proceso por el cual se eliminan las sinapsis no utilizadas, fortaleciendo aquellas que están activas. Este proceso es importante para la maduración del córtex prefrontal en la adolescencia.
¿Cómo se ha utilizado la fMRI para estudiar los cambios en la actividad cerebral durante la adolescencia?
-La fMRI se ha utilizado para observar cambios en la actividad cerebral en respuesta a tareas que implican pensar en los demás, revelando que ciertas áreas del córtex prefrontal son más activas en la adolescencia que en la adultez.
¿Qué hallazgos se han realizado con respecto a la toma de decisiones sociales en la adolescencia en comparación con la adultez?
-Los estudios han encontrado que la corteza prefrontal medial, implicada en la toma de decisiones sociales, es más activa en la adolescencia y disminuye su actividad con la edad, lo que sugiere que los adolescentes y los adultos pueden utilizar estrategias cognitivas diferentes para estas tareas.
¿Cómo se ha demostrado que la capacidad para considerar la perspectiva de otros se desarrolla en la adolescencia?
-Se han utilizado tareas de comportamiento que involucran la toma de decisiones basadas en la perspectiva de otros, mostrando que mientras que ciertas habilidades cognitives están maduras en la adolescencia media, la capacidad para tomar en cuenta la perspectiva de otros sigue mejorando hasta la adultez.
¿Qué implicaciones tiene el conocimiento de los cambios en el cerebro adolescente para la educación y el desarrollo social?
-El entendimiento de los cambios en el cerebro adolescente puede ayudar a adaptar el entorno educativo y social para apoyar el aprendizaje y el desarrollo adecuadamente, aprovechando la plasticidad y la capacidad de adaptación del cerebro en esta etapa.
¿Cómo se describe el comportamiento adolescente en el pasado y cómo se relaciona con la comprensión actual?
-El comportamiento adolescente ha sido descrito de manera similar en el pasado, como se muestra en citas de Shakespeare. Sin embargo, ahora se intenta entender este comportamiento en términos de los cambios subyacentes en el cerebro, como la sensibilidad hiperactiva del sistema límbico a las recompensas y el desarrollo del córtex prefrontal.
Outlines
🧠 Desarrollo cerebral durante la vida
Hace quince años, se pensaba que el desarrollo cerebral se completaba en los primeros años de vida. Sin embargo, gracias a avances en la tecnología de la resonancia magnética (MRI), los neurocientíficos han podido observar cambios en la estructura y función cerebral a lo largo de toda la vida. Se ha descubierto que el cerebro continúa desarrollándose durante la adolescencia y hasta los 20 o 30 años. El área prefrontal cerebral es especialmente importante durante esta etapa, involucrándose en funciones cognitivas avanzadas como la toma de decisiones, la planificación y la interacción social. El MRI estructural y funcional (fMRI) son herramientas clave para estudiar estos cambios.
📉 Cambios en la corteza prefrontal durante la adolescencia
El volumen de la materia gris en la corteza prefrontal aumenta durante la infancia y alcanza un pico en la adolescencia temprana, con una diferencia en el tiempo entre chicos y chicas debido a las diferencias en la edad de la pubertad. Esta región cerebral experimenta una significativa reducción en el volumen de materia gris durante la adolescencia, un proceso asociado a la poda sináptica, que es esencial para el desarrollo y la especialización del cerebro. La poda sináptica refuerza las conexiones neuronales utilizadas y elimina las que no son necesarias, similar a podar un rosal para que las ramas importantes crezcan más fuertes.
🤔 Cerebro social y desarrollo cognitivo en la adolescencia
El laboratorio del narrador se enfoca en el estudio del 'cerebro social', es decir, la red de regiones cerebrales implicadas en la comprensión y el intercambio con otros. Se ha encontrado que el cortex prefrontal medial, una parte del cortex prefrontal, está más activo en los adolescentes al tomar decisiones sociales en comparación con los adultos. Además, se realizan estudios de comportamiento para entender cómo los adolescentes y los adultos manejan tareas que implican la toma de decisiones basadas en la perspectiva de otros. Estos estudios muestran que la habilidad para considerar la perspectiva de otros y guiar el comportamiento en consecuencia sigue desarrollándose en la adolescencia media hasta la edad adulta.
