(How It Works) DK - How The Brain Works - The Facts Visually Explained (2020) MEMORY, LEARNING, AND THINKING
(How It Works) DK - How The Brain Works - The Facts Visually Explained (2020) MEMORY, LEARNING, AND THINKING
(How It Works) DK - How The Brain Works - The Facts Visually Explained (2020) MEMORY, LEARNING, AND THINKING
LEARNING,
AND THINKING
What Is Memory?
Our memory allows us to learn from experience and shapes us as
individuals. Memory is not a single discrete brain function; there
are several types, involving different brain areas and processes.
Parietal lobe is
Mammillary body important for
is involved in spatial memory
episodic memory
Thalamus helps
Short-term
Olfactory bulb links direct attention
memory
to the amygdala Short-term memory is very
so smells are Hippocampus
turns experience limited—storing only around 5–9
potent triggers for items, but this varies between
emotional memories into episodic
memory individuals and for different types
of information. To keep something
Temporal lobe in short-term memory, we often
Brain areas holds general repeat it to ourselves, but if we
Memory areas often relate to the knowledge are distracted, we instantly
information stored. Memories of forget it.
movement, for example, use the Amygdala is vital for Cerebellum is
motor cortex. Limbic areas, linked to forming emotional vital for “muscle
emotion, are also involved in memory. memories memories”
Long-term
memory
Our long-term memory allows us
to store a—theoretically—almost
infinite number of memories for most
of our life. Long-term memories are
stored as distributed networks of
neurons spread out across the outer
layer of the brain, the cortex.
Recalling the memory sparks
the network to fire again.
Nondeclarative Declarative
(implicit) (explicit)
Nondeclarative memories are Declarative memories can be told
unconscious so cannot be passed to someone else. They are conscious
from person to person using words. and sometimes learned through
You might try, for example, to explain repetition and effort, although others
to someone how to tie their shoe can be stored without awareness of
laces or ride a bike, but they would the process. They include memories
probably still fail or fall off of events that have happened
the first time they attempted in your life (episodic) and
to do it for themselves. facts (semantic).
Strengthening connections
When you repeatedly activate a group of neurons—by practicing a
skill or revising facts, for example—they begin to change. This is how AUDITORY
we form long-term memories (see p.135) in a process called long-term CORTEX
potentiation, which depends on various mechanisms taking place
in brain cells. The first (presynaptic) neuron makes more VISUAL
neurotransmitters release when the signal reaches it, and the second CORTEX
inserts more receptors into its membrane. This speeds up transmission
Memories of sounds
at the synapse. Something like driving a car, which seems complex are stored partly in or
when you start, can become effortless as the neural pathways involved near auditory cortex
become more efficient. If this paired activation is repeated enough, new
dendrites can grow, linking the two neurons via new synapses, giving
the message alternative pathways and helping it travel even faster. NG
NI
AR
Electrical signal
LE travels along axon
MORE THAN 100 DIFFERENT of sending neuron
RE
FO
NEUROTRANSMITTERS
BE
RI
TE
ON
SYNAPSE
Firing together
Long-term potentiation
occurs across the brain but
has been best studied in the Before learning, only a weak connection exists between
hippocampus. Electrical signals 1 neurons. One action potential (pulse of electrical current)
travel along a neuron’s axon to from the first cell releases only a small amount of neurotransmitters,
the synapse, where chemical and this may or may not be enough to activate the next neuron,
messengers are released. which has just a few receptors.
MEMORY, LEARNING, AND THINKING
How a Memory Forms 136 137
Emotional memories
When something strongly emotional happens, whether that is good or bad,
KEY
stress chemicals such as adrenaline and noradrenaline are released. These
Neurotransmitter
make it easier for long-term potentiation to occur with fewer repetitions.
This explains why emotionally arousing memories are stored more rapidly Phosphate
in the brain and why they are easier to recall than nonemotional memories.
