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Response of the brain to enrichment


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Before 1960, the brain was considered by scientists to be immutable, subject only to genetic control. In the early sixties, however, investigators were seriously speculating that environmental influences might be capable of altering brain structure. By 1964, two research laboratories proved that the morphology and chemistry or physiology of the brain could be experientially altered (Bennett et al. 1964, Hubel and Wiesel 1965). Since then, the capacity of the brain to respond to environmental input, specifically "enrichment," has become an accepted fact among neuroscientists, educators and others. In fact, the demonstration that environmental enrichment can modify structural components of the rat brain at any age altered prevailing presumptions about the brain's plasticity (Diamond et al. 1964, Diamond 1988). The cerebral cortex, the area associated with higher cognitive processing, is more receptive than other parts of the brain to environmental enrichment. The message is clear: Although the brain possesses a relatively constant macro structural organization, the ever-changing cerebral cortex, with its complex microarchitecture of unknown potential, is powerfully shaped by experiences before birth, during youth and, in fact, throughout life. It is essential to note that enrichment effects on the brain have consequences on behavior. Parents, educators, policy makers, and individuals can all benefit from such knowledge.
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Response of the Brain to Enrichment
Department of Integrative Biology, 3060 Valley Life Sciences Building
University of California, Berkeley, CA94720, USA
Manuscript received on March 5, 2001; accepted for publication on March 12, 2001;
presented by Leny A. Cavalcante
Before 1960, the brain was considered by scientists to be immutable, subject only to genetic control. In
the early sixties, however, investigators were seriously speculating that environmental influences might be
capable of altering brain structure. By 1964, two research laboratories proved that the morphology and
chemistry or physiology of the brain could be experientially altered (Bennett et al. 1964, Hubel and Wiesel
1965). Since then, the capacity of the brain to respond to environmental input, specifically “enrichment,
has become an accepted fact among neuroscientists, educators and others. In fact, the demonstration that
environmental enrichment can modify structural components of the rat brain at any age altered prevailing
presumptions about the brain’s plasticity (Diamond et al. 1964, Diamond 1988).
The cerebral cortex, the area associated with higher cognitive processing, is more receptive than other parts
of the brain to environmental enrichment. The message is clear: Although the brain possesses a relatively
constant macrostructural organization, the ever-changing cerebral cortex, with its complex microarchitecture
of unknown potential, ispowerfully shaped by experiences before birth, during youth and, in fact, throughout
life. It is essential to note that enrichment effects on the brain have consequences on behavior. Parents,
educators, policy makers, and individuals can all benefit from such knowledge.
Key words: enrichment, cerebral cortex, hippocampus, aging, adult neurogenesis, dendrites.
Can experience produce measurable changes in the
brain? The hypothesis that changes occur in brain
morphology as a result of experience is an old one.
In 1815 Spurzheim asked whether organ size could
be increased by exercise. He reported that the brain
as well as muscles could increase with exercise “be-
causetheblood is carriedingreaterabundancetothe
parts which are excited and nutrition is performed
by the blood.” In 1874 Charles Darwin mentioned
that the brains of domestic rabbits were consider-
Invited paper
E-mail: diamond@socrates.Berkeley.EDU
ably reduced in bulk in comparison with those from
the wild because, as he concluded, these animals
did not exert their intellect, instincts, and senses as
much as did animals in the wild. However, it was
not until the 1960s, that the first controlled studies
in animals demonstrated that enriching the environ-
mental condition in which they were confined could
alter both the chemistry and anatomy of the cerebral
cortex and, in turn, improve the animals’ memory
and learning ability.
In these early experiments only the brains of
young animals were studied. Although many were
impressed to learn that the cerebral cortex could in-
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An. Acad. Bras. Cienc.,(2001)73 (2)
crease its thickness in response to enriched living
conditions, they raised the question about whether
enrichment might similarly affect older animals.
Once middle-aged rats brains showed positive re-
sponses to enrichment, the next step was to experi-
ment with very old animals. Once again, increases
in corticalthickness were found. It then becameim-
portant to discover what was responsible for these
One step at a time, the level of morphologi-
cal changes from neuronal soma size, to num-
ber and length of dendrites, to types and numbers
of dendritic spines, to synaptic thickening, to capil-
lary diameter, and to glial types and numbers – was
examined. Age, gender, duration of exposure, etc.
were critical variables that had to be tested in new
Most of the basic data reported on the enrich-
ment paradigm and its impact on brain and behavior
have accumulated through studies on the rat. Ef-
fects of enriched and impoverished environments
on the nerve cells and their neurotransmitters in the
cerebral cortex have now been generalized to sev-
eral mammalianand avianspecies (Rosenzweigand
Bennett 1996). Some corroborating studies men-
tioned herein involved cats and monkeys, as well
as isolated studies in human subjects. For example,
Jacobs et al. (1993) using an isolated portion of the
human cerebral cortex responsible for word under-
standing, Wernicke’s area, compared the effects of
enrichment in tissue from deceased individuals who
had had a college education and from those who
had had only a high school education. They demon-
strated that the nerve cells in the college-educated
showedmore dendrites than those in the latter. (Tis-
suewasobtainedfromtheVeteran’sHospitalin west
Los Angeles.) Experiments on human tissue fre-
quently support the data obtained from studies in
the rat, and, in turn, benefit from these animal stud-
ies. We can now safely say that the basic concept of
brain changes in response to enrichment hold true
for a wide variety of animals and for humans.
What do we mean by “enrichment” for the rats who
haveserved asthe animalof choicefor mostof these
studies? Thirty six Long-Evansrats were sortedinto
three experimental conditions using 12 animals in
each group: 1) enriched 2) standard or 3) impov-
erished environments. All animals had free access
to food and water and similar lighting conditions.
Eventually, it was determined that animals main-
tained in their respective environments from the age
of 30 days to 60 days developed the most extensive
cerebral cortical changes. For the enriched environ-
ment, the 12 animals lived together in a large cage
(70× 70× 46 cm) and were provided 5-6 objects to
explore and climb upon (e.g., wheels, ladders, small
mazes). Theobjectswerechangedtwotothreetimes
a week to provide newness and challenge; the fre-
quent replacement of objects is an essential com-
ponent of the enriched condition. The combination
of “friends” and “toys” was established early on by
Krech as vital to qualify the experiential environ-
ment as “enriched.” (Krech et al. 1960). For the
standard environment, the animals were housed 3 to
a small cage (20× 20 × 32 cm) with no exploratory
objects. For the impoverished environment, one an-
imal remained alone in a small cage with no ex-
ploratory objects.
