The occipital lobe contains most of the visual cortex and is the visual processing center of the brain. Cells on the posterior side of the occipital lobe are arranged as a spatial map of the retinal field. The visual cortex receives raw sensory information through sensors in the retina of the eyes, which is then conveyed through the optic tracts to the visual cortex. Other areas of the occipital lobe are specialized for different visual tasks, such as visuospatial processing, color discrimination, and motion perception.
Damage to the primary visual cortex located on the surface of the posterior occipital lobe can cause blindness, due to the holes in the visual map on the surface of the cortex caused by the lesions. The parietal lobe is associated with sensory skills. It integrates different types of sensory information and is particularly useful in spatial processing and navigation. The parietal lobe plays an important role in integrating sensory information from various parts of the body, understanding numbers and their relations, and manipulating objects.
Its also processes information related to the sense of touch. The parietal lobe is comprised of the somatosensory cortex and part of the visual system. Several portions of the parietal lobe are important to language and visuospatial processing; the left parietal lobe is involved in symbolic functions in language and mathematics, while the right parietal lobe is specialized to process images and interpretation of maps i.
The limbic system is a complex set of structures found on the central underside of the cerebrum, comprising inner sections of the temporal lobes and the bottom of the frontal lobe. It combines higher mental functions and primitive emotion into a single system often referred to as the emotional nervous system.
It is not only responsible for our emotional lives but also our higher mental functions, such as learning and formation of memories.
The limbic system is the reason that some physical things such as eating seem so pleasurable to us, and the reason why some medical conditions, such as high blood pressure, are caused by mental stress. There are several important structures within the limbic system: the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus.
The amygdala is a small almond-shaped structure; there is one located in each of the left and right temporal lobes. Known as the emotional center of the brain, the amygdala is involved in evaluating the emotional valence of situations e. It helps the brain recognize potential threats and helps prepare the body for fight-or-flight reactions by increasing heart and breathing rate. The amygdala is also responsible for learning on the basis of reward or punishment.
The amygdala : The figure shows the location of the amygdala from the underside ventral view of the human brain, with the front of the brain at the top of the image. Due to its close proximity to the hippocampus, the amygdala is involved in the modulation of memory consolidation, particularly emotionally-laden memories.
In fact, experiments have shown that administering stress hormones to individuals immediately after they learn something enhances their retention when they are tested two weeks later. The hippocampus is found deep in the temporal lobe, and is shaped like a seahorse. It consists of two horns curving back from the amygdala. Psychologists and neuroscientists dispute the precise role of the hippocampus, but generally agree that it plays an essential role in the formation of new memories about past experiences.
Some researchers consider the hippocampus to be responsible for general declarative memory memories that can be explicitly verbalized, such as memory of facts and episodic memory. Damage to the hippocampus usually results in profound difficulties in forming new memories anterograde amnesia , and may also affect access to memories formed prior to the damage retrograde amnesia.
Although the retrograde effect normally extends some years prior to the brain damage, in some cases older memories remain intact; this leads to the idea that over time the hippocampus becomes less important in the storage of memory.
Hippocampus : This image shows the horned hippocampus deep within the temporal lobe. Both the thalamus and hypothalamus are associated with changes in emotional reactivity.
The hypothalamus is a small part of the brain located just below the thalamus on both sides of the third ventricle. Lesions of the hypothalamus interfere with several unconscious functions such as respiration and metabolism and some so-called motivated behaviors like sexuality, combativeness, and hunger. The lateral parts of the hypothalamus seem to be involved with pleasure and rage, while the medial part is linked to aversion, displeasure, and a tendency for uncontrollable and loud laughter.
The cingulate gyrus is located in the medial side of the brain next to the corpus callosum. There is still much to be learned about this gyrus, but it is known that its frontal part links smells and sights with pleasant memories of previous emotions. This region also participates in our emotional reaction to pain and in the regulation of aggressive behavior.
The basal ganglia is a group of nuclei lying deep in the subcortical white matter of the frontal lobes that organizes motor behavior. The caudate , putamen, and globus pallidus are major components of the basal ganglia. The basal ganglia appears to serve as a gating mechanism for physical movements, inhibiting potential movements until they are fully appropriate for the circumstances in which they are to be executed.
The basal ganglia is also involved with:. The brain is constantly adapting throughout a lifetime, though sometimes over critical, genetically determined periods of time. It refers to changes in neural pathways and synapses that result from changes in behavior, environmental and neural processes, and changes resulting from bodily injury. Neuroplasticity has replaced the formerly held theory that the brain is a physiologically static organ, and explores how the brain changes throughout life. Neuroplasticity occurs on a variety of levels, ranging from minute cellular changes resulting from learning to large-scale cortical remapping in response to injury.
