Von Neumann vs Human Brain

Lauren Williams Extended Project Qualification
A comparison of the processing architecture of a Von
Neumann Computer and the Human Brain
The human brain is a vast, complex area of science which has yet to be fully discovered, and likely
never will be. Its immense complexity is what makes it so unique compared to other organs in the
body. However, one question that has intrigued me over the years is exactly how similar a computer
is to the human mind. Humans designed and constructed computers, so it seems likely that the two
should be similar as we may possibly have based them on our own processing. Artificial
intelligence is a growing science which, as time goes on, is becoming more necessary as many
human tasks require learning, which a computer will need to mimic. Artificial intelligence has
featured a lot in books, film and various other media. For a long time, it has been a debated subject.
But just how close are humans to computers? How close are we to achieving true artificial
intelligence?
By definition, a Von Neumann central processing unit is “the key component of a computer
system, which contains the circuitry necessary to interpret and execute program instructions. (1)” A
CPU, or microprocessor, does this by performing arithmetical and logical
operations on a set of binary units. These binary units then represent simply
off, and on. The Von Neumann architecture of a computer is a design based
on Alan Turing and John Von Neumann’s revolutionary idea that data
should be stored in memory, alongside the program that is processing that
data, all in the same memory. This would make a computer far easier to
reprogram, rather than start from scratch, building an entirely new
computer. This is also known as the stored-program architecture. According
to the Von Neumann architecture, within memory there will be data, and
the program that processes that data – within
modern computers, the most common form of memory is RAM, or
random access memory. The control unit’s responsibility is executing
program instructions one at a time, as well as moving data and programs
in and out of memory. The registers within the processor are fast
memory stores, which hold intermediate values for the control unit. The
input and output, as seen above, allows the user to interact with the
machine, and the machine to interact with the user. Examples of inputs
are: keyboard, mouse, microphone. Whereas, examples of outputs are:
headphones, printer, visual display unit (monitor). The arithmetic/logic
unit performs calculations such as addition, multiplication, subtraction
and multiplication as well as logical operations (less than, more than)
upon the data. The arrows as seen in the image are buses – they allow each of the units to
communicate. There are three types of bus: the address bus, the data bus and the control bus. The
address bus carries information on where the data is going, the data bus carries the actual data and
the control bus carries information on what is going to happen to that data. (20)
Computers operate in a completely discrete and digital nature, as there is only 1 and 0 (on
and off) – nothing outside or in between. The human brain is thought to also use electricity for
processing, however this is completed by electrical impulses. These electrical impulses are sent by
neurones (or specifically in this case, sensory neurones), which can fire at varying strengths.
Therefore the brain is analogue in this way as there is fluctuation (2). The human brain can also
communicate chemically using a substances known as neurotransmitters. These include such
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Image 1: Core i7
CPU (3)
Image 2: Von Neumann
Architecture (21)

