Cerebral Cortex (E2)

Question 0

Layers of the gray matter of the cortex?

Answer 0

I - Molecular Layer
II - External Granular Layer
III - External Pyramidal Layer
IV - Internal Granular Layer
V - Internal Pyramidal Layer
VI - Multiform Layer

Question 1

Number of neurons housed within the cortex?

Answer 1

10 billion

Question 2

Types of neurons housed within the layers of the cortex?

Answer 2

Pyramidal cells
stellate cells
fusiform cells
horizontal cells of Cajal
Cells of Martinotti

Question 3

Axons that run radially?

Answer 3

Fun at right angle to the cortical surface - Radial Fibers
Terminate within the gray matter, between layers, but also project out of the cortex becoming projection, association, and commisural fibers of the white matter

Question 4

Axons that run tangentially?

Answer 4

Run parallel to the cortical surface - tangential fibers

terminate within the gray matter providing cortico-cortical connections within layers

Question 5

Division of cortex into functions? (not layers)

Answer 5

Vertical columns - 300 - 600 m wide of functional activity
Functionally specialized areas - clusters of vertical columns
Lobes or cortices - groups of specialized areas functionally and anatomically
Pathways- connection between the lobes or cortices

Question 6

Types of pathways?

Answer 6

Association - from other regions within the same hemisphere
Commissural Fibers - from regions in the contralateral hemisphere
Projection Fibers - from the thalamus (thalamocortical projections)

Question 7

Primary Sensory Cortices

Answer 7

Receive sensory information

Question 8

Sensory Association cortices

Answer 8

complex analysis of sensory information

Question 9

Motor Planning Cortices

Answer 9

Organize/plan movement

Question 10

Primary Motor Cortices

Answer 10

Control movement

Question 11

Association Cortices

Answer 11

Behavior, emotions, memory, sensory interpretation

Question 12

Somatic Sensation (sensory)

Answer 12

Primary Somatosensory Cortex (post-central gyrus) - contains somatotopic representation of the body (sensory homunculus)

Receives input from the thalamus regarding discriminative general senses as well as pain and temperature sense from the body and face

A lesion of the somatosensory cortex produces deficits in discrimitive touch and position sense (hemi anesthesia on the side of the body opposite the cortex)

Question 13

Somatic Sensation (association)

Answer 13

Somatosensory Association Cortex

Superior parietal lobule and supramarginal gyrus

used for perception of shape, size, texture and identification of objects by feel (sterognosis)

lesion of the somatosensory association cortex can cause asterognosis

Question 14

Visual Sense (Sensory)

Answer 14

Primary visual cortex (cuneus and lingual gyri)

This is the termination of the retinogeniculostriate pathway (optic radiations)

This area fuses the inputs form both eyes into one image.

Analyzes the visual world with respect to orientation of visual stimuli, with special attention paid to lines and edges of image.

Question 15

Visual Sense (association)

Answer 15

Visual Association Cortex (medial and lateral occipital gyri, angular gyrus)

Essential for comprehension of a visual image

mediates slow pursuit (tracking) movements of the eyes through connections with the superior colliculus of the midbrain tectum and cranial nerve nuclei of the extraocular muscles

mediates vergence eye movements (convergence and divergence when focusing near and far)

mediates conjugate eye movements

Question 16

Auditory Sense (sense)

Answer 16

Primary Auditory cortex - located in superior temporal gyrus and the transverse temporal gyri of heschl in the temporal lobe

neurons in these regions respond to different frequencies of sound (tonotopic organization)

Question 17

Auditory Sense (association)

Answer 17

Auditory Association cortex (superior temporal gyrus)

Important in the interpretation of sounds

Lesion to a specialized portion of this area (Wernicke’s area) makes spoken language difficult to understand

Question 18

Olfactory Sense (sense)

Answer 18

The primary olfactory cortex consists of the uncus, pirirform cortex, the periamygdaloid, and part of the parahippocampal gyrus

projects to he hypothalamus, hippocampus, amygdala, thalamus, and orbitofrontal olfactory area of the cortex

