Week B1 Memory & Sleep I Flashcards
Types of Memory (list)
Working STM Semantic Episodic Motor Sequencing Emotional Learning
Primary Brain Areas for Each Type of Memory
Working = Prefrontal cortex - controlling other cortical regions
STM = Hippocampus - Forming associations across cortical activity
Episodic = Temporal Lobe - associating other regions
Semantic = Connectional structure of the Whole Cortex
Motor Sequencing = Striatum, Cerebellum & Pre-motor cortex
Emotional Learning = Amygdala, Cingulate, Hippocampus, Reward Systems
Description: Working Memory
To do with attention -> sustained mental representations, associated with focus on a task - “holding it in working memory”
A type of ‘controlled’ mental attention - attention is paid to a certain or certain stimuli, whilst disregarding other stimuli
This can only be maintained will we need to process other inputs
(Prefrontal cortex)
Description: STM
Orientation, sequence of the day and sequence of activity
Forms temporary linkages between different areas of the cortex, indexing the days events
STM become lasting (LTM) if relevant enough. EMotional responses from the anygdala can attribute salience to STM in this way*
(Hippocampus)
Description: Semantic
Facts - ‘general’ knowledge about the world, not related to a time-frame
(Connectional structure of Whole cortex)
Description: Episodic
Long-term recollection of specific times and event sequences
LTM of this type requires that the associations/linkages between areas of the cortex endure - requiring alterations to the cortex
*
(Temporal)
Description: Motor Sequencing
Learned patterns of movement, enabling smooth movements and sequencing
(Striatum, Cerebellum and Pre-motor cortex)
Description: Emotional Learning
Emotional responses associated with people, places, things, etc.
(Amygdala, Cingulate, Hippocampus and Reward Systems)
How do the different areas of the brain, and sleep, interact to form memories (long term, and semantic ‘knowledge’)
Working memory (prefrontal cortex) sends flow of information to the Hippocampus, which organises indexing of the days events. The Amygdala feeds emotional associations into the hippocampus as these events are being indeed. During REM (slow-wave) sleep, information is send to the Tempotal Lobe for longder-term ndexing and formation of associations. With ongoing time and familiarity, ‘knowledge’ separates somewhat from ‘time-based memory’, and becomes associated with the ‘whole cortex’ -> this ‘knowledge’ can be accessed without need for temporal indexing.
How are LTMs formed?
Temporal Lobe
Formation of enduring associational links between different cortical regions -> because long term, requires alterations to the cortex
Describe the act of remembering, in basics?
The act of remembering involves reconstructing the activity in parts of the cortex that originally processed the experience
*Note: memories can be altered by subsequent experiences
What is sleep?
Daily loss of consciousness.
Reversible state of reduced/loss of responses to the environment and percentual disengagement.
A complex mixture of physiological and behavioural processes.
How is the activity level of the cortex modulated?
Kept active by arousal from thalamus
And from modulatory neurotransmitter systems in the brainstem - ascending arousal systems
Multiple nuclei in the brainstem and midbrain modulate cortex activity during the day
How do we observe sleep?
EEG: electro-encephalogram
EOG: electro-oculargram
EMY: electro-myogram
What does EEG measure?
Categorizations?
Electric impulses along the scalp
-> arising from voltage flactuations resulting from ionic current flows through neurons
Categorized into ‘desynchronized’ (associated with wakefulness and REM sleep) and ‘synchronised’ (associated with non-REM sleep)
What does EOG measure?
Eye movements (not in response to visual stimuli)
What does EMG measure?
Electrical activity produced by skeletal muscles
What are the types of EEG rhythms, and what stages of sleep/waking are each associated with?
Awake:
Alert = Beta
Drowsy = Alpha
Sleeping:
Non-REM stage 1 = Theta
Non-REM stage 2 = Theta with sleep spindles and K-complexes
Non-REM stage 3-4 = Delta waves (increasing)
REM sleep = Beta with sawtooth pattern
Describe Alpha Waves:
Frequency= 8-13 Hz
Amplitude shifts up and down, repsresenting transient relaxations during waking
(Awake but drowsy)
Describe Theta Waves:
The most common wave form described during sleep
Lower frequency= 3-7 Hz
Most prominent in Vertex (upper surface of the head) region
No particular amplitude requirements
NREM stage 1-2
Describe Delta Waves:
“Slow waves” at very low frequency: 0.5-2 Hz
High amplitude: at least ~75um
Occur independently in local regions.
Propagate from the Cortex to Hippocampus
NREM stage 3-4
What is ‘sensory gating’?
Bursts of activity between the Cortex and Thalamus
Visualized on EEG as ‘Spindles’ usually seen amongst Theta Waves during NREM stage 2
Describe Spindles
Short oscillations 12-14 Hz
Ranging from 0.5-3 seconds, 6-7 cycles
Represent bursts of activity between the Cortex and Thalamus
Localized in small regions - thus represent Desynchrony
Occur amongst Theta Waves of NREM stage 2
Describe K Complexes:
Slow, sharp waves
Steep negative then positive wave form
Indicitive of NREM stage 2
No amplitude criteria
Predominantly central-vertex in origin
Occur with or without stimulation
Also thought to be associated with sensory gating
