Psy 137 Behavioral Endocrinology

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Psy 137 Behavioral Endocrinology Lecture 15
Sex Differences Cognition
Website http//mentor.lscf.ucsb.edu/course/summer
/psyc137/
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Types of Information Storage aka Learning/Memory
Info storage system(s) in the brain acquires,
stores (consolidation), and retrieves information
to organize future behavior. There are multiple
types of memory which seem to have somewhat
independent neural substrates.
(Learning)
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Conceptualized Storage of Information
Hormones?
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Stress Memory
Stress has complex interactions with memory. Two
well described phenomena have been widely
reported and studied clinically flashbulb
memories for stress-related information. -due
direct action of stress-response on memory
consolidation. Post-traumatic stress disorders
-poorly understood and appears to involve many
complex psychological processes, including
alterations learning/memory
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Stress Memory
Acute mild to moderate stress (i.e. not
traumatic) has a bi-modal influence of the
storage of information.

• These effects appear to be largely (if not
  entirely) explained by changes in the
  consolidation process under control of
  epinephrine.
• Gluccoorticoids generally appear to reduce
  retrieval processes.

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Sex Differences in Cognition

• Sex differences in brain structure and function
  have been widely examined with some effects being
  moderate and reliable and others inconsistently
  reported across studies.
• Bases of the differences appear to be due to
  organizational and activational effects of
  steroid hormones, as well as, social and
  environmental.
• Interpretation of the data is complex and highly
  political

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Sex Differences in Cognition
Are they innate? Primate infants have
preferences for toys similar to those observed in
human children. -males prefer vehicles and
mobile toys -females prefer dolls and bright
colored toys.
Access to these toys are environmental controlled
and may lead to changes in later expression of
sex differences
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Sex Differences in Cognition

• Primates also show similar play patterns as
  humans.
• males shown increased rough-and-tumble play,
  increased initiation of play, increased threat
  displays, increased simulated fighting.
• Produced perinatally by androgen stimulation.
• Similar play patterns are found in rodents.

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Sex Differences in Cognition

• Sex differences in behavior (including cognition
  reflects a combination of organizational and
  activational influences of steroid hormones.

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Sex Difference Cognition

• Sex difference have been recognized in a variety
  of behaviors and reflect combined organizational
  and activational effects of hormones on the
  nervous system.
• Organizing effects occur perinatally, puberty,
  and adult (e.g. chronic stress later)
• Effects can also reflect socialization/environment
  al impacts, particularly in humans.

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Sex differences in human brain

• Male brain gt female brain.
• These differences are corrected for overall size

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Sex Difference in Neurotransmitters

• There are sex differences in neurotransmitter
  levels between men and women
• 5HT lower in women
• DA higher in women
• Also regionalization of neuropeptides e.g.
  vasopressin.
• Differences in receptor expression are also
  reported and important for transmission.

Nishizawa and colleagues used positron emission
tomography (PET) to assess serotonin synthesis
rates in healthy men and women. a Images show
PET scans taken from a representative male and
female subject. Images are shown before and after
depletion of plasma tryptophan. The mean rate of
synthesis was found to be 52 higher in males
than in females. b Magnetic resonance images
for reference taken from the same level as the
PET images. The results may help to explain why
some disorders (such as unipolar depression) that
involve serotonin dysfunction do not equally
affect men and women.
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Sex Differences in Neurotransmitters
E2
oil

• DA in striatum is high in females which reflects
  E2 activational effects
• Also, behavioral differences after ovx are
  apparent (DA not measured) reflecting
  organizational effects. .

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Sex Differences in Sensory/Perceptual Processes

• Olfaction
• Women show far greater sensitivity,
  discrimination, and preferences for odors
  relative to men.
• For some odors, up to 1000 times more sensitive.
• Due to both organizational and activational
  effects.
• Androstadien-3-one (putative male pheromone) can
  elevate mood in women.
• Odors produced increased fMRI activation in women
  than in men.
• Disrupted androgen function disrupts olfactory
  bulb development.
• Similar differences have been demonstrated in
  other species.

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Sex Differences in Sensory/Perceptual Processes

• Taste
• Women show greater sensitivity, discrimination,
  and preferences for tastes relative to men.
• Due to largely activational effects
• Differences appear post-puberty
• Enhanced during pregnancy and follicular phase
  reduced postmenopause.
• In rats, perinatal androgen does not alter sweet
  preferences but adult E2 increases sweet
  preferences.

• Audition
• Women show greater sensitivity, discrimination,
  and preferences (auditory reinforcement of
  operants) for sound perception relative to men.
• Structural differences in auditory canal (evoked
  clicks).
• Due to largely organizational effects

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Sex Differences in Sensory/Perceptual Processes

• Vision
• Men show greater sensitivity and discrimination
  for visual stimuli relative to women.
• Due to largely organizational effects
• Present before puberty.
• In rats, perinatal androgen increases number of
  neurons in V1 of females.

