There has been a raging debate over the issue of nature versus nurture in the docket of developmental psychology since time immemorial. The side to be considered the most critical is that which will prove to be the most responsible for an individual’s most effectual development. Nature is a term that is used to refer to an individual’s genetic composition, while the surrounding environment’s impact on the growth of the same individual is what is referred to as nurture (Robinson, 2004). Regarding the effect that both nature and nurture have played on the development of a person, it has become an uphill task quantifying using measurable statistics which of the two has more impact than the other. Research in the contemporary world has pushed the debate into other dockets of research and psychology (Ridley & Pierpoint, 2003). Research and knowledge in epigenetics have taken the trouble of comprehending the difference between Nature and Nurture insightfully.
Epigenetics encapsulates the study of genes that can be inherited alongside the explanation that can be extracted from changes in DNA. According to the study done in epigenetics, it is recorded that there are characteristics in people which may or not be provoked to manifest, which implies thus that neither the environment nor the genetic characteristics in their DNA may have little to no impact (Pastore, 1949). According to researchers, the implication that epigenetics try to demonstrate is that both environment and heredity have a critical role that they play in the expressions of specific genetics. In the same way that exposure to some irritating environment can cause a person to fall sick, it has also been established that specific genes impact and cause diseases and defects in other genes (Pastore, 1949). The latter, therefore, means that the genetic makeup of human beings is among the factors that predispose us to all sorts of diseases throughout our lifetime.
Action Potential Conduction and Neurotransmission
The presence of electrical impulses necessitates the communication of the neurons. Upon stimulus detection, electrical impulses are transferred by the receptor cells to the sensory neurons. Once the sensory neurons receive the stimulus, it is further conveyed to the relay neurons, which are situated in the central nervous system, where the motor neurons are ready to receive it. With the electrical impulses, the motor neurons travel through synapses to the effectors, triggering a response. In the course of triggering a response, an action potential provokes the release of neurotransmitters into the synapse by travelling the length of the axon (Khakh & Henderson, 1998). In conjunction with the action potential, the transmitter release permits smooth communication between the active and other neurons. The presence of a stimulus necessitates the resting membrane to reach the threshold potential, culminating in an action potential. The next step is opening the voltage-gated sodium channels, which depolarize the cells to a point when the membrane potential reaches approximately +40Mv. At this point, the channels of voltage-gated sodium channels shut, allowing the voltage-gated potassium channels to open, bringing about the repolarization of the cell. The process of inhibiting the target neuron is achieved by travelling the neurotransmitter across the synapse. Different types of neurons use diverse neurotransmitters, meaning dissimilar impacts are effected on their targets. A small gap exists between the neurons’ synapses called synaptic cleft which provides optimum conditions for communication between two neurons. The process of relaying messages by the neurotransmitters happens when they travel between cells and further cling to specific receptors on target cells (Kress & Mennerick, 2009). Every neurotransmitter involved in the relaying of messages attaches itself to a receptor different from that already occupied. A case in point is when the dopamine molecules attach themselves to dopamine receptors, triggering an action in the target cells through the attachment.
Reuptake is when neurotransmitters are recycled because of active processes within the nerve terminals reabsorbing neurotransmitters released. Uptake inhibitor is essential in substantially deescalating neurotransmitters’ reabsorption rate into the presynaptic neuron. The latter actions lead to the proliferated concentration of neurotransmitters in the synapse. On the other hand, enzymatic degradation entails the process of a specific enzyme changing the structure of the neurotransmitter to ensure that it is not familiar to the receptor. Acetylcholinesterase is an example of an enzyme that alters the structure of neurotransmitters. For instance, acetylcholine takes the form of acetate and choline, which are alien to the receptor.
Influence of Multiple Genes on Behavior
Multiple genes significantly affect behaviour not only in human beings but also in animals. There are three popular methodological approaches that can be used to establish the impact that multiple genes have on behaviour, including studying people’s behaviour while sequencing their genes. Since different people showcase a dissimilar sequence of genes, it is undoubtedly apparent that individuals with the same sequence will possess the same behaviour (Flint et al., 2020). Therefore, once a gene sequence is identified and matched with certain behaviours, individuals of similar behaviours will only demand identifying those with familiar gene sequences. On the part of the animals, the other two methodologies apply: first, taking animals from different lineages and testing their behaviours to understand how they compare with those of their parent animals which existed years back (McInerney, 1999). A lineage with animals with the same behaviour implies a similarity in gene composition among them. The use of transgenic animals is the other way that can be applied in the same course.