chemicals as Dopamine, Acetylcholine and Endorphins, each of which have a specialised functions.
The brain also has different sections, each of which are responsible for different functions
within the body. The Cerebrum is considered to be related to thought and actions,
and consists of the frontal lobe, the parietal lobe, the occipital lobe and the
temporal lobe. The frontal lobe is responsible for actions
such as reasoning, planning, some aspects of speech,
movement, emotions and problem solving. The parietal
lobe is associated with movement and co-ordination, as
well as recognition and perception of stimuli. The
occipital lobe is mainly regarded with visual processing,
and the temporal lobe is mainly associated with sound
(speech, perception and recognition of auditory stimuli) as well as
memory. Other sections include the Cerebellum which involves co-
ordination, movement and balance; the limbic system which is associated
with emotion and contains the hypothalamus, the thalamus, the hippocampus and the amygdala; and
finally the brain stem which is associated with homoeostasis. I will be focusing on the cerebrum as
most processing occurs here (5).
The cerebrum is the largest part of the human brain, and tends to be associated with more
complex processes. The cerebrum consists of cerebral hemispheres, which are mirror images of
each other. These two hemispheres are connected by a series of nerve fibres known as the corpus
callosum and are separated by a layer called the falx cerebri (6).
A CPU however, executes what is known as stored program instructions. Computers must
have a central processing unit(9), and also have main (primary) memory (RAM). The CPU will
interact with main memory for instructions and data, and is often
considered part of the CPU, however it, technically, is not. Main
memory is also not permanent – as soon as you turn the computer
off, all data and instructions in main memory will be lost. Secondary
memory is permanent, and consists of peripherals such as hard disk
drives, compact discs, digital versatile discs, flash drives and solid
state drives.
The central processing unit consists of several
components. The control unit, first of all, uses electrical signals
from the circuitry within the control unit, to signal the entire
computer to execute stored program instructions. The control unit
does not directly execute these instructions, but it instructs other parts of the system to. It also
communicates with the arithmetic/logic unit and main memory.
The arithmetic/logic unit performs arithmetic and logical operations upon binary digits. This
unit can perform four mathematical calculations: addition, subtraction,
multiplication and division. This doesn't only cover numerical values, but
letters and special characters also. The logical operations include the
equal-to condition, the less-than condition, and the greater-than conditions.
A computer can also combine operators to complete more logical
operations.
Within the CPU there are registers; temporary storage areas for
instructions or data. They work under the control unit – they are not part
of memory and are fast, special additional storage locations. They accept,
hold, and transfer data or instructions, performing arithmetic and logical
comparisons and very high speeds. Examples of specialised registers are
Image 3: A
neurone (4)
Image 5: The
Arithmetic/Logic and
Control Units (8)
Image 6: The Machine
Cycle (12)
Image 4: The lobes of
the Cerebrum (7)

accumulators, address registers and storage registers. The accumulator collects the outcome of
various computations, the address register holds where instructions or data are stored in memory
and the storage register holds data temporarily which has been taken from or about to be sent to
memory. There are also general purpose registers, which are used for several functions. For
example, a program may be interrupted in its state so the value of the registers such as the memory
address register and the value may be saved in the general purpose
registers, ready for recall when the program is ready to start again.
Generally, the more registers a CPU has, the faster it can function
(10).
In order to execute program instructions, the CPU must partake
in the machine cycle. Program instructions and data must be placed
into main memory before an instruction can be executed. Once this
is completed, the control unit retrieves the instruction from memory
and decodes the instruction, directing data to the arithmetic/logic
unit. The result of this operation is stored in memory or a register by
the ALU. The result is then directed, by the control unit, to an output
device or a secondary storage device (such as a hard disk drive).
CPUs also have unique machine instruction sets. For example, an Intel processor will not
understand the machine instructions for an AMD processor. This is similar to humans – we each,
depending on our knowledge, understand a language. If I were to speak to a Indonesian woman, it is
unlikely she would understand me as we have different knowledge, and do not understand each
other's language.
There are several theories within Psychology, none of which right or wrong, however I will
be focusing on the cognitive theory, as it compares itself to a computer and suggests that we too are
information processors. The information processing approach makes several basic assumptions.
Four of these are:
1) A series of processing systems processes information from the environment.
2) Information is transformed and altered in systematic way by these processing systems.
3) Specifying the processes and structures that underlie cognitive performance is the aim of
research
4) Information processing in humans resembles that in computers.
In the 1950s and 1960s, the development of computers hugely influenced psychology, and
was likely the cause of cognitive psychology dominating behaviourist psychology, the dominant
approach at the time. As investigated earlier, computers perform operations on information, store
information, use information and outputs that information. This idea was used by cognitive
psychologists to explain how human thought worked. For example, the hand feels something hot.
That information is sent to the brain, manipulated, stored, used to create a reaction and tha t reaction
is executed, outputting the pulling away of the hand. The information processing approach suggests
that the environment is an input, and that we use “mental programs” upon this input, resulting in
behavioural processes. Humans can only process a limited amount of information at a time without
becoming overloaded – the brain is thought to be a limited capacity information processing system
(11).
The modal model of memory, proposed by Atkinson and Shiffrin shares many similarities to
a computer. It includes sensory memory, short term memory and long term memory, each of which
can be likened to a computer. The sensory memory is responsible for encoding and transforming
input from the environment into neural impulses, then sending these to short term memory. This can
Image 7: Information
Processing Model (13)