Action potential in
Changes presynaptic neuron triggers
triggered in neurotransmitter release
hippocampal
neurons Neurotransmitter
released
Noradrenaline
released by neurons Phosphates guide
in locus coeruleus, receptors to insert
located in pons themselves next to synapse
HIPPOCAMPUS
LOCUS
Hormone released Strong connection
1 Noradrenaline released
COERULEUS 2 An enzyme adds
Neuron is
primed for
PO
NG NG
RNI Repeated activation causes NI More neurotransmitters
EA more neurotransmitters
AR produced and
to be released released
E
L
RL
G
RIN
TE
AF
DU
More Strong
receptors connection
move to allows
membrane signal to
surface pass quickly
More receptors
on receiving
cell
Action potential
triggered in
second neuron
Both neurons firing repeatedly at the same time causes a Now, a single action potential causes the release of
2 chemical cascade within the second cell (see p.26), which 3 more neurotransmitters, carrying the message quickly
makes it more sensitive to the neurotransmitter, and causes extra and efficiently across the synapse, where it is received by
receptors to migrate to the edge of the synapse. A signal travels many receptors. This makes it easier for the second neuron
back to the first cell, telling it to produce more neurotransmitters. to be activated, sending its electrical signal onward.
Storing Memories CO
R TEX
X
TE
(see pp.136–137).
OR
LC
TA
Storage in the cortex WHY DO I
ON
To transfer memories for long-term
FR
FORGET WHERE I
PRE
storage, the hippocampus repeatedly LEFT MY KEYS?
activates a network of connections
in the cortex. Each activation Often, things we “forget”
strengthens connections until they actually weren’t stored
are secure enough to store the as memories in the first
memory. It was thought that place, because we weren’t
memories formed first in the
paying attention when
hippocampus, with the cortical
memory trace forming later, but we did them.
recent research in mice suggests
that they may form simultaneously,
although the cortical memory is Memory bank
initially unstable. Repeated Memories are stored as networks
reactivation of the network of connections in the cortex. The
number of neurons here creates
somehow “matures” the cortical a near infinite amount of possible
memory, meaning we can use it. combinations—in theory, long-
term memory is virtually unlimited.
N
ATIO
ING OLID
Consolidation ARN NS
LE CO
This storage process, known as Study Sleep
consolidation, happens mainly 1 When you learn something new, 2 While you sleep, new
while we sleep. During this time, your brain takes in that information and information is consolidated. The
forms new connections, or strengthens memory becomes less reliant on
your brain is not processing synapses that already exist. the hippocampus and less likely
information from the outside to be affected by interference
world so it can carry out these from other inputs or brain injury.
housekeeping tasks. Memories
are sorted, prioritized, and the
gist extracted. They are also
linked with older memories,
already in storage. This makes
it easier to retrieve important
memories in the future. Studies
have shown it is better to take a
nap after learning something
new than it is to keep studying!
MEMORY, LEARNING, AND THINKING
Storing Memories 138 139
A certain combination of
Memory stored in cortex neurons fires repeatedly
2 Networks across the cortex to consolidate memory
store memories for things that M
happened less recently. Different
EM
types of memories might be stored
OR
in various combinations of regions.
Y TR
X
E
ACE
RT
CO
RY
SON
SE
ATO
SOM
AUDITORY
CORTEX
Synapses strengthen,
storing memory as
a trace
US
AMP
HIPP
OC HIPPOCAMPAL
INJURY CAN MAKE
CO AL
1 FORMING NEW
SU
RT
L
RIE
VA PRACTICE MAKES PERFECT
T
RE
Remember If you learn something just once, over time that memory
3 When you wake up, the memory trace will fade as the connections weaken. The more times
of what you learned is stored more you practice or revise something, the stronger those
securely. It has also been linked to other connections between neurons become and the more likely
facts, making it easier to recall, and you you are to remember it in the future.
may find that you
understand the
underlying KEY
Strength of memory trace
concepts better.
Rest
Study
Time
Recalling a Memory
Recalling a memory is not the passive process we once
thought, like playing back a recording on your phone.
