Brain and Behaviour

Behavioural Neuroscience

2.3 The Brain and Behaviour
This trail mainly follows the outlay of Russel Conduit's lectures at La Trobe University, Autumn 2001. His lectures are also one of the main sources for this material.

Behavioural Neuroscience draws upon the insights of both psychology and biology, with a strong focus on the biological aspect. When we respond to stimuli, what does actually happen in the brain?

To a certain extent, a behavioural neuroscientist is a biological reductionist. He believes that all behaviour can be reduced to biological processes; that the brain is the basis of behaviour, and that there is no "mind", only the brain.

2.3.0.1 Studying the brain

There are three main ways of studying the brain:

1. Autopsy

When doing an autopsy, you study the structure of the brain, not the function.

2. Lesion Studies

When doing lesion studies, you study a brain that has been damaged, and the functional effects of this damage. But beware, this method does not necessarily pinpoint the localization of a brain function, because the part that was damaged may be only a neural circuit (a link) of the function or functions which seem to be affected.

3. Brain Imaging: EEG, MRI, PET & CAT

2.3.1 Cell Biology

2.3.2 Neurons and Glia

2.3.3 Neural Communication
Main source: Nolte

To communicate, neurons use electrical signals. The currents is not carried by electrons, but by movement of ions. Neurons are bounded by a semipermeable membrane that is electrically polarized to a resting membrane potential of typically -65 mV. To communicate, neurons use two different mechanisms:

(1) passively propagated potentials (in the dendrites)-- graded, relatively slow, local potential changes (e.g. synaptic potentials, receptor potentials). These can be summed (temporal summation and spatial summation).

(2) actively propagated potentials (action potentials) (in the axons) -- for sending information over long distances

2.3.3.1 Neural Membrane

The neural membrane is a lipid bilayer.

2.3.3.2 Action Potential

2.3.3.3 Synaptic Transmission

2.3.4 The nervous system on a large scale
Main source: Rosenzweig

On a large scale, the nervous system consists of central and peripheral divisions.

2.3.4.1 The 3 components of the peripheral nervous system

1) The cranial nerves
these are connected directly to the brain, and are mainly concerned with sensory and motor systems.

2) The spinal nerves
these are connected at regular intervals to the spinal cord

3) The autonomic nervous system
the a.n.s. originates both from the brain and the spinal cord

1. The 12 pairs of cranial nerves

I.    Olfactory -- Smell.
II.   Optic -- Vision.
III. Oculomotor -- All eye muscles except superior oblique and lateral rectus.
IV. Trochlear -- Superior oblique muscle.
V.   Trigeminal -- Face, sinuses, teeth. Jaw muscles.
VI. Abducens -- Lateral rectus muscle.
VII. Facial -- Tongue, soft palate. Facial muscles, salivary glands, tear glands.
VIII. Vestibulocochlear -- Inner ear.
IX.   Glossopharyngeal -- Posterior tongue, tonsils, pharynx, pharyngeal muscles. Same.
X.     Vagus -- Heart, lungs, gastrointestinal tract, bronchi, trachea, larynx. Same.
XI.    Spinal accessory -- Sternomastoid and trapezius muscle.
XII.   Hypoglossal -- Tongue muscles.