Cerebral Cortex

Newest area of our human brain

Neocortex

Layers of the Neocortex

6 layers arranged parallel to the cortical surface

First recognized by

Korbinian Brodmann, created the Brodmann’s areas

4 general regions of the cortex

Primary sensory cortex, Primary motor cortex, Association cortex, Limbic cortex

Primary Sensory Cortex

detects sensory stimuli, receives input from thalamus, occupies less and less of cortical surface over the course of mammalian evolution

Primary Motor Cortex

initiates voluntary action, gives rise to much of the corticospinal and corticobulbar tracts, occupies less and less of cortical surface over the course of mammalian evolution

Association Cortex

carries out higher-order information processing, occupies most of the cortical surfaces of the human brain

Limbic Cortex

Emotional brain

Primary somatosensory cortex

Postcentral gyrus in parietal lobe, impairments include ability to discriminate intensity or localize sensations on contralateral body, but does not typically make sensation absent. Occupations affected include: safely cook with heat source

Primary Visual Cortex

Occipital lobe, impairment include cortical blindness in contralateral visual field, occupations affected would be mobility ADLs

Primary Auditory Cortex

Transverse temporal gyri, impairments include loss of ability to localize sound and minor hearing loss on the contralateral side, occupations such as listening to music

Primary Motor Cortex

Precentral gyrus in the frontal lobe, impairment include contralateral paresis, occupations such as bathing

Topographical Organization

Primary sensory and motor areas characterized, mapped onto the cortical surface

2 Types of Association Cortex

Unimodal & Multimodal

Unimodal Association cortex

higher-order processing mostly for single sensory or motor modality, impairments lead to agnosia (sensation without perception)

Agnosia

Sensation without perception

Somatosensory association cortex (unimodal)

Interpretation of somatosensation, impairments include astereognosis, occupations include finding keys in purse

Visual association cortex (unimodal)

interpretation of visual information, impairment includes visual agnosia, occupations such as grooming

Auditory association cortex (unimodal)

interpretation of auditory information, impairments include auditory agnosia, Wernicke’s area- language interpretation

Wernicke’s area

language interpretation, found in the posterior part of the superior temporal gyrus

Premotor cortex & supplementary motor area (unimodal)

motor planning and postural adjustments, impairments include limb apraxia, motor perseveration, Broca’s area, occupations affected included awkward grasp

Broca’s Area

Language expression, found in opercular and triangular parts of the inferior frontal gyrus

Multimodal (heteromodal) Association cortex

involved in integrating functions from multiple sensory and/or motor modalities

Posterior multimodal association area

located where the pareital, occipital, and temporal lobes meet, integrates sensory info for the complete sensory experience

Impairments of Posterior Multimodal Association area (Right)

Contralateral neglect, occurs after right hemisphere damage because the right hemisphere is dominant for spatial attention

Impairments of Posterior Multimodal Association area (Left)

Lead to apraxia (lack of action), unable to perform some actions

Anterior Multimodal Association Area

called the prefrontal cortex, responsible for executive functions

Two areas of prefrontal cortex

Dorsolateral prefrontal cortex & Ventromedial prefrontal cortex

Dorsolateral prefrontal cortex

integrates sensory data from the PMAA and uses it for executive function, plays a critical role in working memory

Ventromedial prefrontal cortex

integrates emotions from the limbic structures and uses it for executive functions

Anterior multimodal association area impairments

difficulty combining cognitive stratgies and emotional reactions to situations when making decisions and plans

Disinhibition

Inability to constrain emotions or behaviors

Flow of info in prefrontal cortex

Primary sensory cortex to unimodal association cortex→ posterior multimodal association cortex→ anterior multimodal association cortex→ sends info to premotor area→ premotor area sends info to primary motor area

Left Brain

Language

Right Brain

Attention

Major connections between two hemispheres

Corpus callosum and anterior commissure

Aphasia

inability to use language, typically left hemisphere function (nonfluent and fluent aphasia)

Broca’s aphasia

Typically, nonfluent, produce few words and with great difficulty, can comprehend language

Wernicke’s aphasia

typically, fluent, but sequences are defective, typically comprehending language

Paraphasia

substitution of one letter or word for another

Neologisms

insetion of a new and meaningless word

Jargon aphasia

stringing together words and phrases in an order that conveys little or no meaning

Global aphasia

involves both Broca’s and Wenicke’s areas

Prosody

musical and rhythmic aspects of speech, typically right hemisphere function

Consciousness

state of self-awareness in which it is possible to direct attention and manipulate abstract ideas (content and level)

3 terms to differentiate consciousness

Coma, vegetative state, minimally conscious state.

Coma

No arousal, awareness, or responsiveness

Vegetative state

Arousal but not responsiveness or awareness

Minimally Conscious state

Arousal and emerging responsiveness and awareness

Sleep

normally occurring state of unconsciousness and can be aroused, an active process, hoppocampus actively consolidates days memories for storage during sleep