Presentation on theme: "Connectomes. A big difference between the Connectome and Genome projects is in data volumes. The difference between 1.6 GB for the genome and my estimate."— Presentation transcript:
A big difference between the Connectome and Genome projects is in data volumes. The difference between 1.6 GB for the genome and my estimate of 13 PB for the connectome is a factor on the order of 10 billion. A projection based on Moore’s Law – still the most reliable guide to our ability to handle data volumes – stipulates 67 years to advance from the 2003 achievement of the Genome Project to what is needed to record all connections in a human brain.
A diffusion tensor imaging scan of a healthy brain adds color to its white matter. "It's not perfect...but it's so much better than anything we've had before," says Gregory Sorensen, an associate professor of radiology at Harvard Medical School. Image credit: Zephyr/Science Photo Library
Precuneus Brain: Precuneus Medial surface of left cerebral hemisphere. (Precuneus visible top left.) Medial view of a halved human brain Gray's subject #189 823 NeuroNames hier-92 The precuneus is a part of the superior parietal lobule hidden in the medial longitudinal fissure between the two cerebral hemispheres. It is sometimes described as the medial area of the superior parietal cortex. It is involved with episodic memory, visuospatial processing, reflections upon self, and aspects of consciousness. The location of the precuneus makes it difficult to study. Furthermore, it is rarely subject to isolated injury due to strokes or trauma, such as gunshot wounds. This has resulted in it being "one of the less accurately mapped areas of the whole cortical surface".  While originally described as homogeneous by Korbinian Brodmann, it is now appreciated to contain three subdivisions.  It is also known after Achille-Louis Foville as the quadrate lobule of Foville.  The Latin form of praecuneus was first used in 1868 and the English precuneus in 1879.  Gray'ssubject #189 823NeuroNameshier-92superior parietal lobulemedial longitudinal fissurecerebral hemispheresparietal cortexepisodic memoryvisuospatialselfconsciousnessstrokes  Korbinian Brodmann Achille-Louis Foville  
86 billion neurons and 85 billion neuroglial cells7000 connections per neocortical neuron in adults. (Young children have many more. A unique number identifying a single neuron in a population of 86 billion can be expressed in 37 bits of information. To identify the two neurons would take 37 + 37 = 74 bits per connection, or 518,000 bits (65 kilobytes) per neuron. Multiplying by 86 billion neurons gives a total of 5.59 petabytes (PB) of information. That’s just for the basic connectivity map: a record of which neurons are connected to which. More information would be required. We would also need to know the type of synaptic connection (whether electrical or chemical, and if chemical, the specific neurotransmitter to which the synaptic receptor responds). As that is largely a function of the transmitting neuron, it might not need to be expressed as a property of the connection; but if it were, then estimating 100+ neurotransmitters, that would take another 9 bits per connection. The 3D spatial location of the synapse is also important; it could be expressed to 1 nm precision (probably overkill) using 93 bits. Therefore we could express the type and location of each neural connection, and the identities of the transmitting and receiving neurons, in 74 + 9 + 93 bits = 176 per connection. That multiplies out to over 13 PB for the whole brain. Although my brain weighs just 2% of my body, the ‘informational weight’ of my brain – dominated by the connectivity map – might well come in at 95% or higher! Let’s work with those numbers. Remember, the 13 PB estimate is only for neural connectivity. Other properties of the neurons are important, as are attributes of the glia and blood vessels of the brain. But the volume of information required to capture those attributes is on the level of whole cells rather than connections; as such it is insignificant compared to the connectivity information. One more petabyte should be enough. Accordingly, I will revise my estimate of the volume of information required to replicate a person to a whopping 15 petabytes. Although that’s 15 times my first estimate, it makes very difference to the prediction of when human replication technology will become commercial reality. Assuming Moore’s Law, a factor of 15 adds eight years. We should be able to transmit 15 PB in one second by 2057.Moore’s Law
The central core region seems to be the brain's "default" network. The brain contains a central core consisting of 8 distinct subregions in the posterior medial area of the cortex. This core radiates a dense network of fibres to other parts of the cortex, and may act as an integrated system which co-ordinates the combined activity of the two hemispheres.
POSTERIOR CINGULATE CORTEX AND PRECUNEUS Moral Sensitivity Processing Self Relevant Stimuli Frontooccipital tracts processing information from Frontal Eye Fields to occipital areas and secondary projection into parietal association areas and the “the Theater of the Mind”
A reconstruction of 114 rod bipolar nerve cells from a piece of mouse retina. The dense bundles (top) are dendrites, and the sparser processes below are axons (credit: MPI for Medical Research)
Dendrites form dense bundles where bipolar cells receive signals from rod photoreceptors (gray spheres) staining the neurons of a section of tissue with heavy metals to make them visible (credit: MPI for Medical Research)
Virtual reconstructions of nerve fiber tracts crossing the corpus callosum in the human (right) and rhesus monkey brain in vivo (left). green = prefrontal lobe, light blue = premotor and supplementary motor areas, dark blue = primary motor cortex, red = primary sensory cortex, orange = parietal lobe, yellow = occipital lobe, violet = temporal lobe
Axial tractographic image demonstrates white-matter tracts in the brain in the left- right (red), anterior-posterior (green), and superior-inferior (blue) directions. Courtesy of Dr Andrei I. Holodny, MD.
Brain Network Related To Intelligence Identified
IQ inheritance: By comparing the brain scans of twins, scientists discovered that the quality of the fatty tissue that insulates neural wires is largely inherited. The parietal lobe, which is involved in logic and mathematics, is 85 percent genetically determined, whereas the visual cortex is about 76 percent, and the temporal lobe, which is involved in learning and memory, is only 45 percent genetically determined. Credit: David Shattuck, Arthur Toga, Paul Thompson/UCLA
Parcellation Scheme for human left lateral parietal cortex
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