Unit 5

Question 1

Arousal

Answer 1

the physiological and psychological state of being awoken or of sensory organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (RAS) in the brain (which mediates wakefulness and relays arousal info), the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, mobility, and readiness to respond.

Question 2

Increased arousal

Answer 2

Highly active, alert, ready to respond to changes in the environment, prep to fight/flee

Question 3

Decreased arousal

Answer 3

Sleepy, lethargic, difficulty concentrating

Question 4

How is arousal regulated

Answer 4

Several NT and neuromodulators are produced in specific groups of cell bodies (nuclei) in brainstem and surrounding areas
These nuclei project brain wide, all over the CNS, PNS,ANS to modulate arousal

Question 5

Neurotransmitter

Answer 5

 signaling molecule released by a neuron, used to communicate with another neuron across a synapse (often use ionotropic receptors)
 Released from presynaptic neuron moving across the cleft of post synaptic neuron
 Cell to cell communication

Question 6

Criteria to be a neurotransmitter

Answer 6

1) The substances must be present within the presynaptic neuron
2) The substance must be released in response to presynaptic depolarization (AP) and the released must be Ca dependent (involves influx of calcium)
3) specific receptors for the substance must be present on the postsynaptic cell
(Punitive NT do 2 out of the 3 things)

Question 7

Neurotransmitter types

Answer 7

1) small molecule NT
2) peptide NT (string of animo acids put together)
3) Unconventional NTs (not released the same as NT)

Question 8

Neuromodulator

Answer 8

 signaling molecule released by a neuron that potentiates or inhibits the transmission of a nerve impulse in a group of neurons but is not the actual means of transmission itself (often use metabotropic receptors; ex: axo-axonic synapses)
 Causing an influence to increase/decrease transmission at the synaptic cleft
 Not acting as chemical signaling itself

Question 9

Types of synapses: Axo Axonic

Answer 9

1) Pain neuron releases NT called substance P to signal injury
2) Activity along pain neuron activates endorphin cells
3) In turn, endorphin cells release endogenous opioids as a modulator onto terminal of pain axon to turn off pain signal

Question 10

Hormone

Answer 10

signaling molecule produced by glands in multicellular organisms, that are transported by the circulatory system (blood supply) to target distant organs to regulate physiology and behavior (neurohormone = in brain)
Chemicals that act at a greater distance away from where they’re produced causing a change/regulating behavior

Question 11

Reticular formation

Answer 11

 Contains various interconnected nuclei along with numerous ascending and descending tracts located throughout the brainstem
 Nuclei involved in NT production
 Ascending tracts integral to arousal and consciousness
 to the cortex in the ascending reticular activating system (ARAS or RAS)
 Descending tracts involved in modulating sensory and motor functions
 descending pathways to the spinal cord via the reticulospinal tracts
 Nuclei associated with the cranial nerves
 Fibers give the region a net like appearance (reticular means net-like)
 Was thought to lack organization, but is actually highly organized, just very intricate and complex

Question 12

Reticular formation NT

Answer 12

 FT neuronal populations have extensive connections throughout the central nervous system and are involved in the regulation/modulation of activity throughout the brain
 Acetylcholine: pedunculopontine nucleus (PPM) & laterodorsal tegmental nucleus (LDT)
 Norepinephrine: locus coeruleus (LC)
 Dopamine: ventral tegmental area (VTA)
 Serotonin: raphe nuclei (RN)
 Histamine: Hypothalamus (posterior: TMN)
 Orexin: Hypothalamus (lateral)
 GABA & Ach: Basal forebrain

Question 13

Reticular formation terminology

Answer 13

 ARAS=RAS=ascending RF
 ARAS/RAS also may refer to entire RF
 Nonspecific sensory projection system throughout RAS relays arousal

Question 14

RAS: Ascending reticular activating system

Answer 14

composed of several groups of cells that produce neurotransmitters; these neuronal populations have extensive connections throughout the central nervous system and are involved in the regulation of activity throughout the brain. ‘Nonspecific’ sensory projection system through RAS relays ‘arousal’ information via the thalamus to cortex, where this info meets up with primary sensory specific inputs to produce conscious perception of a sensory event. (See associated neurotransmitter charts for breakdown of specific NT, brain regions, and roles.) Functions in parallel with the flow of specific sensory input through the primary sensory thalamic nuclei that is then relayed to the cortex
 Ascending pathways controlling arousal, attention, sleep cycle
 Includes numerous nuclei and NTs/NMs
 Temporal summation in cortex of nonspecific inputs with primary sensory specific inputs > conscious perception of a sensory event

Question 15

Reticulospinal tracts

Answer 15

Descending pathway that arise from the RF that influences spinal motor neurons based on changes in arousal. Motor control includes voluntary and reflexive movements (esp. stereotyped movements like stepping), modulation of muscle tone to either aid or inhibit movement, postural control, and autonomic functions.

