Chapter 5: Cerebral Cortex

neocortex

newest part of the brain; most of the brain is made up of this (language, abstract though, etc.)

paleocortex

old part of the brain

archiocortex

oldest part of the brain

pyramidal cells

predominant output neurons; have very long axon that usually leaves cortex

non-pyramidal cells

predominant input neurons; most are short axons or granule (stellate) cells

Betz cell

a very large pyramidal cell

layer I

molecular make-up, relatively cell-free; has intracortical fibers

layer II

made up of external granule cells and has association fibers (same hemisphere)

layer III

made up of external pyramidal cells and has association and commissural fibers (cross hemispheres)

layer IV

made up of internal granule cells and is the primary INPUT layer

layer V

made up of internal pyramidal cells and is the primary OUTPUT layer

layer VI

deepest, polymorphic layer with lots of cell responsible for thalamic projections

intracortical fibers

found in layer I and are horizontal cell projections

association fibers

found in layers II and III, go from gyrus to gyrus, lobe to lobe, but stay within the same hemisphere

superior longitudinal fasiculus (arcuate)

connects frontal lobe to other 3 lobes

superior occipitofrontal fasiculus

connects the frontal and occipital lobes

inferior occipitofrontal fasiculus

connects frontal and occipital lobe through temporal lobe

cingulum

course parallels cingulate/parahippocampal gyri

commissural fibers

found in layer III; found in homologous (same) areas of right and left hemisphere and crosses hemispheres

corpus callosum

crucial bridge of nerve fibers that connect right and left hemispheres

rostrum genu

connects anterior right and left frontal lobe

trunk

connects posterior right and left frontal lobes, right and left parietal lobes

splenium

connects right and left occipital lobes

anterior commissure

connects the right and left temporal lobes and right and left olfactory bulbs

projection fibers

found in layers IV, V, and VI - input and output fibers

corticofugal

efferent (output) fibers to corpus callosum striatum, brainstem, and spinal cord

corticopetal

afferent (input) fibers from thalamus

internal capsule

a thick band of white matter located deep within the brain, connecting the cerebral cortex to other parts of the brain and spinal cord

hubs

areas of gray matter (called nodes) highly connected to other areas, forming hubs

brodmann areas

52 areas originally based on cytoarchitectural features, but now matches functionally as well

frontal lobe

primary motor

Broadmann area 4, controls contralateral body movements

lesion hemiparesis

weakness of planning a movement

premotor area

Broadmann area 6

supplementary motor

Broadmann area 6, complex movement programs

lesion apraxia

cannot perform movement on command

prefrontal cortex

dorsolateral

part of prefrontal cortex responsible for working memory, planning, solving problems and maintaining attention

ventromedial

part of prefrontal cortex responsible for appropriate responses, emotional reactions, and relating to other people (associated with limbic system)

parietal lobe

biggest sensory area of brain

primary somatosensory

Broadmann’s area 3, 1, 2; contralateral body sensation response

lesion hemianesthesia

loss of sensation

somatosensory association

Broadmann’s area (5,7); posterior parietal cotex/superior parietal lobe

lesion asterogonosis

failure to recognize objects by touch

lesion contralateral neglect

right inferior parietal lobe neglected symptoms vary ignorning the left side

Temporal Lobe

strongly associated with auditory system

primary auditory

Broadmann’s area 41; senses sound distancce and direction recognition

Auditory association cortex

Broadmann’s area 42, 22

Posterior temporal cortex

visually-based information, face recognition, face recognition

lesion prospagnosia

failure to recognize someone’s face

Occipital lobe

visual lobe

primary visual

Broadmann’s area 17, focuses on visual fields

Visual association

Broadmann’s area 18,19; visual perception, color, and movement

lesion visual agnosia

failure to recognize objects by sight

insula

“hidden” area by temporal lobe

primary gustory

part of insula; Broadmann’s area 43; sense of taste

dominant hemisphere

the hemisphere in a person that contains centers for language (in 95% of people it’s left)

Wernicke’s area

posterior part of superior temporal gyrus/inferior parietal lobe; receptive speech/work comprehension or formulation

lesion fluent aphasia

normal word production, but inappropriate usage; poor comprehension

Broca’s area

inferior frontal gyrus; contributes to motor speech and word production

lesion non-fluent aphasia

slow speech, poor articulation, but intact comprehension

reading pathway step 1

visual input areas to 17-19

reading pathway step 2

left angular gyrus (object recognition)

reading pathway part 3

Wernicke’s area (word formulation)

reading pathway step 4

Broca’s area (word production)

reading pathway step 5

motor cortex

reading pathway step 6

brainstem/cranial nerves (vocalization)

conduction aphasia

sounds like fluent aphasia, but intact comprehension

word blindness

alexia without agraphia; no way to get visual input to language part of brain

prosody

rhythmic, emotional content of language; usually on right hemisphere; interprets tone

lesions motor aprosodia

lack of ability to put emotion into voice

lesions sensory aprosodia

inability to comprehend emotion in voice

left hemisphere dominance

dominance in mathmatics, logic, sequential problem-solving; tends to think linearly

right hemisphere dominance

dominance in musical skills, facial recognition, and spacial relationships; tends to thing relationally

Alzheimer’s disease

accumulation of amyloid B-peptides forming diffuse and neuritic plaques; interferes with normal axonal transport and leads to formation of neurofibrillary tangles and memory problems

frontotemporal dementia (FTD) “Pick’s disease”

causes behavioral, speech, and motor problems because of inclusions or “pick bodies”