The Cortex Flashcards
Gyri
plural: singular = gyrus) -
- convolution or bump
- protruding rounded surfaces (folds)
- hills
Sulci
(plural: singular = sulcus)
- valley between gyri or enfolded regions that appears as surface lines (gaps between gyri)
Fissure
very deep sulcus
What do the sulci and gyri function in?
Sulci and gyri maximize surface area - triples area of the brain.
What is cortical folding correlated with?
The degree of cortical folding is correlated with intelligence.
Opossum has a very smooth brain, cats have more sulci and gyri, chimpanzees have lots of cortical folding
Bottlenose dolphins have even more cortical folding than us- maybe could be more intelligent than us
Corpus Callosum
Thick band of nerve fibers that connect the left and right hemispheres.
How are sulci and gyri created
Cortical material is folding in on itself and creating these valleys and hills
What is the cortex?
The wrinkly brain tissue outside of the brain
grey matter
dendrites and synapses
is made up of non-myelinated cells that have a layered appearance in cross section according to different cell types and groupings.
white matter
axons
is made up of myelinated axons or fiber tracts
Describe specializations of the human brain
- larger representations of the hands- we use tools
- neocortical specializations for speech- we can speak
- extreme hemispheric specialization- left hemisphere is dominant in speech
- expanded prefrontal cortex- executive area of brain is much larger
What does the cortex look like?
Very layered, rock like
Layers are different cell differentiation
Coretx generally had 6 layers but size and shape of cells and thickness of layers differs across brain regions.
Cytoarchitecture
the cellular composition of a bodily structure
- architecture of the cells
Longitudinal fissure
Also known as the interhemispheric fissure as it divides the 2 hemispheres
What is a myth
The myth that the left is dedicated to logic and right is creativity is not true
Left and right do control diff body movements
Language- left
Attention-right
Corpus Callosum
Thick band of nerve fibers that connect the left and right hemispheres.
What differs across species?
Proportions of brain also differ across species
Humans have way more brain devoted to neocortex than
- could be a indication of intelligence
What else is correlated with intelligence?
The proportion of frontal cortex to the rest of the brain is also thought to be correlated with intelligence.
What is on either side of the central sulcus?
we have the sensory cortex (somatosensory- touch feeling) and motor cortex
Brodman’s areas
Cytoarchitectonically defined regions (assigned numbers).
Cytoarchitectonics
cellular organization differs across regions.
What is Area 17?
primary visual cortex
Cortical topography
refers to the practice of ‘mapping’ functions (e.g., motor control) onto specific regions of the brain.
Hughlings Jackson
first noticed that specific body parts were involved in specific epileptic seizures – the Jacksonian march.
- Seizure starts in one area of the body and then spread to other areas
Proposed a “map” of the body in the brain – the homunculus.
- Seizures are caused by to much electrical activity in the brain
Why do the hand and face regions “get” more cortex than other regions?
more fine motor control or more touch receptors than other areas.
More sensitive the area the more involved in motor control and more brain area they get
What did Penfield do?
Stimulated areas of the brain and saw what happened (mapping out the brain) ; cortical topography
Did this because they didn’t want to accidentally remove an important part of the brain that had an important function
What is phantom limb pain?
Limb amputation often leads to phantom limb pain.
The phantom limb can be mapped onto the face (Ramachandran).
Hand representation actually next to chin (Servos - fMRI).
probably due to fetal position (Farah).
same would be true for feet and genitals being close together
Occipital Lobe
Important for visual system
upper bank of calcarine (cuneus)
lower visual field(everything below the horizon)
lower bank of the calcarine (lingual)
upper visual field(everything above the horizon)
Retinotopy
mapping the visual world onto the visual cortex.
Scotoma
small lesion on visual cortex
- have a blindspot
Quadrantanopia
largerlesion on visual cortex that results in blank section that is full quadrant of visual field
Hemianopia
all of the visual cortex on half the brain is damaged- cant see half the visual world
Areas of the brain that have.______
higher acuity get more larger section of cortex
Parietal Association Cortex
integrates sensory information from multiple modalities(sensory and motor systems)
goal directed actions.