The numbers of animals placed in these sepa-
rate conditions were based on the manner in which
theroutinehousingwasestablishedin therat colony.
Three rats in a cage has been considered standard
for all experimental work over the decades. Since
priorto theseexperimentsnoone haddesignedstud-
ies to examine brain changes in response to differ-
ent environmental conditions, the decisions about
what represented “impoverishment” and what rep-
resented“enrichment”wasmorearbitrarily than sci-
entifically reasoned.
After 30 days in their respective environments,
all animalswere anesthetized beforethe brains were
removed for comparison among the three groups.
Twenty micrometer frozen sections were cut and
An. Acad. Bras. Cienc.,(2001)73 (2)
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stained, and the thickness of the frontal, parietal
and occipital cortices were measured. Results in-
dicated clearly that the cortex from the enriched
grouphad increasedinthickness compared withthat
living in standard conditions, whereas, the brains
from the impoverished group decreased compared
to thestandard. Because the nerve cellswere farther
apart in the enriched vs. the impoverished brains, it
was thought that the major component of the brain
changes due to enrichment had to do with alter-
ations in the dendritic branching. With more de-
tailed studies, the cortical thickness increases were
found to be due to several factors, including in-
creased nerve cell size, number and length of den-
drites, dendritic spines, and length of postsynaptic
tures of synapses. (Diamond et al. 1964 and 1988).
In the initial experiments designed to explore
the impact of an enriched environment on the brain
of post-weaned rats, only enriched and impover-
ished groups were used. Rats were maintained in
theirrespectiveenvironmentsfrom25 to105 daysof
in the cortex. Chemical and anatomical measure-
ments taken from these animals showed significant
differences between the two groups in cortical
thickness, cortical weight, acetylcholinesterase,
cholinesterase, protein and hexokinase levels, (Ben-
nett et al. 1964, Diamond et al. 1964). In these
initial experiments, however, it was not clear if the
changes were due to enrichment or impoverishment
because there were no standard conditions estab-
lished as controls.
Nonetheless, the differences in cortical thick-
ness with this 80-day exposure to the two environ-
mental conditions were not as great as during the
30-day exposure. Consequently, in subsequent ex-
periments, the period of exposure to the experimen-
tal conditions was reduced from 80 days to 30 days,
then 15 days, 7 days and finally to 4 days. At each
of these intervals, animals from the enriched envi-
ronment showed increases in cerebral cortical thick-
ness in some areas but not in others. For example,
in the male animals exposed for 80 days to enriched
conditions, the somatosensory cortex did not show
significant changes, whereas male animals exposed
for 30days did developsignificant differences inthe
somatosensory cortex. The occipital cortex showed
significant changes for both the 80- and the 30-day
experiments,but, again, the differenceswere greater
at 30 days than at 80 days. It is possible that the
inthe early days of enrichment butthat overtime the
environmental condition became monotonous and
this effect decreased. In later experiments the ex-
perimental conditions were modified to try to es-
tablish what the major factors were that created the
observed cortical changes. For example, wasthe ef-
fect associated with the number of rats exposed or
to the presence of stimulus objects?
The new conditions included one rat living
alone in the large enrichment cage with the objects
that were changed several times each week. The
cortex of these rats did not show a significant effect
of enrichment. Twelve rats living together in the
largecage without thestimulus objects did notshow
as great an effect as 12 rats living with the stimulus
objects. In other words, the combination of social
conditions and frequent exposure to new stimulus
objects were necessary for the animals to gain the
full effect of enrichment.
Establishing what constitutes “enrichment” for
human beings is more problematic. Not only are
controlled experiments not feasible, but no two hu-
man brains are identical. Individuals differ in their
geneticbackgroundsandenvironmentalinputs. Fur-
thermore, what is considered enrichment for one in-
dividual may be quite different for another. Yet, as
mentioned earlier, the enrichment effect was evi-
dent in Wernicke’s area from measurements of the
amount of dendritic branching in brain tissue from
college-educated individuals versus that from high
school-educated people. The basic finding of den-
dritic growth in response to environmental stimula-
tion appears in all brains studied to date. It would
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An. Acad. Bras. Cienc.,(2001) 73 (2)
appear that newness and challenge are important for
the human cortex as well as for that of animals.
Independent Variables: Age and Gender
Among the many variables researchers must con-
sider as they seek to understand and accurately in-
terpret the effects of enrichment on the brain, age
and gender are important considerations. Enrich-
ment has been shown to enhance many aspects of
cortical structure at any age from prenatal to ex-
tremely old rats (904 days of age). The amount of
change varies with the age of the animal. For ex-
ample, when a 30-day-old rat is put in an enriched
environment for fourdays, the effectsare notas pro-
in enriched conditions for four days. Is four days
too short a time for the very young animal to ad-
just and benefit from enrichment? A young animal
maintained for 30 days in an impoverished environ-
ment shows reduced morphological development of
its cortex when compared to that of an adult animal
maintained in impoverished conditions for 30 days.
In further age-related experiments, another compo-
nent was added to the enrichment conditions of old
rats. Despite significant increases in the length of
the dendrites in the brains of 600-day-old rats that
had been placed in an enriched environment for 30
days (600 to 630 days), several of the old rats in this
population died.
To determine whether the enrichment condi-
tions could be modified to extend the animals’ life
span, the investigators added a new component:
hand-holding the rats each day for several minutes
while the cages were cleaned. In an attempt to in-
crease the life spanof therats, rats wereplaced three
to a cage after weaning at 25 days of age, and main-
766 days,at which timehalf went into enriched con-
ditions until they reached 904 days of age and half
stayed in the standard conditions. The only variable
added was the daily hand-holding of the rats as they
aged. Is it possible that handling the rats had ex-
tended their life span? Indeed, many investigators
have been amazed that these rats survived to 904
days of age. The 904 day-old rats in enriched con-
ditions developed a cortex significantly thicker than
the cortex of rats living in the standard conditions
(Diamond 1988). These experiments offered sup-
port to the thesis that the cerebral cortex is capable
of respondingpositively toan enriched environment
at any age (See Fig. 1).
