The document discusses several key anatomical and functional differences between male and female brains. It notes that while human brains show 99% similarity, the 1% difference accounts for meaningful distinctions. Specifically, it reports that females have a larger limbic cortex and frontal/temporal lobes, better for emotional processing and multi-tasking. Males tend to have better spatial and math abilities due to larger specific regions. Additionally, it explores sex differences in brain structures, hormones, and their clinical implications.

2.  Introduction
 Anatomical differences
 Sculpting the Brain
 Inborn inclinations
 Under stress
 Sex and mental disorders
 Hormones
 Clinical implications
 Structural connectome of Human Brain
 Neurosteroids
 Key
 References
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Physically- Men are larger, stronger, higher
testosterone levels
More sensitive to smaller moving objects, target
focused; women focus on colour changes, better
peripheral vision
More fat on belly, women on thighs
Biologically- 22 pairs of autosomes; 23rd pair sex
chromosome (XX and XY)
The 80 or so genes on Y chromosome in male
and absent in female account for several
differences
Mentally- women can do multi-tasking and are
more emotional

4.  Human brains show 99% similarity it’s the 1%
that makes a difference.
 The limbic cortex is larger in females- better
emotional bond
 Frontal lobe (problem-solving), temporal cortex
is larger in females
 Women have ten times more white matter-
better multi-taskers
 Males better at math due to better logistics in
the left hemisphere (larger inferior-parietal
lobule)
 Women equally utilize both hemispheres, better
linguistic abilities
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6.  Earlier study- Hypothalamus hormone
production, eating, drinking and sex
 Current study- memory, emotion, vision,
hearing, recognition
 PET and fMRI scanning- non-invasive
techniques
 Males have better motor and spatial
abilities, whereas females have superior
memory and social cognition skills.
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7.  Some Sexual differences present before birth
 At around the 26-week stage, girl fetuses
develop a thicker corpus callosum
 Boys and girls inclined towards varied toys;
trucks or dolls
 Equal interaction with gender neutral toys in
experiment performed on vervet monkeys
 Nature vs nurture regarding sex differences-
built-in cognitive differences
 Girls spent more time looking at the student,
whereas the boys spent more time looking at
the mechanical object
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8.  Males have the Amygdala 4 times larger
than females, more aggressive behavior,
fight or flight response, sexual desire, higher
suicide rates
 In an expt-measured concentration of 5-HT
receptors after separation of pups from
mother; in males, in females
 Neurons in male rats have more
interconnections
 Women experience more pain (left-
amygdala activation responsible for
internal functions)
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9.  Hippocampus(memory storage) larger in
women
 Males-Navigation in space and orientation;
females-using landmarks
 In an expt-placed rats in an “enriched
environment” promoting social interactions;
bushiness of dendritic trees in females,
slight in males
 Males have greater I.Q variance than
females
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10.  Serotonin production 52% higher in men;
women more prone to depression
 Women more prone to addiction;
estrogen boosts DA release- cause
dependence more rapidly with drugs of
abuse (cocaine, amphetamine)
 Women possess significantly larger
orbitofrontal-to-amygdala ratio, better at
controlling emotions
 Women OAR; Men OAR
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11.  Hormonal changes is cyclic in females, acyclic in
males
 Exposure to higher levels of testosterone in the
womb leads, on the one hand, to the
development of greater abilities in ‘systematising’
kinds of thinking, and, on the other, lower social
skills.
 Sexually Dimorphic Nucleus (SDN) larger in males
in Hypothalmus, in Corpus callosum (gender
identity), ant. commissure (sexuality)
 INAH-3 nuclei half the size in homosexual males as
well as females; SCN double the cell volume
 Oxytocin releases during stress. But female
estrogen combines with oxytocin to produce a
calming effect, whereas male testosterone only
makes men more aggro.
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12.  To diagnose and provide sex-specific
treatment for disorders like depression,
addiction, post-traumatic stress disorder
and schizophrenia
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14.  Using diffusion
tensor imaging
(water-based)
 Male- perception
and coordinated
action
 Female- analytical
and intuition
processing
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 949 human subjects (428 M, 521 F; 8-22yrs)
 In all supratentorial regions, males show
greater within-hemispheric connectivity, as
well as enhanced modularity and
transitivity
 Females show between-hemispheric
connectivity and cross-module
participation
 Males have stronger intra hemispheric
connections bilaterally (HCR).
 In cerebellar regions it was opposite.

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Schematic of the pipeline for creating the SC

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18.  CNS is more sensitive to the organizational effects
of gonadal hormones (imprinting effect)
 Produced locally in the Hippocampus; pregnane
steroids (allopregnanolone & THDOC),androstane
steroids (androstanediol & etiocholanone)&
sulfated neurosteroids (pregnenolone sulfate (PS) &
DHEAS)
 Epilepsies higher in males, localization-related
symptomatic epilepsy
 Women tend to have less structural atrophy than
men, regardless of the seizure rate
 Sexual dimorphism (GABAergic neurosteroids
activation in SNr underlie gender-related
differences in seizure susceptibility and protection.),
sensitivity to neurotransmitter, receptor distribution
etc are responsible factors
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20.  LCW Lobar Connectivity Weight
 HCR Hemisphere Connectivity Ratio
 SC Structural Connectome
 PC Participation Coefficient
 ROI Regions Of Interest
 INAH 3 Interstitial Nucleus of the
Anterior Hypothalamus number 3
 SCN Suprachiasmatic Nucleus
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21.  Ingalhalikar, M., Smith, A., Parker, D., Satterthwaite,
T., Elliott, M., Ruparel, K., Hakonarson, H., Gur, R.,
Gur, R., & Verma, R. (2013). Sex differences in the
structural connectome of the human brain,
Proceedings of the National Academy of Sciences,
111 (2), 823-828
 Viatcheslav Wlassoff, PhD, January 13, 2015 .Mars
Vs Venus – Differences in Male and Female Brains,
NEUROSCIENCE & NEUROLOGY
 Larry Cahill, May 1, 2012. His Brain, her Brain
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