LEARNING GOALS – T5 LIMBIC SYSTEM
LEARNING GOAL 5.1: LIMBIC SYSTEM ANATOMY
WHAT STRUCTURES AND CIRCUITS ARE THERE IN THE SYSTEM (NIEUWENHUYS)?
• Limbic system is regarded as the interface between the cerebral neocortex (voluntary) and
brainstem autonomous system (involuntary)
• At the intermediate level are the Amygdala (emotional processing) and hippocampus (memory
processing)
Cortical • Orbitofrontal cortex – perceive smell, involved in formation of memories
components • Hippocampus – long term memory
(limbic lobe) • Insular cortex – desires, cravings, addiction
• Cingulate gyrus – perception of neuropathic pain and nociception
• Parahippocampal gyrus – provides path for communication between cortical
association areas and hippocampus
Subcortical • Amygdala – fear, anxiety responses
components • Olfactory bulb – receives olfactory input about smells detected
• Hypothalamus – final output of limbic system
• Anterior / dorsomedial nuclei of thalamus
• Septal nuclei
STRUCTURES
BROCA’s LIMBIC CORTEX / CINGULATE GYRUS
• Light pink arc
• Edge of cerebral cortical sheet à allocortex
• Starting at lower left, the ring comprises the uncus, the medial part of parahippocampal gyrus,
ictus, ventral part of cingulate gyrus, caudal orbitofrontal cortex, and rostral border of insula
• This ring of allocortex is the high-end side of limbic system à interacts with the voluntary behavior
system of the cerebrum
• Place where signals from hypothalamus and sensory cortex converge (convergence = conscious
experience of feeling)
HYPOTHALAMUS
• Low end of limbic system à interacts with autonomic centers responsible for generating ‘instinctive’
behaviors
• Considered top of autonomous motor system hierarchy
• Hypothalamic cells are ‘central pattern controllers à generate motivational states which control the
generation of primitive actions (by their connections to the midbrain and spinal cord motor pattern
centers)
, • By connecting to nuclei they also give rise to the affects accompanying motivational states
• The intermediate limbic structures modulate this autonomous infrastructure, and allow using it for
the expression of internally generated emotional states
AMYGDALA
• Extended amygdala = medial nuclei + bed nucleus of stria terminalis
o Gives rise to an organized system of pathways to many hypothalamic and brainstem areas
and forms the main output channel of the amygdaloid complex
• Central nuclei + medial nuclei + bed nucleus of stria terminalis = generating emotional responses
HIPPOCAMPUS & FORNIX (inner arc)
• Memory functions
• Circuit of Papez
OLFACTORY BULB
• Initial role was likely to categorize objects and events as good or bad, by remembering their odors
• Odors opened the way for entering a component of valence to object identification. The amygdala
receives inputs from neocortical representations of the other sensory systems and inputs directly
from the olfactory bulbs
§ Place learning evolved in the limnic telencephalic structures of the posterior
hemispheres à Hippocampal formation, near the visual and auditory ‘analysers’ of
the neocortex
• Olfactory cortex, amygdala, hippocampus joined together by the enclosing paleocortex of the
uncus à previously called Rhinencephalon
, CIRCUITS
CIRCUIT OF PAPEZ
• Neural circuit involved in control of emotional expression and
memory processing
• Leaves the mammillary bodies, goes to anterior nucleus of the
thalamus, cingulate cortex, cingulum, back to the hippocampus
o Sensory info from thalamus à hypothalamus
1. Hypothalamus DOWN à brain stem, spinal cord
= emotional responses
2. Hypothalamus UP à cortex = feelings
• Signals from the hypothalamus go first to the anterior thalamus
and then to the cingulate cortex, where signals from the
hypothalamus and sensory cortex converge (convergence = conscious experience of feeling)
• The sensory cortex then projects to both the cingulate cortex and hippocampus, which in turn makes
connections with the mammillary bodies of the hypothalamus, thus completing the loop
EMOTIONAL LIMBIC SUBSYSTEM
• Starts in caudal-medial amygdala (central / medial nuclei) à via stria terminalis à anterior
diencephalon & anterior commissure à terminates in pre-optic nucleus (septal nuclei and
hypothalamus) = controls expression of emotions
• The central nuclei of the amygdala are thought to be responsible for generating emotional
responses, together with the medial nuclei and the bed nuclei of stria terminalis (BST)
o BST together with the central and medial nuclei of amygdala, is considered the extended
amygdala
LEARNING GOAL 5.1: LIMBIC SYSTEM ANATOMY
WHAT STRUCTURES AND CIRCUITS ARE THERE IN THE SYSTEM (NIEUWENHUYS)?
