Module 3.2 Definitions Flashcards
Corpus Callosum
Bundle of axons that connects the two hemisphere of the cerebral cortex
-neurons in each hemisphere communicate with neurons in the corresponding part of the other hemisphere through two bundles of axons, corpus Callosum
Cerebral cortex
-the most prominent part of the mammalian brain
-cells on the outside surface of the cerebral cortex are gray matter
& their axons extending inward are white matter
Layers of cells on the outer surface of the cerebral hemisphere of the forebrain
Anterior commissure
Smaller than corpus Callosum
Bundle of axons that connects the two hemispheres of the cerebral cortex
Laminae
The cerebral cortex contains up to six distinct laminae
Layers of cell bodies that are parallel to the surface of the cerebral cortex and separated from each other by layers of fibers
- varies in thickness and prominence from one part of the cortex to another, and a given lamina may be absent from certain areas.
- lamina v (sends long axons to the spinal cord & other areas) thickest in the motor cortex, has the greatest control of the muscles
- lamina lv (receives axons from the sensory nuclei of the thalamus) is prominent in the sensory areas of the cortex-visual, auditory, and somatosensory- but absent from the motor cortex
Columns
Cells of the cortex are organized into columns
Collection of cells having similar properties, arranged perpendicular to the laminae
-not straight
-have similar properties to one another: if one cell column responds to touch on the left Palm, then other cells in that column do too
If one cell responds to a horizontal pattern of light at a particular location, then other cells in the column respond to the same pattern in nearby locations
-each extends through several laminae
Occipital lobe
-at the posterior (caudal) end of the cortex
Is the main target for visual information
The posterior pole of the occipital lobe is known as the primary visual cortex, or striate cortex, because of its striped appearance in its cross section
- destruction of any part of the striate cortex causes cortical blindness in the related part of the visual field
- extensive damage to the striate cortex of the right hemisphere causes blindness in the left visual field
A person with cortical blindness has normal eyes and pupillary reflexes, but no conscious visual perception and no visual imagery (not even in dreams)
People who have eye damage & become blind, but have an intact occipital cortex and previous visual experience, they can still imagine visual scenes and can still have visual dreams.
Eyes provide the stimulus, and the visual cortex provides the experience.
Parietal lobe
Where is it at?
Lies between the occipital lobe and the central sulcus
-monitors all information about eye, head, and body positions and passes it on to brain areas that control movement
-is essential not only for spatial information but for numerical information too!
This overlap is why we use our fingers to count
Central sulcus
One of the deepest grooves in the surface of the cerebral cortex
Postcentral gyrus
Or primary somatosensory
Area just posterior to the central gyrus
Primary receptor site for touch and other body sensations
-touch receptors, mus-cle-stretch receptors, and joint receptors
Includes 4 bands of cells parallel to the central sulcus
Separate areas along each band receive simultaneous information from different parts of the body
Two of the bands receive mostly light-touch information, one receives deep-pressure information, and one receives a combination of both
Temporal lobe
Is the lateral portion of each hemisphere, near the temples.
It is the primary cortical target for auditory information
- In humans, mostly the left temporal lobe, is essential for understanding spoken language
- also contributes to complex aspects of vision, including perception of movement and recognition of faces
- a tumor here may=elaborate auditory or visual hallucinations
- a tumor in the occipital lobe typically evokes simple sensations, like flashes of light
- important for emotional and motivational behaviors
- damage can lead to klüver-Bucy syndrome
Klüver-Bucy syndrome
Temporal lobe!
A behavioral disorder caused by temporal lobe damage
Previously wild and aggressive monkeys fail to display normal fears and anxieties after temporal lobe damage
-may handle a snake because it’s no longer afraid (emotional change) or because it no longer recognizes what a snake is (cognitive change)
Frontal lobe
Extends from the central sulcus to the anterior limit of the brain
Contains the primary motor cortex and the prefrontal cortex
Precentral gyrus
The posterior portion of the frontal lobe just anterior to the central sulcus
Known as primary motor cortex
Specialized for the control of fine movements,
Such as moving one finger at a time
Separate areas are responsible for different parts of the body, mostly on the contralateral (opposite) side but also with slight control of the ipsilateral (same) side
Prefrontal cortex
Most anterior portion of the frontal lobe
Responds mostly to the sensory stimuli that signal the need for a movement
The larger a species cerebral cortex, the larger percentage that the prefrontal cortex occupies
The dendrites have up to 16 times as many dendritic spines as neurons in other cortical areas
Integrates an enormous amount of information
Prefrontal lobotomy
Walter freeman
Surgical disconnection of the prefrontal cortex from the rest of the brain
Common consequences= apathy, loss of the ability to plan and take initiative, memory disorders, distractibility, and a loss of emotional expressions
Lost their social inhibitions, ignoring the rules of polite, civilized conduct. They often acted impulsively because they failed to calculate adequately the probable outcomes of their behaviors.