🚸 Comprensión del comportamiento adolescente desde una perspectiva cerebral
El comportamiento de los adolescentes, que a menudo es caracterizado por el riesgo y la autoconciencia, está siendo comprendido a través de los cambios en el cerebro, especialmente en el sistema límbico, que procesa emociones y recompensas. Los adolescentes tienden a tomar más riesgos que los niños o los adultos, y esto se intensifica en la presencia de sus amigos. Los estudios cerebrales han demostrado que, mientras el sistema límbico es hipersensible a la recompensa del riesgo en la adolescencia, el cortex prefrontal, que regula los riesgos, está en desarrollo. Esto tiene implicaciones educativas y para el desarrollo social, destacando la importancia de la educación en esta etapa adaptable y moldeable del cerebro.
Mindmap
Keywords
💡Desarrollo cerebral
💡Imagenología por resonancia magnética (MRI)
💡Materia gris
💡Corteza prefrontal
💡Adolescencia
💡Podado sináptico
💡Actividad cerebral
💡Cerebro social
💡Perspectiva
💡Riesgo
💡Educación
Highlights
15年前,人们普遍认为大脑的大部分发育在生命的最初几年内完成。
由于磁共振成像(MRI)等脑成像技术的进步,神经科学家开始研究不同年龄段的活体人脑。
使用结构性MRI可以高分辨率地拍摄活体人脑内部的快照,了解灰质含量及其随年龄的变化。
功能性MRI(fMRI)可以记录参与者在进行思考、感觉或感知等任务时的大脑活动。
全球许多实验室参与了这类研究,揭示了活体人脑的发育过程,改变了我们对人类大脑发育的看法。
大脑发育并非在儿童早期就完成,而是一直持续到青少年时期甚至20至30岁。
青春期被定义为从青春期的生物学、荷尔蒙和身体变化开始,到个体在社会中获得稳定独立角色结束的时期。
前额叶皮层是青少年时期变化最显著的大脑区域之一,它在人类中的比例远大于其他物种。
前额叶皮层涉及高级认知功能,如决策制定、规划、抑制不当行为、社交互动和自我意识。
MRI研究显示,前额叶皮层在青春期经历了显著的发育变化,灰质体积在儿童时期增加,在青春期早期达到峰值。
青春期前额叶皮层灰质体积的显著下降,可能对应于突触修剪,这是一个重要的发展过程。
突触修剪是环境依赖的过程,使用中的突触被加强,不使用的突触被修剪掉。
功能性MRI用于追踪青少年大脑活动的变化,研究社交大脑的网络。
青少年在进行社交决策和思考他人时,内侧前额叶皮层的活动比成人更活跃。
行为研究表明,青少年在考虑他人视角以指导行为的能力上仍在发展,直到中到晚期青春期。
青少年的行为,如冒险、情绪波动和自我意识,不应被污名化,而应视为大脑变化提供教育和社会发展的良机。
历史上对青少年的描述与今天相似,如莎士比亚在《冬天的故事》中对青春期的描述。
青少年的大脑发育对教育、康复和干预有深远的影响,环境包括教学可以塑造发育中的青少年大脑。
世界上许多青少年无法接受中学教育,而这个时期是大脑特别适应和可塑的,是学习和创造力的绝佳机会。
Transcripts
fifteen years ago it was widely assumed
that the vast majority of brain
development takes place in the first few
years of life back then 15 years ago we
didn't have the ability to look inside
the living human brain and track
development across the lifespan in the
past decade or so mainly due to advances
in brain imaging technology such as
magnetic resonance imaging or MRI
neuroscientists have started to look
inside the living human brain of all
ages and attract changes in brain
structure and brain function so we use
structural MRI if you like to take a
snapshot of photograph at really high
resolution of the inside of the living
human brain and we can ask questions
like how much gray matter does the brain
contain and how does that change with
age and we also use functional MRI
called fMRI to take a video a movie of
brain activity when participants are
taking part in some kind of task like
thinking or feeling or perceiving
something so many labs around the world
are involved in this kind of research
and we now have a really rich and
detailed picture of how the living human
brain develops and this picture has
radically changed the way we think about
human brain development by revealing
that it's not all over in early
childhood and instead the brain
continues to develop right throughout
adolescence and into the 20s and 30s
so adolescence is defined as the period
of life that starts with the biological
hormonal physical changes of puberty and
ends at the age at which an individual
attains a stable independent role in
society it can go on a long time
one of the brain regions that changes
most dramatically during adolescence is
called prefrontal cortex so this is this
is a model of the human brain and this
is prefrontal cortex right at the front
prefrontal cortex is an interesting
brain area it's proportionally much
bigger in humans than in any other
species and it's involved in a whole
range of high-level cognitive functions
things like decision-making planning
planning what you're going to do
tomorrow or next week or next year
inhibiting inappropriate behavior so
stopping yourself saying something
really rude or doing something really
stupid it's also involved in social
interaction understanding other people
and self-awareness so MRI studies
looking at the development of this
region have shown that it really
undergoes dramatic development during
the period of adolescence so if you look
at gray matter volume for example gray
matter volume across age from age four
to twenty two years
increases during childhood which is what
you can see on this graph it peaks in
early adolescence the arrows indicate
peak gray matter volume in prefrontal
cortex you can see that that peak
happens a couple of years later in boys
relative to girls and that's probably
because boys go through puberty a couple
of years later than girls on average and
then during adolescence there's a
significant decline in gray matter
volume in prefrontal cortex now that
might sound bad but actually this is a
really important developmental process
because gray matter contains cell bodies
and connections between cells the sign
APS's and this decline in gray matter
volume during prefrontal cortex is
thought to correspond to synaptic
pruning the elimination of unwanted
signups --is this is a really important
process it's partly dependent on the
environment that the animal or the human
is in in that sign APS's that are being
used are strengthened and synapse is
that aren't being used in that
