Johan Dahlin
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334 lines
4.2 KiB
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# Cirkadiansk rytm, sömn och medvetande.pdf
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**OCR Transcript**
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- Pages: 25
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- OCR Engine: pymupdf
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- Quality Score: 1.00
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---
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## Page 1
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Cirkadiansk rytm, Sömn och
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Medvetande
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Eric Hanse HT 2025
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---
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## Page 2
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Circadian rhythms appeared 2-3 billions years ago
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Sleep, like ageing17,18, may be an inescapable consequence
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of aerobic metabolism.
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---
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## Page 3
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Circadian organization in mammals
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Hastings et al 2018 Nat Rev Neurosci 19:453-469
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---
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## Page 4
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The central clock in nucl. suprachiasmaticus
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(SCN) synchronizes circadian rhythms
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Control
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After lesion of the SCN
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---
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## Page 5
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Model for the circadian clock
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---
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## Page 6
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The molecular clock is based on delayed negative
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feedback
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---
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## Page 7
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The SCN does not keep an exact 24 hour
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cycle if not entrained
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”The third eye”
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-melanopsin-containing
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ganglion cells
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sleep
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wake
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---
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## Page 8
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SCN signals to the rest of the brain and body
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both electrically and with hormones
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Higher frequency of action potentials during the day
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Homones, for example:
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Cortisol – highest levels when we wake up
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Melatonin – a “dark hormone”, released from corpus pineale
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Welsh et al (1995) Neuron 14:697
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---
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## Page 9
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Pracucci et al 2023 Nat Comm 14:7108
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Alfonso et al 2023 Nat Neurosci 26:64-78
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I.c.[Cl-] is higher during wake and lower
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during sleep in cortical pyramidal neurons
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---
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## Page 10
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Sleep
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“Sleep is the readily reversible state of
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reduced responsiveness to and
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interaction with the environment”
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---
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## Page 11
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Why do we sleep?
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Processing of memories
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”Brain wash”
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Hauglund et al 2025 Cell 188: 1-17
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Brodt et al 2023 Neuron 111: 1050-1075
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---
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## Page 12
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NA, 5-HT, Histamin
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High
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Low
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Very Low
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Ach
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High
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Low
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High
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Orexin
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High
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Low
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Low
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Energy consumption
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High
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Somewhat lower
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High
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Awake, NREM and REM
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Hobson (2005) Nature 437:1254
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---
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## Page 13
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The ”wake nucleus” in the hypothalamus
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(LHA) excites the modulatory transmitter
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systems using Glu/Orexin
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Saper et al (2005) Nature 437:1257
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LC –Locus Coeruleus
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BF – Basal forebrain
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LH – Lateral Hypothalamus
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VLPO – VenteroLateralPreOptic
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TMN - TuberoMammillary Nucl
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LDT/PPT – LateroDorsal- and PeduncoPontine
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Tegmental nucl
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---
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## Page 14
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The ”sleep nucleus” in the hypothalamus
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(VLPO) inhibits the modulatory transmitter
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systems using GABA/Galanin
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Saper et al (2005) Nature 437:1257
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---
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## Page 15
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The cells in LHA and VLPO are under
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circadian control by the SCN via the DMH in
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the hypothalamus
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Saper et al (2005) Nature 437:1257
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---
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## Page 16
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SCN
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DMH
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VLPO
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GABA/Galanin
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NA, 5-HT,
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NA, ACh
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Light
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Meals, Temperature,
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Emotions / Cognition
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-
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LHA
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Orexin
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+
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-
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-
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Somnogenic
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factors
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Somnogenic
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factors
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+
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-
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Sleep control
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-
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Somnogenic
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factors
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-
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---
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## Page 17
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Adenosine is an ”somnogenic”
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factor contributing to sleep pressure
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---
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## Page 18
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Three different brain states:
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Wake, NREM & REM
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Wake
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Non-REM
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REM
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NA, 5-HT, Histamin
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High
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Low
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Low
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ACh
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High
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Low
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HIGH
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Orexin
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High
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Low
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Low
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EEG
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Desynchronized
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Synchronized
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Desynchronized
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Energy consumption
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High
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Moderate
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High
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Muscle tonus
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High
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Moderate
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Low
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Breating / Heart rate
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Regular
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Regular
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Oregelbunden
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Temperature regulation
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Functioning
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Functioning
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Non-functioning
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Eye movements
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Vision
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Slow
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Fast (REM)
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---
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## Page 19
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Timofeev & Chauvette (2018) Neuron 97:1200-1202
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Modulatory transmitters and changes of e.c. ion
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conc. regulate the activity of cortical neurons
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EMG
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I.c.
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EEG
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---
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## Page 20
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An optimal level of neuronal network
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activity in the brain - Criticality
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Hengen & Shew (2025) Neuron 113:1-17
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---
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## Page 21
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Loss of consciousness during sleep and
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anaesthesia because ”decoupling” of cortical
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pyramidal neurons?
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Marvan et al (2021) Neurosci Conscious 7: 1-17
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---
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## Page 22
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Cortical pyramidal neuron with two action potential
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initiation zones comparing Content with Context
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Granato et al 2024 Neurosci and Biobehav Rev 161: 105688
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”Predictive coding” and
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”Predictive error”
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---
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## Page 23
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Simultaneous apical feedback and basal
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feedforward inputs provide synergistic firing
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output
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Larkum (2012) TiNS 36:141-149
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---
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## Page 24
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Promoting apical and basal coupling enables
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consciousness
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Suzuki & Larkum (2020) Neuron 180: 666-676
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---
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## Page 25
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(No content)
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---
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