be likened to input devices, such as a keyboard or scanner. Recently
processed and currently being processed information is held in short
term memory. It can hold information from the sensory register and then
pass it on to long term memory. Short term memory has. as suggested, a
short memory length, and it can hold only 7±2 pieces of information.
Short term memory is similar to main memory, and the CPU. The
capacity of short term memory can also be likened to word length, which
refers to how many bits the registers in a CPU can hold. Long term
memory, however, is responsible for storing information on a relatively
permanent basis. It it thought to have an unlimited capacity. Forgetting is
thought of as retrieval failure, rather than loss of information. New
information can often clash with old information and vice versa, leaving
with failure of retrieval once more. Long term memory can be likened to
hard disk drives – loss of memory is due to corruption, and deletion. Items are placed into the HDD
when items in the CPU are to be stored and saved. Retrieval pulls items from the long term store
into the short term, similar to how a CPU retrieves data from the HDD into the main memory and
uses it.(14)
The brain consists of 100 billion neurones which all communicate to transmit signals across
the brain. They consists of three basic parts – the cell body, the axon and dendrites. The cell body
contains the nucleus (holds DNA), endoplasmic reticulum, ribosomes (endoplasmic reticulum and
ribosomes involved in protein synthesis) and mitochondria (synthesising energy). The axon carries
the electrochemical messages along the cell. The axon can also be covered in myelin, a mix of fat
and protein. The myelin sheath helps speed the nerve impulses down the axon. Dendrites are small
branches of the cell that make connections to other cells, and allow the neurone to communicate
with other cells. These are either at both ends of the cell, or only one side of the cell(15). The output
of a neurone can either lead to excitation or inhibition to the cell it is currently attached to. When an
excitatory signal is sent, then the signal will be added to all the other inputs of that neurone. If it
exceeds a given threshold, then the target neurone will fire an action potential. If not, no action
potential occurs. Action potential is an electric pulse that moves down the axon until it reaches the
synapses, where neurotransmitters are then released. Neurotransmitters then diffuse across and fit
into the receptors that are located on the target neurone. This leads to some action to take place on
that neurone which will either increase or decrease the membrane potential. Increasing the
membrane potential excites the neurone, whereas decreasing the membrane potential inhibits the
neurone. If the membrane potential passes the firing threshold, then it will activate an action
potential in the target neurone, and this action potential then passes down the axon. On the surface,
a computer and the brain may seem similar as both use electrical signals. However, energy for a
computer comes from the power supply. If we were to liken neurones to wires, then wires should be
able to power themselves to an extent. Obviously the mitochondria require glucose in order to
produce energy, which we could say is similar to a power supply as it has to come from an external
source, however a glucose->energy conversion must occur. Also, as I briefly mentioned before,
action potential is continuous and therefore an analogous signal, compared to the discrete value that
voltage holds.(17)
Within a computer, there are components known as buses. These are a collection of wires
through which data and instructions are sent from one component to another. They connect all the
internal components to the CPU and main memory. These include an address bus and a data bus.
This has a closer likeness to neurones, as buses transport information to and from components to the
CPU. The address bus carried data about where the item in the data bus will be going in regards to
main memory or a register, whereas the data bus carries the data. A bus has width, and the width of
Image 8: neurone Action
Potential (16)