particular environment are pruned away
you can think of it a bit like pruning a
rosebush you prune away the weaker
branches so that the remaining important
branches can grow stronger and this
process which effectively fine-tunes
brain tissue according to the species
specific environment
happening in prefrontal cortex and in
other brain regions during the period of
human adolescence so a second line of
inquiry that we use to track changes in
the adolescent brain is using functional
MRI to look at changes in brain activity
across age so I'll just give you an
example from my lab so in my lab we're
interested in the social brain that is
the network of brain regions that we use
to understand other people and to
interact with other people so I like to
show a photograph of a soccer game to
illustrate two aspects of how your
social brains work so this is a soccer
game Michael Owen has just missed a goal
and he's lying on the ground and the
first aspect of the social brain that
this picture really nicely illustrates
is how automatic and instinctive social
emotional responses are so within a
split-second of Michael Owen missing
this goal everyone is doing the same
thing with their arms and the same thing
with their face even my clone as he
slides along the grass is doing the same
thing forward disarms and presumably has
a similar facial expression and the only
people who don't are the guys in yellow
at the back a nice I think they're on
the wrong end of the stadium and they're
doing another social emotional response
that we all instantly recognize and
that's the second aspect of the social
brain that this picture really nicely
has illustrates how good we are reading
other people's behavior their actions
their gestures their facial expressions
in terms of their underlying emotions
and mental states so you don't have to
ask any of these guys you have a pretty
good idea of what they're feeling and
thinking at this precise moment in time
so that's what we're interested in
looking at in my labs we in my lab we
bring adolescents and adults into the
lab to have a brain scan we give them
some kind of task that involves thinking
about other people their minds their
mental states their emotions and one of
the findings that we found several times
now as have other labs around the world
is part of the prefrontal cortex called
medial prefrontal cortex which is shown
in blue on the slide and it's um right
in the middle of prefrontal cortex in
the midline of your head this region is
more active in adolescence when they
make these social decisions and think
about other people than it is in adults
and this is actually a meta-analysis of
nine different studies in this
area from labs around the world and they
all show the same thing that activity in
this medial prefrontal cortex area
decreases during the period of
adolescence and we think that might be
because adolescents and adults use a
different mental approach a different
cognitive strategy to make social
decisions and one way of looking at that
is to do behavioral studies whereby we
bring people into the lab and we give
them some kind of behavioral task and
I'll just give you another example of
the kind of tasks that we use in my lab
so imagine that you're the participant
in one of our experiments you come to
the lab you see this computerised task
in this task you see a set of shelves
now there are objects on these shelves
on some of them and you'll notice
there's a guy standing behind the set of
shelves and there are some objects that
he can't see they're occluded from his
point of view with a kind of gray piece
of wood this is the same set of shelves
from his point of view notice that there
are only some objects that he can see
whereas there are many more objects that
you can see now your task is to move
objects around the director standing
behind the set of shells is going to
direct you to move objects around but
remember he's not going to ask you to
move objects that he can't see this
introduces a really interesting
condition whereby there's a kind of
conflict between your perspective and
the directors perspective so imagine he
tells you to move the top truck left
there are three trucks there you're
going to instinctively go for the white
truck because that's the top truck from
your perspective but then you have to
remember oh he can't see that truck so
he must mean me to move the blue truck
which is the top truck from his
perspective now believe it or not normal
healthy intelligent adults like you make
errors about 50% of the time on that
kind of trial they move the white truck
instead of the blue truck there we give
this kind of tasks to adolescents and
adults mules have a control condition
where there's no director and instead we
give people a rule we tell them okay
we're going to do exactly the same thing
but this time there's no director
instead you've got to ignore objects
with a dark gray background you'll see
that this is exactly the same condition
only in the no director condition they
just have to remember to apply this
somewhat arbitrary rule whereas in the
direct
condition they have to remember to take
into account the directors perspective
in order to guide their ongoing behavior
okay so if I just show you the
percentage errors in a large
developmental study we did this is a
study ranging from age 7 to adulthood
and what you're going to see is the
