Sensory nerves enter the back side of the spine, while the motor nerves
leave the by the front
Spinal reflexes allow a stimulus-response without the involvement of the
brain. For example, if you put your finger over fire, sensory receptors will
trigger nerve impulses into the spinal cord and synapse with interneurons.
The interneurons will then excite the motor neurons that will cause the
hand to pull away.
Transmitting messages to and from the brain takes slightly longer than it
does with the spine; therefore, spinal reflexes reduce reaction time and
any potential damage
o The Brain
The most active energy consumer within the body, taking up the 20% of
the oxygen in rating state
Brain is never at rest.
Scientists have developed four methods to study brain-behaviour methods
Neuropsychological tests measures verbal and non-verbal behaviours
that have been affected by brain damage, usually from people who have
suffered from accidents or diseases
Destruction and stimulation techniques. This method involves
destroying specific nerve tissues with electricity, cold/heat or chemicals.
Afterwards, the consequences are studied. Stimulation is an alternative
method in which electric current or chemicals are applied to a certain
region of the brain.
Electrical recording measures the electrical activity of the neurons. EEG
(electroencephalogram) measures large groups of neurons. It then
produces patterns that correspond to certain states of consciousness,
such as wakefulness and sleep. The patterns can also indicate certain
Brain imaging is the latest method that allows neuroscientists to peer into
Computerized Axial Tomography (CT) scans uses narrow X-ray
beams to construct a picture of brain structures.
Positron emission tomography (PET) scans measures brain
activity by radioactive substance injected into the brain. Active
areas accumulate radioactive glucose.
Magnetic resonance imaging (MRI) combines the features of CT
and PET scans, thus allowing both brain structures and activity to
be measured. MRI images are produced based on the response of
atoms to the magnetic impulse delivered by the device. A computer
analyzes the voltage emitted by the tissues. MRI also displays the
active neurotransmitters in the brain regions.
2) THE HIERARCHICAL BRAIN: STRUCTURES AND BEHAVIOURAL FUNCTIONS