Cerebral Cortex

cortex =

bark

what happen when you increase surface area?

more computing power in small cranial vault

3 parts of the inferior frontal gyrus?

pars opercularis, pars triangularis, pars orbitalis

function of paracentral lobule

motor and sensory function of the legs

paracentral lobule characteristics

medial surface of the cerebral hemisphere (both frontal and parietal)

medial continuation of precentral and postcentral gyri

cerebral hemisphere are separated by ______, which accommodates the ____

great longitudinal fissure, falx cerebri

deep in the fissure, what connect the hemisphere?

corpus callosum

neocortex

6 layers, 95% of surface of hemisphere

paleocortex

3 layers

• Parahippocampal gyrus

• cingulate gyrus

archicortex

four layers

• hippocampus

cortical layers

1: axons and dendrites

2/3: corticocortical

4: thalamic afferents (most)

5: subcortical efferents (some thalamic afferents)

6: thalamic efferents

an ex of cortical cell type

pyramid cells

pyramidal axon

output cells, make up white matter

ex of output cells

betz cell of motor cortex

characteristics of pyramidal neurons

spiny excitatory (glutamatergic) neurons

project (pyramidal) neurons

characteristics of interneurons

relay information locally

non spiny inhibitory (GABAergic) interneuron

ex of non pyramidal cells

granule, stellate, basket cells

what does corpus callosum do?

connect homologous cortical area in each cerebral hemisphere

present a picture to the left visual field (right brain), split brain patient

will not know what it is but left hand can show you what it is not right hand

present a picture to the right visual field (left brain), split brain patient

left hemisphere tell you what it is and right hand can show you not left hand

primary cortex

first cortical area processing of sensory input or motor output

secondary cortex

second stage of processing

tertiary cortex

multimodal cortex

association cortex includes

secondary and tertiary cortex

first step of how association and primary cortices work together

sensory info sent to sensory cortex from peripheral

second step of how association and primary cortices work together

after processed in primary sensory cortex, info is passed to sensory association cortices (via short fibers)

third step of how association and primary cortices work together

reciprocal feedback with frontal cortices (via longer association pathway) allow previous and current sensory input to decide if a response is needed (if yes, how to best execute it)

last step of how association and primary cortices work together

primary motor cortex execute the behavioral response via descending projection fibers

test use to check if prefrontal cortex is functioning

wisconsin card sorting test

dorsolateral lesion affect

executive functioning

characteristics of dorsolateral lesions

incapacity to shift cognitive sets to meet changing task demands

preservation, stimulus-bound behavior, echopraxia, echolalia

working memory impairment

memory retrieval deficit

what happen to the eye motor control in dorsolateral lesion

deficit in eye motor control - frontal eye fields direct EM

medial orbitofrontal lobe

bilateral lesion cause adynamia and akinetic mutism

is the pt aware in medial orbitofrontal lobe

self aware but does not initiate behavior (goal of frontal lobotomy)

characteristics of pt in medial orbitofrontal lobe

apathetic, rarely move, incontinent, eat when only fed, and speak in monosyllables when questioned

characteristics of orbitofrontal syndrome

arousal change: adynamia or agitation

low motivation, dec initiative

reduce insight and impulse control

what does stimulus bound mean

pt see water and reach to drink it even though pt is not thirsty or didn’t intend to drink

pt with orbitofrontal syndrome had no difficulty in

card sorting task

broca area

motor program to talk stored here

what connect the broca and wernicke area together?

arcuate fasciculus

wernicke’s area

contain sound images of words

wernicke aphasia

pt unable to comprehend command, able to speak but speech lack meaning,

wernicke area location

next to auditory area on superior temporal lobe

pathway of how info get to wernicke area

spoken word → A1 → wernicke area → comprehend word heard

broca aphasia

comprehension is intact but difficulty in producing words

conduction aphasia

impaired repetition of words only

what area is damaged in conduction aphasia?

