Limbic System

At what developmental boundary does the limbic system arise?

Between the diencephalon and telencephalon

What three major functions are associated with the limbic system?

Emotional behavior, motivation, and memory

Which instinctive behaviors are regulated by the limbic system?

Attack or defense, reproduction, and feeding

What major sensory system provides limbic input related to smell?

Olfactory system or rhinencephalon

What ascending sensory pathway is a major limbic afferent?

Spinothalamic system

What two structures are major effectors of limbic-system activity?

Hypothalamus and reticular formation

Which neocortical gyri are components of the limbic lobe?

Cingulate gyrus and parahippocampal gyrus

Which paleocortical structures are components of the limbic lobe?

Paraterminal gyrus, subcallosal area, and entorhinal area

Which archicortical structures are components of the limbic lobe?

Hippocampus, dentate gyrus, and subiculum

Which telencephalic subcortical nuclei are part of the limbic system?

Amygdaloid body, septal nuclei, nucleus accumbens, and nucleus basalis of Meynert

Which diencephalic nuclei are part of the limbic system?

Anterior thalamic nuclei, mediodorsal nucleus, mammillary nuclei, habenular nuclei, and nonspecific thalamic nuclei

Which mesencephalic nucleus is included in the limbic system?

Interpeduncular nucleus

What structures form the hippocampal formation?

Hippocampus, subiculum, and dentate gyrus

What is another name for the hippocampus?

Ammon's horn

What is the subiculum?

A transitional area between hippocampus and entorhinal cortex

How many cortical layers does the hippocampus have?

Three

What are the three layers of hippocampal cortex?

Polymorphic layer, pyramidal cell layer, and molecular layer

Which hippocampal fiber layer covers the hippocampus?

Alveus

What structure continues from the alveus?

Fimbria

Which cytoarchitectural fields are found in the hippocampus?

CA1, CA2, CA3, and CA4

Where is the dentate gyrus located relative to the hippocampal sulcus?

Above it

What cortical layer contains the principal cells of the dentate gyrus?

Granule cell layer

What are the three layers of the dentate gyrus?

Polymorphic layer, granule cell layer, and molecular layer

Which structures continue from the dentate gyrus toward the corpus callosum?

Gyrus fasciolaris and indusium griseum

Which paired fiber bundles run in the indusium griseum?

Medial and lateral longitudinal striae

Which pathway carries afferents from entorhinal cortex to dentate gyrus and hippocampus?

Perforant pathway

Which limbic tract provides septal input to the hippocampal formation?

Fornix

Which association tract provides input from cingulate cortex to the hippocampal formation?

Cingulum

Which hippocampal cells contribute fibers to the alveus?

Hippocampal pyramidal cells

Which hippocampal structure contributes fibers to the alveus?

Subiculum

What is the sequence of hippocampal efferent fibers from cortex to the fornix?

Subiculum and hippocampal pyramidal cells to alveus to fimbria to fornix

What are the targets of the postcommissural fornix?

Medial mammillary nucleus and anterior hypothalamus

What are the targets of the precommissural fornix?

Septal nuclei, nucleus accumbens, and subcallosal area

What is the overall shape of the amygdaloid body?

Almond-shaped

Where is the amygdaloid body located?

Rostromedial temporal lobe beneath the uncus

Where is the amygdaloid body located relative to the hippocampal formation?

Rostral to it

What are the two main nuclear groups of the amygdaloid body?

Basolateral group and corticomedial group

Which structures provide afferents to the basolateral amygdaloid nuclei?

Dorsal thalamus, prefrontal cortex, cingulate gyrus, parahippocampal gyrus, and subiculum

Which sensory modality provides major input to corticomedial amygdaloid nuclei?

Olfactory input

Which hypothalamic areas project to corticomedial amygdaloid nuclei?

Ventromedial nucleus and lateral hypothalamic area

Which limbic nuclei project to corticomedial amygdaloid nuclei?

Septal nuclei and bed nucleus of the stria terminalis

Which brainstem structures project to corticomedial amygdaloid nuclei?

Brainstem nuclei

Which pathway carries corticomedial amygdaloid output to hypothalamus and septal nuclei?

Stria terminalis

Which striatal structures receive amygdaloid output through the stria terminalis?

Nucleus accumbens and rostral caudate nucleus and putamen

Which amygdaloid nuclei give rise to the ventral amygdalofugal pathway?

Basolateral nuclei and central nucleus

Which thalamic nucleus receives output through the ventral amygdalofugal pathway?

Mediodorsal thalamic nucleus

Which brainstem targets receive output through the ventral amygdalofugal pathway?

Visceral and reticular nuclei

Where is the septal region located relative to the anterior commissure?

Rostral to it

Into which structure does the septal region extend?

Base of the septum pellucidum

Which limbic structure provides fornical afferents to the septal region?

Hippocampus

Which structures provide afferents to the septal region besides hippocampus?

Amygdala, ventral tegmental area, and hypothalamic nuclei

Which limbic structure receives septal efferents?

Hippocampus

Which fiber bundle connects the septal region with habenular nuclei?

Stria medullaris thalami

Which pathway connects the septal region with the ventral tegmental area?

Medial forebrain bundle

Where is the nucleus accumbens located?

Rostral and ventral forebrain

Which fornical division provides hippocampal afferents to nucleus accumbens?

Precommissural fornix

Which amygdaloid pathway provides afferents to nucleus accumbens?

Ventral amygdalofugal pathway

Which midbrain region provides medial-forebrain-bundle input to nucleus accumbens?

Ventral tegmental area

Which structures receive efferents from nucleus accumbens?

Hypothalamus, brainstem nuclei, and globus pallidus

What is the association pathway of the cingulate gyrus?

Cingulum

Which fiber tract forms reciprocal connections between hippocampal formation and septal or mammillary regions?

Fornix

Which division of the fornix is connected with the septal area?

Precommissural fornix

Which division of the fornix is connected with the mammillary body?

Postcommissural fornix

Which pathway connects the amygdaloid body with hypothalamus, septal area, and striatum?

Stria terminalis

Which pathway connects septal nuclei and hypothalamus with habenular nuclei?

Stria medullaris

Which tract connects mammillary bodies with anterior thalamic nuclei?

Mammillothalamic tract

Which tract connects habenular nuclei with the interpeduncular nucleus?

Fasciculus retroflexus

Which pathway connects the septal region, hypothalamus, and brainstem visceral and reticular nuclei?

Medial forebrain bundle

Which pathway connects the entorhinal cortex with the dentate gyrus and hippocampus?

Perforant pathway

Which limbic circuit links hippocampus with cingulate cortex through mammillary and anterior thalamic nuclei?

Papez circuit

What is the sequence of the Papez circuit from hippocampus to cingulate cortex?

Hippocampus and subiculum to postcommissural fornix to medial mammillary nucleus to mammillothalamic tract to anterior thalamic nuclei to thalamocortical fibers to cingulate gyrus

Which pathway returns Papez-circuit activity from cingulate gyrus to entorhinal cortex?

Cingulum

Which limbic circuit links amygdala, hypothalamus, habenula, and interpeduncular nucleus?

Amygdalo-hypothalamo-habenular circuit

What is the sequence of the amygdalo-hypothalamo-habenular circuit?

Amygdaloid body to stria terminalis to septal area to anterior hypothalamus to stria medullaris to habenular nuclei to fasciculus retroflexus to interpeduncular nucleus