Emotions, memory and sleep Flashcards by Tara Sheridan

What does orexigenic and anorexigenic mean?

Orexigenic- stimulate eating and are used when hungry

Anorexigenic- suppress apetite and are used when full

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What are the 4 F’s?

Feeding
Fighting
Fleeing
Mating

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How does leptin work?

Released by body fat
Anorexigenic- causes the ardate nucleus to release POMC/aMSH/CART
This inhibits the lateral hypothalamus

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What is leptin?

Hormone produced by fat that reduces fat

Increases metabolic rate and inhibits the lateral hypothalamus to signal to eat

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What does the amygdala control?

The amygdala has an important role in fear

Also related to aggression

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What are the different types of aggression and what parts of the brain control this?

Affective aggression is related to defense and fighting enemies, controlled by medial hypothalamus
Predatory aggression is more primal and it linked to the obtaining of food, controlled by lateral hypothalamus

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Electrical stimulation of what part of the hypothalamus causes aggression?

Ventromedial hypothalamus,

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What is declarative memory?

Available to the conscious mind

Can be encoded in symbols and language

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Procedural memory

Skills and associations largely unavailable to the conscious mind

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What is explicit and implicit memory?

Explicit- memory that can be consciously recalled

Implicit- memory that cannot be consciously recalled (procedural memory, classical conditioning, priming)

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Memory duration types

Immediate memory- a few seconds
Short term memory- seconds or minutes, also known as working memory
Long term memory- weeks, months, years

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What does electrical stimulation of the temporal lobe result in when it comes to memory?

Hallucinations and recollection of past experiences

Epileptic seizures- complex sensations and memories

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How is the pre-frontal cortex involved in memory?

Working memory

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How is the amygdala involved in memory?

Multiple processed sensory units (smell)

Responsible for implicit, emotional/learnt fear

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How is the hippocampus involved in memory?

Responsible for converting short term memory into long term
Also declarative memory
Lesions in the hippocampus impair memory

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How is the cerebellum involved in memory?

Procedural and sensorimotor memory

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In what cases is the hippocampus enlarged?

People who’s jobs require good spatial memory

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How does memory change synapses?

Synaptic strength changes
Facilitation or depression changes the amplitude of the action potentials
Can be short or long term

How was aplysia californica used to demonstrate associativity?

Repeated gentle stimuli to siphon causes reduced gill withdrawal- habituation
When paired tail pinch with siphon touch this reestablished the siphon reflex
Whole process is called long term sensitisation

How does long term potentiation occur?

Evidence suggests a postsynaptic event
Most indicates a critical role for Ca2+
Involves trafficking of AMPA receptors to the postsynaptic membrane

How is sleep defined behaviorally?

Reduced motor activity
reduced response to stimulation
stereotypical postures
relatively easy reversibility

What are the three main ways physiological activity can be recorded? What do they measure?

Electromyography- muscle movements
Electro-oculography- eye movements (potential difference between retina and cornea)
Electroencephalogrpahy- brain activity

How does an electroencephalogram work?

Measures the synchronous electrical activity from large populations of neurons in the brain
Electrodes placed on the scalp detect these electrical fields, linked to an amplifier and a monitor

What are the main types of brain wave picked up by EEG?

Alpha, beta, theta, delta

What are the main characteristics of non-REM sleep?

Neuronal activity is low, not much AP firing Metabolic rate and brain temp are at their lowest Heart rate and blood pressure low, decreased sympathetic NS outflow and increased parasympathetic Muscle tone and reflexes are intact

What is the first stage of non-REM sleep? What happens?

Drowsiness- awakens easily, eyes move slowly and muscle activity slows Many people experience muscle spasms paired with a sensation of falling EEG- low voltage activity, mixed frequencies and mostly theta waves

What is the second stage of non-REM sleep? What happens?

Light sleep- eye movement stops, begins to prepare for deep sleep, body temp drops and heart rate slows bursts of sinusoidal waves called sleep spindles biphasic waves called K complexes

What does an EEG look like during stage 2 of non-REM sleep?

Characterized by bursts of sinusoidal waves called sleep spindles and biphasic waves called K complexes

What is the third stage of non-REM sleep? What happens?

Deep sleep- extremely low delta waves interspersed with smaller faster waves Sleepwalking, nightmares, talking in sleep, parasomnia occur in the transition between non-REM and REM

What is the fourth stage of non-REM sleep? What happens?

Very deep sleep- brain produces delta waves almost exclusively Disorientation for several minutes after arousal during this stage

In humans, stages 3 and 4 of non-REM sleep are also called what?

Slow wave sleep

What is the fifth stage (REM)?

EEG mimics wakefulness Closed eyes move rapidly from side to side, could be related to intense dream/brain activity Low voltage mixed frequency brain waves- paradoxical sleep

What happens physiologically in REM sleep?

Brain temp and metabolic rate rise- consistent with increased neuronal activity All skeletal muscles are atonic- flaccid and paralyzed Muscles controlling movements of eyes, inner ear ossicles and diaphragm remain active

How much time is there between the first stage and the end of REM?

90-110 minutes

What proportion of total sleep is spent in each stage?

Stage 1: 5% Stage 2: 50-60% Stages 3 and 4: 15-20% REM: 20-25%

How does the time spent in each stage change throughout the night?

During each cycle stages 3 and 4 decrease and REM increases

How is sleep regulated in the nervous system?

Diffuse modulatory system controls rhythmic behavior in the thalamus Inhibition of motor neurons

How is wakefulness stimulated?

Activation of neurons in brain stem precedes awakening Stimulation of brainstem causes awakening Depolarizing effect

What happens in the nervous system during non-REM sleep?

Decrease of firing in the brainstem Spindles- correlated activity in the thalamus Delta rhythms are from activity in the thalamus

What happens in the nervous system during REM sleep?

Fairly similar firing to when awake apart from early sensory systems No activity in frontal lobe, raphe nuclei and locus coeruleus Inhibition of motor neurons

What are the different theories on dreaming?

Strange imagery due to brain not fully functioning Exercising synapses without any external activity Memory consolidation Circuit testing

What are circadian rhythms?

Sleep-wakefulness patterns following periodicity of around 24 hours modulated by external timing cues that adapt the rhythm to the environment

What part of the brain acts as the internal clock? How does it do this according to light?

Suprachiasmatic nucleus of the anterior hypothalamus | Regulates the timing of sleep, not sleep itself