Instead, our brain actively reconstructs our experience from
the information it has stored. This introduces the opportunity
for mistakes, meaning our memories can change over time. Nerve-cell connection
activated during recall
Nerve-cell connection
strengthens
Strong emotions
make it easier for Cortex
connections to
strengthen
RY
MEMO
ED
Strong connections OR
2 If we do not recall a memory ST
frequently, the connections between
the cells will weaken and the memory
HOME DATES
will fade. Memories associated with LIF
strong emotions, however, are less
E
Reactivating a memory
When we recall a memory, we activate
the same network of neurons that
fired during the original experience, IONSHIP TRIPS
bringing it back to mind. While being LAT S
RE
recalled, the memory enters a flexible,
or labile, state. This means that once
we have finished thinking about that
memory, it must be reconsolidated Stored memories
Most memories are stored
and stored again. If new information long-term in the cortex, but
is presented while the memory is you can’t point to the area for
labile, it can be stored alongside old your 18th birthday, for example.
Each memory is represented
information. This allows memories to by a network of neurons,
be changed and updated. spread across the brain.
MEMORY, LEARNING, AND THINKING
Recalling a Memory 140 141
False memories
When a memory is reconsolidated,
True memory
new information is stored with old. 1 Scientists asked participants to watch
But when we next recall the memory, clips of car accidents. After each clip, they had
it is impossible to tell which is which. to describe what happened and answer
questions. This meant they were recalling
This means we can end up with and reactivating
false memories. Just talking about the memory.
an event can change our memory of
it, so in legal cases, witnesses must
be questioned carefully, to avoid
contaminating their memories.
ATI
VAC ONS False memory recalled
3 One week later, subjects recalled the video again
and were asked whether there was any broken glass (there
was not). Significantly more people in the “smashed”
group “remembered” broken glass. The
words used had changed their
memory of the event.
HD
BIRT AYS
M
M
ME
ME
cause us to forget (see pp.146–147).
Broadly, there are two possibilities
for what happens in the brain when
we do. The simplest idea is that
over time memories fade away;
information is lost as the trace that
was formed is no longer there. But
evidence for this is hard to come by, Memory cannot
as other factors could be involved. be accessed or
brought to mind,
Most of us have experienced the
perhaps giving
struggle to remember information a “tip of the
that later pops into your head for no L tongue” feeling
CAL
reason—this suggests memories RE
Y
can still exist but be inaccessible.
OR
WHY DO I FORGET
WHAT I WENT
UPSTAIRS FOR?
Leaving a room changes the
environmental cues that help
us remember. When you Memory retrieved Failure to retrieve
When we recall If recall is unsuccessful, it
go back to where you were, something, we must may be that the memory
the memory often reactivate the network is still in the cortex,
of neurons that stores it. we are just unable to
reactivates. If this is successful, access it (above). Or
we remember the connections may have
fact or event. been lost (see right).
MEMORY, LEARNING, AND THINKING
Why We Forget 144 145
Interfering memories
Our brains experience interference, particularly when information ACTIVE FORGETTING
is similar. Learning new information can block recall for old, and
old information can also affect new. These problems might arise Forgetting seems passive,
but you can choose to forget.
because the wrong memory trace is activated when you go to recall
In one study, subjects’
the information, blocking access to the right one. Or it may be that prefrontal cortices—involved
old information can disrupt consolidation of new, and if successful, in suppression—were activated
the new memory may actually replace the old one. when they were told to forget
a specific word.
Proactive
interference
Old memories may
disrupt new ones. BONJOUR, HOLA,
For example, when ÇA VA? ¿CÓMO
starting to learn ESTÁS? Prefrontal
Spanish, you may cortex
experience interference
from French words
learned as a child.
WE MAY BE LESS
LIKELY TO RECALL
Retroactive INFORMATION WE
interference
If you later went to BONJOUR, HOLA, CAN FIND EASILY
speak French and ÇA VA? ¿CÓMO ESTÁS?
instead spoke Spanish, ONLINE; THIS IS THE
that would be new
memories disrupting GOOGLE EFFECT
the recall of old ones.
