Neuro 14 - Cerebral cortex and Limbic system Flashcards
What are the 3 types of cerebral white matter?
- Association fibres (in cortex) - connect areas within same hemisphere
- Commissural fibres - connect left hemisphere to right hemisphere. Largest commissural pathway = corpus callosum (joining the 2 hemispheres).
- There is also anterior commissural pathway (basal forebrain)
- Smaller posterior commissural pathway - join the 2 hippocampi posteriorly - Projection fibres - connect cortex with lower brain structures (e.g. thalamus), brainstem and spinal cord. Biggest projection fibre pathway is the corticospinal tract
How many layers does the neocortex have?
Describe the lateral arrangement
6 (for majority of cortex)
Layers 1-3 = mainly cortico-cortical connections
Layer 4 = input from thalamus
Layers 5 and 6 = connections with subcortical, brainstem and spinal cord
The neocortex is arranged in layers (lamina structure) and?
Columns - dense vertical connections. This formed the basis for topographical organisation - neurones with similar properties connected in same column
The posterior border of the frontal cortex is?
Central sulcus
Whatolder part of the cortex can be seen if you retract the frontal, parietal and temporal lobes?
Insula
Describe primary cortices
- Predictable function
- Organised topographically
- Left right symmetry - NB lt part controls right side of body
Where is the primary somatic sensory cortex?
Parietal lobe
Where is the visual cortex
Occipital lobe
Where is the auditory cortex?
Temporal lobe
All taste sensation goes to a single nucleus in the brainstem - the ?
Nucleus solitarius (has CN input from CN7, 9, little bit of 10)
Describe association cortices
- Less predictable function
- Not organised topographically
- Left-right symmetry weak or absent
e.g. language - largely a left based function
Where is the auditory association area?
On the auditory cortex (which is on the superior temporal gyrus)
Where is the visual association area?
Surrounding the visual cortex (calcarine) in the occipital lobe
Where is the sensory association area
Sensory association area provides sensory information from skin and viscera (and taste buds)
Located in parietal lobe
Where is the prefrontal association area
Frontal lobe - quite diffuse
Prefrontal association area involved in behaviours, coordinating information from other areas, etc
Where is motor association area?
Anterior to central sulcus
Motor association area involved in SkM movement
What are the 2 visual pathways (once the PVC has occurred)
- “where” pathway (spatial relationships) - dorsal stream
2. “what” pathway (colour, form)- ventral stream
What may lesions in the visual posterior association area (fusiform gyrus) lead to
Prosopagnosia - inability to recognise familiar faces or learn new faces
What may frontal lobe lesions result in
Lack of planning, disorganised behaviour, diminished concentration and attention span, impaired self-control
What may parietal cortex lesions result in
Post. parietal association cortex = creates spatial map of body in surroundings from multi-modality information
Injury - may cause disorientation, inability to read maps/understand spatial relationships, apraxia (inability to carry out programmed movements), hemispatial neglect
What may temporal cortex lesions cause
Agnosia, receptive aphasia
Temporal lobe involved in language, object recognition, memory, emotion
Patients who have had a callosotomy (removed corpus callosum) have?
Lateralised deficits in function
as commissural pathways compromised, which links the 2 hemispheres
Which hemisphere is dominant for verbal processing?
Left
What is TMS
Transcranial Magnetic Stimulation (TMS)
Magnetic filed induces electric current in cortex –> causing neurones to fire
Can be used to test whether a specific brain area is responsible for a function (e.g. speech)