Question 16

Pain pathway

Answer 16

descending pathway that arise from the raphe nuclei of the RF to the dorsal horn of spinal cord. The nerve fibers in these pathways act in the spinal cord to block/inhibit the transmission of some pain signals to the brain, especially during traumatic events.
(we’re able to ignore a painful injury in order to run away)

Question 17

Cranial nerves

Answer 17

a set of 12 paired nerves that arise directly from the brain. The first two nerves (olfactory and optic) arise from the cerebrum, whereas the remaining ten emerge from the brain stem. RF circuitry helps coordinate activity of neurons in these CN nuclei, and thus is involved in the regulation of simple motor behaviors, including eye movements.

Question 18

External influences on arousal

Answer 18

 Diet (Adenosine) provides precursors for making NT/NM/Hormones can effect lv. of NT
 Drugs directly affect synapses
- Mimics NT/NM at receptor
- Changes NT/NM amount in synapse (reuptake changes)
 Trauma (Mild, severe, more severe damage)
- Damaged RF interrupts normal arousal circuitry

Question 19

Diet effect on arousal

Answer 19

 Provides precursors for NTs/NMs/Hormones.
 Increases intake of a particular type of amino acid
 Increases production of related NT
 Example: amino acid tryptophan from food like turkey is a precursor for serotonin, which itself is a precursor for melatonin = makes us sleepy.

Question 20

Adenosine

Answer 20

a naturally occurring purine nucleoside that forms from the breakdown of adenosine triphosphate (ATP). It is thus a metabolic that builds up in cells while we are awake.

Question 21

Drugs effect on arousal

Answer 21

Directly affect synapses by either mimicking the NT/NM at the receptor or by changing the NT/NM amount within the synaptic cleft (e.g., reuptake changes). Example: caffeine blocks adenosine inhibition of acetylcholine, doesn’t inhibit ACh cells which raises arousal, suppressing GABA, keeping you awake

Question 22

Trauma effect on arousal

Answer 22

Damaged RF interrupts normal arousal circuitry
 Mild damage: fatigue, changes in sex arousal, disrupted sleep patterns
 Severe damage: coma or vegetative state from inhibited ability to wake up
 More severe: fatal

Question 23

Sleep

Answer 23

a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with sleep displaying very different and active brain patterns.
 Consists of multiple repeating phases
 Non-REM sleep (several stage)
 REM sleep (rapid eye movemement)
 Dreams occur in this phase

Question 24

EEG

Answer 24

 Electroencephalogram
 Gross average change in electrical potentials in area under electrode
 Amplitude = voltage (how large the signal is)
 Frequency = Cycles per second (Hz) (how rapidly signals are changing)

Question 25

Sleep Stages

Answer 25

Wake – Active, Wake - Relaxed, NREM Stage 1, NREM Stage 2, NREM Stages 3 & 4, Rapid eye movement (REM)

Question 26

Wake – Active

Answer 26

EEG is dominated by low-voltage fast-activity in the beta (~16–30 Hz) and gamma (>30 Hz); active muscles
 Small hyper frequencies happen

Question 27

Wake - Relaxed

Answer 27

Alpha waves (8–12 Hz) – from synchronous electrical activity of thalamic pacemaker cells
 More regular pattern of osculation, sign that we are relaxing

Question 28

NREM Stage 1

Answer 28

transitional role, 1 to 7 minutes, easily interrupted by a disruptive noise; low-voltage, mixed-frequency waves with theta waves (4-7Hz)
 Lightest stage of sleep, loss of alpha waves

Question 29

NREM Stage 2

Answer 29

10 to 25 minutes or more in later cycles; requires more intense stimuli to wake; has a further decrease in frequency and increase in amplitude, together with intermittent high-frequency spike clusters called sleep spindles and low-frequency/high amplitude K-complexes
 Memory consolidations

Question 30

NREM Stages 3 & 4:

Answer 30

(now considered one deep-sleep stage) low frequency (1–4 Hz), high-amplitude delta waves = slow wave sleep
Mostly considered to be a single stage of deep sleep
 Increase amplitude and decrease frequency

Question 31

Rapid eye movement (REM) sleep

Answer 31

Also called paradoxical sleep
EEG desynchronized (low-voltage, mixed/high-frequency) EEG like wake, includes sawtooth waves, muscle atonia (genitals active but muscles are paralyzed) with variable heart rate and breathing and bursts of rapid eye movements; primary dreaming stage

Question 32

EEG synchronization

Answer 32

 Goes from desynchronized (awake to stage 2)
 Highly active and uncoordinated
 Unregulated
 Synchronized (stage 2 &3)
 Desynchronized (REM)

