Lecture 9: Complex Brain Functions Flashcards
normal 24 hour functions of sleep/wake
2/3 in wakefuless
1/3 in sleep
describe the circadian rhythm and what parts of the brain are stimulated with sleep and wake
sleep wake cycle
when brainstem is stimulated = wakefulness via ascending reticular activating system
when thalamus is stimulated = sleep
melatonin and regulated gene expression also play a role in sleep/wake
describe the action potentials in the thalamocortical neurons with sleep vs wake cycles
asleep = oscillatory, low frequency AP, Ca2+ spike
awake = high frequency, no Ca2+ spike
ARAS still needs that thalamus to relay this info for the function of sleep wake even though ARAS is technically in control
how does the function of thalamocortical neurons relate to the understanding overall nervous system execution
nervous system works the by same principles; i.e. calcium spikes, frequency modulation, etc
examples:
- synapses of climbing fibers with purkinje cells: similar calcium spikes
- polymodal sensory neurons: different action potential frequency encodes different modalities
- synaptogenesis and pruning during learning: via long term potentiation and depression
what does it mean to be alert and what part of the brain controls alertness
active cognitive status
ARAS in brainstem releases neurotransmitters for alertness of cerebral cortices
what are the nuclei involved in alterness and what corresponding neurotransmitters do they release
cholinergic nuclei (at boundary of midbrain and pons) release ACh (both ascending and descending tracts)
Raphe nuclei (midline of brainstem) release seratonin
Locus coeruleus (postganglionic axons of sympathetic nervous system) release norepinephrine
**good to know because agonists/antagonists of these neurotransmitters are common for many meds
purpose of the lateral nucleus and its orexin neurons in the sleep/wake cyle
for awakeness
improves alertness of the higher level cortical and subcortical structures
activates ARAS system = increase alertness via mammillotegmental tract
activates tuberomammillary nucleus = increase arousal
what is arousal
active cognitive AND physiological status
function of the tuberomammillary nucleus
helps keep awake
histamine as neurotransmitter
increases arousal in whole nervous system
function of the venterolateral preoptic nucleus (VLPO)
asleep
inhibits ARAS and tuberomammillary nucleus
decreases alertness and arousal
what is the default mode network
wakefulness at rest
brain structures active at cogntive rest:
- posterior cignulate cortex (PCC)
- Ventromedial pre-frontal cortex (vmPFC)
- Temporal parietal junction
when is the posterior cingulate cortex active and when does activity increase or decrease
most active at cognitive rest (wake idle status)
decreases when performing attention or memory tasks
goes back to baseline when stopping the activities
what happens when the brain is out of the DMN to perform activities
attention must be selected
i.e. salience of attention, selection, sustenance, division, change
what are the primitive subcortical structures that are conserved during evolution (reflexive)
superior colliculus for coordinated locomotor functions (in the mesencephalic locomotor region or MLR)
pulvinar nucleus of thalamus (in the diencephalic locomotor region or DLR)
both of the above are related to the visual pathways (think box jellyfish; eyes directly connect to SC; reflective direction changing based on threat)
cortical structures involved in attention control network
dorsal frontal parietal pathways
- for endogenous stimuli
- voluntary (top down)
- includes dorsal stream of visual system
ventral pathways
- reorienting
- exogenous stimuli
- reflexive
- includes ventral stream of visual system
**visuospatial perception or spatial cognition is related to attention
L vs R hemisphere roles in attention and the implication this has on education types
L hemisphere
- serial processing
- details
R hemisphere
- parallel processing
- full picture
L hemisphere alone can be responsible for competence based educatio ‘
Both hemispheres are required for capability based education
what happens with attention if there is a lesion in the R hemisphere vs the L
Lesion in R = they can see details but not the full picture (i.e. in letter M made up of letters Z, they can see the Zs that make up the full picture but cannot make the full picture)
Lesion in L = can see big picture but not the details (i.e. in letter M made up of a bunch of small letter Zs, they can draw an M but not draw it using the details of the Zs)
selection of attention is based on what
learned experience or memory
types of long term memory and what they break down into
declarative (explicit) and non declarative (implicit)
explicit is broken down into episodic (events) and semantic (facts) memory types
implicit is broken down into priming, skill learning, and conditioning
declarative is related to regions of the temporal lobe while nondeclarative is related to the temporal lobe and some other brain structures
describe how motivation and memory are related
better encoded when motivated (salience)
i.e. experiment where they tried to get people to memorize pictures of food when they were hungry and when they were not; they remembered many more details when they were hungry compared to not
how can memories be enhanced by emotions
amygdala for emotional memory; improved encodign and consolidation while also preventing extinction
