Chapter 4: Sex Differences in Human and Nonhuman Animals

Sex Differences

Variations in behavior or physiology between sexes.

Neural Bases

Brain structures influencing sex-specific behaviors.

Medial Preoptic Area (MPOA)

Brain region controlling sexual behavior and homeostasis.

Preoptic Area (POA)

Region anterior to hypothalamus, divided into lateral and medial.

Dendritic Spines

Small outgrowths on dendrites involved in synaptic transmission.

Sexually Dimorphic Nucleus (SDN-POA)

Nucleus larger in males, linked to sexual behavior.

CNS Structural Differences

Variations in brain structures between men and women.

Hemispheric Connectivity

Degree of communication between brain hemispheres.

Birdsong

Sexually dimorphic behavior influenced by hormones in birds.

Zebra Finches

Male finches sing to attract females; females do not.

Ambien Metabolism

Drug metabolization varies between men and women.

Parenting Behavior

Sex differences observed in caregiving roles.

Sex Steroids

Hormones influencing sexually dimorphic behaviors.

Stroke Impact on Women

Women less likely to have speech issues post-stroke.

Male Brain Size

Generally larger brain structures linked to masculine traits.

Female Brain Size

Certain structures, like language areas, larger in women.

Synaptic Connectivity

Female rats have more synapses on dendritic spines.

Behavioral Phenomena

Typical and atypical behaviors influenced by sex differences.

Medication Dosage

Differences in drug response based on sex.

Sexual Behavior Control

MPOA involved in regulating sexual motivation.

Hormonal Activation

Behavior activated by hormones in various species.

Testosterone

Hormone increasing singing in female canaries.

Type 1 Males

Large midshipman fish guarding nests and attracting females.

Type 2 Males

Sneaker males that release sperm opportunistically.

11-ketotestosterone

Produced only by Type 1 male midshipman fish.

Vocalization Duration

Modulated by steroids in midshipman fish.

Organizational Effects

Hormonal influences during development affecting behavior.

Activational Effects

Hormonal influences activating behavior in adulthood.

Sexually Dimorphic Behaviors

Behaviors differing between sexes due to hormones.

Aggression Variation

More variation within sexes than between sexes.

Lankford Study

Only one female among 292 mass shooters studied.

Gender Role

Culturally defined behaviors appropriate for each sex.

Gender Identity

Self-perception of being male or female.

Gender Identity Development

Typically established by age two.

CAH in Girls

Higher likelihood of switching gender identity.

Sexual Orientation

Development of erotic attraction to others.

INAH-3 Size

Smaller in homosexual men than heterosexual men.

Genetic Factors

Potential reasons for INAH-3 size differences.

Organizational Effect Hypothesis

Hormonal influences may affect INAH-3 size.

INAH-3

Region in hypothalamus with sex differences.

Interstitial Nuclei

Neuronal cell bodies in anterior hypothalamus.

INAH-2

Another region with reported sex differences.

SDN-POA Equivalent

INAH-1 comparable to rat's SDN-POA.

Quantitative Skills

Stronger in males compared to females.

Language Skills

Stronger in females compared to males.

Causation vs Correlation

Causation cannot be inferred from correlation alone.

African Cichlids

Fish species exhibiting behavioral and structural changes.

Territorial Males

Brightly colored males defending specific areas.

Non-Territorial Males

Dull-colored males blending with surroundings.

GnRH Neurons

Neurons in the POA affected by territory changes.

Hormonal Replacement Therapy

Restores sexual preferences in gonectomized individuals.

Pain Tolerance

Women have a lower threshold for pain.

Olfaction Sensitivity

Women are more sensitive to musk odors.

Chemosensory Detection

Women generally outperform men in odor identification.

Gustation Sensitivity

Women identify and discriminate tastes better.

Auditory Sensitivity

Women hear pure tones at lower thresholds.

Visual Acuity

Men generally have better visual acuity.

Cerebral Lateralization

Cognitive functions confined to one brain hemisphere.

Perceptual Speed

Women outperform men in quick matching tasks.

Fine Motor Coordination

Women excel in tasks requiring precise movements.

Mathematical Calculations

Women perform better in basic calculations.

Target-Directed Skills

Men are more accurate in catching and throwing.

Mathematical Reasoning

Men outperform women in complex reasoning tasks.

Mental Rotation

Men excel in visualizing object rotations.

Grey Matter

Contains more cell bodies than white matter.

White Matter

Contains more axons than grey matter.

Drawing Preferences

Boys draw moving objects; girls draw people.

Color Preferences

Boys prefer blue; girls prefer red and pink.

Drawing Perspectives

Boys use overhead views; girls use ground-level.

CAH Girls' Drawings

Exhibit more bisexual traits in artistic expression.