What is the brain involved in? Everything. Seeing? Yes. Moving? Yes. Breathing? You guessed it – also yes. The brain also named itself – the only organ to do so!
What follows is an overview of the brain, its divisions, and some cool facts about each part
The brain has two hemispheres, known as the left and the right. The left hemisphere is involved in verbal memory, thinking, and language, while the right hemisphere is involved in perception, visuospatial ability, art, music, and intuitive thinking. The two hemispheres of the brain are connected by the corpus callosum, a thick white band of fibers that operates as a bridge for information
to pass between the two hemispheres. For example, if a
picture is shown in the left visual field, it will be
processed in the right hemisphere and vice versa.
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If the corpus callosum is cut (to help control
seizures, for example), an interesting phenomenon
can occur. If these split-brain patients (who have a
cut corpus callosum) are shown a word to their
left visual field, they cannot say the word they are
shown as the right hemisphere does not contain
language.
The brain has four lobes in each hemisphere: frontal, parietal, temporal, and occipital.
Frontal Lobe is involved in thinking, executive functioning, and personality (prefrontal cortex), planning movements (premotor area), and executing movements (motor area). Broca’s area is located in the left frontal lobe and controls the muscle movements involved in speaking; if damaged, a person may have difficulty making the motor movements involved in saying words.
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Parietal Lobe is home to the primary somatosensory cortex and is involved in sensory processing. The parietal lobe is involved in processing pain, heat, and proprioception (knowing where your body is located in space), as well as directing attention and visual-spatial skills (such as mapping). Damage to the parietal lobe can result in unique challenges including anomia (not being able to remember what objects are named), agraphia (difficulty writing), alexia (difficulty reading), acalculia (difficulty with math), challenges with drawing, difficulty telling left from the right, and hand-eye coordination challenges.
Occipital Lobe is home to the primary visual cortex. Damage to the occipital lobe is rare but can include difficulty in recognizing drawn objects, knowing colours, recognizing words, difficulty reading and writing, and challenges with illusions and hallucinations.
Temporal Lobe is home to the primary auditory cortex and the limbic system. The limbic system is involved in memory and emotions. Damage to the temporal lobe can result in aggression, an increase or decrease in sexual activity, memory challenges, and Wernicke’s aphasia (person can speak but what they say does not make any sense)
The limbic system are a series of sub-cortical structures that have been referred to as our primitive brain and plays an important role in survival and influences our autonomic nervous system (flight, fight, freeze, fawn, and rest systems) as well as our endocrine (hormones) system. The limbic system has 5 main structures: thalamus, hypothalamus, hippocampus, amygdala, and septum.
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Thalamus – Sits below the corpus callosum and is a major relay centre for sensory systems. The thalamus integrates sensory information (except smell) to help create 3D understandings of the environment. The thalamus has been noted to be involved in pain perception and schizophrenia.
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Hypothalamus – Structure that is connected to the endocrine system (pitituary gland, thyroid, adrenal glands) and the autonomic nervous system (stress/rest system). The hypothalamus is involved in the 5 F’s (fighting, feeding, fever, falling asleep, and f…. sex)
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Hippocampus – Structure involved in memory system. More on that later.
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Amygdala – Structure that attaches emotional meaning to sensory input. Of note, the amygdala has been shown to be involved in fear, aggression, and emotional memory. Damage to the amygdala has resulted in an interesting set of traits. When monkey’s had their amygdala’s removed, they exhibited apathy and placidity (low energy, low emotions), hyper sexuality, hyperphagia (including eating non-food items, and agnosia (not knowing). This was called Kluver-Bucy Syndrome
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Septum – Moderates aggression and when damaged can result in septal rage syndrome (i.e., a lot of aggressive behaviours)