1 12. Anatomical, physiological, and pharmacological properties underlying hippocampal sensorimotor...

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12. Anatomical, physiological, and 12. Anatomical, physiological, and pharmacological properties underlying pharmacological properties underlying hippocampal sensorimotor integrationhippocampal sensorimotor integration

BRAIN H. BLAND

PT : Kim, Hoon-Hee (SNU-BI)

(C) 2007 SNU CSE Biointelligence Lab

ContentsContents

The Cellular basis of theta-band oscillation and synchrony

The ascending brainstem hippocampal synchronizing pathways

The ascending brainstem hippocampal desynchronizing pathways

Data supporting the sensorimotor integration model of hippocampal function

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The Cellular basis of theta-band oscillation The Cellular basis of theta-band oscillation and synchrony (1)and synchrony (1) Limbic cortex , Limbic structure Hippocampal formation (HPC) Theta oscillation and synchrony. The asynchrony activity : large amplitude irregular

activity(LIA) Type 1 theta

Atropine-resistant movement

Type 2 theta Atropine-sensitive Immobility Sensory processing

(C) 2007 SNU CSE Biointelligence Lab

The Cellular basis of theta-band oscillation The Cellular basis of theta-band oscillation and synchrony (2)and synchrony (2)

Theta-ON cells

Hippocampal CA1, CA3 pyramidal cell MPOs occurred only during theta field

activity Oscillation : voltage-dependent Frequency : voltage-independent No phase changes observed during

current injection

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The Cellular basis of theta-band oscillation The Cellular basis of theta-band oscillation and synchrony (2)and synchrony (2)

Theta-OFF cells

Hippocampal CA1 basket cells MPOs occurred only during theta field

activity Amplitude : voltage-dependent Frequency : voltage-independent

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways The rostral pontine region

The nucleous reticularis pontis oralis (RPO) The pedunculopontine tegmental nucleus (PPT)

Cellular activity in the RPO and PPT in relation to hippocampal theta generation have revealed only irregular (tonic) discharge patterns.

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways The caudal diencephalic

region Primarily the posterior

hypothalamic (PH) The supramammillary

(SUM) nucleus PH and SUM nuclei A critical part of the

ascending synchronizing pathway

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways Phasic theta-ON cells in

the HPC translated the level of activation of the ascending synchronizing pathways through their discharge rates

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways A phasic theta-OFF cell during

the transition from higher-frequency theta to lower-frequency theta to LIA

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways Phasic theta-OFF cells

were inhibited by PH stimulation and the inhibition was not abolished by the administration of atropine sulfate

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways Rhythmic and non-rhythmic patterns Tonic theta-ON cells in the PH discharged at significantly

higher rates during theta Tonic theta-ON Cells

Thalamic centromedial (CM)

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways Tonic theta-off cells discharging at significantly higher rates

during LIA

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways From SUM Phasic theta-on cells Not significantly increase their discharge rate during the

transition from LIA to theta field activity.

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways The medial septal region

(MS/vDBB) “pacemaker” function

NMDA effect Lon-lasting (20-30mins)

induction of hippocampal synchrony at the field and cellular level

ATSO4 (atropine)

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The ascending brainstem hippocampal The ascending brainstem hippocampal synchronizing pathwayssynchronizing pathways The combination of carbachol and bicuculline microinfusions

into the HPC of septally deafferented rats produced theta-like field oscillations

Rhythmic discharges of phasic theta-ON cells

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The ascending brainstem hippocampal The ascending brainstem hippocampal desynchronizing pathwaysdesynchronizing pathways The median raphe (MR) Electrial stimulation of the MR in anesthetized rats also has a

disruptive effect on rhythmically discharging medial septal neurons while in freely moving rabbits such stimulation also disrupted the rhythmic discharges of both medial septal cells and hippocampal theta.

The sensorimotor integration model would predict that MR stimulation in the freely moving rat should result in the inhibition of Type 1 theta-related behaviors.

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Data supporting the sensorimotor Data supporting the sensorimotor integration model of hippocampal functionintegration model of hippocampal function Two separate theta inputs to

the HPC Type 1 movement related

theta Type 2 sensory processing

theta The number of discharges

per rhythmic bust was always lower during type 2 theta compared to type 1 theta.

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Data supporting the sensorimotor Data supporting the sensorimotor integration model of hippocampal functionintegration model of hippocampal function The immobility period prior to

the execution of the jump could be divided into two components: a sensory processing period a movement preparation

period

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Data supporting the sensorimotor Data supporting the sensorimotor integration model of hippocampal functionintegration model of hippocampal function An updated

diagrammatic representation of the sensorimotor model for the hippocampal formation theta subsystems.

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