Experiments comparing the effects of enrich-
ment on male and female brains are few. Most en-
richmentstudieshavebeencarriedout on malebrain
estrous cycle. In one study focused on gender, the
female neocortex was found to respond differently
fromthe maleneocortexexposedtothe sametypeof
enrichment conditions (Diamond 1988). The male
showed significant changes in cortical thickness in
theoccipital cortex,butno significantchangesin the
somatosensory cortex. (Although the right cerebral
cortex in the brain of the male rat is thicker than the
left, especially in the visual or occipital region, an
enriched environment appears to alter both the right
and left cortex similarly.) In the female, the thick-
ness of the occipitalcortexincreased significantlyin
response to enrichment, although not as much as in
tex increased significantly more in the female than
in the male. In a follow-up experiment, however,
in which obstacles were piled up in front of the fe-
male food cup to provide a greater challenge to her
already enriched environment, the thickness of the
occipital cortex increased as much as did that of the
male without the additional challenge.
or at 30 days of age before the rats were placed in
an enriched environment for 30 days, the increases
observed in cortical thickness were similar to those
of their littermates with intact testes. (Diamond
1988) These findings suggested that testosterone is
not implicated in the increases in cortical thickness
observedin thebrains of rats livingin enrichedenvi-
ronments. Since sex differences were evident in the
responses of the animals to enrichment, interest was
An. Acad. Bras. Cienc.,(2001)73 (2)
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Fig. 1 Two possible patterns of age-related alterations in cortical pyramidal
cells. The normal mature neuron (A) may show regressive dendritic changes
characterized by loss of basilar dendritic branches and eventual loss of the entire
dendritic tree (D, E, F). Other neurons (B, C) may show progressive increase in
dendritic branching. Drawing based on Golgi impregnations.
nowfocused on the brains of pregnant rats, in which
the concentrations of sex steroid hormonal concen-
trations are greatly altered. The brains of female
rats living in the enriched environment from 60 to
90 days and then becoming pregnant and returning
to enrichment until 116 days of age were compared
betweennonpregnantand pregnantanimals livingin
ods. Whenanimalsfromthe twogroupswere autop-
thickness were found. Evidently, pregnancy has an
effect on the cerebral cortex regardless of whether
the environment is impoverished or enriched.
These initial experiments, all of which were
replicated, clearly indicate gender differences in the
brain’s response to enrichment. Having dealt with
the independent variables, we turn to the impact
of dependent variables in the enrichment paradigm.
For these studies, one must look at: duration of ex-
posure, brain anatomy and chemistry, presence of
lesions or fetal neocortical grafts, negative air ions,
stress, physical activity and nutrition, as well as be-
havioral effects. These are discussed in turn below.
Duration: The duration of exposureto the enriched
environment is clearly a significant dependent vari-
able that must be factored into research in this area.
As short a period as 40 minutes of enrichment has
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An. Acad. Bras. Cienc.,(2001) 73 (2)
been found to produce significant changes in RNA
andin thewet weightof cerebral corticaltissue sam-
pled. One day of enrichment was insufficient to
produce measurable changes in cortical thickness,
whereas four consecutive days of exposure (from
60 to 64 days of age) to an enriched environment
did produce significant increases in cortical thick-
ness, but only in the visual association cortex (area
18) (Diamond 1988).
Whenyoung adult ratswereexposedto 30days
of enrichment, however, the entire dorsal cortex, in-
cluding frontal, parietal and occipital cortices, in-
creased in thickness. Extending the duration of the
stay in enriched conditions to 80 days did not pro-
duce any greater increase in cortical thickness than
that seen at 30 days (in fact, it was often even less);
however, the longer the rat remained in the enriched
conditions, the longer the cortex retained its in-
creased dimensions following return to the standard
environment (Bennettetal. 1974). Whenwe looked
at age-related differences in the context of duration
of stay in the enriched environment, we found that
old rats ( 766 days of age) placed in enriched con-
ditions for 138 days showed an increase in cortical
thickness that was quite similar to that observed in
young adult rats (60 days of age) that had lived in
enriched conditions for 30 days.
Anatomical and chemical components: Early ex-
periments, and those to follow in subsequent years,
again demonstrated significant differences in brain
ing conditions. Anatomical increases include all
of the structural constituents measured in the cere-
bral cortex to date, such as cortical thickness (Di-
amond et al. 1964), nerve cell soma size, nerve
cell nuclear size (Diamond 1988), dendritic dimen-
sions(Holloway1966, Greenoughet al. 1973), den-
dritic spines, synaptic size and number (Mollgaard
et al. 1971, Black et al. 1990), number of glia, cap-
illary diameter (Diamond 1988), dendritic number
after lesions (McKenzie et al. 1990), and success-
ful tissue grafts, (Mattsson et al. 1997). Chemi-
cal increases include: total protein, RNA-to-DNA
ratio, cholinesterase-to-acetylcholine ratio, Nerve
Growth Factor mRNA, cyclic AMP, choline acetyl-
transferase, cortical polyamines, NMDA (N Methyl
D Aspartate) receptors, and hexokinase, etc.
Lesions: Another variable has to do with the im-
pactofenrichedconditionson purposefully incurred
brain lesions. In a 1990 study, 60-day-old rodents
were exposed for 30 days to either an enriched or
a lesion inthe left frontal cortexthat created a motor
dysfunction in the right forepaw. Animals living in
the enriched condition showed significant increases
in cortical dendritic branching in both hemispheres,
the lesioned and the non-lesioned sides, along with
a significant return of motor function in the right
forepaw compared to those animals living in stan-
dard conditions (McKenzie et al. 1990).
Fetalneocorticalgraft: Similarly, providinganen-
riched environment to rats that had undergone fe-
tal neocortical grafts one week after lesioning was
found to improve behaviorally and to reduce the at-
rophy in the thalamus, a major structure beneath the
son et al. 1997). The fact that the fetal neocortical
graft when placed in the lesioned cerebral cortex
could prevent atrophy in the underlying thalamus
as a consequence of enrichment is of great interest
to researchers considering the future possibility of
using such grafts for brain-damaged individuals.
