Lecture 18 Cerebral cortex Flashcards
What are the 3 kinds of gray matter in the cortex?
Granular
Pyramidal
Interneurons
True or false: the cortex has a cellular layer and a purkinje layer
False
What is the major output cell of the cortex?
Pyramid cells
Each layer of the cortex has 6 layers except….
Olfactory and medial temporal corticies, they have 3
True or false: motor and sensory neurons extend down to the sulcus of the gyrus
True
Brodmann’s areas are particularly helpful during __________
Surgical techniques and research (measure cortical activity)
Primary somatosensory cortex -> Secondary somatosensory cortex -> _______________________ -> _____________________ -> Primary motor cortex
Association cortex
Motor planning areas
what part of the cortex sends descending motor signals?
Primary motor cortex
What part of the corticies differentiates intensity and qualities of sensory info?
Primary sensory cortex
What part of the cortex handles more complex sensory processing/ recognition of sensations
secondary sensory cortex
Where is the primary somatosensory cortex found?
Postcentral gyrus
Where is the auditory cortex found?
Within lateral fissure and superior temporal lobe
What cortex is found within calcarine sulcus and adjacent gyri
visual cortex
What cortex is found within posterior end of lateral fissure and parieto-insular cortex
Vestibular cortex
Which part of the visual cortex analyzes color and movements?
Secondary visual cortex
The secondary visual cortex projects to the _____________ to guide visual fixation keeping item in central vision
superior colliculus
what cortex constrasts sounds heard from memories and categorizes them?
Secondary auditory cortex
vast collection of cell bodies, axons and dendrites covering the surface of the cerebral hemispheres
cerebral cortex
-goal selection,planning monitoring
-interpretation of sensation
-emotions, memory processing
which functional category of cerebral cortex is this?
association cortex
which functional category of cerebral cortex is this?
movement composition, sequencing
motor planning areas
what receives sensory info from thalamic nuclei
primary somatosensory cortex
primary sensory cortex discriminates among different intensities and qualities of sensory input all but?
-somatosensory
-auditory
-visual
-vestibular
OLFACTION does not go thru thalamus
what discriminates shape, texture, and size of objects
primary somatosensory cortex
what is conscious discrimination of loudness and pitch of sounds (intensity of sounds)
primary auditory cortex
what distinguishes intensity of light, shape,size and movement of objects
primary visual cortex
what discriminates among head positions and movements relative to gravity
primary vestibular cortex
1
secondary somatosensory cortex
2
secondary visual cortex
3
secondary somatosensory cortex
4
secondary visual cortex
5
secondary auditory cortex
secondary sensory cortex analysis sensory input from?
thalamus and primary sensory cortex
the secondary somatosensory cortex integrates ___ and ___ information obtained from manipulating an object
tactile and proprioceptive
the secondary somatosensory cortex provides ___ and memory of ____ and ___ environment
stereognosis; tactile; spatial
what contrasts sounds heard from memories and categorizes them
secondary auditory cortex
what analyzes color and movement
secondary visual cortex
what receives somatosensory information from our three neuron pathways/ discriminates shapes, textures, sizes
primary somatosensory cortex S1
what is the function of the secondary somatosensory cortex S2
-process and refine info analyzed in S1
-integrates info from both sides of body (body awareness in space and understanding body as whole)
-involved in attention, learning and memory
-stereognosis and memory of tactile and spatial environment
what integrates info from both sides of body (body awareness in space and understanding body as whole)
secondary somatosensory cortex S2
what is secondary sensory and association cortex
posterior parietal cortex PPC
what receives projections from S1,S2,visual system and others involved in attention and motivation, forming the highest level of somatosensory processing
posterior parietal cortex
what sends output to motor system and critical for integration of sensory and motor info (sensorimotor integration), motor planning and spatial awareness
posterior parietal cortex
the primary auditory cortex receives information from _____ via a pathway that synapses in the _____ and ______ before reaching the cortex
bilateral cochlea
inferior colliculus and medial geniculate body (thalamus)
what classifies the sound
secondary auditory cortex
the primary vestibular cortex perceives head movement and position relative to gravity via ___ nuclei ipsilaterally and contralaterally
vestibular nuclei
describe primary visual cortex when info travels from retina to ______ (thalamus) to primary visual cortex
lateral geniculate body (you would be goofy if your eyes were more lateral to your ears)
does the secondary or primary visual cortex have streams
secondary
information processed by the secondary visual cortex flows in two directions
- dorsally: action stream –> from secondary visual cortex DORSALLY thru PPC to frontal lobe
- adjusts limb movements
2.ventrallly: perception stream –> from secondary visual cortex VENTRALLY to temporal lobe
-recognizing objects
these two streams are ind of each other
what are other association cortices that are not directly involved with sensation or movement?
1.parietotemporal association cortex
2. dorsolateral prefrontal cortex
3.ventral and medial dorsal prefrontal association cortices
what association cortex is for problem solving
parietotemporal association cortex
what association cortex constructs image of own body and planning movements
pareitotemporal association cortex
where does secondary somatosensory cortex project to
motor and limbic areas
S2’s projections to limbic areas connect sensory experiences (like touch or pain) to emotional and motivational responses.