The role of neuroplasticity is widely recognized in healthy development, learning, memory, and recovery from brain damage. During most of the 20th century, the consensus among neuroscientists was that brain structure is relatively immutable after a critical period during early childhood. However, recent findings show that many aspects of the brain remain plastic even into adulthood.
Plasticity can be demonstrated over the course of virtually any form of learning. For one to remember an experience, the circuitry of the brain must change. Learning takes place when there is either a change in the internal structure of neurons or a heightened number of synapses between neurons. Studies conducted using rats illustrate how the brain changes in response to experience: rats who lived in more enriched environments had larger neurons, more DNA and RNA, heavier cerebral cortices, and larger synapses compared to rats who lived in sparse environments.
A surprising consequence of neuroplasticity is that the brain activity associated with a given function can move to a different location; this can result from normal experience, and also occurs in the process of recovery from brain injury. In fact, neuroplasticity is the basis of goal-directed experiential therapeutic programs in rehabilitation after brain injury.
At birth, there are approximately 2, synapses in the cerebral cortex of a human baby. By three years old, the cerebral cortex has about 15, synapses. Since the infant brain has such a large capacity for growth, it must eventually be pruned down to remove unnecessary neuronal structures from the brain. This process of pruning is referred to as apoptosis, or programmed cell death.
As the human brain develops, the need for more complex neuronal associations becomes much more pertinent, and simpler associations formed at childhood are replaced by more intricately interconnected structures. Pruning removes axons from synaptic connections that are not functionally appropriate. This process strengthens important connections and eliminates weaker ones, creating more effective neural communication.
Generally, the number of neurons in the cerebral cortex increases until adolescence. Apoptosis occurs during early childhood and adolescence, after which there is a decrease in the number of synapses. Neuron growth : Neurons grow throughout adolescence and then are pruned down based on the connections that get the most use. Synaptic pruning is distinct from the regressive events seen during older age.
While developmental pruning is experience-dependent, the deteriorating connections that occur with old age are not. Synaptic pruning is like carving a statue: getting the unformed stone into its best form. Once the statue is complete, the weather will begin to erode the statue, which represents the lost connections that occur with old age. Privacy Policy. Skip to main content. Biological Foundations of Psychology.
Search for:. Structure and Function of the Brain. Development of the Human Brain The mental processes and behaviors studied by psychology are directly controlled by the brain, one of the most complex systems in nature. You might be eating a lot. You might have hypersexuality. And, of course, you get disinhibited behavior. Think of the person with a lamp shade on their head.
They're ignoring certain social conventions because of the effect of alcohol. So that's how I remember the effect of stimulating versus destroying the amygdala. And this green structure here that you curving around the thalamus is known as the hippocampus.
And the hippocampus plays a key role in forming new memories. What it does is it helps to convert your short-term memory-- I'll abbreviate it as "STM"-- it helps convert that short-term memory into your long-term memory. And I mention that in this conversation because when you think back on your memories, whether it's short-term memory or long-term memory, these memories can evoke emotions as well. So the hippocampus is an important structure in forming long-term memories.
And people with damage to this area, they have difficulty forming new memories. So everything that they experience just basically fades away. Now what's interesting about this is if your hippocampus is destroyed, while you can't form new memories, you still have your old memories intact. So your long-term memory functions just fine. So that's the hippocampus. Now lastly, this orange structure here, this orange structure is the hypothalamus.
And "hypo" means below. So hypothalamus is below the thalamus. And here's the thalamus. And it's below it. So that's where it gets its name from. And the hypothalamus is actually a very tiny structure. And this diagram here really exaggerates the size of the hypothalamus. It's about the size of kidney bean. And the hypothalamus plays an incredible role in regulating so many functions in your body.
But for our purposes, we're talking about the limbic system structures in terms of emotion. So when it comes to emotion, the hypothalamus you can think of as regulating the autonomic nervous system. I'll abbreviate it as "ANS. Now, I'm going to discuss this further in a different video. But right now, just think of it as regulating the autonomic nervous system.
And it does this by controlling the endocrine system, by triggering the release of hormones into your bloodstream. And some of these hormones that are triggered to release are things like epinephrine or norepinephrine. And epinephrine is actually very commonly known as adrenaline. So if you ever think of the phrase like "a lot of adrenaline pumping through your veins," that's actually being regulated by the hypothalamus.
Your hypothalamus is also involved in regulating other basic drives, like hunger, thirst, sleep, sex. But in terms of emotion, I think it's most important to note that it regulates the autonomic nervous system, that fight or flight or rest and digest response. So that's the limbic system. And these are the four basic structures, the thalamus, the amygdala, the hippocampus, and the hypothalamus.
So these are the basic structures of the limbic system. Recently QBI researchers have confirmed that new neurons are made in the amygdala. QBI newsletters Subscribe. Help QBI research Give now. Download the pdf. Download printable poster. Skip to menu Skip to content Skip to footer.
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