S S S
NTH AR ADE
O YE C
DE
M
LO
both hippocampi, to treat severe during World War I to describe
B E
epilepsy. This controlled his
seizures, but he forgot several an effect thought to be caused
years before the surgery
and developed anterograde
by the sound of exploding
MPUS
amnesia. He could retain new shells. Soldiers were, in fact,
declarative memories (see
suffering from PTSD, brought
CA
p.135) only for a few seconds O
but could learn new skills. HIPP on by the trauma of war.
CE
Large areas
RE
S
NT
Savant syndrome VA FLASHBULB MEMORIES
SA
FEMALE
Scientists think these talents may
develop because of savants’
MALE
extreme focus and interest in one 79%
area. There is also evidence they
see the world as building blocks, By genetics and gender
not whole pictures, by accessing One database of savants, as reported by their
parents or caregivers, found that the vast
perceptual information most of us majority (90 percent) are born with the
are not consciously aware of. condition, and of these, most were male.
MEMORY, LEARNING, AND THINKING
Special Types of Memories 148 149
KEY
Taxi driver’s Taxi driver’s posterior Posterior hippocampus
Posterior hippocampus
hippocampus hippocampus returns to original size
increases in volume
“Photographic” memory
There is no such thing as photographic memory—no one can literally CAN PEOPLE
recall pages of text or images as if they were really in front of them. The REMEMBER
closest is eidetic memory, which occurs in 2–10 percent of children. After EVERYTHING?
looking at an image, “eidetikers” continue to “see” it in their visual field,
until it gradually fades or disappears as they blink.
A perfect memory does
not exist, but a few people
Picture imperfect
Studies have shown that eidetic images are not have superior autobiographical
perfect. Children may not manage to remember memory, giving them
all the letters in a word they were shown, or
they may invent details, for example, “recalling” exceptional recall for
something in a picture that was not really there. events during
their lives.
MEMORY
PEOPLE WITH
Sometimes, people
with an eidetic memory INCREDIBLE RECALL
vividly recall details that
were not present in the FOR FACES ARE
original scene, such as
the color of this roof CALLED SUPER
PHOTOGRAPH CHILD RECOGNIZERS
Intelligence Network implicated
in hypothesis testing—an
integral component
of intelligence
There are many theories about how intelligence
evolved, what it actually constitutes, and which
factors are key to high intelligence.
Plasticity is brain’s
ability to reorganize
Plasticity
Higher intelligence is
Parietal lobe has numerous related to the ability
functions associated with to make alternate and
intelligence, including additional connections
spatial awareness within the brain.
Linguistic
Has a way with words and INTELLIGENCE IS INHERITED
uses this understanding to
craft stories, convey complex
concepts, and learn languages. Physical features are not
the only traits passed from
one generation to the next. In
Intrapersonal fact, intelligence is thought to
A deep understanding of self be one of the most heritable
that can be used to predict behavioral traits in humans. It
one’s own reactions and is estimated that between 50
emotions to new situations.
and 85 percent of the
differences in adult
intelligence can be MOTHER FATHER
Visual–spatial
Able to easily judge distance,
explained by genetics.
recognize fine details, and
solve spatial problems by CHILD
visualizing the world in 3-D.
Measuring Intelligence
Measures of intelligence have been used for well over
a century, but the methods used and the way the results IQ scores are standardized
are put to use remain hotly debated, even today. so the curve is always
centered on a score of 100
Normal distribution
When scores from IQ tests are AN INDIVIDUAL’S
plotted on a frequency graph,
the result is a bell curve, or IQ SCORE CAN VARY
normal distribution, in which
most people’s scores cluster
BY 20 POINTS OR
symmetrically around the
average. For every 100 people,
MORE DEPENDING
68 will have an IQ score
between 85 and 115. At both
ON THE TEST USED
the upper and lower ends of
the scale, the frequency falls
away rapidly.
DOES A PERSON’S
IQ STAY THE SAME?