S2’s projections to motor areas help to integrate sensory information with the motor system to guide future movements or actions based on what you feel.
A lesion to the secondary somatosensory cortex causes what?
astereognosis
A lesion to the secondary visual cortex causes what superiorly and what in the middle portion?
Superiorly: optic ataxia
Middle portion - Visual agnosia
Lesion to the secondary auditory cortex causes what?
auditory agnosia
What cortex is responsible for discriminating shapes, texture, size
primary somatosensory
The secondary somatosensory cortex projects to __________ and _________
Motor and limbic areas
what cortex has the highest degree of convergent somatosensory info?
Posterior parietal cortex
note: it’s a secondary sensory and association cortex
Outputs of the _____________ are critical for integration of sensory and motor info
posterior parietal cortex
The primary auditory cortex does what?
Allows awarenes of intensity and sounds
the primary auditory cortex receives info from the cochlea of both ears through pathways that synapse in the ___________ and _______________ (thalamus)
inferior colliculus -> medial genticulate body
True or false: The vestibular cortex is well defined
False, not well defined
Some sources have primary vestibular cortex in only _____ hemisphere and some evidence says its in both hemispheres
right
What are the two streams of the secondary visual cortex
action stream (dorsal)
-adjusts limb movement
perception stream (ventral)
-recognizes objects
The secondary visual cortex perception stream runs where?
ventrally to temporal lobe
The secondary visual cortex dorsal stream runs where?
dorsally through posterior parietal cortex to frontal lobe
1
Medial dorsal prefrontal cortex
perceives others emotions/beliefs and makes assumptions about what others believe and their intentions/personality/emotions/motivation
2
ventral prefrontal cortex
-mood and affect
3
parietotemporal association lobe
-intellegence (includes wernicke)
what is at the junction of parietal,occipital, and temporal lobes
parietotemporal association cortex
Wernicke’s area is contained in what cortex
parietotemporal association cortex
What cortex is involved in intellegence, problemsolving, and understanding communication
parietotemporal association cortex
What does the dorsolateral prefrontal cortex do?
self awareness/executive functions
remember, it’s dorsal bc you have to take a step back and observe yourself to have self awareness
what does the ventral and medial dorsal prefrontal association cortices do
impulse control,reactions to surroundings
which association cortex deals with mood and affect (observable demeanor)
ventral prefrontal association cortex
The premotor cortex contains ________% corticospinal neurons especially from trunk and shoulder
20-30
which perceives others emotions and makes assumptions about what others believe and their intentions, personality, emotions, motivation
medial dorsal
what cortex is for anticipatory postural adjustments, and execution and planning?
pre-motor cortex
What cortex is for motor planning, mvmt initiation
supplementary motor cortex
which cortex is for planning bimanual and sequential movements
supplemental motor area SMA
The source of most corticospinal tract neurons is in the……
primary motor cortex
what cortex is for execution and controls contralateral fractionated movements
primary motor cortex
remember it’s contralateral bc the corticospinal tract is contralateral
damage to what cortex causes flexion or extension synergies?
primary motor
bc you lose the ability to do fractionated movement
What is prosopagnosia
Disorder of ventral visual stream
inability to recognize faces but can describe facial expressions
Disorders of _____________ can cause visual object agnosia
ventral visual stream
what is auditory agnosia
can percieve sounds but cannot recognize them
if the lesion affects left secondary auditory cortex, the person is unable
to understand speech
if the lesion affects the right secondary auditory cortex, it interferes with
interpretation of environmental sounds
ex: inability to differentiate b/w sounds of footsteps and doorbell
-disorder of secondary auditory cortex
What is anosagnosia?
inability to recognize deficits
ex: someone with hemiparesis stating can walk
-occurs in people with severe hemiparesis and personal neglect
-some people believe the limb belongs to someone else
-associated with lesion to right anterior insula
loss of visual info from one hemifield
homonymous hemianopsia
a complete lesion of the visual pathway anywhere posterior to the optic chiasm results in loss of info from contralateral visual field
Is astereognosia a problem with the primary or the secondary somatosensory cortex?
secondary
note: they have intact sensation but still cannot describe object in hand
pt must be able to physically manipulate objects to test this
Disorders of the dorsal visual stream cause what?
optic ataxia
-inability to use visual info to direct eye movement
does optic ataxia affect ability to consciously percieve visual info
no
optic ataxia occurs with damage to
dorsal visual stream in parietal lobe
The most common neglect disorder happens on the ______ side
left, because R parietal cortex dominates attention
What cortex dominates control of attention
right parietal cortex
True or false: damage to primary motor cortex can cause dysarthria
true
also weakness and loss of fractionated limb movement
Broca’s area is inside of what gyrus
inferior frontal gyrus
damage to the supplementary motor cortex
acutely a person will show _______________
hemiparesis/hemiplegia
(only acutely/right after)
damage to the premotor cortex leads to what?
Problems w/
speed/automaticity of reaching grasping
movement sequencing
posture and gait
Uncontrolled repetitive movements are called what?
