Lecture 17: Association Cortex and Cognition Flashcards
what is the unimodal association cortex
2nd level of processing, but still of just 1 sense
what is Heteromodal association cortex.
These areas put together information provided by various unimodal association areas to accomplish more complex functions
do unimodal or heteromodal association cortices take up more of the brain
heteromodal association cortices take up most of the cerebral surface of the brain
what are the three kinds of cognition
Attending to complex stimuli (Parietal cortex)
Identifying these stimuli (Temporal Cortex)
(Responding) Planning appropriate responses (Frontal Lobes)
what does damage to the right side of the parietal lobe cause
left sided neglect
what does damage to the left side of the parietal lobe cause
apraxia
what does damage to the right side of the temporal lobe cause
visual agnosia
what does damage to the left side of the temporal lobe cause
aphasia
Each cortical region of the heteromodal association cortices have 4 distinct connections:
- Primary source of inputs and outputs
- Vertical and horizontal axis connections
- Radial alignment
- Inter-neurons connect functionally similar cell groups
what are the 3 Primary source of inputs to the heteromodal association cortices
thalamus
other cortical areas
brainstem modulatory systems
does the thalamus only receive information from the extremities?
no, it also receives info from the cortex (the head)
which 2 nuclei in the thalamus receive information from the cortex
Medio-dorsal thalamus
Pulvinar Nuclei
what is the input and output of the Medio-dorsal thalamus
input: cortex
output: Frontal association cortex
what is the input and output of the Pulvinar Nuclei
input: cortex
output:
Parietal association cortex
how do the main sources of input (other cortical areas) provide input to the heteromodal association cortices
Ipsilateral connections
Inter-hemisheric connections
what is the main source of input to association cortices
Other cortical areas (cortico-cortical connections)
what are Ipsilateral connections
From primary and secondary sensory and motor cortices on same side of the brain. (left parietal communicating with left temporal)
what are Inter-hemisheric connections
From corresponding and non-corresponding regions of cortex on the other side of the brain (via corpus callosum and anterior commissure)
(right parietal communicating with left temporal)
what are the 3 Brainstem modulatory centres
turn overall activity up or down.
upper brainstem
upper brain stem +reticular formation
basal forebrain
what are Vertical and horizontal axis connections
cells that do similar things are grouped together in the 6 levels
Where do association cortices get the majority of their input?
a) Axons from the periphery
b) The frontal lobe
c) Other parts of the brain
Other parts of the brain
what is the content of consciousness
Memory, emotion and drives, language, executive function
what is the Level of Consciousness
The three A’s
1.Alertness
2.Attention
3.Awareness
what are the Four key brain areas that sustain the level of consciousness
the consciousness system networks
- Upper brainstem
- Thalamus
- Hypothalamus
- Basal forebrain
what is the diencephalon
thalamus together with hypothalamus
to have alterness, what needs to be functioning
- Consciousness system network
- Cortex
to have attention, what needs to be functioning
- Consciousness system network
- Cortex
+ fronto-parietal association cortex
to have awareness, what needs to be functioning
Ability to combine various higher-order forms of information from disparate regions into a unified and efficient summary of mental activity - which can be remembered at a later time.
what are the 4 Brain centres involved in alertness
Brainstem
Diencephalon
Basal Forebrain
Cortex
what are the 2 Determinants of alertness
- Neuromodulatory systems in the brainstem
- The cortical regions to which these neuromodulatory systems project
do all brainstem modulatory systems use the same neurotransmitters
each system uses different neurotransmitters and impacts either alertness or cognitive processes
Which brain regions provide input to the upper brain stem and reticular formation for alertness?
Ascending sensory inputs (like pain)
Frontoparietal association and limbic cortices (emotions)
Hypothalamus (fight or flight)
What happens when we damage brainstem modulatory systems
Lack of alertness / consciousness.
what are the 3 levels of Lack of alertness / consciousness
coma
vegetative state
minimally conscious
what happens in the brain during a comma
severely depressed brain function
no Psychologically meaningful or purposeful responses
May show:
Reflexive eye movements
* Respiratory movements
* Posturing
what is decorticate posturing during coma
damaging to corticospinal track, flexor pattern
what is decerebrate posturing during coma
worse outcome, damage to rubrospinal track, more damage to brainstem
what is a vegetative state
No meaningful responses, speech or gestures, but may:
Open eyes and arouse in response to stimulation
May turn eyes and heads toward auditory and tactile stimulation
have unintelligible sounds
what is a Minimally conscious state
Can occur after the vegetative state OR as a primary state
Appearance of visual tracking may be one of earliest signs.
Minimal or variable degree of responsiveness
* Simple commands
* Single words
* Reach/hold objects
Not reliable yes/no
what does acetylcholine as a neurotransmitter do
goes all over the brain to help with alertness and memory
without acetylcholine, we see depressed brain function
what does dopamine as a neurotransmitter do
focuses on the frontal part of the cortex
alertness and memory
crucial for sustained attention (concentration)
what are the 4 neurotransmitters released?
acetylcholinr
dopamine
norepinephrine
serotonin
