To gain a deeper understanding of neuroscience, one must understand how the Central Nervous System (CNS) is organized. The CNS is split into the brain and the spinal cord. The brain is further split into three parts: cerebrum, cerebellum and the brain stem. This week, we will be looking at how the cerebrum is organized and some of its important structures. The cerebrum, also known as the forebrain or telencephalon, is the largest section of the brain. It is essential for higher order functioning such as planning or language, often functions thought of as uniquely human. It also controls voluntary behavior. The cerebrum is separated into two halves wherein the right half connects the left side of the body and vice versa. The two sides of the cerebrum communicate using the corpus callosum, a bundle of fibers.
The cerebrum is further divided into two sections – white and grey matter. The outer layer (grey matter or cerebral cortex) is folded into numerous grooves (known as gyri and sulci) and is composed of cell bodies. The grooves increase the surface area of the brain allowing an increased number of neurons while keeping the brain condensed. The inner layer (white matter) is thicker than the grey matter and made of myelinated axons. The white matter connects different parts of the grey matter.
The cerebral cortex is divided into four lobes: frontal, parietal, occipital, and temporal. The frontal lobe is essential for planning, “thinking”, and makes up aspects of your personality. The parietal lobe processes sensory information. The right side is involved with navigating spaces. The left side is involved with understanding language (Wernicke’s area). The occipital lobe processes visual information transmitted through the optic nerve. The temporal lobe processes auditory information and integrates the information from the other senses to help form a complete picture. It also plays a role in memory, specifically short-term memory, as it contains the hippocampus.
Other notable structures include the basal ganglia, hypothalamus and thalamus. The hypothalamus regulates the pituitary gland and is the control center for behaviors such as appetite. The thalamus routes the sensory information to its intended location, as a sort of sorting machine. The basal ganglia are cerebral nuclei that coordinate fine muscles and the reward cycle. Examples include the caudate and putamen. Broca’s area, which controls speech production, is located in the frontal lobe (Blah blah = Broca’s; can help you remember the difference between Broca’s and Wernicke’s). If this area is damaged, the patient usually has difficulty moving the tongue to produce speech but can understand language (if Wernicke’s area remains undamaged). This condition is known as Broca’s aphasia. Wernicke’s area is located at the lateral sulcus, where temporal and parietal lobe meet. This area is essential to understanding written and spoken language (Writing = Wernicke’s can help your remember the difference between Broca’s and Wernicke’s). If damaged, the patient may “may speak in long sentences that have no meaning, add unnecessary words, and even create new words. They can make speech sounds, however they have difficulty understanding speech and are therefore unaware of their mistakes.” This condition is known as Wernicke’s aphasia.
Pineal gland helps regulate the circadian rhythms by secreting melatonin
“In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.”