Cerebral Cortices

Parietal Lobe Brodmann Areas

*Low numbers -3-1-2 correspond to postcentral gyrus (somatosensory) -5,7 -----association areas(meeting room)

In general, Pupils do this

-change size -React in sync -should be symmetric and round

Dorsal/"where?" pathway

-lateral part of area 19 - detects movement taking place in the contralateral visual hemifield. -visual cortex sends projections to area 7 in the posterior parietal cortex -posterior parietal cortex in turn sends projections to the premotor cortex (front eye fields) -saccades

Describe the structures of the cerebral cortex

-varies in thickness (2-4mm) -thinnest in primary visual cortex -thickest in the primary motor area -layered or laminar appearance -90% or the majority of the cerebral cortex has six laminae except olfactory, hippocampal, & denate gyrus

Six layers of the Neocortex

1 molecular 2 outer granular & pyramidal 2 inner granular & pyramidal 1 fusiform parts of the cortex that have 3 layers are NOT part of this type of cortex

Occipital Lobe Brodmann's areas

Area 17,18,19 area 17: principal visual cortex 18 &19: visual association areas (2 sets on each side of calcarine fissure)

Frontal Lobe Brodmann Areas

Area4- Precentral gyrus Area 6- Premotor or supplemental motor area Area 8- FEF (frontal eye field): controls voluntary conjugate deviation of the eyes Area 44,45: Motor speech (Broca's area)

Association Areas

Areas that are involved in the same function as " Primary area" and that receive projections it -usually adjacent to each of the primary cortical areas They have less precise somatotropin, tonotopic, and retinotopic maps than the primary areas, but their cells have more complex response properties

V1

Brodmann area 17

V4

Brodmann area 19 (color vision) "what is it?" pathway

Parietal Lobe

FUNCTIONS: SITE OF PRIMARY SOMATOSENSORY CORTEX(post-central gyrus -Main Sulci: Supramarginal gyrus *****Angular Gyrus: significant in transferring visual information to Wernicke's area(located in left temporal), in order to make meaning out of visually perceived words lesions here may result in agraphia -Precuneus- medial aspect, adjacent to occipital lobe

Occipital Lobe

Functions: - Primary Visual Cortex Main sulk and gyri: -Parieto-occipital fissure *calcarine fissure- divides the medial surface of the occipital lobe into the cuneus(top) and the lingual(bottom) gyrus

Temporal Lobe

Functions: Primary auditory cortex (brodmann's areas 41,42) *Wernicke's area for speech comprehension -Uncus (interacts with pupillary pathway) -fusiform (medial occipital temporal gyrus) -Parahippocampal gyrus

Somatotopic map

HAL (legs, arms, head) pre-central and post-central cortices follow this - the area of the cortex devoted to a particular body part is proportional to the degree of precision with which movement and can be executed or the amount of sensory innervation- These cortical area are linked to contralateral body parts

Frontal Lobe

Motor cortex -working memory -decision making -Creativity -social interaction --- Bilateral prefrontal damage may cause little change in basic intelligence but have all other aspects affected ---Precentral gyrus

condition when basal ganglia is affected

Parkinson's disease

Brodmann Area

a constructed map of cortical areas based on the appearance of cortical tissue under the microscope -K. Brodmann split the cortex into 52 different areas and assigned each a number

Ventral/ "what" pathway

a function is -Recognition of individual objects and faces - involves areas of the temporal cortex (areas 20 & 38)

Example of what happens when two hemispheres can't talk to each other

a lesion in the left occipital lobe affects the selenium of the corpus callosum -info. from the right occipital cannot flow to the angular gyrus -Result: Alexia (can't read) without agraphia(can't write), so pt can't read but can still write

Dorsal Midbrain Syndrome

aka Pretectal Syndrome or Parinard Syndrome - a lesion affecting the dorsal aspect of the midbrain -Presents w/ poor pupil reactions to the light -also affects vertical eye movements, eyelid position & causes nystagmus

Cerebral cortex Efferents

are axons of pyramidal cells (excitatory)

Broca's area

area 44: motor speech

Brodmann's area relevant to optometry

area 8: FEF (frontal eye field) area 17: visual cortex (striate) area 18-19: visual association area 22: Wernicke's area area 44: Broca's area