• Limbic system is regarded as the interface between the cerebral neocortex (voluntary) and
brainstem autonomous system (involuntary)
• At the intermediate level are the Amygdala (emotional processing) and hippocampus (memory
processing)
Cortical • Orbitofrontal cortex – perceive smell, involved in formation of memories
components • Hippocampus – long term memory
(limbic lobe) • Insular cortex – desires, cravings, addiction
• Cingulate gyrus – perception of neuropathic pain and nociception
• Parahippocampal gyrus – provides path for communication between cortical
association areas and hippocampus
Subcortical • Amygdala – fear, anxiety responses
components • Olfactory bulb – receives olfactory input about smells detected
• Hypothalamus – final output of limbic system
• Anterior / dorsomedial nuclei of thalamus
• Septal nuclei
STRUCTURES
BROCA’s LIMBIC CORTEX / CINGULATE GYRUS
• Light pink arc
• Edge of cerebral cortical sheet à allocortex
• Starting at lower left, the ring comprises the uncus, the medial part of parahippocampal gyrus,
ictus, ventral part of cingulate gyrus, caudal orbitofrontal cortex, and rostral border of insula
• This ring of allocortex is the high-end side of limbic system à interacts with the voluntary behavior
system of the cerebrum
• Place where signals from hypothalamus and sensory cortex converge (convergence = conscious
experience of feeling)
HYPOTHALAMUS
• Low end of limbic system à interacts with autonomic centers responsible for generating ‘instinctive’
behaviors
• Considered top of autonomous motor system hierarchy
• Hypothalamic cells are ‘central pattern controllers à generate motivational states which control the
generation of primitive actions (by their connections to the midbrain and spinal cord motor pattern
centers)
, • By connecting to nuclei they also give rise to the affects accompanying motivational states
• The intermediate limbic structures modulate this autonomous infrastructure, and allow using it for
the expression of internally generated emotional states
AMYGDALA
• Extended amygdala = medial nuclei + bed nucleus of stria terminalis
o Gives rise to an organized system of pathways to many hypothalamic and brainstem areas
and forms the main output channel of the amygdaloid complex
• Central nuclei + medial nuclei + bed nucleus of stria terminalis = generating emotional responses
HIPPOCAMPUS & FORNIX (inner arc)
• Memory functions
• Circuit of Papez
OLFACTORY BULB
• Initial role was likely to categorize objects and events as good or bad, by remembering their odors
• Odors opened the way for entering a component of valence to object identification. The amygdala
receives inputs from neocortical representations of the other sensory systems and inputs directly
from the olfactory bulbs
§ Place learning evolved in the limnic telencephalic structures of the posterior
hemispheres à Hippocampal formation, near the visual and auditory ‘analysers’ of
the neocortex
• Olfactory cortex, amygdala, hippocampus joined together by the enclosing paleocortex of the
uncus à previously called Rhinencephalon
, CIRCUITS
CIRCUIT OF PAPEZ
• Neural circuit involved in control of emotional expression and
memory processing
• Leaves the mammillary bodies, goes to anterior nucleus of the
thalamus, cingulate cortex, cingulum, back to the hippocampus
o Sensory info from thalamus à hypothalamus
1. Hypothalamus DOWN à brain stem, spinal cord
= emotional responses
2. Hypothalamus UP à cortex = feelings
• Signals from the hypothalamus go first to the anterior thalamus
and then to the cingulate cortex, where signals from the
hypothalamus and sensory cortex converge (convergence = conscious experience of feeling)
• The sensory cortex then projects to both the cingulate cortex and hippocampus, which in turn makes
connections with the mammillary bodies of the hypothalamus, thus completing the loop
EMOTIONAL LIMBIC SUBSYSTEM
• Starts in caudal-medial amygdala (central / medial nuclei) à via stria terminalis à anterior
diencephalon & anterior commissure à terminates in pre-optic nucleus (septal nuclei and
hypothalamus) = controls expression of emotions
• The central nuclei of the amygdala are thought to be responsible for generating emotional
responses, together with the medial nuclei and the bed nuclei of stria terminalis (BST)
o BST together with the central and medial nuclei of amygdala, is considered the extended
amygdala
