Structure of the Brain
The Hindbrain and Midbrain
o Develops originally as one of three bulges in the embryo's neural tube.
o Most primitive functions
o Contains three major structures:
1. Medulla Oblongata- or simply medulla, transmits information from the spinal
cord to the brain and regulates life support functions.
2. The Pons- Latin for bridge. Acts as a neural center, facilitating the crossover of
information between the left and right sides of the brain. It also plays a role in
balance and the processing of visual and auditory information.
3. The Cerebellum- contains neurons that coordinate muscular activity. It is
immensely primitive. It governs balance and is involved in general motor
behaviour and coordination.
Damage to this structure could lead to jerky movements, tremors, and
impairment of balance and of gait.
o Many of it's structures (such as the inferior and superior colliculi) are involved in
relaying information between other brain regions, such as the cerebellum and
o Reticular Formation- keeps us awake and alert; involved in sudden arousal.
Thalamus- another structure for relaying information, especially to the cerebral cortex.
Hypothalamus- controls the pituitary gland by releasing hormones and the homeostatic
Hippocampus- involved in the formation of long-term memories.
Amygdala- modulates the strength of emotional memories and is involved in emotional
Basal Ganglia- production of motor behaviour.
Focusing on the Cerebrum:
Consists of a layer called the cerebral cortex which is a layer of neurons with white matter
underneath that carries information between the cortex and the thalamus or between
different parts of the cortex.
This cortex is divided into four lobes:
1. Frontal (underneath the forehead)
Motor Cortex- located in the precentral gyrus; directs fine motor
Premotor Cortex- involved in planning fine motor movement.
Prefrontal Cortex- (or lobe) executive functioning such as planning,
making decisions, implementing strategies, inhibiting inappropriate
behaviours, and using working memory to process information. Damage to this cortex may mark change in personality, mood, affect, and the
ability to control inappropriate behaviour.
2. Parietal (underneath the top rear part of the skull)
Contains somatosensory cortex, which is contained in the postcentral
gyrus (a ridge of the brain). It is involved in the processing of sensory
information from the body (ex. Touch, pain, or temperature).
3. Occipital (at the back of the head)
Processes visual information
4. Temporal (on the side of the head)
Processes auditory information and the ability to recognize certain stimuli
such as faces.
Due to its proximity to the amygdala and hippocampus, damage to this
lobe may result in memory loss.
It is also divided into two hemispheres which are connected by either the corpus callosum
(in the frontal, parietal, and occipital lobes) or the anterior commisure (in the case of the
Central Sulcus- a shallow groove on the surface of the brain; divides the frontal and
Lateral Sulcus- defines the temporal lobes.
Localization of Function
A method of mapping brain areas to different cognitive or motor functions; identifying
which neural regions control or are active when different activities take place.
Franz Gall (1758-1828)- faculty psychology: different mental abilities, such as reading or
computation, were independent and autonomous functions, carried out in different parts
of the brain. He believed different parts of the brain were associated with faculties such
as parental love, secretiveness, etc.
Johan Spurzheim developed the study of phrenology: psychological strengths and
weaknesses could be precisely correlated to the relative size of different brain areas. The
problem with this idea was the assumptions that size was related to strength and
different faculties were absolutely independent.
Paul Broca (1824-1880)- Injury to a particular part of the left frontal lobe resulted in a
particular kind of aphasia, or disruption of expressive language. This is now known as
Broca's area; injury results in Broca's or non-fluent aphasia.
Carl Wernicke (1848-1904) discovered the second "language center" now known as
Wernicke's area located