CORTICAL ORGANISATION AND FUNCTION Flashcards
How many layers is the cerebral cortex organised into?
6 layers
How many areas is the cerebral cortex split into based on cytoarchitecture?
52 regions
List the functions of the frontal lobe
Regulating and initiating motor function, language, cognitive functions, attention, memory
List the functions of the parietal lobe
Sensation - touch, pain
Sensory aspects of language
Spacial orientation, self-perception
What is the function of the occipital lobe?
Processing visual information
What is the function of the temporal lobe?
Processing auditory information
Emotion
Memories
What does the limbic lobe contain?
Amygdala, hippocampus, mamillary body, cingulate gyrus
What is the limbic lobe concerned with?
Learning, memory, emotion, motivation and reward
What is the insular cortex concerned with?
Visceral sensations, autonomic control, interoception, auditory processing, visual-vestibular integration
What makes up grey matter in the brain?
Neuronal cell bodies and glial cells
What makes up white matter?
Myelinated neuronal axons arranged in tracts
Describe the 3 types of white matter tracts in the brain
Association fibres - connect areas within same hemisphere
Commissural fibres - connect homologous structures in left and right hemispheres
Projection fibres - connect the cortex with lower brain structures (e.g. thalamus, brain stem and spinal cord)
Which association fibre connects the frontal and occipital lobes?
Superior longitudinal fasciculus
Which association fibre connects the frontal and temporal lobes?
Arcuate fasciculus
Which association fibre connects the temporal and occipital lobes?
Inferior longitudinal fasciculus
Which association fibre connects the frontal and temporal lobes?
Uncinate fasciculus
Name 2 commissural fibres
Corpus callosum, anterior commissure
What do projection fibres present as in the cortex?
Corona radiata
Where do projection fibres converge through?
Internal capsule between thalamus and basal ganglia
Whats the difference between primary and secondary/association cortices?
Primary - function predictable, organised topographically, symmetry between left and right
Secondary - function less predictable, not organised topographically and weak symmetry or none at all
Name the areas secondary to the primary motor cortex and what they do
Both involved in planning complex movements
Supplementary area - internally cued (e.g. speech)
Premotor area - externally cued (external stimuli e.g. seeing object and reacting to it)
Name the area associated with the primary somatosensory cortex and its function
Somatosensory association area - interprets the significance of sensory info e.g. recognising an object placed in your hand
Also gives awareness of self and personal space
Name the area associated with the primary visual cortex
Visual association area - gives meaning and interpretation of visual input
Name the area associated with the primary auditory cortex
Auditory association area - gives meaning and interpretation to auditory input
What does it mean when I say that the primary auditory cortex is tonographic?
Different frequencies of sound are mapped onto different parts of the auditory complex
What is Broca’s area?
Motor production of language
What is Wernicke’s area?
Sensory understanding of language
What does the prefrontal cortex control?
Attention, adjusting social behaviour, planning, personality expression, decision making
What can a frontal lobe lesion present as?
Changes in personality
Inappropriate behaviour
What can a parietal lesion present as?
Contralateral neglect
e.g. lack of awareness on self on contralateral side (internal neglect)
lack of awareness of extrapersonal space on contralateral side (external neglect)
What can a lesion in the temporal lobe present as?
Agnosia - inability to recognise
What can a lesion in Broca’s area present as?
Expressive aphasia - poor production of speech
What can a lesion in Wernicke’s area present as?
Receptive aphasia - poor comprehension of speech
What can a lesion in the primary visual cortex present as?
Blindness in corresponding part of visual field
What can a lesion in the visual association area present as?
Deficits in interpretation of visual information e.g. prosopagnosia (inability to recognise familiar faces or learn new faces)
Name 2 imaging techniques to see cortical function
Positron emission tomography (PET)
Functional magnetic resonance imaging (fMRI)
How does PET work?
A radioactive isotope is bound to glucose which is carried by the blood and allows viewer to see which part(s) is undertaking activity when patient carries out specific task
How does fMRI work?
Allows you to see the amount of blood oxygen in a brain region whilst subject performs task
What is the difference between EEG and MEG?
EEG - electroencephalography - measure electrical signals produced by brain
MEG - magnetoencephalography - measure magnetic signals produced by brain
EEG is often used in the diagnosis of which condition?
Epilepsy due to out of control depolarisation of neurones in brain
How do somatosensory evoked potentials help to recognise an abnormal nervous system?
A series of waves that reflect sequential activation of neural structures along the somatosensory pathways is created. These waves should occur at specific times after stimulation in normal people
What is transcranial magnetic stimulation (TMS)
Use of electromagnetic induction to stimulate neurones and allows the assessment of functional integrity of neural circuits
What is transcranial direct current stimulation (tDCS)
Use of low direct current over the scalp to increase or decrease neuronal firing rates
What is an imaging techniques used to asses structure of the brain?
Diffusion tensor imaging (DTI) - based on the diffusion of water molecules showing the pathways of the brain