Question 19

Tactile Agnosia (asterognosis)

Answer 19

mostly involves a lesion in area 40

Question 20

Visual agnosia

Answer 20

mostly involves a lesion in area 39; inability to recognize objects by sight
prospagnosia - inability to recognize faces

Question 21

Auditory agnosia

Answer 21

mostly involves a lesion in area 22; inability to recognize familiar sounds and words

Question 22

Primary motor cortex

Answer 22

the precentral gyrus

contains somatotopic representation of the body for motor function (motor homunculus) with disproportionate representation of the areas for the hand, face and tongue

A lesion in the motor cortex produces:

a. contralateral paresis
b. increased deep tendon reflexes
c. positive Babinski sign

Question 23

Premotor cortex and Frontal eye fields

Answer 23

Middle frontal gyrus (posterior aspect)
motor planning area

Receives input from the cerebellum and is involved in teh production of externally reference movements

Stimulation produces postural or tonic movements, and contralateral eye movements and head movements (connections to ocular motor nuclei)

Lesion produces hypertonus and increased resistance to passive movements

Question 24

Supplemental Motor Cortex

Answer 24

Superior Frontal Gyrus (posterior aspect) Motor planning area Superior to the premotor cortex Receives input from the basal ganglia and is involved in the production of internally referenced movements

Question 25

Broca's area

Answer 25

Inferior frontal gyrus (posterior aspect) Speech planning area (usually in the left hemisphere) Connected to Wernicke's area by the arcuate fasciulus Broca's aphasia or expressive aphasia : normal comprehension of language; expression of speech is difficult and crudely articulate; muscles involved in speech are not damaged; patients can express memorized words correctly

Question 26

Lesions of motor planning areas can cause:

Answer 26

Apraxia - disorder of sensory integration interfering wiht the ability to plan and perform skilled and complex movements. Akinetic apraxia: loss of ability to carry out spontaneous movement Amnestic apraxia: inability to carry out movement on command due to inability to remember the command. Motor apraxia: inability to perform complicated motor tasks Ideational apraxia: inability to demonstrate use of objects (tools placed in a patients hand) Facial apraxia: inability to perform facial-oral movements on command (e.g., lick the lips) - most common

Question 27

Frontal and Prefrontal association cortices

Answer 27

superior, middle forntal gyri, and medial frontal lobe: have many connections with the sensory association area, thalamus, hypothalamus and the limbic system All activities (motor, cognitive or emotional) are planned in the frontal lobe (executive function) These areas also regulate the affect associated with sensation (happy, sad, friendly, disagreeable) Prefrontal lobotomy think of Phineas Gage

Question 28

Limbic Association Cortex (psychical cortex)

Answer 28

the anterior pole of the temporal lobe involved in the regulation of emotions, mood, affect, and memory electrical stimulation of this area elicits recall of things seen or heard a tumor or stroke here may cause visual or auditory hallucinations. sights and sounds are vivid in the mind

Question 29

Parietotemporal association cortex

Answer 29

involved in sensory integration, problem solving, speech, and spatial processing Interpretation and integration of sensations are localized here lesion of the non-dominant cortex causes no disturbance of language because in most people language function is located in the left hemisphere - does cause lack of appreciation of spatial aspects of all sensory input from the left side of the body (hemineglect syndrome)

Question 30

Cerebral dominance

Answer 30

left hemisphere is considered the dominant hemisphere in the majority of individuals 90% of pop is right handed over 90% of right handed individuals are left brain dominant around 60-70% of left handed individuals are left brain dominant

Question 31

Functions of the dominant hemisphere

Answer 31

language skilled motor formulation (praxis) arithmetic: analytical skills sequential processing

Question 32

Functions of the non-dominant hemisphere

Answer 32

prosody (emotion, tone and rhythm of voice) visual-spatial analysis and spatial attention arithmetic: spatial skills spatial orientation and processing