Limbic system Flashcards
(25 cards)
Cells in the olfactory bulb
Mitral Cells
Smell in Parkinson’s
Anosmia is common in this
Nose is one of the environmental triggers of Parkinsons along with through the gut
Limbic system function
Maintenance of homeostasis
Agnostic behaviour (fight or flight)
Sexual and reproductive behaviour
Memory
Papez Circuit
Circuit in the brain
Cingulate cortex connects to hippocampus via cingulum bundle
Which connects to hypothalamus by the fornix
This connects to anterior nucleus of thalamus by mamilo thalamic tract
This connects to cingulate cortex by cingulum bundle
Cortex next to hippocampus providing large input and the name of pathway
Entorhinal cortex
Perforant pathway
Alzheimer’s Disease
The progression of it
1 in 20 >65y
1 in 5 >85
Pathology spreads to hippocampus/enterhinal cortex giving short term memory problems
Then spreads to parietal lobs giving dressing apraxia
Then spreads to frontal lobe giving loss of executive skills
Amygdala- location, interconnections, function
Embedded in anterior part of temporal lobe
Highly interconnected
Afferent- olfactory cortex, septum, temporal neocortex, hippocampus, brainstem
Efferent- stria terminalis
Function- Fear and anxiety, fight or flight
Kluver Bucy Syndrome
Completely fearless
Damage to amygdala
Visual agnosia and hypersexuality
Structures associated with aggression
Anterior part of hypothalamus
Brainstem
Amygdala
Septum- location, interconnections and function
Membrane between two lateral ventricles anteriorly
Afferent- amygdala, olfactory erect, hippocampus, brainstem
Efferent- Stria medlars thalami, hippocampus, hypothalamus
Function- reinforcement and reward
Mesolimbic pathway and its relevance with drugs
Known as reward pathway
Dopaminergic neurones located in midbrain and project via median forebrain bundle- going to cortex, nucleus accumbens and amygdala
Drugs effecting- opioids, nicotine, amphetamines, ethanol, cocaine- cause DA release in nucleus accumbens- causing person to feel happy
White matter- 3 types of fibres
Association fibres- connect areas in same hemisphere
Commissural fibres- Connect left to right
Projection fibres- connect cortex with lower brain structures- brainstem and spinal cord
Grey matter- 6 cortical layers
1-3- mainly cortico cortical connections
4 input from thalamus
5-6 connections with subortical , brainstem and spinal cord
Primary cortices
Primary motor Somatic sensory Visual Auditorial Olfactory Gustatory- tesate
Function of each lobe in cortex
Frontal- judgement, foresight
Temporal- language, emotion, memory
Parietal- Spacial map of body in surroundings
Occipital- visual
Visual association cortex lesion
Prosopagnosia-face blindness
Frontal cortex lesions
Lack of planning, disorganised behaviour and
Parietal cortex lesions
Disorientation, inability to read maps or understand spatial relationships, apraxia
Temporal cortex lesions
Agnosia and receptive aphasia
Dominance of both hemispheres
Left- language dominant
Right- spatial processing dominant
Transcranial magnetic stimualtion
Magnetic field induces electric current in cortex causing neurones to fire
Can test whether area is responsible for a function
Transcranial direct current stimulation
Changes excitability of neurones
with anode and cathode
Positron emission tomography (PET)
Uses radioactive tracer to examine where particular molecule e.g dopamine is being absorbed
Magnetoencephalography and electroencephalography
Measures magnetic and electric field
Measures surface activity of brain but not interior structures