Air ions: The possibility that physical environmen-
tal stimuli other than those classically regarded as
“sensory” could have an effect on the brain was
tested experimentally by exposing rats living in en-
riched or standard environments to high concentra-
tions of negative air ions. The experiments were un-
dertaken to determine whether the effect of negative
ions on serotonin, the putative second messenger
cyclic-AMP, and on cyclic GMP in the cerebral cor-
tex, differ depending on whether the animals lived
in enriched or standard conditions. Studies demon-
strated that rats placed in the enriched environment
An. Acad. Bras. Cienc.,(2001)73 (2)
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in the presence of enhanced negative air ions (ion
density of 1× 10
) showed a significant decrease in
serotonin, an effect not found in the brains of ani-
mals living in standard conditions (Diamond et al.
1980). Measurements of cyclic AMP decreased as
well in the brains of the animals living in the en-
riched conditions, but cyclic GMP did not. These
results indicate the importance of considering air
quality and atmospheric conditions in determining
the brain’s response to enrichment.
Stress: The presence or absenceof stress represents
yet another variable to be taken into consideration
in such studies, certainly so in any extrapolation of
these findings to humans. Stress is a major factor in
contemporary, fast-moving urban life. Crowding,
for example, is deemed stressful under conditions
where competition for space or food is likely. Ex-
periments were set up to assess the effect of crowd-
ing on the brains of rats maintained in an enriched
environment. To create a condition in which crowd-
ing would be experienced as stressful, 36 rats were
placed in an enrichment cage usually housing only
12 rats, and kept there for 30 days. The results indi-
catedthat, comparedwithratslivinginstandardcon-
ditions, the thickness of the medial occipital cortex
increased significantly whether the enrichment cage
housed 12 or 36 animals, (Diamond et al. 1987).
One hypothesis to come from this study was that the
animals’ interaction with the toys might be divert-
ing their attention or entertaining them sufficiently
to mitigate the stress of the crowded condition.
Chronic stress has been reported by Meaney
et al. (1988) to produce excess glucocorticoids,
which are toxic to neurons – especially those of the
hippocampus. Aged rats are particularly vulnera-
ble to chronic stress. The investigations of Meaney
showed that enriching the living conditions of old
rats, or handling them in their infancy, helps to pre-
vent stress-related hippocampal damage.
It is possible that stress can be produced by
increasing the frequency with which the various ob-
jects in the enrichment cage are changed. In all pre-
vious studies, objects had been replaced daily or at
leastseveraltimeseachweek. Thenthequestionwas
asked whether increasing the frequency of chang-
ing the objects would further increase the growth
of the cortical thickness, or, alternatively, would it
be experienced as a stress factor, given that the an-
imals were inhibited from interacting with them in
themoreleisurely manner towhichtheywereaccus-
tomed. For these experiments, rats 60 to 90 days of
age found their objects changedeveryhour for three
hours on four nights of each week for four consec-
utive weeks. Under this regime, the cerebral cor-
tical thickness did not grow significantly compared
to cortices from rats whose objects were changed
several times each week for four weeks (Diamond,
Corticosteroids, released under stress, have
been shown to reduce cortical thickness and future
experiments would be necessary to compare differ-
ences in corticosteroid levels in animals exposed to
these differing conditions.
Behavior: Psychologists have known for a long
time that early experience influences the adult per-
formance of an animal. In experiments in the 1950s
(Bingham and Griffiths 1952 and Forgays and For-
gays 1952) investigators were interested in de-
termining how much experience in complex envi-
ronments was necessary to produce a highly intel-
ligent adult animal and when, specifically, during
early life these experiences had to occur. These
studies showed that all of the animals maintained
in enriched conditions were better problem solvers
than those with no enrichment; however, in some
other occasions, using other tests, enriched rats did
not perform significantly better than controls.
One of the most robust effects of environmen-
tal enrichment on the behavior of rats appears in the
areas of learning and memory. Investigators (York
et al. 1989 and Kempermann et al 1997) study-
ing the effects of enrichment in the rat brain have
reported that new nerve cells develop in the adult
dentate gyrus, an area dealing with recent memory
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An. Acad. Bras. Cienc.,(2001) 73 (2)
processing. IntheYorkexperimentsthe ratswere 60
to 90days of age(truly adult animals) during the en-
richment experience, whereas in the Kempermann
experiments the mice were 21 to 40 days of age.
These finding are significant because neurogenesis
had not previously been found in the cerebral cortex
of the mammalian adult. Earlier studies had found
that enriched environments stimulate the growth of
dendrites in the dentate gyrus, and only in female
rats. (Juraska et al. 1985).
PhysicalActivity: Onecomponent ofenrichmentis
the physical exercise involved in the animals’ hav-
ing to move about the cage, interacting with and
climbing upon the novel objects. These activities
appear to influence the motor cortex as well as the
hippocampus. Olsson et al. (1994) showed that
rats living in enriched environments at 50 days of
age showed higher expression of the gene-encoding
glucocorticoid receptors and induction of genes for
Nerve Growth Factors in the hippocampus.
Nutrition: Nutritionisclearlyanimportantvariable
to consider in all studies dealing with brain and be-
havior. Environmental enrichment and impoverish-
ment have pronounced effects on nutritionally defi-
cientanimals. Onestudycomparedtheeffectsofen-
vironmental enrichment on the offspring of mother
rats living on protein-rich or protein-deficient di-
ets during pregnancy (Carughi et al. 1990). The
rats and even more so when combined with an en-
riched environment.
The cerebral cortical dendrites in rat pups from
mothers with a protein-deficient diet were signifi-
cantly less well developed than those of their coun-
terparts, but, of greater importance, the cortex from
crease with enrichment. On the other hand, when
protein-deficient pups were fed a protein-rich diet
and maintained in an enriched environment during
their early postnatal life, cortical development im-
proved almost to the level seen in rat pups from
mothersona high-proteindietduringpregnancyfol-
lowed by postnatal enrichment. These data are very
encouraging, because they suggest the possibility of
making up for lost brain growth during pregnancy
by enriching both the diet and the environmental
conditions during the postnatal period.
