internal brain - limbic system

what is the limbic system

part of the brain responsible for behaviour and emotion

terms:

• lentiform nucleus is made of

• striatum is made of

• corpus striatum is made of

Lentiform nucleus: putamen and globus pallidus  

Striatum: caudate nucleus and putamen  

Corpus striatum: striatum and globus pallidus (or caudate N, globus pallidus and putamen) 

what is:

• putamen

• globus pallidus

• caudate nucleus

• basal ganglia

• putamen - part of BG involved in regulating motor movements

• globus pallidus - part of BG regulated voluntary movement, muscle tone

• caudate nucleus - pair of c shaped structures forms part of BG

• BG - group of nuclei resp for motor control, emotion processing

what is the thalamus - structure and location

• what info does it receive

• motor involvement 2

• interconnected with which system

• Oval mass of grey matter protruding the 3^rd ventricle  

• Receives nearly all sensory information on the way to cerebral cortex, integrates and directs information to appropriate area  

• Motor involvement: mainly with basal ganglia and cerebellum  

• Interconnected to limbic system, involved in emotional and memory functions  

limbic system

• what structure does it surround

• what is limbus

• which 3 systems does it link to

• A system of interconnected subcortical structures within the brain (on both sides) largely forming a ring around the corpus callosum  

• Limbus = margin, ring 

• Linked to autonomic, immune, neuroendocrine systems  

what are the 5 Fs

• fight

• flight

• freeze/fear

• fornicating

• feeding

functions of limbic system

• 5 F’s 

• Autonomic preparation, memory formation/recall 

• enjoyment 

what structures are part of limbic system

• A

• Hc

• Ht

• T

• CG

• ERC

• OB

• F

• MB

• Amygdala: Processes emotions, particularly fear, aggression, and social cues.

• Hippocampus: Responsible for forming new long-term, declarative memories.

• Hypothalamus: Regulates hunger, thirst, sexual arousal, sleep, blood pressure, and hormone production

• Thalamus: Relays sensory information and is involved in emotional processing (specifically anterior/mediodorsal nuclei).

• Cingulate Gyrus/Cortex: Located above the corpus callosum, it manages emotion, behavior, and pain processing.

• Entorhinal cortex – the hippocampus receives its major cortical input from medial entorhinal cortex(MEC) and lateral entorhinal cortex (LEC) 

• Olfactory Bulbs: Process the sense of smell and link it to memories and emotions.

• Fornix: A fiber bundle that acts as the primary output tract for the hippocampus.

• Mammillary Bodies: Involved in memory recollection.

what are the 4 categories of function in the LS

1. Emotions/drives via AMYGDALA 

2. Homeostasis/motivation (autonomic and neuroendocrine) via HYPOTHALAMUS 

3. Olfaction via OLFACTORY CORTEX 

4. Memory formation (learning) via HIPPOCAMPUS  

what structure is responsible for

• emotions

• homeostasis

• olfaction/smell

• memory formation

• emotions - AMYGDALA

• homeostasis - HYPOTHALAMUS

• olfaction/smell - OLFACTORY CORTEX

• memory formation - HIPPOCAMPUS

whaat is the hypothalamus composed of

• what does it include

• where is it

• what does it release, whats its functions

• what does the supraoptic nucleus produce

• what does the paraventricular nucleus produce

• Composed of numerous nuclei that have afferent and efferent connections with widespread regionsof the NS  

Includes: 

• Pituitary gland 

• ANS 

• Limbic system  

• Most ventral (ant) part of diencephalon  

• Lies beneath the thalamus and ventromedial to the subthalamic nucleus 

• Releasing factors that act on the pituitary are released by the hypothalamus  

• Supraoptic nucleus produces ADH (vasopressin) 

• Paraventricular nucleus – oxytocin (induced by suckling, stimulates milk production), stim) 

what is the fornix

• where does it travel over

• what is it the output of

• Arch shaped bundle of fibres 

• Travels over diencephalon 

• Output of hippocampus  

what are the mammillary bodies

• involved in

• part of which structure

• Involved in memory formation  

• Part of hypothalamus  

where is the hippocampus found

• function

• where does it receive memory from

• Found in temporal lobe  

  Essential in memory consolidation and learning  

• Receives information from all sensory association areas  

amydgala

• location

• function

• what is it connected to

• main output to hypothalamus via which function

• Lies near temporal pole at the tip of the tale of the caudate nucleus  

• Provides an emotional component to experiences and memory, the ability to recognise fear in others  

• Has extensive connections with all cortical association area allowing integrative function between perception and emotion  

• Main output to hypothalamus via stria terminalis  

olfactory system

• does it have thalamic relay

• where does it travel to

• OS has which type of neurons, does it form ganglions

1. no thalamic relay, central projection of olfactory structures reach parts of the temporal lobe and amygdala without thalamic relay  

2. whole olfactory nerve consists of numerous bipolar neurons, whose cell bodies do not form a ganglion  

3. primary neurons continuously replaced  

what are the 3 olfactory deficits

• H

• D

• A

1. Hyposomnia (partial loss of smell) 

2. Dysosmia (distorted smell) 

3. Anosmia (complete loss of smell) 

what are the 3 different association cortices

• Prefrontal, inferior temporal and parietal-temporal-occipital 

what do each association cortices do

• Prefrontal

• inferior temporal

• parietal-temporal-occipital 

• Prefrontal AC - in frontal lobe, handles planning, decision making, personality

• inferior temporal AC - visual processing, recognising faces, objects

• parietal-temporal-occipital AC - located at the junction of the 3 lobes, spacial awareness, multi sensory information 

where do all limbic components project into

the hippocampus

brain affects from alzheimers

Clinical features  

• Memory loss 

• Progressive disorientation  

• Loss of learned motor skills and language  

• Behaviour and personality changes  

• Mood disturbance  

• Bedridden and mute  

 

First effects: hippocampus  

• Anterograde amnesia, unable to form new memories  

• Shrinks in size  

brain affects from korsakoff syndrome

• Thiamine deficiency, leads to degeneration of dorsomedial nucleus of the thalamus, mammillary bodies, hippocampus and vermis of cerebellum  

• Anterograde amnesia, retrograde amnesia and confabulation  

 

brain affects from klüver-bucy syndrome

• Bilateral temporal lobe lesions (amygdala and hippocampus) 

• Anterograde amnesia  

• Visual recognition impairments (visual agnosia) 

• Heightened sexual appetite (hypersexuality) 

• Loss of fear and conditioning 

• Hyper orality 

• Flattened emotions (placidity)