Lecture 9: Complex Brain Functions

Question 1

normal 24 hour functions of sleep/wake

Answer 1

2/3 in wakefuless

1/3 in sleep

Question 2

describe the circadian rhythm and what parts of the brain are stimulated with sleep and wake

Answer 2

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

Question 3

describe the action potentials in the thalamocortical neurons with sleep vs wake cycles

Answer 3

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

Question 4

how does the function of thalamocortical neurons relate to the understanding overall nervous system execution

Answer 4

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

Question 5

what does it mean to be alert and what part of the brain controls alertness

Answer 5

active cognitive status

ARAS in brainstem releases neurotransmitters for alertness of cerebral cortices

Question 6

what are the nuclei involved in alterness and what corresponding neurotransmitters do they release

Answer 6

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

Question 7

purpose of the lateral nucleus and its orexin neurons in the sleep/wake cyle

Answer 7

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

Question 8

what is arousal

Answer 8

active cognitive AND physiological status

Question 9

function of the tuberomammillary nucleus

Answer 9

helps keep awake

histamine as neurotransmitter

increases arousal in whole nervous system

Question 10

function of the venterolateral preoptic nucleus (VLPO)

Answer 10

asleep

inhibits ARAS and tuberomammillary nucleus

decreases alertness and arousal

Question 11

what is the default mode network

Answer 11

wakefulness at rest

brain structures active at cogntive rest:
- posterior cignulate cortex (PCC)
- Ventromedial pre-frontal cortex (vmPFC)
- Temporal parietal junction

Question 12

when is the posterior cingulate cortex active and when does activity increase or decrease

Answer 12

most active at cognitive rest (wake idle status)

decreases when performing attention or memory tasks

goes back to baseline when stopping the activities

Question 13

what happens when the brain is out of the DMN to perform activities

Answer 13

attention must be selected

i.e. salience of attention, selection, sustenance, division, change

Question 14

what are the primitive subcortical structures that are conserved during evolution (reflexive)

Answer 14

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)

Question 15

cortical structures involved in attention control network

Answer 15

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

Question 16

L vs R hemisphere roles in attention and the implication this has on education types

Answer 16

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

Question 17

what happens with attention if there is a lesion in the R hemisphere vs the L

Answer 17

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)

Question 18

selection of attention is based on what

Answer 18

learned experience or memory

Question 19

types of long term memory and what they break down into

Answer 19

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

Question 20

describe how motivation and memory are related

Answer 20

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

Question 21

how can memories be enhanced by emotions

Answer 21

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

Question 22

who is patient K.F and the relevance

Answer 22

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

Question 23

who is patient H.M and the relevance

Answer 23

medial fronal lobe and hippocampus were removed surgically

normal working memory (normal encoding)

no new declarative memory formed; anterograde amnesia, compromised consolidation

Question 24

regions of the brain important for encoding of memories

Answer 24

parietotemporal junction

dorsolateral prefrontal cortex

Question 25

describe the significance of the fact that long term memory is dispersed and stored in different regions of the brain

Answer 25

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

Question 26

what is dissociation of memory

Answer 26

only part of memory is lost but functions can be impaired

Question 27

function of the inferotemporal cortex

Answer 27

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?)

Question 28

what are place cells

Answer 28

in hippocampus

specific neuron active at one specific spatial location

recall male brain

Question 29

what are grid cells

Answer 29

in entorhinal cortex

specific neuron active with a spatial hexagonal area

recall female brain

Question 30

functions of grid and place cells

Answer 30

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

Question 31

describe how forgetting is a normal brain function

Answer 31

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)

Question 32

CNS components of language

Answer 32

L vs R hemisphere

M1, S1, A1, V1

wernickes and brocas area

Question 33

peripheral organs and peripheral nn involved in language

Answer 33

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

Question 34

language issues that occur if there is damage to the CNS vs PNS components

Answer 34

CNS = aphasia

PNS = dysarthria

Question 35

what are semantics vs grammar

Answer 35

semantic = extracting meaning of words

grammar = meaningful alignment of words

Question 36

what is Lexicon

Answer 36

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

Question 37

different language related regions in the L hemisphere

Answer 37

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

Question 38

importance of L vs R hemisphere for language

Answer 38

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

Question 39

critical period for language learning

Answer 39

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

Question 40

what are the major ares of the brain that are involved in thinking, planning, and deciding

Answer 40

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

Question 41

how does the circadian rhythm work with light vs no ligh

Answer 41

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

Question 42

what are the homeostatic changes that take place with asleep and awake cycles

Answer 42

decrease in body temp during sleep (evolutionary benefit to conserve energy)

increase in hormone release during sleep (i.e. growth hormones and cortisol)

Question 43

what are the cycles of sleep

Answer 43

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