Another dietary factor significant to optimal
brain function is glucose. The brain depends almost
exclusively on glucose for its energy. Synapses use
a great deal of energy and glucose supplies this en-
ergy. Although we know that different parts of the
brain useglucose at different rates, to learn which of
30 discrete brain regions were most active in adult
rats placed in enriched living conditions from 57 to
87 days of age, we studied their radioactive glucose
uptake during this 30-day period and compared it
with that of rats raised in standard conditions (Dia-
mond 1988). Again, the cerebral cortex showed the
greatest differences between enriched and nonen-
riched groups, but, surprisingly, of the two groups,
glucose uptake was lower in rats maintained in en-
riched conditions. We concluded from this finding
that glucose uptake is more efficient in the brain of
animals living in enriched environments. Out of the
30 areasof thebrain measured, including thecortex,
only one area showed significantly greater glucose
uptakeintheenrichedanimals: thecorpuscallosum,
specifically, the large mass of axons connecting the
nerve cells between the two cerebral hemispheres.
Could the axons forming the corpus callosum from
the nerve cells in the cerebral cortex be more active
than the nerve cell bodies from which they arise?
Yet the right and left cerebral cortices show compa-
rable cortical thickness increases with enrichment
due to the effects on dendritic branching, but now
the data show that the rates of glucose utilization in
in the enriched rats than in the standard control rats,
a paradox to be untangled in the future.
Methodological issues associated with enrich-
ment research in humans: Of the vast number of
animal studies that yield results of interest to human
An. Acad. Bras. Cienc.,(2001) 73 (2)
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research, studies on the impact of an enriched envi-
ronment on brain development and behavior can be
ofenormousinteresttohumans. Despitesimilarities
insome key respects betweenthe brainof therat and
other mammals, replicating or extrapolating from
anatomical and chemical studies conducted in ani-
mals is fraught with difficulty, for obvious reasons.
Not only is it not presently possible to control all of
the experimental variables at work in humans, but
the diversity and complexity of human experience
militates against designing experiences comparable
to those used with lower animals.
Nevertheless, these studies and what few hu-
man studies have been done, suggest that there are
measurable benefits to enriching an individual’s en-
vironment in whatever terms that individual per-
ceives his immediate environment as enriched. At
theveryleast, thisworkindicatesthattherearemany
opportunities for enhancing brain activity and be-
havioratall ages, and thattheycanhavepronounced
effects throughout the life span.
Antes de 1960, os cientistas consideravam o encé-
falo como imutável, sujeito apenas ao controle genético.
Entretanto, no início dos anos 60, alguns pesquisadores
especulavam seriamente que influências ambientais po-
diam ser capazes de alterar a estrutura cerebral. Por volta
de 1964, dois laboratórios de pesquisa demonstraram que
a morfologia e a química ou a fisiologia do cérebro pode-
ria ser modificada pela experiência (Bennett et al. 1964,
Hubel e Wiesel 1965). Desde então, a capacidade do
cérebro a responderpara responder ainsumos ambientais,
especificamente ao “enriquecimento”, tornou-se um fato
aceito por neurocientistas, educadores e outros. De fato,
a demonstração de que o enriquecimento ambiente pode
modificar componentes estruturais do cérebro de rato, em
qualquer idade, alterou suposições prevalentes a respeito
da plasticidade cerebral (Diamond et al. 1964, Diamond
O córtex cerebral, a área associada com o processamento
cognitivo superior, é mais receptivo do que outras partes
do encéfalo ao enriquecimento ambiental. A mensagem é
clara: embora o encéfalo possua uma organização macro-
estrutural relativamente constante, o sempre-mutável cór-
tex cerebral, com sua microarquitetura complexa de po-
tencial desconhecido, é fortemente moldado pelas expe-
riências antes do nascimento, durante a juventude e, em
verdade, ao longo de toda a vida. É essencial que se note
que os efeitos do enriquecimento sobre o encéfalo têm
consequências no comportamento. Pais, educadores, ge-
radores de políticas e quaisquer indivíduos podem todos
se beneficiar de tal conhecimento.
Palavras-chave: enriquecimento, córtex cerebral, hipo-
campo, envelhecimento, neurogênese em adultos, den-
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AABC 73 2 b 2
... Based on other research, prof. Marian Cleeves Diamond (2001), the founder of modern neuroscience, has challenged previous knowledge about the brain, genetics, and the invariability of brain potential. She proved that the brain is not determined by genetics but is rather influenced by the environment. ...
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Subject competitions provide valuable support to the teaching / learning process. Particular attention should be paid to competitions recommended by pedagogical supervision bodies, which should be very popular, both among students and teachers. The aim of the article was to investigate trends in the participation in Polish competition miniLogia. The contest is organized for children from the Mazovian primary schools and is aimed at revealing and developing computing talents, and raising the level of informatics education. The quantitative research exploited data from the thirteen years, from school year 2006/2007 to 2018/2019. In particular, the results obtained by 850 students in the third level of each year of the competition were analysed. The results show the decreasing participation of students, especially from the towns outside Warsaw. There is also an increasing share of non-public school students among finalists. The proportion of girls who advance to the highest level of the competition is still significantly lower than the corresponding percentage of boys. Moreover, the results show male participants still score higher than girls. The findings indicate the need for change in Polish computing education on the primary level and suggest a direction for future research.
... Investigating the ecological conditions under which successful problem-solving occurs is critical because natural selection can only act on traits to the extent to which they are expressed in an animal's natural environment [47]. In addition, environments that favor a high rate of problemsolving success or a high proportion of problem-solvers in a given population, very likely exert strong cognitive demands on their inhabitants [48]. Environments that are cognitively demanding for extant species may share similarities with the environment of evolutionary adaptedness (EEA) and can thus shed light on conditions under which problem-solving evolved. ...
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Physical problem-solving paradigms are popular for testing a variety of cognitive abilities linked with intelligence including behavioral flexibility, innovation, and learning. Members of the mammalian order Carnivora are excellent candidates for studying problem-solving because they occupy a diverse array of socio-ecological niches, allowing researchers to test competing hypotheses on the evolution of intelligence. Recent developments in the design of problem-solving apparatuses have enhanced our ability to detect inter-specific and intra-specific variation in problem-solving success in captive and wild carnivores. These studies suggest there may be some links between variation in problem-solving success and variation in urbanization, diet, and sociality.
