cognitive functions and organization of the cerebral cortex Flashcards
what can cognition be defined as
anything that happens “in between” - information recombination and transformation
where does cognition take place
mostly in cortex (also in cerebellum and BG)
ex of cognition (5)
- memory
- learning
- attention
- executive functions
- “consciousness”
what is the cortex
wrinkled, 2D sheet of layered neurons
why is the cortex wrinkled
to fit everything
what can tertiary and associative cortices be defined as
regions of cortex where injury causes cognitive deficits that cannot be explained by impairment of sensory or motor functions alone
inputs of primary and higher-order sensory areas
primary: thalamic sensory relay nuclei (like LGN)
higher-order: other thalamic nuclei and lower-order areas of sensory cortex
RFs of primary and higher-order sensory areas
primary: small RFs
higher-order: larger RFs
map of neuronal arrangement in primary and higher-order sensory areas
primary: precise map of sensory receptor surface
higher-order: imprecise maps of array of peripheral receptors
effect of injury to primary and higher-order sensory areas
primary: simple sensory loss
higher-order: deficits of perception and cognition + intact detection of sensory stimuli
connectivity of primary and higher-order sensory areas with other areas
primary: limited connections to other cortical areas
higher-order: connected to nearby unmodal areas & distal areas in frontal and limbic lobes (far away)
information flow in nervous system
sensory organs + BG/cerebellum -> thalamus <-> sensory cortices + motor cortices + association cortices
brainstem modulatory inputs -> association cortices <-> sensory cortices + motor cortices
what kind of connections bw sensory or motor cortices and association cortices
cortico-cortical association fibers
how is sensory information processed; how is each modality processed
in series; in parallel
how does information change when brain areas go up in hierarchy (3)
information more abstract, more distant from peripheral sensors, complexity increases
flow of goal-directed behavior information in the frontal lobe
associative cortex -> M3 -> M2 -> M1 -> movement
flow of sensory information in the cortex
1 -> 2 -> 3 -> associative cortex
what is bottom-up processing
sensory -> associative cortex -> motor
principles of organization of functional areas in cortex (3)
- all areas fall into a few functional categories
- areas in a category occupy discrete, continuous portion of cortical sheet
- areas that are functionally related occupy neighboring sites
number of layers in the (a) neocortex (b) archicortex (c) paleocortex
(a) 6
(b) 4
(c) 3
organization of inputs and outputs of cortical layers
each layer has primary source of inputs and primary output target; each layer has different inputs and outputs
types of connections in layers of cortex
- vertical axis - bw layers
- horizontal axis - within layer (interneurons)
which aspects did brodmann use to organize the cortex into areas (3)
- cell density, cell size
- cortical thickness
- laminar size
what do brodmann’s cytoarchitecture areas represent
regions of the brain with similar cell type layering
which techniques showed that cytoarchitectonically different regions were also functionally different (3)
- neurological cases (stroke or injury)
- in-vivo electrophysiology in animals
- neurosurgical patients (penfield and MC stimulation)
modern neuroscience studies in humans (3)
- neuropsychological testing (lesion patients)
- functional neuroimaging (EEG, fMRI) combined with psychological tasks
- neuromodulation (stimulate or inhibit while patient does psychological task)
unique features of association cortices (3)
- thalamic nuclei (input to association cortices)
- information that arrives from thalamus is already processed by sensory and motor areas
- majority of input is from corticocortical connections
corticocortical connections within same hemisphere and interhemispheric
within same hemisphere: U shaped fibers & long association fibers
interhemispheric: long association fibers through CC
important sources of innervation to subcortical nuclei (4)
- cholinergic
- dopaminergic
- noradrenergic
- serotoninergic
functional specialization of association areas (3)
- parietal - attention & perceptual awareness
- temporal - categorization, recognition, semantic memory
- frontal - planning and regulation of behavior (decision making and behavioral inhibition)
parietal association cortex important for (2)
- attention
- awareness of body and stimuli around it
parietal association cortex integrates (4)
somatic, visual, acoustic and vestibular sensory information
what aspect of motor control is the parietal association cortex involved in
motor control of the eyes and the extremities
intraparietal sulcus involved in control of (3)
- ocular movements
- reaching and grasping of the upper extremities
- spatial working memory
where does intraparietal sulcus project to (3)
premotor area, frontal eye fields and prefrontal area
inferior parietal lobule and precuneus project to (2)
parahippocampal and entorhinal cortices
inferior parietal lobule and precuneus important for
long-term memory formation (hippocampal function)
special neuron found in parietal association cortex
attention sensitive neurons
lesion in parietal association cortex
hemineglect: lesion in right parietal lobe only, ignore everything on left side (spatial awareness)
lateral temporal association cortex
auditory association cortex (including wernicke’s area)
ventral temporal association cortex
‘what’ pathway -> recognition of sensory stimuli (faces, words, objects)
lesion in ventral temporal association cortex
agnosia
what is agnosia
see features, don’t know what it is (can’t associate meaning to object)
what does anterior pole of temporal association cortex store (3)
representation of knowledge, semantic memory, meaning
temporal association cortex strong connection to
limbic system -> emotion and memory
anterior temporal association cortex lesion
associative agnosia -> don’t know meaning
posterior temporal association cortex lesion
apperceptive agnosia -> can’t copy
lesion in FFA (right temporal lobe)
prosopagnosia -> can’t recognize faces
lesion in VWFA (left temporal lobe)
alexia
highly specialized areas in ventral surface of temporal association cortex (2)
- FFA
- VWFA
frontal association cortex integrates (4)
sensory, motor, parietal and temporal cortices
frontal association cortex important for (4)
- appreciation of self in relation to the world
- selection
- planning
- execution of appropriate behavior (social context)
damage in frontal association cortex causes
change in character/personality
ex of functional deficits from lesioned frontal association cortex (4)
- cognitive disabilities
- impaired restraint
- disordered thought
- inability to plan appropriate action
dorsolateral frontal association cortex important for
short-term memory
what is working memory
information hold onto for short amount of time to use it, will forget it
ventromedial frontal association cortex important for
value and decision making
short-term memory and value + decision making are processed where in frontal association cortex
short-term memory -> dorsolaterally
value + decision making -> ventromedially
orbital and ventromedial limbic association cortex connected to … and important for …
amygdala and hippocampus; emotional processes
hippocampal formation of limbic association cortex important for
formation of long-term memories and transfers them to neocortex
where are emotional processes and long-term memories processed in limbic association cortex
emotional processes -> orbital and ventromedially (amygdala and hippocampus)
long-term memories -> hippocampal formation
