Page 55 - Coespu Magazine 2017-2

peripheral vision; they are more sensitive to the movement, are used for vision in the dark being
able to distinguish only between black and white. The work of the cones is individual in the sense
that each of them generates a pulse that is launched to the brain independently from the others.
In the case of the rods, however, several thousand elements converge on a single interneuron and
the impulse that starts in the brain emerges from the sum of all individual pulses. The rods are thus
about 4000 times more
sensitive to light than the
cones and, thus, more
functional for night
vision.
At the same moment the
excitement of the
sympathetic nervous
system causes
vasoconstriction in the
peripheral of the retina,
and so the reduction of
blood flow. This cuts
dramatically the activity
of the rods, with a
collapse of of the
extension of the visual field (the reduction is until 70% ), and a strong limitation in the
identification of moving parts.
The effects produced by activation of the sympathetic nervous system and its effects on visual
organs, are the following:
• the narrowing of the visual field until of 70% leads to a tunnel of 48 cm and in some cases
even lower, and this means that the field of view regarding the surrounding environment and around
the source of danger, is completely obscured;
• the inhibition of the rods reduces the ability to identify the movement and so the reaction to
moving targets suffers an elongation of the times. In added the inhibition of the rods worsen the
sensitivity to the light and the contrast distinction. There is also the worsening of the visual
capabilities in low light conditions, or in the case of mimicry with the surrounding environment.
Motor Skills
There is a strong correlation between the heartbeat and motor skills, and the heart rate is hardly
influenced by acute stress. Motor skills can be classified into three categories:
1) gross motor skills: involve the action of large muscle groups. They are involved in
symmetrical and simple movements with great force. Example of this type of movements are
punching, running, etc.;
2) fine motor skills: involve the coordination of limbs and eyes, especially hands, and express
themselves in movements of skill and precision
3) motor skills complex: requiring the intervention of a number of muscle groups in the
presence of movement and coordination between hand and eye. There are therefore movements of
precision and timing.
Now we are going to see how the movement are influenced by heart rate:

49