A child’s IQ score can be quite
variable with potentially
FREQUENCY
55 70 85 100 115
IQ
152 153
Alternatives to IQ
IQ is not the only measure of intelligence. There are RECORD IQS
several alternatives, many of which are more visually
based, with pictures, illusions, or pattern sequences Claims of exceptional IQs (including scores over
at their core. Psychometric testing is an approach often 200) are often made but rarely verified. The
American Marilyn vos Savant held the IQ record
used in job recruitment to assess a person’s aptitudes—
(228) in the Guinness World Records from 1986
for example, to evaluate empathy when selecting a to 1989, after which Guinness retired the
carer. People who score well on IQ tests are also likely category because it concluded the tests were
to score well on other tests. This probably indicates not reliable enough.
a high level of overall cognitive ability, sometimes Attempts have also been
referred to as general intelligence factor (g). made to measure the
IQs of people who can
no longer be tested.
General intelligence
The ability to do well
Albert Einstein, for
across several specific example, is estimated
areas of intelligence to have had an IQ
is indicated by of over 160.
the general MECHANICAL
intelligence factor.
Is IQ on the rise?
There is evidence for a widespread increase in
GENERAL
VERBAL INTELLIGENCE SPATIAL
IQ. When IQ tests are revised every 10–20 years,
(g) the test-takers who are used to standardize
the new test are asked to take the previous test
as well, and they consistently score higher on
the old test. In other words, if American adults
today took an IQ test from the 1920s, the vast
majority would score in the upper extreme,
NUMERICAL above 130. This is supported by evidence from
around the world, although the rate of increase
is most rapid in developing countries. Recent
evidence suggests that this rise, known as the
Flynn effect, has started to plateau.
20
130 145 10
N E
the mind wanders
to time, but what makes some of us
OD
DEFAULT M
more creative than others is linked
to our connections and coordination
between three different brain networks.
JAPANESE INVENTOR
SHUNPEI YAMAZAKI
HAS A REPORTED 5,255
PATENTS TO HIS NAME
EC
ET
EX
received particular task
EN
AL
C
SALIEN
CENTR
Switching Focusing
2 The salience network 3 The central executive network
detects sensory information to engages the conscious brain to think
determine whether the central and maintain focus on a task. Studies
executive network should engage. have shown that the default mode
For example, when hearing your network is reengaged within a fraction
name while daydreaming, the of a second of the task being completed.
salience network triggers a switch.
To boost creativity, you must first Creativity-friendly activities create mental distance from it. Imagine
remove barriers to it. Stress, time new neural connections. Learning how someone from another country,
constraints, and lack of sleep or to play a musical instrument, for time period, or age group would
exercise are known creativity example, opens and strengthens deal with the issue.
killers. People tend to be creative links between different brain areas. Allow yourself to disconnect.
when they are rested, happy, and Simply varying your routine can If you are stuck in a line, don’t
can let their thoughts wander freely. also foster creativity, so pick a more default to your phone to check
Many people claim to have their interesting route to work, a color emails or social media; instead,
best ideas during their morning you don’t usually wear, or a new zone out and let the ideas flow.
shower or walk to work. It seems recipe to cook. Surround yourself The next time you are stuck for
that ideas flow most freely around with like-minded, creative people ideas, try one of the following:
our brains when they are not in a as much as possible. Whether it is • Get enough rest, destress,
task-orientated state but instead in in a gallery or a garden shed, new and exercise.
a condition called the resting state. input stimulates new ideas. • Learn a new skill. Spend time
Unsolvable challenges encourage with other creative people.
Cultivate new connections novel ways of thought. How many • Think outside the box. Think
Routines help regulate our daily things can you think of to do with of new ways to solve old problems.
lives, but they also reinforce a paper clip, for instance? If you are • Switch off from digital devices
existing neural pathways. stuck on a problem, get some to give your brain some downtime.
156 157
Belief
Our brains can distill complex information, taking
unexplainable observations and evaluating and
categorizing them. From this, we form propositions—
true or not—that guide us in life.
Ventromedial
prefrontal cortex
activated in belief
Insula registers
disbelief