Exam summaries – Neuro
Primary Emotions
The brain contains four p rimary basic-emotion
command systems . All of these basic-emotion
systems project down into the p eriaqueductal
gray (PAG) in the upper brainstem, which acts
as the core hub for generating the qualitative
feelings of pleasure (ventral PAG) and
unpleasure (dorsal PAG).
1. The SEEKING System (Ap p etitive /
Curiosity / Exp ectancy)
• Neural Pathway & Structures : Source cells
originate in the ventral tegmental area
(VTA). Their axons pass through (and synapse
on) the dorsolateral hyp othalamus en route
to terminating in the nucleus accumbens .
Projections also extend upward to the
anterior cingulate gyrus and other frontal
areas, as well as downward to the amygdala.
, • Command Neurochemical: Dop amine (forming
part of the mesocortical-mesolimbic dopamine
system).
• Function: Generates general curiosity,
interest, foraging, and appetitive behavior.
• Associated Subsystem (LUST): Arises from
the sep tal region and hyp othalamic nuclei
(mainly p reop tic area) and terminates in the
PAG. It is mediated by endorp hins and
converts appetitive seeking into pleasurable
consummatory behaviors.
2. The RAGE System (Anger / " Hot"
Aggression)
• Neural Pathway & Structures : Centered in
the medial nucleus of the amygdaloid
comp lex. The circuit courses through the
bed nucleus of the stria terminalis and
the hyp othalamus (anterior, ventromedial,
and perifornical regions) before projecting
down into the dorsal PAG.
, • Function & Trigger: Activated by states of
frustration when goal-directed behavior is
thwarted, releasing the "fight" or "affective
attack" motor program.
3. The FEAR System (Fear-Anxiety /
Flight)
• Neural Pathway & Structures : Centered in
the lateral and central nuclei of the
amygdaloid comp lex . It projects through the
medial and anterior hyp othalamus to
terminate in the dorsal PAG.
• Key Neurochemistry : Heavily regulated by
GABA (and inhibited by GABA-A agonists
like benzodiazepines).
• Dual Circuits : Operates via a "quick and
dirty" subcortical pathway directly from the
amygdala to the PAG (bypassing cortical
awareness) and a slower, extended circuit
involving the hip p ocamp us for conscious,
autobiographical reflection.
, • Function: Triggers "flight" (escaping/hiding) or
"freeze" motor responses to danger.
4. The PANIC System (Sep aration-
Distress / Sadness / Grief)
• Neural Pathway & Structures : The core hub
is the anterior cingulate gyrus , which
maintains extensive connections with
thalamic and hypothalamic (preoptic) nuclei,
the bed nucleus of the stria terminalis, and
the VTA, projecting down to the ventral
PAG.
• Command Neurochemicals : Dominated by
endogenous op ioids . It also centrally
involves oxytocin and p rolactin.
• Function & Trigger: Triggered by separation
from caregivers or loved objects. Separation
causes a drop in opioid activity, making loss
feel literally "painful" and evoking distress
calls or depressive withdrawal.
Primary Emotions
The brain contains four p rimary basic-emotion
command systems . All of these basic-emotion
systems project down into the p eriaqueductal
gray (PAG) in the upper brainstem, which acts
as the core hub for generating the qualitative
feelings of pleasure (ventral PAG) and
unpleasure (dorsal PAG).
1. The SEEKING System (Ap p etitive /
Curiosity / Exp ectancy)
• Neural Pathway & Structures : Source cells
originate in the ventral tegmental area
(VTA). Their axons pass through (and synapse
on) the dorsolateral hyp othalamus en route
to terminating in the nucleus accumbens .
Projections also extend upward to the
anterior cingulate gyrus and other frontal
areas, as well as downward to the amygdala.
, • Command Neurochemical: Dop amine (forming
part of the mesocortical-mesolimbic dopamine
system).
• Function: Generates general curiosity,
interest, foraging, and appetitive behavior.
• Associated Subsystem (LUST): Arises from
the sep tal region and hyp othalamic nuclei
(mainly p reop tic area) and terminates in the
PAG. It is mediated by endorp hins and
converts appetitive seeking into pleasurable
consummatory behaviors.
2. The RAGE System (Anger / " Hot"
Aggression)
• Neural Pathway & Structures : Centered in
the medial nucleus of the amygdaloid
comp lex. The circuit courses through the
bed nucleus of the stria terminalis and
the hyp othalamus (anterior, ventromedial,
and perifornical regions) before projecting
down into the dorsal PAG.
, • Function & Trigger: Activated by states of
frustration when goal-directed behavior is
thwarted, releasing the "fight" or "affective
attack" motor program.
3. The FEAR System (Fear-Anxiety /
Flight)
• Neural Pathway & Structures : Centered in
the lateral and central nuclei of the
amygdaloid comp lex . It projects through the
medial and anterior hyp othalamus to
terminate in the dorsal PAG.
• Key Neurochemistry : Heavily regulated by
GABA (and inhibited by GABA-A agonists
like benzodiazepines).
• Dual Circuits : Operates via a "quick and
dirty" subcortical pathway directly from the
amygdala to the PAG (bypassing cortical
awareness) and a slower, extended circuit
involving the hip p ocamp us for conscious,
autobiographical reflection.
, • Function: Triggers "flight" (escaping/hiding) or
"freeze" motor responses to danger.
4. The PANIC System (Sep aration-
Distress / Sadness / Grief)
• Neural Pathway & Structures : The core hub
is the anterior cingulate gyrus , which
maintains extensive connections with
thalamic and hypothalamic (preoptic) nuclei,
the bed nucleus of the stria terminalis, and
the VTA, projecting down to the ventral
PAG.
• Command Neurochemicals : Dominated by
endogenous op ioids . It also centrally
involves oxytocin and p rolactin.
• Function & Trigger: Triggered by separation
from caregivers or loved objects. Separation
causes a drop in opioid activity, making loss
feel literally "painful" and evoking distress
calls or depressive withdrawal.
