Bain Electricity

Question 1

Amplitude of brain waves are measured in what?

Answer 1

MicroVolts, or millionths of volts

Question 2

How many neurons in human brain?

Answer 2

86 billion

Question 3

How many non neuronal cells in human brain?

Answer 3

85 billion

Question 4

Weight of brain

Answer 4

1.3-1.4kg (3 lbs)

Question 5

What % of body weight is brain in humans

Answer 5

2%

Question 6

Herculano-Houzel 2012 on # of non neuronal cells

Answer 6

There are actually as many non neuronal cells as there are neuronal cells

Question 7

Metabolism cost of neurons

Answer 7

6kcal/day per billion neurons [ Herculano-Houzel S (2011 ]

Question 8

Brain metabolism scales linearly with

Answer 8

The number of neurons

Question 9

Body metabolism (I assume excluding brain ) scales how?

Answer 9

Sub linearly with body mass (exponent of 3/4). Apparently scales linearly with body surface area

Question 10

Thin apical dendrite diameter

Answer 10

diameter, 2.0 +- 0.4 micrometer,

Question 11

How many neurotransmitter molecules does a synaptic vesicles contain?

Answer 11

5000

Question 12

How does a neuron “decide” which synapses will release neurotransmitter when a neuron spike occurs?

Answer 12

The synapse decides , not the neuron

https://www.quora.com/How-does-a-neuron-%E2%80%9Cdecide%E2%80%9D-which-synapses-will-release-neurotransmitter-when-a-neuron-spike-occurs

Question 13

Computer transistor width as of 2022

Answer 13

2nm

Question 14

Neocortex accounts for what percentage of the brains volume?

Answer 14

80%

———-

Dunbar references anatomical measurements from 1981 and writes “With a neocortical volume of 1006.5 cc and a total brain volume of 1251.8 cc (Stephan et al. 1981), the neocortex ratio for humans is CR = 4.1.” (p. 682

https://aiimpacts.org/rate-of-neuron-firing/

Question 15

Estimated number of neocortical neurons?

Answer 15

20 billion
—————

https://aiimpacts.org/rate-of-neuron-firing/
———-

The average total number of synapses in the neocortex of five young male brains was 164 x 10(12) (CV = 0.17).” Tang et al, 2001

“Number of synapses in cortex = 0.15 quadrillion (Pakkenberg et al., 1997; 2003)” – Eric Chudler

“The human brain has a huge number of synapses. Each of the 10^11 (one hundred billion) neurons has on average 7,000 synaptic connections to other neurons. It has been estimated that the brain of a three-year-old child has about 10^15 synapses (1 quadrillion). This number declines with age, stabilizing by adulthood. Estimates vary for an adult, ranging from 10^14 to 5 x 10^14 synapses (100 to 500 trillion).” Wikipedia accessed April 13 ’15, citing Drachman, D (2005). “Do we have brain to spare?”. Neurology 64 (12): 2004–5. We have not accessed most of the Drachman paper, but it does at least say “Within the liter and a half of human brain, stereologic studies estimate that there are approximately 20 billion neocortical neurons, with an average of 7,000 synaptic connections each”. It seems improbable that the average number of synapses per neuron in the brain is the same as that in the neocortex, weakly suggesting the Wikipedia contributor made an error.

These figures suggest that the neocortex accounts for between a third and most of synapses.

Question 16

Average number of synapses per neocortical neuron

Answer 16

7000
——-

The average total number of synapses in the neocortex of five young male brains was 164 x 10(12) (CV = 0.17).” Tang et al, 2001

“Number of synapses in cortex = 0.15 quadrillion (Pakkenberg et al., 1997; 2003)” – Eric Chudler

“The human brain has a huge number of synapses. Each of the 10^11 (one hundred billion) neurons has on average 7,000 synaptic connections to other neurons. It has been estimated that the brain of a three-year-old child has about 10^15 synapses (1 quadrillion). This number declines with age, stabilizing by adulthood. Estimates vary for an adult, ranging from 10^14 to 5 x 10^14 synapses (100 to 500 trillion).” Wikipedia accessed April 13 ’15, citing Drachman, D (2005). “Do we have brain to spare?”. Neurology 64 (12): 2004–5. We have not accessed most of the Drachman paper, but it does at least say “Within the liter and a half of human brain, stereologic studies estimate that there are approximately 20 billion neocortical neurons, with an average of 7,000 synaptic connections each”. It seems improbable that the average number of synapses per neuron in the brain is the same as that in the neocortex, weakly suggesting the Wikipedia contributor made an error.

These figures suggest that the neocortex accounts for between a third and most of synapses.

Question 17

The average cortical neuron fires how many times a second?

Answer 17

.16 . This is an estimate based on the energy budget of the brain