Perseveration
note: due to damage of motor planning areas
ideational apraxia is…
inability to use objects appropriately especially when sequencing is necessary
ideomotor apraxia is what?
inability to develop movement sequence especially to a command
note: they can still do it instinctively/automatically when not thinking about it
What is magnetic gait?
Person has extreme difficulty lifting foot from floor to initiate gait
What are the 4 As of cerebral cortex disorders
Aphasia
Apraxia
Agnosia
Asterognosis
What are functional neurologic disorders
-used to be called conversion/psychogenic disorder
-not a psychiatric or psychological disorder
genuine motor and sensory dysfunction unexplained by medicine
worse or different symptoms than expected from testing
Complex regional pain syndrome and persistent perceptual postural dizziness are examples of…
functional sensory disorders
If a person has absent proprioception during testing but is able to do a finger to nose task with eyes closed or tandem walk, they might have…
functional sensory disorder
Functional movement disorders have test findings that are….
not consistent with preformance
What is a hoover sign?
indicative of functional movement disorder
Weak hip extension initially but then with contralateral hip flexion, the hip extensors will activate strongly
What is whack-a-mole sign
indicative of functional movement disorder
tremor moves to another body part when you restrain it
What is give-way weakness?
indicative of functional movement disorder
strong but then abrupt collapse without pain (when resisting MMT i guess)
READ THIS!!!
Mechanoreceptors:
Specialized receptors in the skin, muscles, and other tissues detect mechanical stimuli (touch, pressure, vibration, proprioception).
- Spinal Cord:
The sensory information travels from mechanoreceptors to the spinal cord via sensory neurons.
Information ascends through pathways like the dorsal column-medial lemniscal pathway (fine touch, vibration, proprioception) or the spinothalamic tract (pain, temperature).
- Medulla:
Sensory information enters the medulla and synapses in the nucleus gracilis and nucleus cuneatus.
After processing, the sensory information crosses to the opposite side (decussates).
- Thalamus (Ventral Posterior Nucleus):
The sensory information is relayed to the thalamus, which acts as the major relay station for sensory signals. - Primary Somatosensory Cortex (S1):
The thalamus sends the information to the primary somatosensory cortex (in the postcentral gyrus of the parietal lobe), where basic sensory processing occurs. - Association Fibers:
Complex sensory information is sent through association fibers connecting different regions of the brain for further analysis and integration. - Secondary Somatosensory Cortex (S2):
The secondary somatosensory cortex processes more complex sensory information, combining both sensory and motor input. - Memory Integration (Association Areas):
The processed information can be sent to various association areas (in the temporal, frontal, and occipital lobes) for memory formation, cognitive processing, and the formation of perceptual experiences.
The hippocampus encodes sensory information into long-term memory.
- Posterior Parietal Cortex:
The posterior parietal cortex integrates sensory information, especially related to spatial awareness and body positioning.
It helps guide movements based on sensory input and is involved in higher-order functions like perception of objects and their relative locations.
After the Posterior Parietal Cortex, the pathway branches into multiple routes:
Motor Response:
The information is sent to the premotor cortex and/or primary motor cortex for generating voluntary motor commands based on sensory input.
The primary motor cortex then sends motor commands down through the corticospinal tract to initiate movements.
Memory and Cognitive Processing:
Processed sensory information can be sent to the association areas in the frontal and temporal lobes for decision-making, problem-solving, and other higher cognitive functions.
The hippocampus integrates sensory experiences into memories.
Integration with Other Sensory Systems:
The posterior parietal cortex can communicate with other sensory regions (such as visual, auditory, and somatosensory areas) to integrate multimodal sensory input.
This integration helps form a holistic perception of the environment, such as combining touch with vision to understand spatial relationships.
Emotional Processing:
Information may be sent to the limbic system (including the amygdala and cingulate gyrus) for emotional responses related to the sensory experience.
Language Processing:
If the sensory information involves language (e.g., reading or speech), it may be sent to Wernicke’s area (for language comprehension) and Broca’s area (for speech production), both of which are located in the left hemisphere.
Visual-Spatial Integration:
The processed sensory information may also go to the occipital lobe for visual processing or the temporal lobe for object recognition and complex visual-spatial tasks.
This helps form a comprehensive understanding of the environment and is important for tasks like object identification or navigation.
Complete Pathway:
Mechanoreceptors → 2. Spinal Cord → 3. Medulla → 4. Thalamus → 5. Primary Somatosensory Cortex (S1) → 6. Association Fibers → 7. Secondary Somatosensory Cortex (S2) → 8. Memory & Cognitive Areas → 9. Posterior Parietal Cortex →
After Posterior Parietal Cortex:
Motor Response → Premotor Cortex/Primary Motor Cortex
Memory & Cognitive Processing → Association Areas/Hippocampus
Integration with Other Sensory Systems → Visual, Auditory, Somatosensory Integration Areas
Emotional Processing → Limbic System (Amygdala, Cingulate Gyrus)
Language Processing → Wernicke’s Area/Broca’s Area
Visual-Spatial Integration → Occipital and Temporal Lobes