... Istovremeno, Erik Bern, tvorac transakcione analize naglašava da je socijalno stimulisanje razvojna potreba svakog djeteta (Jovanović Magyar 2008). Uporedo sa ovim nalazima, neurolog Marien Diamond otkriva mogućnosti poboljšanja mozga mladunaca kroz evolutivno-podržavajuće aktivnosti (Diamond 2001 (2013), jer ukazuju da je novac uložen u predškolsko vaspitanje djece najbolje investirani kapital svake države. Djeca se optimalno razvijaju i kao izgrađeni pojedinci svojim radom više doprinose boljitku društva i ostvarenju državnog kapitala. ...
... Exercise/training directly benefits the brain through the promotion of learning and memory, protection from neurodegeneration, and alleviation of depression, particularly in elderly populations (Cotman et al. 2007). It was established that the enrichment of cages with objects for playing and curiosity caused an increase in rat brain cortex size and performance (Rosenzweig et al. 1962;Bennett et al. 1964;Diamond 2001), and enhanced neurogenesis was also observed for the dentate gyrus (Kempermann et al. 1997). When van Praag et al. (1999) analyzed the individual elements of the enriched cage environment, they found that the running wheel sufficed to explain the neurogenesis effect in the dentate gyrus. ...
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Psychotherapies aim to relieve patients from mental distress by guiding them toward healthier attitudes and behaviors. Psychotherapies can differ substantially in concepts and approaches. In this review article, we compare the methods and science of three established psychotherapies: Morita Therapy (MT), which is a 100-year-old method established in Japan; Cognitive Behavioral Therapy (CBT), which—worldwide—has become the major psychotherapy; and Acceptance and Commitment Therapy (ACT), which is a relatively young psychotherapy that shares some characteristics with MT. The neuroscience of psychotherapy as a system is only beginning to be understood, but relatively solid scientific information is available about some of its important aspects such as learning, physical health, and social interactions. On average, psychotherapies work best if combined with pharmacotherapies. This synergy may rely on the drugs helping to “kickstart” the use of neural pathways (behaviors) to which a patient otherwise has poor access. Improved behavior, guided by psychotherapy, can then consolidate these pathways by their continued usage throughout a patient’s life.
... EE is well utilized experimentally to substantially mitigate conditions like depression and anxiety [154,155]. EE has shown to improve the rate of synaptogenesis and complex dendritic arbors formation [156]. Huntington's disease (HD) mice exposed to EE showed the absence of dendritic spine pathology [157]. ...
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Dendritic spines are small, thin, hair-like protrusions found on the dendritic processes of neurons. They serve as independent compartments providing large amplitudes of Ca2+ signals to achieve synaptic plasticity, provide sites for newer synapses, facilitate learning and memory. One of the common and severe complication of neurodegenerative disease is cognitive impairment, which is said to be closely associated with spine pathologies viz., decreased in spine density, spine length, spine volume, spine size etc. Many treatments targeting neurological diseases have shown to improve the spine structure and distribution. However, concise data on the various modulators of dendritic spines are imperative and a need of the hour. Hence, in this review we made an attempt to consolidate the effects of various pharmacological (cholinergic, glutamatergic, GABAergic, serotonergic, adrenergic, and dopaminergic agents) and non-pharmacological modulators (dietary interventions, enriched environment, yoga and meditation) on dendritic spines structure and functions. These data suggest that both the pharmacological and non-pharmacological modulators produced significant improvement in dendritic spine structure and functions and in turn reversing the pathologies underlying neurodegeneration. Intriguingly, the non-pharmacological approaches have shown to improve intellectual performances both in preclinical and clinical platforms, but still more technology-based evidence needs to be studied. Thus, we conclude that a combination of pharmacological and non-pharmacological intervention may restore cognitive performance synergistically via improving dendritic spine number and functions in various neurological disorders.
... Böylece çocuk bilgi, beceri öğrenmenin yanı sıra bir materyalle vakit geçirmek için sırasını beklemekte ve günlük yaşamdaki gibi başkalarının işine saygı duymayı öğrenmektedir(Temel, 1994). büyüdüğü, bu ortamlarda gerçekleşen öğrenmenin beyin ağırlığındaki artışla, beyin dokusundaki dendritik dallanmanın artmasıyla, nörotransmitter düzeylerinin yükselmesiyle ve beynin başka fiziksel değişimleriyle ilgili olduğu ve beyin üzerindeki bu etkilerin davranışları değiştirdiği belirtilmiştir(Diamond, 2001; Jensen, 2006, s. 31)."Bilindiği gibi üç ila altı yaş arasındaki yaşam döneminin en belirgin özelliği, hızlı fiziksel büyüme ve psişik yeteneklerin gelişmesidir. Bu yıllarda çocuğun duyuları gelişir ve bu nedenle de dikkati çevresine yönelmiştir. ...
