The cortex - limbic lobe Flashcards
What was Limbus used for by the middle ages?
Border or margin of a structure
What is part of the brain surrounding the brainstem?
Cingulate gyrus (border)
What did Broca define the limbic lobe as?
- L-lobe
- L-system
- L-cortex
- L-Function
What is Limbic system involved in?
Emotions
What are included in the Limbic system?
- Hypothalamus
- Part of thalamus
- Amygdala
- Hippocampus
Why is it difficult to do experiment on fear, hate, love or disgust?
All bundled into 1 thing - limbic
What is the Grand lobe limbic divided into?
- Outer Limbic gyrus
2. Intralimbic gyrus
What does the Outer Limbic Gyrus consist of?
- Subcullosal Gyrus
- Cingulate Gyrus
- Isthmus
- Parahippocampal Gyrus
What does the Inner Intralimbic gyrus consist of?
Anterior
- Prehippo rudiment
Superior
- Indusium griseum
- Longitudinal striae
Inferior
- Hippocampus
What is the hippocampus anatomy?
2 Grey matter sheaths which are C-shaped and interlocked
What are the 2 layers of grey matter in the hippocampus?
- Cornu Ammonis
2. Dentate Gyrus
What are the white matter at the surface of the hippocampus?
- Fimbria
2. Alveus
What makes the alveus?
White myelinated fibres that cover ventricular parts of hippocampus
What is Fimbria?
White matter tracts that contain afferent and efferent fibres of hippocampus, travels along hippocampus
What do you find on most of the brain?
6 layered cortex
newest in development e.g. neocortex
Isocortex - always 6 layers
What can have either 3 or 10 layers?
Archicortex and periarchicortex
What is the oldest cortex?
Paleocortex
Around olfactory region
What is found in the archicortex and periarchicortex?
Insula
Limbic lobe
What is found in the Allocortex?
- Hippocampus
- Prox subiculum
- Indusium griseum
What is found in the Archi(periallo)?
Cingulate
What is found in the Peri-Archi?
Parahipp- Insula
What did another group define the limbic lobe as?
All non-isocortical parts of the cortical mantle is the limbic lobe
What does the non-isocortical parts include?
Hippocampus and adjacent cortical areas
Cingulate
Parahippocampus
Olfactory cortex; caudal orbital & medial prefrontal cortex, part of the temporal pole large part of insula
What are all non-isocortical parts of the cortical mantle?
- Amygdala
- Nucleus basalis
- Hypothalamus
The signal intensity on FLAIR image is hyperintensive
- Allo/Archi > Isocortex
2. Limbic + Insula > Other lobes
What is found on the brighter side in comparison to the neocortex?
- Paleocortex
- Cortex
- Cingulate
- Insula
- Old cortex olfactory
- Hippocampus
What has a higher signal than the other lobes/ cortices/ Isocortex?
- Archicortex
- Periarchicortex
- Insula
- Limbic lobe
DWI SI
Limbic > Insula > Other lobe
What are the 4 subregions of the cingulate gyrus?
- Ant-cing cortex
- Mid-cing cortex
- Post-cing cortex
- Retrosplenical cortex
No anatomical boundaries
How many gyri does the Insula have?
5 3 short (ant) and 2 long (post)
separated by the central sulci Insula
What is the triangle of the Insula surrounded by?
Limen Insula
What is central sulcus?
Boundary between anterior and posterior from morphological and functional point of view
Anterior
Motor
Posterior
Sensory
What are the evidence for the cytoarchitectionic concepts?
Anterior to CS, certain cells called pyramidal cells, posteriorly you have granular cells
What are the cytoarchitectonic of Insula?
Anterior: Agranular
CSI
Posterior: Granular
What is continuous?
CS + CSI
What is the organisation vector of Insular?
Radial (Not AP)
How are the connections and function of cortex [Insula, Limbic lobe]
- Structural
- Functional
- DTI Tractography
- fMRI
What is Anterior Insula?
Granular
- Amygdala, Hippocampus, EC, BA6
What is Middle Insula?
Dysgranular
- BA44
What is Posterior Insula?