Question 33

Physiological changes in sleep

Answer 33

 Interim between consciousness and sleep
 Move to stage 2 after 5-15 min
 Heart rate slows, brain does less complicated tasks
 After another 15 minutes move into non-REM sleep, the Delta stage
 Body makes repairs
 Body temperature and BP decreases
 Move into REM sleep approx. 90 minutes after first feeling sleepy
 Increase eye movement, heart rate, breathing, BP and temperatures

Question 34

How long does a sleep cycle last

Answer 34

90 minutes

Question 35

Sleep Switch: VLPO

Answer 35

 Ventral lateral preoptic area

Question 36

Functions of Sleep and REM

Answer 36

Sleep is restorative
 Engage in critical metabolic processes, process waste, etc
REM may have cognitive/psychological advantages
 REM deprived have poorer memory for previous days learning
 Dreams may be involved in helping to resolve psychological conflicts
Slow-wave/REM cycle may also involve temperature regulation
 Brain cools down during slow wave sleep
 REM warms brain (cooling can help with cleaning process)
- Enzymes may be efficient at different temperatures

Question 37

Sleep spindles

Answer 37

8–12 Hz EEG waves that generally last 1 or 2 seconds and arise as a result of interactions between thalamic and cortical neurons; may be important for memory consolidation

Question 38

K-complexes

Answer 38

low frequency, high amplitude: largest event in healthy human EEG; two proposed functions: (1) suppressing cortical arousal in response to stimuli that the sleeping brain evaluates not to signal danger; and/or (2) aiding sleep-based memory consolidation.

Question 39

Atonia

Answer 39

a condition in which a muscle has lost its strength; associated here with the lack of muscle movements in REM sleep.

Question 40

Hypnogram

Answer 40

is a form of polysomnography (EEG sleep measurement); it is a graph that represents the stages of sleep as a function of time.

Question 41

Pontogeniculo-Occipital Waves

Answer 41

the EEG signature of REM sleep. Neural activity spreads from pons (P) to the lateral geniculate nucleus (G) of the thalamus to the visual cortex in the occipital lobe (O) and convey information about upcoming eye movements.

Question 42

Sleep deprivation

Answer 42

short-term and long-term periods of sleep deprivation cause numerous detrimental cognitive and physiological effects

Question 43

Sleep deprivation short term effects

Answer 43

 Increased tolerance of risk
 Decline in working memory
 Decreased psychomotor performance
 Increased error in commission and omission
 Increased incidence of microsleeps
 Impaired performance on attention intensive tasks
 Increased distractibility

Question 44

Sleep deprivation long term effects

Answer 44

Increased risk of
 Hypertension, heart attack/stroke, weight gain/obesity, diabetes, depression/anxiety, faulty brain function, memory loss, immune system deficiency, decreased fertility/sex issues, psychiatric/mood disorders

Question 45

Effect of oscillation and fluid during sleep

Answer 45

 In NREM: low freq oscillations in neural activity support memory consolidation and neuronal computation
 Sleep is also associated with increased interstitial fluid volume and clearance of metabolic waste products
 Slow oscillation neuronal activity leads to oscillations in blood volume, drawing cerebrospinal fluid into and out of the brain facilitating the removal of potentially damaging waste production

Question 46

Circadian rhythm

Answer 46

Physical, mental, and behavioral changes that follow a daily cycle
Clock maintains a close to 24 hour rhythm of activity
Genetically controlled and driven by daylight cycles
Cycle tends to drift in the absence of night/day cues

Question 47

Biological clocks

Answer 47

An organism’s innate timing device composed of specific intracellular proteins that are found in nearly every tissue and organ

Question 48

Master clock

Answer 48

coordinates all the biological clocks in vertebrates, composed of about 20,000 neurons that form the suprachiasmatic nucleus (SCN)

Question 49

Pineal gland

Answer 49

a small endocrine gland in the brain of most vertebrates that produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycles

Question 50

Retinohypothalamic tract (RHT)

Answer 50

a photic neural input pathway involved in the circadian rhythms of mammals. The origin of the retinohypothalamic tract is the intrinsically photosensitive retinal ganglion cells (ipRGC), which contain the photopigment melanopsin. The axons of the ipRGCs belonging to the retinohypothalamic tract project directly, monosynaptically, to the suprachiasmatic nuclei (SCN) via the optic nerve.
 Specialized visual receptors react to ambient light levels
 These ganglions send their axons to the SCN of hypothalamus
 SCN informs pineal gland, so daylight decreases/nightfall increases its release of melatonin
 Pineal gland releases melatonin inhibiting SCN regulating its active/inactive cycle

Question 51

Jet lag

Answer 51

a temporary disorder of circadian rhythms that causes fatigue, insomnia and other symptoms as a result of air travel across time zones; Only occurs when flying East-West or West-East (not North-South): changing time zones. Treatments include bright morning light, daily activity, taking melatonin before sleep.