9. Higher cortical function Flashcards
How many layers is the cerebral cortex arranged into?
6 layers
- containing cells bodies and dendrites i.e. cortex is grey matter
Where are most of the inputs to the cortex from?
From the thalamus and other areas of the cortex
- also from the reticular formation
What is the function of the reticular formation?
maintaining cortical activation (consciousness)
What type of cells are the outputs from the cortex carried in?
Pyramidal neurones
What type of neurons are upper motor neurones?
Pyramidal cells
Where do outputs from the cortex go? (3)
- Outputs can be projection fibres going down to brainstem and cord (e.g. upper motor neurones)
- Outputs can be commissural fibres going between hemispheres (e.g. corpus callosum)
- Outputs can be association fibres connecting nearby regions of cortex in the same hemisphere (e.g. arcuate fasciculus)
What are the general functions of the frontal lobe?
- motor (primary motor cortex)
- expression of speech (Broca’s area)
- behavioural regulation/judgement
- cognition
- eye movements (Contain the frontal eye fields)
- continence
Which parts of the frontal lobes are responsible for behavioural regulation and cognition?
Pre-frontal cortex
Which part of the frontal lobe is responsible for continence?
paracentral lobules
what can damage to the frontal lobe lead to?
o contralateral weakness o expressive dysphasia o impulsive, disinhibited behaviours e.g. sexual inappropriateness, aggression o difficulty with tasks such as complex problem solving, including calculation o problems with conjugate gaze and other eye movement disturbances o urinary incontinence
What are the general functions of the parietal lobes?
- sensory (primary sensory cortex)
- speech comprehension (Wernicke’s area)
- body image and awareness of external environment
- Calculation and writing
- (contain superior optic radiations)
Which parietal lobe is usually responsible for body image and awareness?
Right
What does body image and awareness of external environment relate to?
Seems to be involved with acknowledgement that things (including the body) exist
What does damage of the right parietal lobe lead to?
Neglect
What is neglect syndrome?
Neglect syndrome is when a patient neglects half of space following an injury to the parietal cortex on one side of the brain (contralateral sides?)
- only eat one side of food, shave one side of face etc.
what can damage to the parietal lobe lead to?
o contralateral anaesthesia affecting all modalities
o receptive dysphasia
o neglect.
o affect calculation ability
o contralateral inferior homonymous quadrantanopia
What are the general functions of temporal lobe?
- hearing (primary auditory cortex)
- olfaction (primary olfactory cortex)
- memory
- emotion
- (contain the inferior optic radiations)
Where are the primary auditory and olfactory cortex located?
Auditory: superior temporal lobe
Olfactory: inferiomedial (uncus)
what can damage to the temporal lobe lead to?
o hearing problems o olfaction problems o amnesia o psychiatric disorders o contralateral superior homonymous quadrantanopia
What may temporal lobe epilepsy cause?
can trigger memories, leading to a feeling of deja vu
which structures in the temporal lobe are involved in emotion?
limbic system structures such as the hippocampus and amygdala
What functions are dominant in the left hemisphere of most people? (2)
language and mathematical/logical functions
What functions are dominant in the right hemisphere in most people? (4)
body image, visuospatial awareness, emotion and musical ability
which hemisphere is dominant in speech?
left
what can damage to corpus callous lead to?
o alien hand syndrome
o effects on language processing - present image t left visual field but cannot say name of object as right visual cortex cannot communicate with language centres in left hemisphere
What is alien hand syndrome?
Inability to control the hand as it acts independently
Where is Broca’s area located and what is its function?
- infero-lateral frontal lobe
- sits near mouth/pharynx area of primary motor cortex
- expression of speech
What is Broca’s aphasia?
- partial loss of the ability to produce language
- staccato speech
- non-fleunt
- understand what is being said to them and know what they want to say but cant activate the muscles to say those words
- frustrating for patient
- expressive aphasia
Where is Wernicke’s area located and what is its function?
- parieto-temporal junction
- near primary auditory cortex
- comprehension of speech
What is Wernicke’s aphasia?
- fluent
- nonsensical speech where the patient does not appear to understand what is being said to them
- receptive aphasia
- patient may seem perfectly happy
What connects Broca’s and Wernicke’s area?
arcuate fasciculus (white matter)
What does damage of the arcuate fasciculus lead to?
can cause the inability to repeat heard words
how can large middle cerebral infarct affect speech?
global aphasia where both areas are destroyed leading to virtually no verbal language
function
pathway for repeating a heard word?
- auditory information comes in from primary auditory cortex to wernicke’s areas
- interprets info int language
- language info sent to Broca’s area via arcuate fasciculus
- broca’s area converts it into language of PMC and tells it to produce a pattern of muscle contractions that makes speech
pathway for repeating a heard word?
- visual information comes in from primary visual cortex to wernicke’s areas
- interprets info into language
- language info sent to Broca’s area via arcuate fasciculus
- broca’s area converts it into language of PMC and tells it to produce a pattern of muscle contractions that makes speech
pathway for speaking a thought?
- thought can come from many areas in cortex and converge in wernicke’s area
- interprets thought into language
- language info sent to Broca’s area via arcuate fasciculus
- broca’s area converts it into language of PMC and tells it to produce a pattern of muscle contractions that makes speech
What are the 2 types of memory and what do they relate to?
- Declarative/explicit: facts
- Nondeclarative/implicit: motor skills and emotions
Where are memories stored?
Thought to be stored in a relatively distributed fashion throughout large areas of the brain
where is explicit memory stored?
cerebral cortex
where is implicit memory stored?
subcortical structures (e.g. basal ganglia) and cerebellum
What is short term memory?
Stored for seconds to minutes as a ‘reverberation’ or ‘echo’ in cortical circuits
What is long term memory?
Stored for very long periods in the cerebral cortex, cerebellum etc. (up to a lifetime) following consolidation
What is consolidation?
Converting short term memories into long term memories
What factors influence consolidation? (3)
- emotional context
- rehearsal
- association
What role does the hippocampus play in consolidation?
Helps to consolidate declarative memories
It has multimodal inputs from many brain systems (making it
good at associating stimuli)
It has a role as an ‘oscillator’, facilitating consolidation of
memories in the cortex via its output pathways (primarily the
fornixmammillary bodiesthalamuscortex)
What is long-term potentiation?
key molecular mechanism of
memory consolidation
Causes changes in glutamate receptors in synapses leading to
synaptic strengthening
New physical connections can also form between neurones to
further strengthen connections (axonal sprouting
