Exam 3 Cortex and Cortical Localization Flashcards
Master concepts from Medical Neuroscience Lectures 30, 31 and 32
From which cortical layer do Callosal Fibers originate?
Layer III. These are long-association fibers.
What are Betz Cells?
Large pyramidal cells in Layer V
What type of innervation do Pyramidal Cells provide?
Excitatory via Glutamate
What cortical layer(s) are Pyramidal Cells found in?
All layers except I
Which cortical layers contain predominately Pyramidal Cells?
Layers II, III and V
Which is the most common neuron cell-type in the cerebral cortex?
Pyramidal Cells
From which cell-type do projection axons originate?
Pyramidal Cells
In which cortical layer are Chandelier Cells found?
Layer III
In which cortical layer are Spiny and Aspiny Cells found?
Layer IV
In which cortical layers are Basket Cells found?
Layers III, V
What type of innervation do Granule Cells provide?
Mostly inhibitory
In which layers is the Band of Baillerger found?
Layers IV and V
What is the Band of Baillerger?
A tract of horizontal cortical fibers running in layers IV and V
From which layer do Interhemispheric axons originate?
Layer III
Which cortical regions are connected by the Corpus Callosum?
Left and Right hemispheres, excluding the temporal poles
Which cortical regions are connected by the Anterior Commissure?
The Temporal Poles
Which tract connects the Temporal Poles?
The Anterior Commissure
Which tract connects the L and R Hemispheres?
The Callosal Tract
From which layer(s) do Intrahemispheric axons originate?
Layers II, III, IV
What are the two types of Intrahemispheric axons?
Long Association Axons, Short Association Axons
From which layers do Long Association Axons originate?
Layers III and IV
From which layer do Short Association Fibers originate?
Layer II
Which cortical structures are connected by Long Association Fibers?
Lobes and Lobules
Which cortical structures are connected by Short Association Fibers?
Gyri
Which cortical structures are connected by Local Intrinsic Axons?
Cortical Layers
Which cortical structures are connected by Local Circuit Axons?
Columns
From which cortical layer does Corticothalamic Fibers originate?
Layer VI
From which cortical layers do Corticobulbar Fibers originate?
Layers III and V
From which cortical layers do Coriticospinal Fibers originate?
Layers III and V
From which cortical layer do Corticostriate Fibers originate?
Layer V
From which cortical layer do Corticopontine Fibers originate?
Layer V
To which cortical layers do Thalamocortical Fibers from specific thalamic nuclei project?
Layer IV
To which cortical layers do Thalamocortical Fibers from intralaminar thalamic nuclei project?
Layers II and III
When are all cortical neurons formed?
First half of embryonic gestation
To which cortical layers do subcortical nuclei project?
All layers, with diffuse inputs
What provides the signals for induction of neuroblast migration in the developing cerebral cortex?
NA axons arriving in the plexiform zone
What type of cells are found in Cortical Layer I?
NONE! TRICK QUESTION, BITCH! - Jesse Pinkman
How does Lissencephaly relate to neuronal migration?
Absence of Layer II and reduction of Layers III and IV
What is the cortical region that mediates motor functions of speech?
Broca’s Area located in the inferior frontal gyrus. Pars Triangularis and Pars Opercularis.
Describe the effects of small lesions to V1
scotomas in the CONTRALATERAL visual field
Describe the effects of large lesions to V1
quadrantopsia or hemianopsia in the CONTRALATERAL visual field
Describe the origin and type of input to dorsal V3
Large scale motion from V1 and V2 (Where)
Describe the origin and type of input to ventral V3
Object recognition from V2 (What)
Where does the LEFT ventral visual stream travel and what modalities does it carry?
V1 + V2 –> V3 –> V4 –> Posterior Inferior Temporal Lobe, area IT. It carries object recognition information.
Where does the LEFT ventral visual stream terminate and what is this area responsible for?
Left Posterior Inferior Temporal Lobe. This area processes feature information like color, texture and shape.
Where does the RIGHT ventral visual stream terminate and what is this area responsible for?
Right Posterior Inferior Temporal Lobe. This area processes holistic, non-verbal perception, including face recognition.
What might cause Visual Form Agnosia?