Sex differences in sensory/perceptual effects may
impact cognitive function difficult to unravel
sensory from cognitive effects on memory,
spatial abilities, verbal function, etc.
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Tasks favoring women

• Women have increased verbal skills, perceptual
  skills, fine motor skills, math calculations.
• Most verbal differences present post-puberty
  reflecting activational differences also
  menstrual cycle and menopause effects.
• Some organizational effects (e.g. initial
  langauge acquisition).
• Effects tend to be moderate.

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Functional organizational sex differnces

• Lateralization is also more pronounced in males
  than in females in activation and lesion studies
  (i.e. effects of unilateral damage are greater in
  males).
• Planum temporale enlarged in women highly
  assymetric in men not women.

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Functional organizational sex differnces

• Verbal deficits typically produced in a regional
  specific sex-dependent pattern.
• Presumed to be organizational but not clear data.

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Tasks favoring men

• Typically small pre-puberty (suggests largely
  activational).
• Note early sex differences in math appear to be
  at extreme upper end recent studies suggest
  pre-puberty may be gone or reversed.

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Sex Differences in Cognition

• Damage to right hemisphere affects spatial
  abilities to a similar extent in men and women.
• Suggests that may be using same parts of the
  brain to solve task (very gross analyses).

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Sex Differences in Cognition

• Sex differences in cognitive function exhibit
  different relations to circulating steroid
  levels.
• Some appear to reflect activational effects of
  hormones
• These appear to follow Yerkes-Dobson law
• Others appear to reflect organizational effects
  of hormones (or social/environmental factors).

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Sex Difference in Cognition

• Spatial function in rodents reflects activational
  effects (similar to human).
• Effects are able to be produced by estrogens.
• Aromatase???
• Also, androgen specific effects reported in
  seasonal species (i.e. correlates with
  reproductive suppression).

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Sex Difference in Cognition

• Estrogens able to modulate dendritic fields (some
  species differences).
• Also, increases consolidation and working memory
  (but not reference memory).
• Appears to also have organizational components as
  perinatal androgen will increase female spatial
  memory.

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Sex Difference in Cognition
Emotional memory induced activation of amygdala
appears to exhibit opposite assymetries in males
(right amygdala) and females (left amygdala).
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Sex Difference in Cognition

• Assymetry does not apply to emotional arousal.
• Specific memory related function
• Activational or organizational effects are
  uninvestigated.

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Estrous versus Menustral Cycle
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Sex Difference in Cognition

• Cognitive strategy expressed by female rats is
  regulated by estrus cycle.
• Proestrus use place/spatial
• Estrus use response/habit
• Estrous effect can be blocked by DA antagonist.

a Korol and colleagues31 trained rats over
several trials to find food in a goal arm of a
T-maze. A probe trial with the maze orientation
reversed allowed the investigators to determine
whether each rat was using a 'place' strategy to
find the food (the rat goes to the place in the
room where the food should be) or a 'response'
strategy (the rat simply moves left or right at
the maze choice point). The key finding was that
whether the rats used a 'place' or 'response'
strategy depended heavily on the state of the
oestrus cycle. b Percentage of rats in
proestrus (P), oestrus (O) or dioestrus (D)
choosing a place or response strategy during the
probe trial. Interestingly, the magnitude of
these behavioural effects is similar to those
found in previous studies using this task and
intracranial infusions of drugs into relevant
brain regions, such as the hippocampus and
caudate nucleus94. Numbers on bars indicate the
number of rats tested in each condition. Crosses
indicate a significant difference between the
cycle stages, and asterisks indicate significant
difference within a stage. c The number of
trials needed in each group to reach criterion
performance before the probe test, indicating
that hormonal status did not affect learning
speed despite its pronounced effects on strategy.
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Sex Difference in Cognition

• Maternal brains
• Also, thickening of the cortex, increased
  hippocampal volume (similar to environmental
  enrichment).
• Reduced basolateral amygdala.
• Can be produced by mimicking estrogen levels seen
  in pregnancy.

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Sex Difference in Cognition

• Maternal rats have better spatial learning.
• Also, reduced anxiety, increased defensive
  behavior, increased predation.

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Sex Difference in Cognition

• Males and females show opposite effects to acute
  stress.
• Acute stress increases male dendritic trees but
  decrease those of females.
• Males also perform better on stress related
  learning (e.g. larger improvements in
  consolidation effects).

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Sex Difference in Cognition

• Chronic stress affects male hippocampus much more
  than females (not affected by typical 2-3 week
  protocols).
• Effects on spatial memory match these
  morphological changes.
• Only limited stress paradigms have been examined
  (i.e. could be increased resistance not immunity).

• Bases is unclear
• Females have larger initial HPA activation (males
  have sensitized HPA with chronic stress.
• Females also have increased GR in hippocampus.
• Effects can be produced in males by
  glucocorticoid administration.

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Sex Difference in Cognition
Higher the cortisol, the fewer word recalled
Cortisol concentration is significantly
correlated with memory in men but not
women. -may reflect similar effects seen in rats
(dendritic fields not assessed) -appear to be
organizational effects produced in adulthood.