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draft of introduction

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2013-09-10 12:35:01 -04:00
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wholeBrain_main.md
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@@ -17,19 +17,21 @@ The cerebral cortex exhibits spontaneous and sensory evoked patterns of activity
<!--- This should be one paragraph. Some of this intro material could be combined with intro or concl sentences in abstract for a Nature letter (should be referenced and up to 300 words; 200 words preferred) --->
- Activity and development
Brain development requires neural activity and calcium dynamics for establishing proper circuit structure and function. The importance of neural activity in the prenatal and neonatal period can be easily recognized in children exposed to chemical agents affecting neurotransmission during the fetal period that result in severe brain malformations, epilepsy, and mental retardation. Indeed, embryonic limb movements in species ranging from chick to human are thought to be initiated by spontaneous motor neuron activity in the spinal cord and has been recognized in chick to human and is thought to be crucial for activity-dependent development of motor synapses [Schoenberg:2003] [Marder,Lichtmann]. However it is only recently that we have begun to appreciate the underlying patterns of persistent neural activity that in fact exist in the developing brain in vivo. For example, sensori-motor feedback associated with spontaneous movement generated by spinal motor neurons triggers synchronized 'spindle-burst' potentials among cells in somatosensory cortex [Yang:2009][Khazipov:2004a] before the start of locomotion and tactile behavior. Correlated bursts of activity occur in the developing rat hippocampus in vivo [#Leinekugel:2002] [Mohns&Blumberg]. Spontaneous retinal waves drive patterned activation of circuits throughout immature visual system before the onset of vision [#Ackman:2012] [Hanganu,Colonnese?]. Slow activity transients occur in the human occipital cortex before birth [#Vanhatalo:2005][#Tolonen:2007]. However to understand the informational capacity of neural activty in the developing brain, the structural dynamics of persistent activity must be understood.
- Neural activity, drugs, and birth defects
- epilepsy
- autism
- What is the activity?
- instructive or permissive?
- EEG slow oscillations not detectable until P10 in rodent.
- slice work
- leinekukel and khazipov work [#Leinekugel:2002][#Khazipov:2004a]
- ucla konnerth imaging work [#Golshani:2009][#Adelsberger:2005]
- human occipital cortex and my retinal wave paper [#Vanhatalo:2005][#Tolonen:2007][#Ackman:2012]
- is the activity completely random? Or Is it organized in space and time, and at what scale?
- the little that we know is from work in second postnatal week, not earlier, olavarria work, interneuon migration, synaptic formation, and anatomical studies indicates significant development decisions are being made in first postnatal week
- human occipital cortex and retinal wave paper [#Vanhatalo:2005][#Tolonen:2007][#Ackman:2012]
- To understand the informational capacity of neural activty in the developing brain, the structural dynamics of persistent activity must be understood.
- completely random? Organized in space and time, and at what scale?
- previous work on interneuron migration, axon growth (olavarria work) synaptic formation, and anatomical studies indicates significant development decisions are being made in first postnatal week
@@ -52,8 +54,8 @@ The cerebral cortex exhibits spontaneous and sensory evoked patterns of activity
metric | mean | min | max | unit
------------- | ----- | ---- | ------ | --------------------
diameter | 396.0 | 22.7 | 2383.5 | µm
duration | 0.6 | 0.2 | 14.6 | s
diameter | 396.0 | 22.7 | 2383.5 | µm
duration | 0.6 | 0.2 | 14.6 | s
frequency | 2.9 | | | domains/sec/hemisphere
[**Table 1: Domain statistics**]
@@ -64,6 +66,7 @@ frequency | 2.9 | | | domains/sec/hemisphere
## Cortical domain activity is state dependent ##
* EEG slow oscillations not detectable until P10 in rodent.
* Previously demonstrated that general anesthesia abolishes spontaneous activity in visual system [#Ackman:2012].
* What about ongoing activity in other cortical areas during early brain development? Surgical procedure relevance.
* No population calcium activity found during gen'l anesthesia, only slow traveling waves.
@@ -100,6 +103,7 @@ lenActvFraction>0 | fracCorr | timeCorr_s | fracCorrPos | timeCorrPos_s | fracCo
## Cortical activity is mirrored between the hemispheres ##
* Inter hemispheric functional connectivity, importance for autism, schizophrenia. Maybe an activity-dependent mechanism for commisural connectivity.
* olavarria work, evidence for inter hemispheric activity dependence
* [#Hanganu:2006], 30% of spindle bursts correlated across hemispheres
* Activity correlated in anterior-posterior and medial-lateral directions
* Mirror symmetric and non-mirror symmetric patterns