Transgenic animals have the genome of all their cells integrated with a part of their DNA. The integration also captures the germ line, and the whole process aims to ensure the animal’s offspring can inherit a simple Mendelian trait. That portion of the DNA that is used constitutes cDNA, a cloned gene or sometimes a new gene that methodologies of a recombinant DNA have reformed. The DNA segment responsible for the success of the process of realizing transgenic animals can be introduced into the genome of all the cells through processes including retroviral-mediated transfer. Direct micro-injection embryos with only one cell fertilized and, lastly, transfer of genes in embryonic stem cells (Flint et al., 2020). From the three, the methodology that is most effective in the production of transgenic animals is the direct micro-injection technique. The technique has been identified to have the ability of coming up with specific gene mutations and its great applicability is noted in the creation of models of animals which imitate diseases of human beings for instance cystic fibrosis.
Medial Forebrain Bundle
The medial forebrain bundle is identified as a pathway of projection used by forebrain neurons which are descending to devour in the lower regions of the neuraxis as well as in the hypothalamus. Apart from the descending forebrain neurons, the ascending axons are also known to utilize the medial forebrain bundle projection pathway from the brainstem (MacNiven et al., 2020). The medial forebrain bundle links the nucleus accumbens and the dopamine-rich VTA making it popular for being associated with the mesolimbic dopamine pathway. The mesolimbic dopamine system is known to be the most vital reward pathway in the brain and is composed of the Nucleus accumbens (NAc) and the ventral tegumental area (VTA). In the medial forebrain bundle, the mesolimbic pathway is a component pathway that exists as a set of neural pathways which get involved in mediating stimulation reward. In every sense, the medial forebrain bundle is part and parcel of the reward system and among the roles that it plays is guaranteeing the integration of the pleasure and reward (Wise, 2005). According to the intracranial self-stimulation studies, the electrical stimulation of the medial forebrain bundle is the root of pleasure sensations.
On the other hand we have reward, which is defined as the different types of inducement that provoke an individual to behave in a particular manner. An example to enforce the latter is when an individual acquires a stimulus that would have been more befitting to ancestors for instance sugar, a reward sensation is produced in his brain. Therefore as concerns its involvement in reward, the medial forebrain bundle is recognized as a critical structure in the reward-seeking circuitry even though it is not clearly categorized in human beings regardless of its great significance for the development of depression and addiction as well as emotional processing. In the event of deep-brain stimulation, a rich taste of enduring and effective relief of depression that is beyond treatment can be guaranteed by the medial forebrain bundle (Coenen et al., 2012). Communication among the regions of the brain that make up the reward system use the neurotransmitter dopamine as an effector of the communication process.
Main Structures of the Brainstem, Midbrain and Forebrain
The brainstem is a part of the central nervous system located at the top of the spinal cord. The function of the brainstem is to control the beating of the heart, breathing and also the diameter of the blood vessels (Ackerman, 1992). Another crucial function of the brainstem is that it is involved in the control of deliberate movement. The other one is the midbrain, which is mostly involved in nerve issues. Among the major functions of the midbrain is that it offers a center for relay of motor and sensory nerve impulses between the spinal cord and the pons as well as the cerebral cortex and the thalamus. The same midbrain contains nerves that govern the movement of the lens, pupil, eyeball and reflexes of the head, trunk and eyes (Thau et al., 2019). The last part is the forebrain which together with the frontal lobe form structures which are critical for processing emotions.
The basal ganglia, also known as the basal nuclei is a part of the brain situated within the white matter and is made up of the putamen, caudate nucleus and the globus pallidus (Lanciego et al., 2012). A combination of the latter structures forms the striatum and pallidum. The central role of the basal ganglia therefore is to ensure muscle coordination and movement. Another important part of the brain is the limbic system which comprises hippocampus, piriform cortex, amygdala, hypothalamus, septal nuclei, nucleus accumbens, and the anterior nuclei of the thalamus (Rajmohan & Mohandas, 2007). Fiber and fornix tracts connect the parts of the limbic system permitting them to control motivation, memory and emotions. The outermost layer that surrounds the brain is referred to as the cerebral cortex (Shipp, 2007). This part of the brain is composed of billions of neurons and a region known as gray matter. It is further divided into four lobes named parietal, temporal, frontal and occipital lobes. Each lobe has a role to play for instance the frontal lobe which is situated at the center is involved in the controlling memory, attention, language, problem-solving and voluntary motor function.
References
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