HPA axis = norepinephrine and epinephrine increase alertness and arousal
- directly improved encoding and consolidation
- indirect through amygdala
who is patient K.F and the relevance
brain injury around temporal-parietal region (short term memory issues)
had impaired working memory (slow encode)
normal declarative memory
compromised executive functions
still found to have long term memory even though they could not remember it in the short term
who is patient H.M and the relevance
medial fronal lobe and hippocampus were removed surgically
normal working memory (normal encoding)
no new declarative memory formed; anterograde amnesia, compromised consolidation
regions of the brain important for encoding of memories
parietotemporal junction
dorsolateral prefrontal cortex
describe the significance of the fact that long term memory is dispersed and stored in different regions of the brain
this includes declarative and non declarative memories
broader areas of the brain must be damaged to result in memory loss (i.e. HM could still work normal because all the old memories he had were normal)
more complicated memories have more prominent deficiencies following a brain injury
i.e. experiment with mice in the maze; they still remembered the path even with 50% brain injury; only struggled once the maze became increasingly complex
what is dissociation of memory
only part of memory is lost but functions can be impaired
function of the inferotemporal cortex
gets info from ventral stream of visual system (“WHAT” we see)
stores info about different properties of objects
- medial to lateral = stubby to spiky
- superior to inferior = animate to inanimate
grandmother cell for invariant image (you know what it is no matter how far away?)
what are place cells
in hippocampus
specific neuron active at one specific spatial location
recall male brain
what are grid cells
in entorhinal cortex
specific neuron active with a spatial hexagonal area
recall female brain
functions of grid and place cells
mirror neurons
4D representation of memories (3D+time)
encode episodic memory with location, distance, direction, and time
guide navigation
more than spatial cognition: memory and behaviors through remapping
describe how forgetting is a normal brain function
normal memory loss NOT amnesia
longer time and less use (consolifation) = natural memory loss/extinction
consolidation must be built upon attention (i.e. can you tell which penny was the real one)
forgetting is essential for daily function; problematic if forgetting cannot forget (mental illness, PTSD, ruminating on negative memory, etc)
CNS components of language
L vs R hemisphere
M1, S1, A1, V1
wernickes and brocas area
peripheral organs and peripheral nn involved in language
CN V, VII, IX, X, XII, ansa cervicalis, and phrenic nerve all involved in language production
lungs - for airflow
larynx - for controlled vibration of vocal cord
pharynx - for nasal and oral
mouth - including lips, teeth, palate, and tongue
language issues that occur if there is damage to the CNS vs PNS components
CNS = aphasia
PNS = dysarthria
what are semantics vs grammar
semantic = extracting meaning of words
grammar = meaningful alignment of words
what is Lexicon
meaning of words, consolidated memory
different categories of words are stored in different locations
listening and reading lexicons are different (recall tonotopy vs retinotopy)
2 hemispheres record different lexicons
diffusely distributed
different language related regions in the L hemisphere
visual cortex - reading
auditory cortex - listening
motor cortex - reading aloud or talking
language path = Wernicke’s area and Broca’s area for word association/higher level control
**lots of anatomical variations in these areas
importance of L vs R hemisphere for language
L = comprehension and language production
R = prosody (different voice inflections)
split brain cases
- L hemisphere they can report R hand stereognosis and objects in the R visual field correctly
- R hemisphere can perceive and feel L hand or visual field but cannot report
critical period for language learning
ability to learn a language plateaus from 3-7 years of age and then declines
due to different cortical regions in children vs adults
children use an extreme capsule fiber system in addition to the arcuate fasciculus
what are the major ares of the brain that are involved in thinking, planning, and deciding
dorsolateral prefrontal cortex = for functional execution, L DLPFC
ventromedial prefrontal cortex = compare cost and reward to make decisions
orbitofrontal cortex = gathers results of an action performed
limbic system = emotional involvement
insula, cerebellum, and basal nuclei system also play a role
how does the circadian rhythm work with light vs no ligh
24 hour cycle if exposed to light
if not exposed, there is a delay and increase in the cycle
returns to 24 hour cycle when exposed to the light again
what are the homeostatic changes that take place with asleep and awake cycles
decrease in body temp during sleep (evolutionary benefit to conserve energy)
increase in hormone release during sleep (i.e. growth hormones and cortisol)
what are the cycles of sleep
due to neuron activity producing different wave forms
repeated cycles of 5 stages
- non rapid eye movement = 4 stages; omit stages until mainly stage 4 (decreased frequency)
- rapid eye movement phase; increase in duration until that last one in the morning; all motor functions activated without movement