Granular
BA45, SI, SPL, IPL
How do you define the cortex?
By its connections
What is fMRI connectivity?
Three subregions identified with cluster analysis
Ventral anterior insula (red), dorsal anterior to middle insula (orange), and posterior insula (yellow).
What are the functional domains?
- Sensori-motor
- Chemical-sensory
- Cognition
- Social-emotional
What are examples of sensori-motor?
- Interoception
- Somatosensation
- Pain
- Motion
What are examples of chemical-sensory?
- Olfaction
2. Gustation
What are examples of cognition?
- Attention
- Language
- Speech
- Working memory
- Memory
What are examples of social-emotional?
- Emotion
2. Empathy
What is anterior insula activated by?
- Word generation> repetition
- Synaptic processing during comprehension
- Automatic speech production > word retrieval
- Overt picture naming
- Overt > covert articulation
- Pseudo-words > words
- phonological > semantic decision on written word
What are anterior Insula also activated by?
- Melody production, whistling
2. Subsyllable verbal utterances
What are post Insula activated by?
- Voluntary control of breathing
(non-verbal orofacial function, lip-tongue movement + vocalisation) - Mouth movement interfere with regular breathing pattern
What are the problems with Neurological Model?
- Too simplistic
2. No theory to explain inter-patient variability
What are the alternative for neurological model?
Instead of 1 motor area there are multiple speech production areas
Instead of 1 sensory area - multiple comprehension area
What are the function of Insula?
- Articulatory coding and motor programming
- Coordination of (up to 100) muscles engaged in articulate and phonation
- Control of breathing
What is the consequence of small lesion in area of Insula?
Apraxia of speech
What are the functions of the Insular cortex?
- Primary sensory areas
- Gustatory
- General Viscero-sensory
- Somatosensory
- Vestibular
What does Galvanic stimulation of mastoid act on?
CN 8 to elicit rotational or tilt sensation and tonic torsional eye moves
What does PET activate?
- Insula
- Putamen, Caudate
- Anterior Cingulum
Gustatory cortex
- Taste buds
- CN VII, IX, X
- Rostal Ncl of Solitary tract
- Hypothalamus and medial VPMpc (parvocellular)
- Insula
1ry gust cortex (granular)
2ry gust cortex (dysgr)
Define general viscerosensation?
Feeling of ‘‘throwing up’’, having ‘‘something in the throat’’, ‘‘vibration in the stomach’’ or abdominal sensation
Taste buds gustatory information
From taste buds gustatory information is transferred to the nucleus of the solitary tract (NST) via the chorda tympani and the greater superior petrosal branches of the facial (VIIth), the lingual branch of the glossopharyngeal (IXth) and the superior laryngeal branch of the vagal (Xth) nerve. These nerve fibers are arranged topographically from rostral to caudal with the facial nerve endings being in the rostral parts of the NST and the vagal nerve fibers ending in its caudal part. After the first relay of the taste neurons, gustatory information travels to the hypothalamus and the parvocellular ventromedian nucleus (VPMpc) of the thalamus in primates
stimulation of the Gustatory
Back of oral cavity/tongue Often unpleasant bad, nasty Metallic /aluminum Facial expression of disgust
Viscero-sensory cortex?
External medial parabranchial ncl Caudal Ncl of Solitary tract Lateral VPMpc (ventromedian) Insula (gr) Organotopic Anterior GI Posterior Cardiov/breathing
What is the evidence for the hypothesis of Insula being the central cortical projection of NST
Insular lesion that produced isolated dysphagia
What is the definition of general somatosensation?
''Tingling'' ''Feeling of pulsation'' ''Feeling of vibration'' ''Feeling of numbness'' in different body parts contralateral
What elicited whole body sensations?
Two electrode contacts in the most ventral part of the posterior Insula
Where was the specific and non-specific somatosensations localized?
Posterior-dorsal area of Insula
Immediately posterior to the viscerosensory sensations and gustatory responses
Sensory areas detected in the ins human Insula
Electrocortical stimulation
- Gustation
- Thermosensation
- Pain
- Viscerosensation