V5

brodmann area 19 movement detection "where?" visual pathway

V2 & V3

brodmannarea 18 &19

condition when Brain is affected

cerebral palsy, damage before birth hemiplegia due to stroke

Neocortex

cortex that has six layers - correlated with differences in functions & connections ,leading to maps of cortical areas such as Brodmann's

Corona Radiata

cortical afferent & efferent fibers that go from the cerebral cortex to other structures such as corpus stratum, thalamus, brainstem, & spinal cord

Othe major efferent projection systems

corticopontine corticonuclear corticospinal

Internal capsule

dense sheet of white matter deep in the hemisphere. Carries information past the basal ganglia

condition when spinal cord is affected

device disease or Neuromyelits optic NMO amyotrophic lateral sclerosis (ALS)

prosopagnosia

inability to recognize faces of familiar people, results from brain damage

Arcuate fasciculus

interconnects two prominent language areas

condition when cerebellar dysfunction is affected

intoxicaton metabolic/toxic disorders

visual agnosia

its are unable to recognize previously known objects "what man who mistook his wife for a hat " book

Projection fibers from the primary sensory & motor cortex

largest input to the basal ganglia

Fusiform

layer that contains modified pyramidal cells for association and projection to the thalamus.

inner pyramidal layer

layer that contains the fibers projecting to extracortilal areas such as the striatum, brainstem, and spinal cord

Molecular layer

layer that contains: -dendrites of pyramidal cells -Axons projections to the cortex from the thalamus

Internal capsule

made of : Anterior limb genu posterior limb

Happens when two hemispheres can't "talk" to each other

may result in particular abnormalities reflecting independent operation of the two hemispheres

Layering of neocortex

mechanism for sorting its inputs and outputs

Left hemisphere

most dominant for: -Language -Mathematical ability -planning skilled movements -Logical, sequential analysis

Wernicke's area

name of area 22: speech comprehension

Afferent input to the lobes

one source is: the contalateral hemisphere

venture/ "what?" pathway

pathway begins in the striate cortex (V1) & projects to the angular gyrus for language processing (visual-verbal pathway), the inferior temporal for object identification (visual-visual pathway) and limbic structures(visual-limbic pathway)

Dorsal/"where?" pathway

pathway that begins in the striate cortex and projects to the posterior parietal cortex and superior temporal cortex and is concerned with visuospatial analysis. Continues forward to project to the premotor cortex and the frontal eye fields to convey info used in the guidance of limb 7 eye movements

corticonuclear

projection system to contralateral motor & somatic sensory cranial nerve nuclei in the pons & medulla

corticopontine

projection system to the ipsilateral pontine nuclei

Third nerve palsy of the right eye in a comatose pt with uncle herniation

right eye has abnormal oculomotor nerve function - uncle transtentorial herniation due to Brain edema after ICA occlusion (temporal lobe lesion)

Angular Gyrus:

significant in transferring visual information to Wernicke's area(located in left temporal), in order to make meaning out of visually perceived words lesions here may result in agraphia

Right Hemisphere

spatial & musical patterns -solving problems in a more intuitive fashion

Damage to ventral pathway*: Agnosia

the inability to interpret sensations and hence to recognize things

Where layer V1 pyramidal neurons project...

these project to the thalamus

Where Layer V pyramidal neurons project...

these projects to the striatum, brainstem, and spinal cord

Outer pyramidal layer

this layer contains medium-sized pyramidal cells 7 stellate -gives rise to association fibers and commissures

Outer granular layer

this layer contains small pyramidal & stellate cells

Inner granular layer

this layer receives afferents from the thalamus

V1 -V5 nomenclature

used by vision scientists studying the visual processing

Hemispatial field neglect

when dorsal pathway is affected -more common with damage to the right hemisphere which plays a role in spatial attention (clock example)

Environmental rotation

when dorsal pathway is affected The environment rather than the field is rotated

Visual allesthesia

when dorsal pathway is affected a disorder in which the retinotopic VF is rotated, flipped or even inverted

Balint's Syndrome

when dorsal pathway is affected triad: -inability to perceive the visual field as a whole (simultagnosia) -difficulty in fixating the eyes (oculomotor apraxia) -inability to move the hand to a specific object by using vision (optic ataxia)