Telencephalon & Diencephalon

What makes up 85% of the brain (largest part of the brain)?

telencephalon

What is the structure of the telencephalon?

2 hemispheres separated by the medial longitudinal fissure

What makes up the outer surface of the telencephalon?

-2-4 mm covering of gray matter

-gyri (elevations)

-sulci (grooves)

What makes up the internal surface of the telencephalon?

-subcortical white matter

-basal nuclei

-hippocampus

-amygdala

When does rapid enlargement of the telencephalon occur in development?

8.5 weeks

When does rapid enlargement of the forebrain occur in development?

6.5 weeks

What surface of the cerebrum is the central surface on?

lateral surface

What surface of the cerebrum are the pre and post central gyri on?

lateral surface

Where can the insular lobe be found?

-deep to the lateral sulcus

-lies in an in-folded region of cortex

What does the insular lobe separate?

parietal and frontal lobes from temporal lobe

What acts as a "little lid" for the insular lobe?

operculum

What are the 3 components of the operculum?

-frontal operculum

-parietal operculum

-temporal operculum

What lobe contains the primary gustatory cortex?

insular lobe

What is the function of the insular lobe?

-important connections to language and visual integration

-autonomic functions

-emotions

What is the largest lobe of the brain?

frontal lobe

What is one of the last lobes of the brain to fully develop and about at what age does this occur?

frontal lobe; around 25 years old

Where does the frontal lobe reside in the skull?

anterior cranial fossa lying in the orbital plate of the frontal bone

What is the frontal lobe involved in?

planning, decision-making, behavioral inhibition, personality

What Brodmann area is the primary motor cortex?

Brodmann area 4

What Brodmann area is the secondary motor cortex?

Brodmann area 6

Where is the primary motor cortex?

precentral gyrus

What are the two components of the secondary motor cortex?

-supplementary motor area (SMA)

-premotor cortex

Where is the secondary motor cortex found?

gyri just anterior to precentral sulcus (primary motor cortex)

What are the Brodmann area of Broca's area?

Brodmann area 44, 45

What are the Brodmann area of the frontal eye field?

Brodmann area 8

What is contained in the frontal lobe? (5)

-primary motor cortex

-secondary motor cortex

-Broca's area

-frontal eye field

-prefrontal cortex

What lobe can Broca's area be found in?

frontal lobe

What lobe can the prefrontal cortex be found in?

frontal lobe

What lobe can the primary and secondary motor cortexes be found?

frontal lobe

What is the frontal eye field control?

controls voluntary movement of the eyes (volitional saccades; visual attention and control)

What is the prefrontal cortex important in?

emotional processing, planning, decision making

Where do the olfactory bulb and tract lie?

on the inferior surface of the frontal lobe

What can unilateral lesions in the frontal lobe result in? (4)

-contralateral weakness (hemiparesis/hemiplegia)

-Broca's aphasia

-Right Broca's area

-conjugate deviation of the eyes due to frontal eye field lesion

For most individuals, is Broca's area on the right or left frontal lobe?

left

What is Broca's aphasia?

-typically left-lateralized

-difficulty producing speech

What is Right Broca's area?

-issues with communicative and emotional prosody and pragmatics of language (talk very monotone)

Where is right Broca's area?

opposite side that language center is on (Broca's area); so on the right side of the frontal lobe for most individuals

What is conjugate deviation of the eyes due to a frontal eye field lesion?

sustained shift in horizontal gaze towards one side, along with an inability to move the eyes to the other side

What can bilateral lesions in the frontal lobe result in? (7)

-disinhibition

-personality changes

-intellectual impairment

-highly distractible

-lack of foresight

-lack of ambition

-apathy

What fissure is Broca's area lie just superior to?

lateral fissure

What is Wernicke's aphasia?

difficulty understanding speech and often producing speech of random words that do not make sense together (typically left-lateralized)

What is Right Wernicke's aphasia?

cannot understand prosody of language (emotional tone)

What lobe is the psotcentral gyrus located on?

parietal lobe

What lobe is the primary somatosensory cortex located in

parietal lobe (between central and postcentral sulci)

What are the Brodmann area of the primary somatosensory cortex?

Brodmann area 1-3

What are the components of the parietal lobe?

-postcentral gyrus (primary somatosensory cortex)

-superior lobule

-inferior lobule

What is the Brodmann area of Wernicke's area in the parietal lobe?

Brodmann area 39, 40

What part of the parietal lobe contains Wernicke's area?

inferior lobule

Where do the gyri of the superior lobule of the parietal lobe extend?

onto the medial surface as precuneus

What makes up the gyri of the inferior lobule of the parietal lobe?

angular and supramarginal gyri

What is Brodmann area of Wernicke's area in the temporal lobe?