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Purpose Having critical importance in the development of children in the early years in the Montessori philosophy; features such as sensitive periods, absorbing mind, sensory training, prepared environment, spontaneous learning with repetitions, language-brain, a movement-brain relationship is emphasized. Since these features explain the development and learning of the child, they are also emphasized in terms of neuroscience. In the period when detailed discoveries regarding these issues have not yet been made in neuroscience, Montessori designed and implemented an educational method based on these features. (Catherine, Javier ve Francisco, 2020; Fabri ve Fotuna, 2020; Sackett, 2016). Therefore, it is thought that the Montessori method will have strong connections in terms of the Brain. In this direction, the study aimed to explain the basic features of the Montessori education method with a neuroscientific perspective, based on the question "Which features of the Montessori Method are supported by discoveries about the brain and learning made in the field of neuroscience", and to reveal an interdisciplinary perspective by examining the studies that associate Montessori and neuroscience. Method This research was planned as a compilation, and it was attempted to clarify the subject by accessing and analyzing the sources including Montessori and neuroscience relationship. Document analysis technique was used in accessing and analyzing the research. Document analysis is the analysis of information written materials about the topic or facts to be investigated (Yıldırım ve Şimşek, 2016, s.189). The literature review was carried out in two stages. In the first stage, the sources directly associated with the Montessori method and neuroscience were scanned and the associated basic features were determined. In the second screening study, studies in both disciplines were examined according to the characteristics determined. Findings As a result of the first screening study, three studies conducted in 2020, in which neuroscientific studies were examined with the Montessori Method, were reached. These studies were analyzed according to the topics related to the Montessori method and neuroscientific studies. As a result of the analysis, it was seen that the basic features of "Sensitive Periods", "Structured Environment", "Sensory Education", " Spontaneous Learning with Repetitions ", "Language- Brain" and "Movement-Brain" in the Montessori method were examined and discussed within the scope of neuroscientific research. In the second screening study, after determining the features of Montessori education addressed in neuroscientific research, a total of 37 resources, 26 articles, and 11 books, published between 1994-2020, were examined in the literature review in line with these features. Result and Conclusion As a result of the research, it was seen that when the basic features related to the Montessori method and neuroscience were examined in line with the studies conducted in both fields, findings that support each other were reached. It has been observed that the research results in the neuroscientific field on sensitive periods (Gabard-Durnam ve McLaughlin, 2020; Greenough, Black & Wallace, 2002, s. 186; Hensch, 2005; Reh vd., 2020; Vries, Fields, Peters, Whylings & Paul, 2014; Viru vd., 1999), structured / enriched environment (Arechavala-Lopez vd., 2020; Diamond, 2001; Gabard-Durnam ve McLaughlin, 2020; Jensen, 2006; Lores-Arnaiz vd., 2007; Nithianantharajah ve Hannan, 2006; Vries, Fields, Peters, Whylings & Paul, 2014), sensory training (Casey, Tottenham, Liston & Durston, 2005; Gopalakrishnan, Karpagam, Selvaraj, 2020), spontaneous learning with repetitions (Barker vd., 2014; Greenough, 2002; Greenough, Black & Wallace, 2002; Olson & Hergenhahn, 2016; Tottenham, 2014), language development (Ergenç, 2008; Friederici, 2006; Friederici, Chomsky, Berwick, Moro & Bolhuis, 2017; Kuhl & Rivera-Gaxiola, 2008; Tomele ve Lidaka, 2017) and movement-brain relation (de Giorgio, Kuvacic, Milic & Padulo, 2018; Demir vd. 2016; Ericson, Gildengers & Butters, 2013; Jensen, 2006; Özdoğru, Kaya ve Yertutanol, 2018) support Montessori's thoughts and discoveries. Considering all these dimensions, this model is suitable for understanding processes. Because based on these features are Montessori's medical history, researches, observations, and practices (Catherine, Javier ve Francisco, 2020; Fabri ve Fortuna, 2020). This situation explains the reason why the effect of the approach continues today.
... It is known that housing conditions, or environmental complexity, can affect the morphology, neurochemistry, and physiology of the central nervous system [Rosenzweig and Bennett, 1996;Diamond, 2001;Mohammed et al., 2002;Rosenzweig, 2003]. Several studies have shown an influence of housing systems on spatial-learning ability behaviors and levels of working memory in laying hens [Krause et al., 2008;Campbell et al., 2018Campbell et al., , 2019Dudde et al., 2018]. ...
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The avian class is characterized by particularly strong variability in their domesticated species. With more than 250 breeds and highly efficient commercial lines, domestic chickens represent the outcome of a really long period of artificial selection. One characteristic of domestication is the alterations in brain size and brain composition. The influence of domestication on brain morphology has been reviewed in the past, but mostly with a focus on mammals. Studies on avian species have seldom been taken into account. In this review, we would like to give an overview about the changes and variations in (brain) morphology and behavior in the domestic chicken, taking into consideration the constraints of evolutionary theory and the sense or nonsense of excessive artificial selection.
... Sensors are designed to generate data, and the data is used to examine and find solutions to problems in our surroundings. Using sensor technology, students can become more creative and develop their social, linguistic, cognitive, visual, and emotional skills [10], [11], [12]. ...
... Environmental enrichment paradigms typically have two main components: novel objects and novel social partners. Environmental enrichment in both juvenile and adult animals has been shown to lead to increased cortical thickness 110,111 , driven by increases in dendritic volume and branching 112,113 , dendritic spine count 112,114 , synaptogenesis and glial proliferation 115,116 (reviewed in reF. 117 ). ...
Childhood socio-economic status (SES), a measure of the availability of material and social resources, is one of the strongest predictors of lifelong well-being. Here we review evidence that experiences associated with childhood SES affect not only the outcome but also the pace of brain development. We argue that higher childhood SES is associated with protracted structural brain development and a prolonged trajectory of functional network segregation, ultimately leading to more efficient cortical networks in adulthood. We hypothesize that greater exposure to chronic stress accelerates brain maturation, whereas greater access to novel positive experiences decelerates maturation. We discuss the impact of variation in the pace of brain development on plasticity and learning. We provide a generative theoretical framework to catalyse future basic science and translational research on environmental influences on brain development.
This descriptive overview responds to a rising tide of reviews and RCTs which encourage evidence-based interventions from the first moments of life and across the life course that could increase the Flynn effect and improve global statistics on neurocognitive functioning with a healthspan that approximates longer lifespans. We need to learn more from our centenarians who achieve Healthy Ageing. Evolving neuroscience empowers us to drive neuroplasticity in a positive direction in ways that are associated with enhancing neurocognitive functioning across the entire lifespan for vigorous longevity. Music and Dance could meet these urgent needs in ways that also have physical, emotional, neurobiological, neurochemical, immunological, and social health benefits. Interventions using Music and Dance are likely to have high initial and ongoing use because people are more inclined to do what is fun, easy, free (or low cost), portable, and culturally adaptable.
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The role of the cerebellar cortex in motor learning was investigated by comparing the paramedian lobule of adult rats given difficult acrobatic training to that of rats that had been given extensive physical exercise or had been inactive. The paramedian lobule is activated during limb movements used in both acrobatic training and physical exercise. Acrobatic animals had greater numbers of synapses per Purkinje cell than animals from the exercise or inactive groups. No significant difference in synapse number or size between the exercised and inactive groups was found. This indicates that motor learning required of the acrobatic animals, and not repetitive use of synapses during physical exercise, generates new synapses in cerebellar cortex. In contrast, exercise animals had a greater density of blood vessels in the molecular layer than did either the acrobatic or inactive animals, suggesting that increased synaptic activity elicited compensatory angiogenesis.