a bus determines how many bits it can transfer. For example,
a 16 bit bus can transfer 65536 different words, each of which
consisting of 16 binary digits. (18)
Capacitors store an electrical charge, and are most
frequently used in timer circuits. They are sometimes used to
smooth a current in a circuit as they can prevent false
triggering of other components. A capacitor charges up when
power is supplied to a circuit; the capacitor slowly discharges
when the power is turned off. Capacitors feature in computers
in places like the motherboard and power supply. A capacitor
consists of two conductors, which are then separated by a
dielectric (an insulating material). A dielectric can be anything non-conducting, and can be paper,
plastic film or a vacuum. The plates (conductors) can be anything conductive, so aluminium discs
or foil. This sandwich of materials can either be left flat or rolled into a cylinder. Capacitors can
also be used for a time delay. They are often used in computers to prevent damage to the core
components, and to smooth out any voltage spikes. There are also electrolytic capacitors and non-
electrolytic capacitors. Electrolytic capacitors are polarised – they must be positioned the correct
way around as they have a positive and a negative. They have a much higher capacitance than non-
electrolytic capacitors, which are usually used to smooth a current in a circuit. (19) The most similar
component within a human is glucose. Glucose is a primary source of energy, which is then used in
a process to produce Adenosine Triphopshate (ATP), a chemical compound that breaks down to
release energy. (24) Glucose is obtained by digesting the sugar and starch in carbohydrates, found in
the food we eat. The digestive system then uses bile and enzymes to
break down the start and sugar into glucose. Glucose is then absorbed
through the small intestinal wall, into the bloodstream and carried
throughout the body.(23) This similar to capacitors as both hold stores
of energy, and any excess glucose is excreted, similar to how a
capacitor discharges when there is no power supplied to it.
Recent developments have gone into creating what is known as
an electronic neurones. After studying neurones, it has been found
that there are four degrees of freedom within a neurone. From this,
scientists have constructed numerically and in simple analogue
circuitry; four dimensional models of neurones. They display similar
behaviour shown by biological neurones, and are able to interact between themselves. Electronic
synaptic connections have also been made. Phil Stearns created a neurone network of 45 electronic
neurone, which respond to light and tones with a “squealing sound”. Each neurone has 6 functions –
input, output, summing, threshold, offset and structure. Stearns likened the creation to “some kind
of squid baby”(25). Other developments have been integrated an electronic neurone into a group of
14 other biological neurones retrieved from a california spiny lobster. The artificial neurone was
accepted by the biological neurones, and all signalling synchronised. Artificial neurones have been
an idea proposed since 1940, however scientists have been unable to recreate this idea to until
recently. Although the integration into only 14 neurones is small, it’s a breakthrough and could lead
further developments on a much larger scale. (27)
Another breakthrough is scientists have managed to create a robot that is controlled by a
blob of rat brain cells. This could then give insight into diseases such as Alzheimer’s as you would
be able to view the deterioration of the brain. This idea is known as hybrid machines. The nerves
controlling the robot were taken from the neural cortex of a rat foetus and then treated so that the
connections between the individual neurones were dissolved. The container of the living cells are
Image 9: Capacitors on a
motherboard (29)
Image 10: An electronic
neurone network (26)

