Cognitive Processes & Association Cortex Flashcards
Define cognition:
Our “internal life” (perception, attention, memory, language, emotion, planning & consciousness)
- Involves integration of many kinds of information
- –Produces a perceptual “whole”
- Guides the choice of appropriate behaviors (ex: to achieve a specific goal)
What is the default network involved in?
-Daydreaming or mind wandering
-Autobiographical memories
-Envisioning the future
-Moral decisions
Contrasts with the “task-positive network” active when performing specific tasks
(this is still a form of cognition)
When might the default network be disturbed/less active?
In mental illness:
- Depression
- Obsessive-compulsive disorder
- Schizophrenia
- Autism
What areas are more active in the default network?
- Dorsolateral Prefrontal
- Rostrolateral Temporal
- Posterior Parietal
- Posterior Cingulate/Precuneus
- Medial Prefrontal
- Medial Temporal
When are the active parts in the default network less active?
When you are doing a task.
What are the primary areas of the cortex?
- Primary motor cortex
- Primary auditory cortex
- Primary somatosensory cortex
- Primary visual cortex
When can cognition also occur?
Between stimulus and response. (ex: during default network we are less aware of sounds, ex: waiting for the bus and being aware of it’s presence, planning for the bus by pulling out your umbrella and pulling out the bus pass, waiting for other people to enter the bus first (appropriate social behavior))
What is the association cortex?
- “Not Primary” cortex
- –Unimodal: integrates information within one sensory modality (seeing ball)
- –Multimodal: integrates information across sensory modalities and from other sources (memory, emotion) (hearing ball hit ground and seeing it bounce)
What are the parts of the unimodal association cortex?
- Premotor cortex
- Somatosensory association cortex
- Visual association cortex
- Auditory association cortex
How does information flow through the association cortex?
Hierarchy of projections to carry out an appropriate behavioral response to a stimulus:
- Primary sensory cortex
- Unimodal
- Multimodal
- Premotor cortex
- Motor cortex
What alters information flow through the association cortexes?
- Extensive feedback projections
- “Shortcuts” between areas
What cell types are prevalent in 2/3/5/6 cortex layer?
Pyramidal cells - excitatory cells
What cell types are most prevalent in 4th cortex layer?
Stellate cells - excitatory cells (star-shaped, dendritic trees)
What are the main inputs to the cortex?
- Thalamus
- Other cortical regions
- Brainstem nuclei (modulatory)
What are the three main functions of Association Cortex?
- Integrate input form different modalities
- Mediate “Internal” cognition
- Mediate between sensory inputs and the appropriate behavioral output
What doe the parietal association cortex do in Nondominant hemisphere?
- Attention
- Visuospatial localization: searching or reaching for an object
- Spatial relationships: binding the elements of a visual scene together into a single image
What does the parietal association cortex do in Dominant hemisphere?
- Skilled movments
- Right-left orientation
(this hemisphere is specialized for language)
What can damage in the posterior parietal cortex cause?
- Spatial neglect (nondominant hemisphere)
2. Motor apraxias (dominant hemisphere)
What is spatial neglect?
Failure to acknowledge half of the world
- -Sensory systems are intact
- -Can apply to
- —Environment
- —Body
- —Memories and visualizations
When does spatial neglect commonly occur?
Occurs in about half of right-hemisphere strokes (left visual field is ignored)
What does motor apraxia cause?
- Loss of ability to perform skilled motions
- Sensory and motor systems are intact
What happens in ideomotor apraxia?
Patient may not be:
- able to perform action in daily life, depending on severity
- aware of the deficit
What indicates damage in ideomotor apraxia?
Use of hand in place of imaginary tool.
What are other apraxias?
Inabilty:
-To make specific facial movements (orofacial)
-To sequence actions (ideational)
These involve other parts of the brain
How do face neurons work?
- No ‘grandmother’ neuron
- Represented through population coding:
- –Each neuron responds to particular features
- –Together, groups of these neurons are used to build a unified image
What are deficits in recognition?
Agnosias
- Inability to recognize or identify objects even though sensory systems are working normally
- Damage to several cortical areas can produce agnosia of different types
What is prosopagnosia?
Inability to recognize faces [caused by bilateral lesion of inferior temporal cortex]
What is visual agnosia?
Inability to recognize an object by sight (recognition by other senses remains intact) [caused by damage to unimodal visual cortex]
What is astereognosia?
Inability to recognize an object by touch alone [caused by damage to unimodal somatosensory cortex]