CEREBRUM Flashcards
Types of brain cortex
Isocortex (Neocortex or Homogenetic Cortex)
Allocortex (Paleocortex, Archicortex, or Heterogenetic Cortex)
Mesocortex (Periallocortex, Periarchicortex)
Isocortex in which the six layers are clearly evident (such as the primary sensory cortex) is termed ___________
homotypical cortex.
Isocortex in which some of the six layers are obscured (such as the motor cortex and visual cortex) is termed _______
heterotypical cortex
The visual cortex is also known as granular cortex or _______
koniocortex
It is subdivided into paleocortex (rostral insular cortex, piriform cortex, and primary olfactory cortex) and archicortex (hippocampal formation).
allocortex
This type of cortex is found in much of the cingulate gyrus, entorhinal, parahippocampal, and orbital cortices and is intermediate in histology between the isocortex and allocortex
mesocortex
The neurons of the cerebral cortex are of two functional categories: _____________
(1) principal (projection) neurons: corticocortical and corticosubcortical outputs.
(2) interneurons: local information processing.
types of Principal (Projection) Neurons
PYRAMIDAL NEURONS
FUSIFORM, SPINDLE NEURONS
The apex is directed toward the cortical surface. Apical dendrite directed toward the surface of the cortex and several horizontally oriented basal dendrites that arise from its base
PYRAMIDAL NEURONS
types of Interneurons
STELLATE OR GRANULE NEURONS: only type of excitatory interneurons in the cortex. Inh: GABA, stim: ACH
HORIZONTAL CELLS OF CAJAL: found only in lamina I and disappear or are rare after the neonatal period.
CELLS OF MARTINOTTI: multipolar with short branching dendrites and an axon that projects to more superficial layers,
__________consists primarily of a dense network of nerve cell processes among which are scattered sparse interneurons (horizontal cells of Cajal) and neuroglia
LAYER I (MOLECULAR, PLEXIFORM)
________consists of a dense packing of small and medium-sized pyramidal neurons and interneurons intermingled with axons from other cortical layers of the same and opposite hemispheres (association and commissural fibers), as well as axons and dendrites passing through this layer from deeper layers
Layer II (EXTERNAL GRANULAR)
This layer receives primarily axons of neurons in other cortical areas (association and commissural fibers), as well as axons of neurons in extracortical regions such as the thalamus.
LAYER III EXTERNAL PYRAMIDAL
Layer IV is especially well developed in __________
primary sensory cortical areas.
In the primary visual (striate) cortex, this layer is traversed by a dense band of horizontally oriented tha-lamocortical nerve fibers known as the ________
as the external band of Baillarger or the stripe of Gennari
________consists of large and medium-sized pyramidal cells, stellate cells, and cells of Martinotti.
layer 5
he largest pyramidal cells in the cerebral cortex_________ are found in this layer
(cells of Betz)
_______ consists of cells of varying shapes and sizes, including fusiform cells and the cells of Martinotti, which are prominent in this layer.
Layer VI
Layers ______are present in all types of cortex (neocortex, paleocortex, and archicortex).
I, V, and VI
Neurons in lamina V give rise to corticofugal fibers that target _________. Neurons in lamina VI give rise to corticofugal fibers ______
subcortical areas (brain stem and spinal cord)
to the thalamus.
Inputs to the cerebral cortex
Thalamus
Extrathalamic modulatory
Cortex of the same hemisphere (association fibers)
Cortex of the contralateral hemisphere (commissural fiber
Extrathalamic Modulatory Input
Serotonin Dopamine Histamine Noradrenergic Cholinergic GABA
_____project widely in the cerebral cortex with the visual cortex receiving an especially rich serotonergic innervation
serotonin fibers
function of serotonin fibers
pain control, emotion, and sleep.