kept separately from the robot. The container is temperature controlled and is
pitted with electrodes – the signals are then passed to the robot via Bluetooth.
The robot itself has sonar attached to it, as well as wheels so that the robot can
move. These brain cells have then been taught how to control the robot and
manoeuvre around obstacles, and will be taught how to recognise its
surroundings. This is all so that scientists can disrupt the memory and recreate
the gradual loss as seen in diseases such as Alzheimer’s. Although this
research is to investigate diseases, it shows how the brain and a machine can
be interlinked and communicate with each other. Perhaps this could lead to
computers with human brain cell processors, with unfathomable processing
speeds and capacities. (44)
Cybernetics is “the scientific study of how people,
animals, and machines control and communicate
information”. The field of cybernetics came into
popularity in the late 1940s when ideas of information, feedback and
regulation from engineering in specific applications to systems in
general – this includes living organisms, abstract intelligent processes
and language. (28)
In 1947 Norbert Wiener used the term “cybernetics” to name a
discipline that briefly described fields such as electrical engineering,
mathematics, biology, neurophysiology, anthropology, and psychology.
This field was first used in the control of artillery, designing electrical
circuits and manoeuvring simple robots. The term cybernetics is a term
that has been adapted from a Greek word meaning “the art of steering”,
as it wishes to interact with goals, predictions, actions, feedback and response. This field has
recently become popular due to the lack of advances in AI, leading to scientists beginning to
alternatively view what the brain does, and alternatives to the current view of biological cognition.
The approach is limited by what we can know, differing it from AI, and is often known as applied
epistemology. There are several differences between artificial and cybernetics. Artificial
intelligences views cognitive systems as having an inside and outside; that organisms map external
objects to an internal state; the nervous system stores information; the truth exists in the world; and
that intelligence resides in manipulation of information. Cybernetics however, view cognitive
systems as being autonomous; that organisms map through an environment back onto themselves;
the nervous system reproduces adaptive relationships; that social agreement is primary objectivity
and intelligence resides in observed conversations. (30)
Neurones within the brain are comparable to that of logic gates within a computer. Neurones
function, as mentioned previously, to transmit information throughout the body. Logic gates,
however, perform basic logical functions on binary values. Logic gates can be joined together to
produce logic circuits – some may have millions, some may have only a
few logic gates. Each logic gate has two inputs, except the NOT gate
which has 1. They are like so:
• AND – if A and B are true, then output is true. Otherwise, false.
• OR – if A or/and B are true, then output is true. Otherwise, false.
• NOT – if input is true, output is false. If input is false, output is
true.
• XOR – if A or (not and) B are true, then output is true. Otherwise
false.
Image 11: Norbert
Wiener (31)
Image 12: A
transistor (33)
Image 10: The rat-
brain controlled
robot. (45)

• NAND – the opposite of AND. Only false when both A and B are true.
• NOR – the opposite of OR. If A and B are false, then output is true.
• XNOR – the opposite of XOR. If A and B are true or false, then output is true.
By combining thousands of these logic gates, then a computer is able to perform highly complex
operations. Transistors make up most logic gates, therefore smaller transistors means more complex
and faster processors.
Transistors can be considered as a type of switch. They are used in a variety of applications,
and there are two types: bipolar transistors and field effect transistors. Bipolar transistors consists of
two main types; NPN (negative positive negative) and PNP (positive negative positive). Most
circuits use NPN, and there are hundreds of different transistors that work at different voltages.
Bipolar transistors have three leads:
• Base – lead that activates the transistor.
• Collector – positive lead.
• Emitter – negative lead.
Once the base lead receives 0.6V, the transistor switches on and allows some current to flow from
the collector to the emitter. It acts as an analogue which can be used to amplify the current at the
base lead. However, they are fragile and can be easily damage if the three leads are confused. (32)
Field effect transistors, however, are digital switches. They allow increases in either voltage
or current in response to an input voltage. Field effect transistors are similar
to bipolar transistors as they have three leads. There is:
• Gate
• Drain
• Source
When the gate receives 2V, it switches on sending electricity to flow from
the source to the drain. This continues to flow until the voltage at the gate
falls bellow 2V. Resistors are used to protect the transistor as they are easily
damaged. Transistors can also amplify signals. (33)
Logic gates and neurones are comparable as both control electrical signals, however logic
gates produce outright calculations, compared to neurones which, in collections, can be responsible
for calculations. However logic gates in collection can be used for complex calculations, which
could be argued to be similar to the sections of the brain.
The brain has changeable processing speeds, which is unlike a computer. Processing speed,
in the brain, is a measure of cognitive efficiency. This increases as the task becomes learned and is
repeated. Several other factors affect processing speed with humans – humans may struggle under
stress and other conditions, however arguably a computer can too. Under stress, a computer may
slow down when processing a task. With computers, this occurs when several tasks are being
processed at once or one task is far too CPU intensive. (34) You could also argue however, that
humans experience a different stress as stress tends to be an emotional response rather than an
intense task issue. In order to overcome the inability to compute several tasks on one processor, in
2001, IBM introduced the first multi core processor. The breakthrough in design allowed the two
processors to “work together at very high bandwidth with large on chip memories, and with high
speed buses and input/output channels” (35). A multi core processor is essentially two different
Image 13: The
hypothalamus (40)

