pseudo-unipolar cells
dorsal root ganglion
Biploar nerve cells
special sense organs (ear, eye, nose)
Interneuron
(local processing), is inhibitory or excitatory
short axon
Pyramidal cell
responsible for sending info from the cerebral Cortex
is multipolar with a long axon
Examples of unmyelinated axons are
sensory fibres carrying pain, temperature, itch
unmyelinated axons have what kind of conduction
continuous conduction’ of action potentials due to passive current flow (low conduction)
multiple sclerosis
- Phasic disease
- Demyelination
- Inflammation (T cell/macrophage mediated)
- Conduction block (slowing of propagation)
- Crosstalk (paraesthesia)
- Some re-myelination
- Permanent loss (due cell death/axonal loss)
white matter
contains cell processes and their myelin
appears white because It is fatty
It present centrally in the brain but peripherally in the spinal cord
grey matter
contains cells, processes and synapses
is present peripherally in the brain but centrally in the spinal cord
Astrocyte
metabolic and structural/mechanical support - also present in CNS scar tissue
- control water distribution
- potassium buffering
- ROS scavenging
- Define architecture
- regulate migration/pruning/synaptogenesis
- help maintain but do not make up the BBB
Two types of astrocyte
Fibrous astrocyte found in WHITE matter
Protoplasmic (blobby) astrocyte found in GREY matter
BBB
- A barrier composed of endothelial cells AND their tight junctions
- Integrity highly dependent on astrocyte ‘end feet
- So the barrier consists of endothelial cells and their tight junctions and the astrocytes help to maintain it
Microglial cells
Resident macrophages of the central nervous system
- Phagocytosis and antigen presentation (immune response)
- Synaptic pruning
Ependymal Cells
- Ciliated cuboidal epithelial cells, line ventricle as part of plexus and secrete (also reabsorb) CSF
- CSF (cerebrospinal fluid) – clear, cell-free fluid produced in specialised ependyma on choroid plexus
Lamination - the cerebral cortex layered neocortex
mostly 6: Molecular External granular External pyramidal Internal granular Internal pyramidal
granular layers
stellate interneuron - mostly input and processing locally
pyramidal layers
pyramidal neurons - mostly output
Brodmann areas
Subtle differences in structure (numbered) A great map that relates closely to function Example motor function in area 4
visual cortex is where
the occipital lobe along with motion, object recognition etc.
primary motor cortex - execution of movement
Precentral gyrus
More direct control of motor activity than other motor areas Force, direction and speed of muscle contraction
Premotor cortex
Preparation for action - posture and gait (integration of spatial information and planned movement, grasping)
Posterior parietal cortex
Integrating visual information to formulate motor commands
Association cortex
integration, complex processing of
cognate primary cortex info.
Primary cortex
principal exit (motor) and entry points (sensory)
Unimodal
one type of modality input/output
Polymodal
multiple modal input (e.g. vision and somatic sensation in the dorsal stream)
Damage inferior parietal lobule:
Contralateral neglect (especially right lesions)
Damage in superior parietal –
problems with visuomotor integration (optic ataxia)
Features of frontal lobe damage
(1) Personality changes
(2) Deficits in planning
(3) Perseveration
(4) Primitive reflexes (suckling reflex) (5) Abulia (slowness of intellect)
functions of the frontal lobe
- Contributes to attention
- Morality
- Planning
- Working memory
- Conscious decision making
- Social behavior regulation
Broca’s area damage
Expressive aphasia
Language is reduced to disjointed words and sentence construction is poor Comprehension OK
Wernicke’s
Receptive aphasia
unable to understand/generate meaningful language
Commissural communication
cortex to cortex cross over the midline
association communication
cortex to cortex “stay” on the same side
projection communication
communicate with other structures inside and outside the brain
