Scientific American 201905

May 2019, ScientificAmerican.com 69

Prefrontal

cortex

A Anterior hypothalamic nucleus

AP Anterior lobe pituitary

DMH Dorsomedial hypothalamic nucleus

F Fornix

FM Mammillary fasciculus

Brain stem

Amygdala

Hippocampus

Posterior

amygdalar

nucleus

Cerebral cortex

Bed nuclei of the stria terminalis

Adrenal glands

on kidney

PP

Hypothalamus

Pituitary gland

Impulse

control

and decision-

making

Threat detection

Reward

Hypothalmic

attack area and

physiological

responses

for aggression

LPO Lateral preoptic nucleus

M Mammillary body

MPO Medial preoptic nucleus

NA Nucleus accumbens

OT Optic tract

PM Premammillary nucleus

AP (releases hormones under

control of the hypothalamus)

A

PVN

MPO

LPO

DMH

M

M

FM

SO

PM

PN

PN

PM

VMH

VMH III

F

OT

Adrenaline and

cortisol (fight-or-

flight response)

PVN

DMH

Hypothalamic attack area

(dashed box)

NA

Right

striatum

Left

striatum

Neural substructures PN Posterior hypothalamic nucleus

PP Posterior lobe pituitary

PVN Paraventricular nucleus

SO Supraoptic nucleus

VMH Ventromedial hypothalamic nucleus

III Third ventricle

Aggression and mating

Eating and

drinking

Blood

pressure,

body temperature

and appetite

Regulatory

function: heart

rate, blood

pressure and

fight-or-flight

response

Stress

hormones

A

B

C

D

PVN

built to an orgasm. One patient became flirtatious and
even offered to marry the therapist.
In what are now recognized as unethical studies
published in 1972, psychiatrist Robert  G. Heath of Tu -
lane University attempted to “cure” a young man of ho-
mosexuality. He implanted electrodes into the septal
region of the man’s brain to enable the physicians or
the patient himself to provide neural stimulation that

delivered sexual pleasure while watching heterosexual

pornographic films and while having sex with a female

prostitute. Heath reported that the subject stimulated

himself to the point of euphoria. (His sexual orientation

remained unchanged, however.)

Neurons in this part of the septal area (the bed nu-

clei of the stria terminalis, or BNST), which in animal

studies were activated during maternal aggression,

Illustration by Body Scientific

Pathways of Rage

Conduits within the human brain transmit signals that

fan aggressive behavior—or tamp it down. A key hub is

the “hypothalamic attack area,” minute clusters of neu-

rons where the brain receives inputs that regulate

the racing heart and other physiological responses

that precede a violent incident A. Elsewhere the

amygdala receives inputs from the senses and the

decision-making area on the brain’s surface that

signal the presence of a threat B. The cortex

keeps a check on wayward impulses C. Rage

and reward circuits interconnect D.

© 2019 Scientific American