Cerebral Cortex 2 Flashcards
Describe the larger structure of the Cerebral Cortex?
Covers surface of the brain and contains grey matter ( deep nuclei )
Highly folded gyri + sulci
Organised into lobes
Describe the microscopic organisation of the cerebral cortex?
Organised into layers + columns:
Layers: I - Molecular II - External granular layer III - External pyramidal layer IV - Internal granular layer V- internal pyramidal layer VI-multiform layer
What is cytoarchitecture?
Cell size, spacing or packing density.
Many areas are shown to relate to function
What are the functions of the 4 lobes?
Frontal : motor function language cognitive functions attention memory
Parietal: touch pain, sensory aspect of language, spatial orientation and self perception
Occipital:
visual info
Temporal lobe:
auditory info, emotion and memory
Limbic lobe?
Amygdala, hippocampus, mamillary body, cingulate gyrus
Insular cortex?
deep within lateral fissure
Concerened with visceral sensations, autonomic control, interoception, auditory processing, visual vestibular integration
What do white matter tracts do?
Connect cortical areas
3 types of fibres make up the white matter tract
What do association fibres do?
What subsplits are there? (4)
Connect areas within the same hemisphere
the superior longitudinal fasciculus connects frontal and occipital lobes
Arcuate Fasciculus - connects frontal and temporal lobes
Inferior Longitudinal Fasciculus - connects temporal and occipital lobes
Uncinate Fasciculus - connects anterior frontal and temporal lobes
What do commissural fibres do?
What subsplits are there? (2)
Connect homologous structure in left and right hemispheres
Corpus callosum
+Anterior commissure
What do projection fibres do?
Connect cortex with lower brain structures
Have afferent fibres towards cortex
Efferent away from cortex
deeper to cortex radiate as the corona radiata
converge through internal capsule between thalamus and basal ganglia
What happens when Primary cortices is localised?
The function is predictable
Organised topographically
Symmetry between left and right
- i think this means the somatosensory and motor cortices, if they are stimulated the results are expected and symmetry means along the head the results occur topographically on both sides
What happens when secondary/association cortices are localised?
function less predictable not organised topographically left-right symmetry weak or absent
What three motor areas are found in the frontal lobe?
Primary: controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.
Supplementary: Involved in planning complex movements (e.g. internally cued)
Premotor area: involved in planning movements (e.g. externally cued)
What areas is the parietal lobe split in to?
Primary somatosensory:
processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.
Somatosensory association
Interpret significance of sensory information, e.g. recognizing an object placed in the hand.
Awareness of self and awareness of personal space
How is the occipital lobe split up?
Primary visual:
Processes visual stimuli
Visual association:
Gives meaning and interpretation of visual input
How is the temporal lobe split up?
Primary auditory:
processes auditorystimuli
Auditory association:
Gives meaning and interpretation of auditory input
What does the prefrontal cortex do?
attention adhisting social behaviour planning personality expression decision making
( noticeable change in personality if affected )
What does the brocas area do?
Production of speech (left side of brain) * know what u want to say but if lesion cannot physcially speak
What does the Wernickes area do?
understanding of language (left side of brain) * don’t understand language coming into brain if lesion
What happens after a frontal lobe lesion?
Changes in personality, inappropriate behaviour
What happens after parietal lobe lesions?
in right hemisphere :
contralateral neglect = lose track of the other side of his body e.g. forget to put left arm and leg into trousers and shirt
and
lack of awareness of self on the left side
Lack of awareness of left side of extrapersonal space
What happens after temporal lobe lesions?
Leads to agnosia = inability to recognise + inability to form memories
Lesions to Broca’s?
Expressive aphasia – poor production of speech, comprehension intact
Lesions to Wernicke’s?
Receptive aphasia – poor comprehension of speech, production is fine
Primary Visual cortex lesion?
Blindness in the corresponding part of the visual field
Visual association lesion?
Deficts in interpretation of visual information e.g.
prosopagnosia - inability to recognise familar faces or learn new faces ( face blindness )
How do PETs work?
Positron emission tomography (PET)
blood flow directly to a brain region
How does fMRIs work?
Functional magnetic resonance imaging (fMRI)
amount of blood oxygen in a brain region
How does EEGs work?
good for evoked potentials
Electroencephalography (EEG)
Measures electrical signals produces by the brain
Series of waves that reflect sequential activation of neural structures along the somatosenory pathways
How does MEGs work?
good for evoked potentials
Magnetoencephalography
Measures magnetic signals produces by the brain
How is brain stimulation done?
assessthefunctionalintegrity of neural circuits
Uses electromagnetic induction to stimulate neurons
Transcranial magnetic stimulation (TMS)
What is a transcranial direct current stimulation - tDCS ?
Uses low direct current over the scalp to increase or decrease neuronal firing rates
What type of imaging is DTI?
Diffusion tensor imaging (DTI)
Based on diffusionof water molecules
What is DTI with tractography?
3D reconstruction to assess neural tracts