Brodmann area 22

What is Brodmann area of Wernicke's area in the parietal AND temporal lobe?

parietal = Brodmann area 39, 40

temporal = Brodmann area 22

What lobe can Wernicke's area be found?

where parietal and temporal lobe meet

What can lesions to the parietal lobe result in? (8)

-contralateral sensory loss

-Wernicke's aphasia

-contralateral neglect

-contralateral hemianopia

-topographic memory loss

-anosognosia

-astereognosis

-Gerstamann syndrome

What does Gerstamann syndrome result from?

lesion to the parietal lobe

What is contralateral neglect as a result of a parietal lobe lesion?

lack of awareness or stimuli on one side of the body (typically right-lateralized)

What is contralateral hemianopia as a result of a parietal lobe lesion?

visual field deficit

What is topographic memory loss?

memory loss of spatial layouts of familiar environments

What is anosognosia?

impaired self-awareness

ex. dementia patients may be unaware they have memory loss

What is astereognosis?

inability to identify an object

What is Gerstmann syndrome?

typically left-lateralized; R-L disorientation, finger agnosia, agraphia (writing), acalculia (math)

What is the primary motor and sensory cortex somatotopic organization?

homonculus: cortices correspond w/ different parts of the body and more complex regions are larger

updates to homonculus:

-leg, arm and head, are biggest regions (head region is more inferior than leg region)

-concentric pattern instead of linear pattern

-3 inter-effector regions responsible for forming a link between mind and body

-babies don't have inter-effector regions (fully formed by 9 years old)

Where in the skull can the temporal lobe be found?

middle cranial fossa

How is the temporal lobe divided?

into 5 gyri by 4 sulci

Where on the cerebral hemispheres can the temporal lobe be found?

lateral and inferior surfaces of the hemispheres

What sulci is the temporal lobe between?

lateral and collateral sulci

Which lobe is the primary auditory cortex located in?

temporal lobe

What is Brodmann area of the primary auditory cortex?

Brodmann area 41

Where in the temporal lobe is the primary auditory cortex located?

transverse gyri of Heschl

What lobe is the olfactory cortex located in?

temporal lobe

What is the uncus?

most rostromedial edge of the temporal lobe

What lobe is the fusiform gyrus located in?

temporal lobe

What is the fusiform gyrus associated with?

facial recognition

What can lesions in the temporal lobe result in? (7)

-difficulty interpreting a sound

-memory deficits

-inability to acquire new memory

-agnosia

-olfactory hallucinations

-seizure activity ("uncinate fits")

-Kluver-Bucy syndrome

What does Kluber-Bucy syndrome result from?

bilateral lesions in the temporal lobe

What are olfactory hallucinations that occur from a lesion in the temporal lobe?

false perceptions of smell

What is agnosia that can occur from a lesion in the temporal lobe?

difficulty recognizing items by sight, feel or sound

What are "uncinate fits" seizure activity?

seizures that start in the uncus

What is Kluver-Bucy syndrome?

bilateral lesion of temporal lobe resulting in:

-behavior changes

-attempt to eat inappropriate items

-difficulty recognizing items by sight, feel, or sound

What is the smallest lobe of the brain?

occipital lobe

What lobe contains the primary visual cortex?

occipital lobe

What lobe contains the secondary visual (association) cortex)?

occipital lobe

What is the Brodmann area of the primary visual cortex?

Brodmann area 17

What is the Brodmann area of the secondary visual (association) cortex?

Brodmann area 18 + 19

What can lesions in the occipital lobe result in? (6)

-homonymous hemianopia

-color agnosia

-agraphia

-cortical blindness

-Anton syndrome

-visual hallucinations

What does Anton syndrome result from?

lesion in occipital lobe

What is homonymous hemianopia as a result of an occipital lesion?

retrochiasmal lesion resulting in missing 1/2 of the visual field

What is color agnosia as a result of an occipital lesion?

inability to retrieve color info in the context of normal perception and language

What is agraphia?

inability to write

What is cortical blindness?

bilateral lesion of the occipital lobe (vision is lost due to impaired occipital lobe)

What is Anton syndrome?

individuals that suffer cortical blindness but affirm quite adamantly that they can see

What are visual hallucinations that occur as an occipital lobe lesion?

seeing flashes of light

Generally, what is agnosia?

-loss of ability to recognize objects when the appropriate sensory systems function adequately

Lesions in what lobes of the brain can result in agnosia?

-parietal

-temporal

-occipital

What is visual agnosia?

failure to recognize objects visually in the absence of visual acuity or intellectual impairment

What is tactile agnosia?

inability to recognize objects by touch

What is auditory agnosia?

failure to recognize specific sounds, including speech, music, or familiar noises

What is prosopagnosia?

unable to recognize familiar faces due to damage of the fusiform gyrus

Generally, what is apraxia?

loss of ability to carry out certain movements in response to stimuli that normally elicit these movements

Lesions of what lobe in the brain can result in apraxia?

mainly the frontal lobe (premotor cortex)