Changes in brain through experience, demanded by learning theories, are found in experiments with rats.
To test the persistence of cerebral effects induced by differential experience, littermate rats were placed in an enriched environment (EC) or an impoverished environment (IC) for either 30 or 80 days. Following this initial period, one rat of each litter was transferred from the EC to IC condition while its littermates remained in EC or IC. The second phase lasted either 7, 14, 21, 32 or 47 days. The cerebral differences induced by differential experience began to dissipate when the animals were placed in a common environment, but statistically significant differences still persisted weeks after the end of the inducing conditions. Greater persistence was found after 80 days of initial exposure than after 30 days. Following 80 days in EC, significant persistence of brain weight differences was found 21 days after removal from EC to IC; significant persistence of differences in acetylcholinesterase and cholinesterase activities were found 47 days later. Different brain regions and different measures showed somewhat different patterns of results. Three different kinds of environmental enrichment — devised in three laboratories — were compared for their effects on brain weights and brain enzymes.
In rats, an environmental manipulation occurring early in life resulted in changes in the adrenocortical axis that persisted throughout the entire life of the animals and attenuated certain deficits associated with aging. Rats handled during infancy had a permanent increase in concentrations of receptors for glucocorticoids in the hippocampus, a critical region in the negative-feedback inhibition of adrenocortical activity. Increased receptor concentrations led to greater hippocampal sensitivity to glucocorticoids and enhanced negative-feedback efficacy in the handled rats. Thus, at all ages tested, rats that were not handled secreted more glucocorticoids in response to stress than did handled rats. At later ages, nonhandled rats also showed elevated basal glucocorticoid levels, with the result that there was a greater cumulative exposure to glucocorticoids in nonhandled rats. Increased exposure to adrenal glucocorticoids can accelerate hippocampal neuron loss and cognitive impairments in aging. Hippocampal cell loss and pronounced spatial memory deficits emerged with age in the nonhandled rats, but were almost absent in the handled rats. Previous work showed that glucocorticoid hypersecretion, hippocampal neuron death, and cognitive impairments form a complex degenerative cascade of aging in the rat. The present study shows that a subtle manipulation early in life can retard the emergence of this cascade.
This experiment studied cerebral cortical morphology in rats living in a crowded-enriched condition. Three groups of 60-day-old, male Long-Evans rats were divided accordingly: 12 rats, 3 per small cage (32 X 20 X 20 cm), standard colony condition; 12 rats in a single, large, enrichment cage with "toys" (70 X 70 X 45 cm), enriched condition; and 36 rats in a large, single, enrichment cage with "toys", crowded-enriched condition. Matched toys for the two enriched cages were changed twice a week at the time of cage cleaning. Measurements on 20-micron, transverse brain sections showed that in both the crowded-enriched and enriched groups the thickness of the medial occipital cortex increased by 4 to 6% compared with the cortex from animals in the standard colony condition. In addition, the crowded-enriched group demonstrated a 4% (P less than 0.05) increase in thickness in area 39 in the left hemisphere compared with the standard control. However, the thickness in area 39 in the crowded group was not significantly different from that of the enriched area 39. These results indicate that the cortex increases in thickness as much with "crowding" and enrichment as with enrichment alone. We hypothesize that diversion through interaction with "toys" mitigates the stress of crowded conditions.
Male and female hooded rats were raised from weaning in either a complex or an isolated environment in two separate replications. After one month, the brains were Golgi-Cox stained and dendritic fields of dentate gyrus granule cells were quantified. There was a sex difference in response to the environment. Females raised in the complex environment had more dendrite per neuron than females from the isolated environment in both replications. This difference was evident chiefly in the length of dendritic branches. Males showed few differences in response to the environments in either replication and, to the extent that there were differences, there was a slight tendency for isolated males to have more dendrite per neuron than males from the complex environment. In comparisons between the sexes within an environment, males had more dendritic material per neuron than females in the isolated environment while females had a larger dendritic tree than males in the complex environment. The above pattern of differences was not altered when hemisphere or location of the cell body within the granule cell layer were taken into account, although the shape of the dendritic tree varied with the cell's position in the layer in all groups. Thus, females show greater structural change in the dentate granule cells in response to these environments than do males.
Dendritic branching was studied in Golgi-stained neurons from frontolateral and temporal cortex of rats reared for 30 days after weaning in complex, social, or isolated environments. In temporal cortex, layer-4 pyramidal neurons from rats reared in complex environments had significantly more basal dendritic branches than those from littermates reared socially or in isolation. Layer-5 pyramidal neurons showed similar rearing effects. In contrast, no significant differences due to rearing were detected in frontal cortex. In both regions, there was a high degree of concordance within litters. These results amplify those of previous studies and indicate that: the effects of environmental complexity on dendritic branching are not restricted to those previously seen in visual cortex; the effects are not seen in all cortical areas or neuronal populations as might be expected if they reflected a general hormonal or nutritional difference; and both the non-universality of the effects and the relative concordance within litters suggest that equivalent neuronal populations are stained in the different environmental groups.
Significant differences in size and number of synaptic junctions were found between littcrmate rats assigned at weaning (25 days of age) to enriched or impoverished environments and kept there for 30 days. The synapses measured were asymmetrical axodendritic junctions in the neuropil of layer III of the occipital cortex. Rats given experience in the enriched condition (EC) showed, in comparison to littermates in the impoverished condition (1C). synapses that averaged 52% greater in length but that were only 67% as numerous. The EC rats had more large synapses as well as fewer small synapses than did IC rats, so the EC size distribution could not have been derived simply by loss of small synapses from the IC distribution. The total area of synapses in the EC group, taking both size and number of contacts into account, was 40% greater than in IC. Thickness of cortex was 4.0% greater in EC than in IC, a value that compares closely with the 4.6% found in several previous 25-to-55 day EC-1C experiments. Problems of measurement and sampling in electron microscopy are considered. The results are discussed in relation to concepts of brain mechanisms of learning and memory storage, some aspects of which can now be studied directly.