percentage errors in the adult group in
both conditions so the gray is the
director condition and you see that our
intelligent adults are making errors
about 50% of the time whereas they make
far fewer errors when there's no
director present when they just have to
remember that rule of ignoring the gray
background developmentally these two
conditions develop in exactly the same
way between late childhood and mid
adolescents there was an improvement in
other words reduction of errors in both
of these trials in both of these
conditions but it's when you compare the
last two groups the mid adolescent group
and the adult group where things get
really interesting because there there
is no continued improvement in the no
director condition in other words
everything you need to do in order to
remember the rule and apply it seems to
be fully developed by mid adolescence
whereas in contrast if you look at the
last two gray bars there's still a
significant improvement in the director
condition between mid adolescence and
adulthood and what this means is that
the ability to take into account someone
else's perspective in order to guide
ongoing behavior which is something by
the way that we do in everyday life all
the time is still developing in mid to
late adolescence so if you have a
teenage son or daughter and you think
you sometimes think they have problems
taking other people's perspectives
you're right that they do and this is
why so we we sometimes laugh about
teenagers we they're parodied sometimes
even demonized in the media for their
contemn teenage behavior they take risks
then sometimes moody they're very
self-conscious I have a really nice
anecdote from a friend of mine who said
that the thing he noticed most about his
teenage daughters before and after
puberty was their level of embarrassment
in front of him so he said before
puberty if my two daughters were messing
around in a shop I'd say hey stop
messing around and I'll sing your
favorite song and instantly they'd stop
messing around and he'd sing their
favorite song after puberty that became
the threat
the very notion of their dad singing in
public was enough to make them behave so
people often ask what is adolescents the
kind of recent phenomena is it something
we've invented recently in the West and
actually the answer is probably not
there are lots of descriptions of
adolescents in history that sound very
similar to the descriptions we use today
so there's a famous quote by Shakespeare
from The Winter's Tale where he
describes adolescence as follows
I would there were no age between ten
and three and twenty or that youth would
sleep out the rest for there's nothing
in the between but getting wenches with
child
wronging the ancient tree stealing
fighting he then goes on to say having
said that would any but these boiled
brains of nineteen and two and twenty
hunt in this weather
so almost 400 years ago Shakespeare was
portraying adolescence in a very similar
light to the light that we portray them
in today but today we try to understand
their behavior in terms of the
underlying changes that are going on in
their brain so for example take risk
taking
we know that adolescents are have a
tendency to take risks they do they take
more risks than children or adults and
they are particularly prone to taking
risks when they're with their friends
there's an important drive to become
independent from one's parents and to
impress one's friends in adolescence but
now we try to understand that in terms
of the development of a part of their
brain called the limbic system so I'm
going to show you the limbic system in
red in the slide behind me and also on
this brain so the limbic system is right
deep inside the brain and it's involved
in things like emotion processing and
reward processing it gives you the
rewarding feeling out of doing fun
things including taking risks it gives
you the kick out of taking risks and
this region that the blue regions within
the limbic system have been found to be
hypersensitive to the rewarding feeling
of risk-taking in adolescence compared
with adults and at the very same time
the prefrontal cortex which you can see
in blue in the slide here which stops us
taking excessive risks is still very
much in development and
lessons so brain research has shown that
the adolescent brain undergoes really
quite profound development and this has
implications for education for
rehabilitation and intervention the
environment including teaching can and
does shape the developing adolescent
brain and yet it's only relatively
recently that we have been routinely
educating teenagers in the West all four
of my grandparents for example left
school in their early adolescence they
had no choice and that still the case
for many many teenagers around the world
today forty percent of teenagers don't
have access to secondary school
education and yet this is a period of
life where the brain is particularly
adaptable and malleable it's a fantastic
opportunity for learning and creativity
so what sometimes seen is the problem
with adolescents - risk-taking poor
impulse control self-consciousness
shouldn't be stigmatized it actually
reflects changes in the brain that
provide an excellent opportunity for
education and social development thank
you
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