What is the main feature that distinguishes the mammalian CNS from that of lower vertebrates?
The cerebral cortex
What distinguishes the CNS of higher primates from those of other mammals?
Cortical association areas
What do association fibers do?
They connect cortical areas within the same hemisphere (eg., the superior longitudinal fasciculus and the cingulum)
What do commissural fibers do?
They project to homologous areas in the opposite hemisphere (eg., the posterior commissure, anterior commissure, and the corpus callosum)
What do projection fibers do?
They project to subcortical areas, including the thalamus (eg., corticospinal tract, corticobulbar tract, corticothalamic tract)
What are the six layers of neocortex?
I: Molecular; 2: External granule; 3: External pyramidal; 4: Internal granule; 5: Internal pyramidal; 6: Multiform
What are the inputs and outputs of the molecular layer of the neocortex?
Inputs: Brainstem monoamine neurons
Outputs: None
What are the inputs and outputs of the external granule cell layer of the neocortex?
Inputs: Layer III association and commissural neurons from other areas of cerebral cortex
Outputs: Local pyramidal neurons in layers III and V
What are the inputs and outputs of the external pyramidal granule cell layer of the neocortex?
Inputs: Local granule cells in layer II
Outputs: Association and commissural fibers that innervate granule cells in layer II of other areas of cerebral cortex
What are the inputs and outputs of the internal granule cell layer of the neocortex?
Inputs: thalamic neurons
Outputs: Local pyramidal neurons in layers III and V
What are the inputs and outputs of the internal pyramidal cell layer of the neocortex?
Inputs: Local granule cells in layer II
Outputs: Projection fibers that leave the cerebrum
What are the inputs and outputs of the multiform layer of the neocortex?
Inputs: Local granule cells in layers II and IV
Outputs: corticothalamic fibers