What can damage to the Parietal Association Cortex lead to?
Damages can lead to visual and motor disturbances
What happens when the superior parietal cortex is damaged?
optic ataxia, Balint’s syndrome.
Problem with visually guided movements, if your close your eyes you can make these movements fine but if you try to visually guide the movements you aren’t able to
What can left inferior parietal damage lead to?
apraxia.
Difficulty with hand movements
What can right inferior parietal damage lead to?
hemi spatial neglect.
Somatosensory cortex:
concerned with the conscious perception of touch, pressure, pain, temperature, position, movement and vibration.
What is Hemi spatial Neglect?
damage to the right parietal lobe often results in a failure to attend to or represent information appearing on the left side of space despite intact sensory processing and visual acuity.
- Not just visions but also auditory and perceptual
- Not related to a hemianopia
- Almost like the concept of left itself is imapired
- debilitating in everyday life
unable to construct adequate representations of the left side of space.
ex- if you approach them on their left side they wont see or hear you
Temporal Cortex
- auditory processing
- language – Wernicke’s area
- object and facial recognition
- Memory
- emotional processing – the limbic system
What can damage to the temporal cortex cause?
(damage causes agnosia and prosopagnosia- inability to recognize faces)
Primary auditory cortex:
The region of the superior temporal lobe whose primary input is from the auditory system.
Insular cortex
A sunken region of the cerebral cortex that is normally covered by the rostral superior temporal lobe and caudal inferior frontal lobe.
Frontal Cortex
- executive control – planning and guiding behavior, judgement.
- damage can lead to personality changes, disorganized behavior, disinhibition and inappropriate social behavior, rigidity in thought, emotional lability (inappropriate laughing or crying).
- not fully developed until late teens/early twenties.
Describe what happened to Phineas Gage
injured by a tamping iron piecing his skull
probably affected both frontal lobes to some degree (perhaps left > right).
recovered but wasn’t the same.
became socially inappropriate, had difficulty maintaining a job.
eventually became a sideshow attraction in Barnum and Bailey’s Circus (actually traveled with the tamping iron that had caused his injury).
Gages injury would’ve been like Alzheimer’s disease
Primary motor cortex:
The region of the posterior frontal lobe that contains neurons that control movements of skeletal muscle.
How is the motor cortex organized?
left motor strip represents right sided motor control and vice versa.
same organization for the somatosensory strip.
Touch and motion are contralaterally organized
Sensory association cortex:
Those regions of the cerebral cortex that receive information from regions of the primary sensory cortex.
Motor association cortex
The region of the frontal lobe rostral to the primary cortex; also known as the premotor cortex.
A bulge located between the adjacent grooves in the surface of the human cortex would be termed a_____
gyrus.
After sustaining a stroke involving the right parietal lobe, Mr. M continued to show problems in
A) understanding speech.
B) producing speech.
C) repeating words.
D) moving his right arm and leg.
E) grasping an object on the left.
E) grasping an object on the left.
The planning and execution of movements is a function performed by association cortex in which cortical lobe?
frontal
Damage to the occipital cortex may result in which of the following?
A) problems in naming a song they knew before sustaining brain damage
B) difficulty in playing a tune on a piano
C) difficulty in naming an object the person can touch (but not see)
D) problems in recognizing an object by sight
E) an inability to recognize a familiar odor
D) problems in recognizing an object by sight
Which of the following would be expected as a result of damage to the somatosensory association cortex?
A) problems in recognizing an object by sight
B) difficulty in playing a tune on a piano
C) difficulty in naming an object the person can touch (but not see)
D) problems in naming a song they knew before sustaining brain damage
E) an inability to recognize a familiar odor
C) difficulty in naming an object the person can touch (but not see)