CPUs together on one chip, packaged together into one single integrated circuit. Multi core
processors, depending on whether the program allows it, can split tasks between the cores, reducing
the workload upon the single core. This also lowers the heat the processor produces, allowing more
opportunity for over clocking (running a computer at a speed higher than intended by
manufacturers). (36) In some ways, you could liken the human brain to a multi core processor as the
brain has several sections it is made from. We, as humans, are also able to perform homeostasis
(“The ability or tendency of an organisms or cell to maintain internal equilibrium by adjusting its
physiological processes” (37) ) without thinking about it as it is an innate ability. This is performed
by the hypothalamus, which is a small part of the brain. The hypothalamus secretes hormones
which then control and regulate the secretion of pituitary hormones. (38) The pituitary hormones
help regulate several bodily functions by using pituitary hormones to tell endocrine glands to
release a specific hormone to stimulate the release of the organ specific hormone. (39) Computers
cannot perform this, as all instructions have to be present in main memory in order to be executed
by the CPU. For a computer, there are no processes that it is unaware of. In contrast, you could also
argue that there are processes occurring in the background according to the user of a computer, such
as maintaining fan speeds in concordance to CPU temperature.
There are also some tasks a computer cannot complete, but a human can. An example of this
is the Turing test. The Turing test is a test devised by Alan Turing, which is said to be able to
determine whether or not the
respondent is a human or a
computer. Simply put, two entities
are given a series of questions and
the responses (each are correct) are
used to determine whether or not the
respondent is human. The harder it
is to tell whether or not the
respondent is a computer, the more
intelligent the computer is. The
Turing test is often used in
philosophical debate in order to
determine how close computers are
to being considered as sentient beings. (41)
Computers are also unable to adapt to completely new conditions , unlike humans. For
example, humans are able to cool down when exposed to a higher temperature that they experience
from a completely unfamiliar environment. However, a computer has to have such a situation
programmed into its software and a means to deal with such a situation,therefore the situation is not
unfamiliar in the first place as the computer has an idea of how to cope with the situation. Therefore
humans process differently to computers. Also, even now we still do not have a full understanding
of the human brain, so we cannot possibly create a fully functioning simulation of the human brain.
Computers are also modular and serial. They are modular as we can easily replace parts, and
each module has a specific job it has to complete. The human brain, however, is a huge parallel
machine. Sections of the brain have several purposes, and each contribute towards the task at hand.
However there have been recent developments in computing, including parallel computing. (42)
Parallel computing is the use of several compute resources to all solve one problem. This often
occurs across multiple processes, where the problem is broken down into a series of instructions.
These instructions are then executed on each of the different processors, and an overall control
mechanism monitors it all. However for this to occur, the problem itself should be able to be broken
down into smaller pieces that can be solved at the same time, be able to execute several instructions
Image 14: Diagram of the Lawrence Livermore National
Laboratory parallel computer (43)

at any time, and be solved in less time with multiple computer resources than a single computer
resource. These compute resources may be single computers with many processes, several
computers connected to a network or a combination of both. In the LLNL computer, each compute
node is a multi processor parallel computer in itself, the multiple compute nodes are then networked
together with an InfiniBand network (a type of data transfer between processors and I/O devices at
2.5 gigabytes per second), and special purpose nodes which are also multi-processor and have
specific jobs. (43)
In conclusion, the human mind often can be considered to be similar to a computer, however
in other situations a computer can be considered dissimilar. Computers and humans do seem very
much akin and perhaps ideas of artificial sentient beings is not such a far-fetched idea, and is
entirely possible. Although, there are still many obstacles to overcome in computer engineering, as
we still do not have a computer intelligent enough to match the mind of a human. Until this is
achieved, we cannot possibly suggest that computers can think independently and be truly
intelligent.

Von Neumann vs Human Brain

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