How the camera imitates the human eye:

Sensory information is received from the external environment then:

Within the eye:

1. the human face turns towards the stimuli;

2. the cornea and lens at the front of the eye, focus the light reflected off the external physical object to create an impression on the retina at the back of the eye;

3. the retina converts the light into electro-chemical signals;

4. the optic nerve transmits electrical impulses to the thalamus in the brain. The thalamus acts like a relay station and sends information to two other parts of the brain to interpret the signals poduced from what the eyes have seen.

Within the camera:

1. the camera lens is pointed at the stimuli;

2. for old film cameras the lens at the front of the camera focuses the light reflected off the external object and creates an impression on the film at the back of the camera. For digital cameras, the light is registered at photosites on the digital sensor at the back of the camera;

3. the film is processed in chemicals to produce a negative, or for digital, photosites are demosaiced and converted into digital pixels;

4. the negative or pixels are transported to a photography darkroom or computer software to be processed into a readable image.

How our past experiences influence how we interpret what we see in the present:

Before the brain can instruct the body how to respond to incoming visual information, it needs to understand the meaning of what it is seeing. The thalamus, which is the relay station situated deep in the brain, facilitates this by relaying sensory signals to two specific parts of the brain:

• the amygdala in the centre of the brain, responsible for personal memories and emotions

• and the prefrontal cortex, situated at the front of the brain, responsible for reasoning.

Together these associate an emotional response to the image, whether that visual image is in front of us in real life or is a printed photographic representation.

When we experience something new and positive, the hippocampus in the brain becomes involved, converting short-term memory into long-term memory. This experience then adds to our autobiographical library of personal memories to guide future action.

How the emotional interpretation of what we see is transmitted from the brain to the body:

The information that has come through the eyes and has been processed in the brain to produce an emotion, is then sent to an area of the brain called the hypothalamus. The hypothalamus activates two communication systems:

• the autonomic nervous system

• and the endocrine system.

These communication systems are responsible for sending electrical messages called neurotransmitters and chemical messages called hormones throughout the body. Collectively, neurotransmitters and hormones instruct our cells, muscles and organs how to respond to what we are seeing and sensing.

How our nervous system creates an automatic bodily response to the emotional interpretation of what we are seeing and sensing:

Having created an emotional response to the external sight, the brain transmits electrical impulses to activate one of two specific pathways:

• The parasympathetic nervous system (PNS)
  
  If the emotional response to what we are seeing is positive, the PNS creates pleasant physical states of rest and digest which we experience as relaxed muscles, a slower heartbeat and slower deeper breathing.

  Given it’s chief role in calming the body down, the PNS also has a role to play in managing perceived threat or danger. It is responsible for the survival strategy of freeze when the commonly recognised fight or flight response is deemed impossible. Finally, it resets organ function following a fight or flight response.

• The sympathetic nervous system (SNS)

  If the emotional response to what we are seeing is alarming, the SNS jumps into action to keep us safe from real or perceived threat by activating the body's muscles and organs for the fight or flight response. The SNS: dilates pupils, secretes the hormone adrenaline, increases heart rate, dilates air passages within the lungs, contracts muscles, stimulates sweat glands, stimulates intestinal contraction and relaxes the bladder. Here we recognise the uncomfortable physical symptoms associated with anxiety and/or panic. During a SNS response, less relevant functions such as digestion, insulin regulation, excretion and sexual function are inhibited.

The role that hormones play in our bodily experience of emotions:

The endocrine system uses its network of glands to secrete important hormones. In general terms, we can think of hormones as the body's chemical messengers regulating the organs of the body to perform important functions like: growth, development, sleep cycles, reproduction and the balance of fluid, salt and sugar in the blood. The endocrine system also controls our physiological experience of emotions through the secretion of important hormones which we'll consider here in simple terms as ‘feel good’ and ‘stress’ hormones. Let’s start with stress and work our way to feeling good.

• Stress hormones

  Adrenaline for short-term stress response

  If the sympathetic nervous system (SNS) / fight or flight response has been activated, a signal is sent to the adrenal glands - sitting atop each kidney, to secrete the hormone adrenaline into the bloodstream. Adrenaline activates a short-term ’primed for action’ response in target cells elsewhere in the body: relaxing the airways of the lungs to take in more oxygen; constricting blood vessels to increase blood pressure; increasing heart rate; breaking down fat and increasing glucose levels to increase energy to respond to the real or perceived threat. Digestion and immune response are reduced.

  Cortisol for long-term stress response

  For long-term perceived or real threat, the hypothalamus gland in the brain transmits a message via the pituitary gland to the adrenal gland (a system referred to as the HPA Axis) to produce cortisol. Cortisol releases glucose into the blood to provide energy to the muscles and brain and signals to the SNS that the real or perceived threat is still present - this instructs the body to remain on alert on a long-term basis. Whilst cortisol is known as the ‘stress’ hormone, it is important to understand that it is involved in regulating important functions such as: immune response, inflammation management, metabolism and sleep-wake cycles. Disruption to regular cortisol production through a long-term stress response can have a negative impact on these important functions.

• Feel good hormones
  

  Our brains and bodies are versatile and offer us both the tools to respond to real or perceived threats to safety and improve our experience and enjoyment of life. Through developing an awareness of how the body works, we can become proactive in regularly engaging with activities which release these important feel good hormones, helping us to be well and thrive. Whilst there are lots of ways to encourage production of these hormones - from dietary choices to everyday behaviours, here we capture a brief snapshot of how the multi-sensory experience of photography in the natural world can boost happy hormones:

  
  

  • Simply being outside and absorbing natural daylight produces the feel good hormone serotonin, also achieved through psychological connection to the calm and beauty of the natural environment.

  • As we exercise our bodies further afield, endorphins are produced, also associated with playfulness and sharing laughter with our fellow humans.

  • In making choices and achieving something new, such as climbing to the top of a steep hill or making a new inspirational sculpture, we experience the impact of dopamine associated with a sense of reward. Photographing these instances allows us to tap into the original sensation at a later date and reminds us what we are capable of achieving.

  • When we feel a sense of bonding with our fellow humans we experience the sensation of oxytocin. Many people also release this hormone when in contact with animals, which is why hugging our furry companions feels so good.