Hormone:

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Hormone Chemical secreted into the blood by a
gland. Influences organs that contain the proper
receptor type.
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Pinel
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Pinel
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Gonadal Hormones Androgens Testosterone Di
hydrotestosterone Estrogens Estradiol Estron
e Progestins Progesterone
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Organizational Effects Occur early in life
(shortly before and after birth). Determine
whether the brain and body will develop as a
female or a male.
Activational Effects Can occur any time in
life (may last for hours or months). These
hormones temporarily activate a particular
response.
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Female is the default
Carlson
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Organizing effect
Carlson
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Congenital adrenal hyperplasia (masculinized
females) high levels of androgens produced by the
adrenals early in life due to an enzyme
deficiency DES (masculinized females) synthetic
estrogen given to maintain pregnancy Androgen
insensitivity syndrome (feminized
males) unresponsive testosterone
receptors Testes at 12 (feminized males that
turn male) Accidental circumcision
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Sex Differences in the Hypothalamus Testosterone
must be aromatized into estradiol to have
effects on hypothalamus SDN is larger in males
than females and is linked to male sexual
behavior Alpha-fetoprotein protects females from
seeing these changes in their hypothalamus due
to exposure to their own estrogen
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Rat brain, Roger Gorski
Male
Female
FemaleTestos
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Sex Differences in Brain and Behavior
Females have a larger CC - though this has not
been reliably replicated Female rats have a
smaller CC than male rats Females have a higher
density of cells in the temporal lobe Female
rats have no asymmetry in DG of the
hippocampus (T treat creates the
asymm) Females use their brains more
bilaterally they experience fewer language
deficits after a L hemisphere stroke
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Human Sex differences
Females superior at verbal fluency/recall, visual
memory

• Chicago Word Fluency
• write as many words as you can in 5 mins. that
  begin with the letter s

Complete the sentence M___ A____ R____
G____ P____ I____ M____ C____ G___ W____ S____
B____
Kolb And Whishaw (1990), Fund of Human
Neuropsych, 3rd Ed, p. 392 Eals Silverman
(1994), Ethology and Sociobiology 15 95-105.
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Sex Differences in Brain and Behavior
Males are more lateralized in their brain
use more susceptible to learning impairments and
language disorders Male rats have a larger R
DG of the hippocampus than L Male rats have a
larger DG dendritic field than females
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Human Sex differences
Males superior at visual-spatial tasks, rotation
Kolb And Whishaw (1990), Fund of Human
Neuropsych, 3rd Ed, p. 392
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Congenital adrenal hyperplasia Females show a
slight tendency to prefer male-typical toys, are
more tomboyish and have increased spatial
ability. Males are not affected much by this
disorder. Androgen insensitivity syndrome Males
show decreased visuospatial ability DES Females
show no difference in spatial ability when
compared to siblings. Males had worse spatial
ability (the high side of the T curve)
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Write down as many 5-letter words that begin with
the letter T that you can think of
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Sex differences in rodents with learning tasks
Task Male Female
Morris Water Maze Radial Arm
Maze Contextual Fear Conditioning
faster escape slower escape shorter
distance longer distance
fewer errors more errors fewer trials more
trials
more freezing less freezing to context to
context
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Morris Water Maze Distance to Platform (inches)
800
XX Female (41)
Mean XY
Mean XX
XY Female (38)
600
400
200
Mean
Mean
1
2
3
4
5
6
Days
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Astur et al. (1998). A characterization of
performance by men and women in a virtual Morris
water task a large and reliable sex difference.
Behavioural Brian Research, 93, 185-190.
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Morris Water Maze Distance to Platform (inches)
800
XX Female (41)
Mean XY
Mean XX
XY Female (38)
600
400
200
Mean
Mean
1
2
3
4
5
6
Days
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Male
Female
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Sandstrom et al. (1998). Males and females use
different distal cues in a virtual environment
navigation task. Cognitive Brain Research, 6,
351-360
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