A lesion of the ventromedial occipitotemporal cortex (lingual and fusiform gyri)
What might cause Alexia and Agraphia
Lesion of the Left Posterior Inferior Temporal Lobe
What would result from a lesion of the Left Posterior Inferior Temporal Lobe?
Alexia with Agraphia, the inability to communicate through written words
What would result from a lesion of the ventromedial occipitotemporal cortex?
Visual Form Agnosia, the inability to recognize objects
Where does the dorsal visual stream travel and what modalities does it carry?
V1–>V2–>V3–>V5 (MT)–> Frontal Eye Fields and Posterior Parietal Cortex. It is involved in assemblage of objects in visual space and motion perception. So-called “where”
Where does the dorsal visual stream terminate and what are these areas responsible for?
Frontal Eye Fields (Frontal Lobe) and Posterior Parietal Cortex. These areas process spacial visual information.
What is Balint’s Syndrome?
Simultanagnosia, optic ataxia, ocular apraxia. Bilateral lesion to the posterior parietal cortex.
What might result from a watershed MCA/PCA stroke in the posterior parietal cortex?
Balint’s Syndrome: simultanagnosia (inability to see more than one object at a time), optic ataxia (inability to move hand towards object), ocular apraxia (inability to voluntarily gaze at an object).
Where is the Primary Auditory Cortex located?
Heschl’s Gyrus (dorsal opercular aspect of temporal lobe)
What tract delivers fibers from MGN?
Sublenticular tract, main auditory radiation
Where is the LEFT auditory belt and what does it do?
A ring of cortex surrounding the primary auditory cortex (Heschl’s gyrus). It processes temporal aspects of sound.
Where is the RIGHT auditory belt and what does it do?
A ring of cortex surrounding the primary auditory cortex (Heschl’s gyrus). It processes spectral (musical) aspects of sound.
Where is Wernicke’s area located?
Left Posterior Superior Temporal Gyrus
What function does Wernicke’s area serve?
Left: Interpreting verbal properties of language
What function does the Posterior Superior Temporal Gyrus serve on the RIGHT hemisphere?
Interpreting Prosody of the spoken word
What might lead to sensory aphasia?
Damage to Wernicke’s area on the LEFT
What might result from a lesion in Wernicke’s area?
Sensory aphasia. The inability to communicate verbally. Pt’s can speak but can’t interpret words.
What might result from a lesion on the RIGHT Superior Temporal Gyrus?
Sensory aprosodia. An inability to detect humor or sarcasm (prosodic) elements in speech.
What causes sensory aprosodia?
Lesion to the Right Superior Temporal Gyrus
What causes sensory aphasia?
Lesion to the Left Superior Temporal Gyrus (Wernicke’s area)
Where is the recognition of words and their meaning processed?
more anterior lateral and inferior parts of the temporal lobe. Information gets more specific closer to the temporal pole (i.e., from categories to proper nouns)
What might result from a lesion of the RIGHT Lateral and Inferior Temporal Cortex?
Inability to retrieve the name of an object based on non-verbal information pertaining to these objects
What might result from a lesion of the LEFT lateral and Inferior Temporal Cortex?
Anomia: Inability to recall the names of objects. Increases in severity the closer the lesion is to the temporal pole.
What might cause unilateral agraphesthesia and astereognosis?
Lesion to the postcentral gyrus
Will a lesion to the postcentral gyrus lead to complete loss of pain and thermal sensation?
No. Only a diminution.
What might result from a lesion to the postcentral gyrus?
Agraphesthesia (inability to recognize shapes drawn on palms of hands or body) and astereognosis (inability to recognize objects via tactile sensations)
What might result in construction apraxia?
Lesion to the RIGHT dorsomedial parietal lobe
What might result in tactile agnosia (the inability to recognize objects by touch or name them?)
Lesion to the ventromedial parietal lobe
What might result from a lesion to the RIGHT Inferior Parietal Lobule?
hemispatial neglect on the LEFT side
What might result from a lesion to the LEFT Inferior Parietal Lobule?
Agraphia, Acalculia, Finger Agnosia and Left-Right Confusion. All four signs: Gerstmann’s Syndrome
