Limbic System Flashcards
OLFACTORY SYSTEM can recognise X-Y number of different odours
2000-4000
Where is the Olfactory epithelium
in upper part of nose
primary neurons of the olfactory system are …
Bipolar olfactory neurons
support neurons of the olfactory system are …
Sustentacular cells
- Olfactory receptor cells (bipolar) project into the XX and interact with second order neurons
Olfactory bulb
second order olfactory neurons, which are called project to… (along XX to YYY and then ZZ and ZZ)
to olfactory tract and then split into medial and lateral olfactory stria which then go to the piriform cortex of temporal lobe and orbitofrontal cortex
the 2nd order neurons of the olfactory system are…
mitral cells
Olfactory mitral cells are found in ….
olfactory bulb
the 2 cortices of the olfactory system are….
piriform cortex of temporal lobe and orbitofrontal cortex
ANOSMIA is…
Clinical deficit in response to smell
Loss of smell is common in people developing what? (2)
Parkinson’s (and also Alzheimer’s)
What is the role of the limbic system? (4)
Maintenance of homeostasis vis activation of visceral effector mechanisms, modulation of pituitary hormone release and initiation of feeding and drinking
Agonistic (defence and attack) behaviour
Sexual and reproductive behaviour
Memory
Describe the Papez circuit starting with experiencing an emotional experience in the cingulate cortex:
Describe circuit
Where does emotional colouring interplay?
Where is emotional expression?
Emotional experience -> informs cingulate cortex -> propagates to the hippocampus via cingulum bundle -> hippocampus outputs to the hypothalamus mammillary bodies via the fornix -> hypothalamus outputs to the anterior nucleus of the thalamus via the mammillo-thalamic tract -> this projects to the cingulate cortex again
Neocortex provides emotional colouring to the cingulate cortex
Emotional expression is hypothalamic
Hippocampus: main connections (afferent and efferent?)
What is each pathway involved in?
- Afferent: Perforant pathway- part of the memory encoding process
(also from cingulate cortex) - Efferent: Fimbria/fornix- all about memory and learning
Hippocampus: function? (2)
- Memory and learning
Hippocampus: clinical problems that can arise in the hippocampus? (2)
- Alzheimer’s disease (short-term memory problems), epilepsy (many epileptic foci are in the temporal lobe- where the hippocampus is embedded)
which lobe is the hippocampus in?
Temporal
Hippocampus sits on the floor of the …
lateral ventricle
Fornices of the hippocampus terminate in the…
mammillary bodies of the hypothalamus
Alzheimer’s pathology at the cellular level looks like X and Y
tangles and plaques
Which parts of the brain are affected in the early stages of Alzheimers and what does this lead to
- Hippocampus and entorhinal cortex affected
- This leads to short-term memory problems
Which parts of the brain are affected in the moderate stages of Alzheimers and what does this lead to
- Parietal lobe affected
- This leads to dressing apraxia (inability to dress oneself)
Which parts of the brain are affected in the late stages of Alzheimers and what does this lead to
- Frontal lobe affected
- This leads to loss of executive skills
Amygdala: main connections (afferent (5) and efferent?)
- Afferent Olfactory cortex, septum, temporal neocortex, hippocampus, brainstem
- Efferent Stria terminalis
Amygdala: main functions? (4)
- Fear and anxiety
- Fight or flight
Amygdala: clinical problems can arise in the Amygdala? (2)
- Bilateral damage to amygdala can lead to KLUVER-BUCY SYNDROME
Amygdala: location?
- In the white matter of the anterior part of the temporal lobe
- A medial temporal lobe structure
- No ventricle should be seen on image
- Anterior to hippocampus
What is Kluver Bucy syndrome? (4)
- Hyperorality (putting everything in mouth)
- Loss of fear
- Visual agnosia (can’t recognise things)
- Hypersexuality
Structures associated with aggression? (3 and 1 can be specific)
- Hypothalamus (anterior parts)
- Brainstem (Midbrain- grey matter around the cerebral aqueduct- periaqueductal grey)
- Amygdala
What NT and nuclei is involved in aggression?
is 5-HT (serotonin) in raphe nuclei (just below the PAG)
What is the septum of the brain inbetween
SEPTUM (membrane between the 2 lateral ventricles anteriorly):
Connections of the septum (afferent (4) efferent (3)
- Afferent Amygdala, olfactory tract, hippocampus, brainstem
- Efferent Stria medularis thalami, hippocampus, hypothalamus
Function of the septum?
- Reinforcement and reward
Dopaminergic mesolimbic system neurons in the midbrain have fibres that project via the XXX
the median forebrain bundle
the median forebrain bundle projects to …. (3)
- They go to the nucleus accumbens (area we are interested in) but also the cortex and amygdala
Where does the mesolimbic pathway start?
ventral tegmental area (VTN
What side effect of dopamine pathway potentiation in treating Parkinsons do we have to look out for?
pathological gambling
A, B, C, D and E all increase DA release in the nucleus accumbens
Opioids, nicotine, amphetamines, ethanol and cocaine
