What is cognition?
it's basically our inner life
perception, attention, memory, language, emotion, planning and consciousness
What is the default network and when is it active?
The default network is the combination of brain regions that are more active during "rest" as opposed to during tasks
it's involved in daydreaming or mind wandering, autobiographical memories, envisioning the future and moral decisions
It contrasts with the "task positive network"
What is the status of the default network in schizophrenia, depression, and autism?
schizophrenia = doesn't turn off properly when the task network is on
depression = default network is way overactive (rumination)
autism = default network is hypoactive
What are the two basic types of association cortex?
unimodal (dealing with only one sensory modality)
multimodal (incorporates multiple modalities)
WHat are the 4 primary sensory areas?
What's technically the motor association cortex?
the premotor area
What is the general pathway of sensory informaiton flow through the association cortices?
1. primary sensory cortex
2. unimodal association cortex
3. multimodal association cortex
4. premotor cortex
5. motor cortex (to respond)
How many layers of cortex are there?
How does the primary visual cortex (and other sensory cortices) differ cytoarchtecturally from the primary motor cortex?
primary visual cortex - thinner, but layer 4 is much thicker (this is a granular layer - receives info from the thalamus)
primary motor cortex - thicker, but layer 4 is thin and layer 5 is especially thicker (this is the pyramidal layer for output)
What cell type is located throughout the layers of the cortex? What cell type is really only in layer 4?
pyrmidal cells are everywhere
stellate cells are in layer 4
The primary sensory cortices receive input from what? Into what layer?
from the thalamus into layer 4
What 4 areas of the thalamus provide input to the primary sensory cortices?
lateral geniculate - visual info
medial geniculate - auditory info
ventral posterior medial - somatosensory
ventral posterior lateral - somatosensory
Where do the association cortices get input from? To what layer?
From the MULTIMODAL thalamic nuclei, to layer 4
What are the 4 multimodal thalamic nuclei?
1. pulvinar - visual
2. medial dorsal - supeerior colliculus, olfaction, amygdala, ventral pallidum
2. lateral posterior - association cortex, anterior cingulate, retina
4. anterior - hypothalamus, hippocampus, cingulate
What layers receive input from other areas of the cortex (not thalamus)?
Does this differ between the primary and association cortices?
1, 2, 3, and 5
it differs in that the association cortices just get a lot more information than the primary cortices
From what two layers do the sensory and assocition cortices send output to other cortical areas?
2 and 2
Which two layers project out of the primary and association cortices to the thalamus? Which one also provides output to the other subcortical areas like the basal ganlgia, mdibrain, brainstem and spinal cord?
5 and 6
5 is the one that goes to the thalamus and other subcortial areas
Therefore, what layer of the cortex gives you motor function?
What layer receives MODULATORY input from the thalamus?
Wall cortical layers receive modulatory input from the brain stem with what NTs?
5HT, DA, NE and ACh
How does the function of the parietal association cortex differ based on what hemisphere its in?
nondominant hemisphere = attention, visupspatial localization (where's waldo", spatial relationships
dominant hemisphere = skilled movements, right-left orientation
Specifically, where is the seat of attention based?
in the nondominant posterior parietal cortex (also called the inferolateral parietal cortex)
What is the physiological basis for selective attention found in the posterior parietal?
recordsing in monkey parietal association cortex are only active when they attend to a certain target
this allows selective attention - blocking out stimulus we don't need to pay attention to
What mental disorder has a marked deficiency in selective attention?
What neuropsych test is used to test selective attention?
Damage to the nondominant posterior parietal cortex will result in what?
spatial neglect (left-sided neglect)
Damage in the dominant posteiorr parietal cortex will result in what?
What are some characteristics of spatial neglect?
it's a failure to acknowledge half of the world.
note that it's not an issue of the sensory system or of perception - it's an attention problem
applies to emviornment, patient's own body, and even memory and visualizations
What is the incidence of spatial neglect in right-hemisphere strokes?
Damage to what areas of the brain will result in motor apraxias?
anywhere in the motor cortex obviously, but also in the interparietal sulcus
What is a motor apraxia?
it's a loss of ability to perform SKILLED motions when sensory and general motor systems are still intact
Specifically, what is ideomotor apraxia?
apraxia in which the patient can't use gestures (waving goodbye) or tools (fork and knife for examples)
How can you test for ideomotor apraxia, and what is a positive result?
you have the patients pantomime use of imaginary tools, imitate action, or use actual tools
the test is positive if they can't do this, obviously. but also positive if patient uses the hand in place of an imaginary tool - like using hand to brush the teeth instead of using the hand to pretend to use a tool to brush the teeth
What can't a patient do in orofacial apraxia?
They can't make specific facial meovements (usually in stroke near the language areas on the left)
What can't a patient do in ideational apraxia?
they can't sequence actions
so they'll put on their shoes before their socks, etc.
(usuallyf rontal cortex damage - common in dementia)
Where is the temporal association cortex (2 parts) and what does it specialize in?
the superior temporal sulcus - specializes in language and social attention
inferior temporal cortex (deep) - expert recognition
What special neurons are located in the inferior temporal cortex on the left?
it's the fusiform face area with face neurons
Through what kind of encoding do face neurons convey recognition?
it's not thorugh a "grandmother" neuron
it's thorugh population coding - each neuron responds to a particular feature and together they build up a unified image of grandma
Recognition of wat else will occur like it does int he fusiform face area?
any category of highly salient objects - like birds in bird watchers
What do you call a general deficit in recognition?
Damage to what area causes an inability to recognize faces? What is it called?
bilateral lesions of the inferior temporal cortex
What happens in a visual agnosia? Where is the damage?
inability to recognize an oject by SIGHT - you can still recognize them by using other senses
(so they look at a cup and can't name it, they put the cup in their hand and they can name it)
this is from damage to the UNIMODAL visual association cortex
Wha thappens in astereognosia? Where is the damage?
this is an inability to reocgnize an object by touch alone - but they can do so with other senses like vision
(put cup in hand wiht eyes closed and can't name it, open eyes and can name it)
damage to unimodal somatosensory cortex
What happens in ASSOCIATIVE visual agnosia?
you can identify something, but not name it
this is from damage to the posterior parietal cortex
(for example, they can say, it's what you comb your hair with, but they can't say it's a comb)
What happens in finger agnosia? Where ist he damage?
they can't name their fingers!
damge to the angular gyrus of the dominant parietal cortex
What syndrome does finger agnosia often occur in? WHat are the other symptoms?
WHat neuropsych test is useful for testing prefrontal function?
wisconsin card sort
How does the cortex change during the first few years of life?
it starts out with distinct motor, sensory and prefrontal networks that are not yet integrated and a rudimentary default network
rapidly, it will overproduce synaptic density during the first few years
myelination will occur
gray matter will become thicker for the first few years
During the first few years of life, in what direction does the maturation usually go and what does this mean for degeneration?
usually goes form posterior to anterior basically
the last areas to mature are often the first to degenerate
What happens to the brain through maturation after the first few years of life?
1. synapses are pruned down to what's necessary
2. the grey matter becoems thinner - partially due to loss of excess synapses, and also as myelination expands, you just lose grey matter by definition