arcuate fasciculus

anomic aphasia

comprehension is not affected but naming is impaired

speech is fluent but problem with word finding and writing (sometime with reading)

area lesioned in anomic aphasia

angular gyrus implicated

function of supplementary motor area

encodes sequences of movements

function of premotor cortex

neurons fire just before performing an activity

function of precentral gyrus, area 4

movements produced by electrical stimulation

afferent of precentral gyrus

S1, thalamic VL

efferent of precentral gyrus

basal ganglia, VL, superior colliculus, red nucleus, pontine nucleus, spinal cord

damaged to precentral gyrus produced

dysfunction of contralateral distal muscle

what control the voluntary facial muscle?

postcentral gyrus (parietal lobe)

damaged to postcentral gyrus (facial muscle)

paralysis of voluntary movement

ex of damaged to post central gyrus

you can’t smile for the camera when someone tell you too but you can smile when someone tell a joke

what control the involuntary facial muscle?

limbic cortex

damaged in limbic cortex

inability to express true emotions

ex of limbic cortex damage

you don’t smile in response to a joke but can smile for the camera when asked

somatosensory

S1 = brodmann area 1,2,3

secondary regions in parietal BAs 5 and 7 (parietal association areas)

where does BAs 5 and 7 receive input?

S1

S1 receive dense input from

VP nucleus of thalamus

Area 3 receive projection from

superficial skin

Area 3a receive input from

muscle spindles

S1 is composed of

slow and fast adapting columns alternate

lesion to postcentral gyrus

increase in sensory threshold (pressure sensitivity and two point discrimination threshold)

function of area 3a and 3b

small, simple receptive fields

function of area 1,2

large receptive field, direction sensitive

area 5 function

stereognosis

how to parietal lobe testing

by placing familiar object such as key in their hand and ask to identify it

astereognosis

can’t recognize an object by touch but can draw the object and recognize drawing of it

agraphesthesia

inability to recognize letters or numbers drawn on the pt’s hand

result of parietal lobe lesion

astereognosis, agraphesthesia

phantom limb

lost left arm and when someone brushed left face, pt felt his missing arm is touched

intraparietal sulcus

a horizontal groove that may unite with postcentral sulcus

what lies above and below the horizontal portion of intraparietal sulcus?

superior (above) and inferior (below) parietal lobule

parietal association cortex

higher sensory function (polysensory)

language function (L hemisphere, inferiorly - angular gyrus)

stereognosis

spatial relation

damaged to parietal association cortex

contralateral neglect (R > L)

characteristics of gerstmann syndrome

finger agnosia, agraphia, right 0 left confusion, dyscalculia

what is damaged in gerstmann syndrome

left inferior parietal lobule

finger agnosia

inability to recognize fingers of either hand

what structure for where?

superior longitudinal fasciculus

what structure for what?

inferior longitudinal fasciculus

where does axons in the superior longitudinal fasciculus terminate?

posterior parietal cortex

cell in parietal lobe are tuned for what reason?

detect presence/movement of stimulus (magnocellular layer)

axons in inferior longitudinal fasciculus terminate where

inferior temporal cortex

cell in temporal lobe are tuned for what reason?

analyze object in details (parvocellular layer)

damaged to occipital association cortex

does not cause blindness or loss of visual field but inability to recognize object

visual agnosia

inability to recognize object

stimulation of the occipital association cortex cause

complex visual hallucination like object changing size or distorting shape

alice in wonderland syndrome

distortions in their perception of the world and their own bodies

lesion in temporal association cortex cause

verbal memory problem (left)

visual discrimination problems (right)

prosopagnosia

inability to identify faces (L&R temporal association cortex damage)

stimultagnosia

inability to attend to more than a limited area of the visual field despite nl visual field

auditory pathway

cochlea → superior olive → inferior colliculus → medial geniculate → auditory cortex

insula is covered by

opercula (lips)