Essay Sample on Recent Finds in Nature-Nurture Controversy: Implications for Biopsychologists

Describe the recent finds on the “Nature-Nurture Controversy.” How do evolutionary theory (evolutionary biology and evolutionary psychology) and the study of genetics fit into this discussion? What are the implications for the biopsychologist? And finally, is there a controversy at all?

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The concepts of nature, nurture as well as evolution have a significant impact on the progressive development of an individual as they influence how the person behaves. Nature comprises genes that individuals inherit from their parents, while nurture incorporates the impacts of the environment on the development of the individual. Some people suppose that a person requires specific genes for the environment to trigger the specific genes (Greenberg & Partridge, 2010). However, the “Nature vs. Nurture” discussion has resulted in a depiction of how both inherited genes and the environment significantly affect how we turn out as human beings. Furthermore, the theory of evolution that states that all living things are bound to change over time suggests that the environment that we grow in is likely to influence our behavior that will change with the change in environment (Greenberg & Partridge, 2010). Additionally, the concept of natural selection by Darwin suggests that only the strongest genes will survive may be useful to explain the absence of some genes in the child’s DNA (Greenberg & Partridge, 2010).

Further study of the epigenetic, as well as the epistasis relations with specific genes, can help to advance technological improvements in science. Epigenetics describes the data contained in genes that identify the type, function, and number of cells that should be produced (Greenberg & Partridge, 2010). Epigenetics can adjust a cell, activate, inhibit, or modify a specific gene. Moreover, the gene is not changed directly, which creates opportunities for reversal or adjustments of epigenetic modifications. The majority of these modifications are connected directly to the environmental factors that have preventative measures so that the gene can disappear as a result of evolution (Greenberg & Partridge, 2010). On the other hand, the study of Epistasis is essential as it explains how genes interface such that the stronger gene suppresses the expression of the weaker gene (Greenberg & Partridge, 2010). This information may be useful to biopsychologists as they may learn what activates different genes, what traits different genes have as well as the different genetic factors that will impact the future of human beings.

Describe the process of action potential conduction and neurotransmission from one neuron to another, both electrically (including saltatory conduction) and chemically. Describe how a cell fires an action potential and be sure to address which structures are involved in neurotransmission. Discuss reuptake and enzymatic degradation (breakdown) in the context of the appropriate neurotransmitters.

Neurotransmission can be identified as communication between neurons and is achieved by the transfer of electric signals or chemicals across a synapse. When using electrical synapses, two neurons are linked physically through gap junctions that facilitate the change in electrical properties of one neuron to affect the other. As such, the two neurons will behave as one (Lodish et al., 2000). Therefore, electrical synapses transmit signals faster as compared to chemical synapses. Some synapses are both chemical and electrical. However, the electrical responses in these synapses occur faster than the chemical synapses (Lodish et al., 2000).

In contrast, chemical neurotransmission takes place at chemical synapses. It involves the separation of the presynaptic and the postsynaptic neurons that are separated by a small gap known as the synaptic cleft. The cleft is filled with extracellular fluid and creates a physical barrier for the electrical signal contained in the neurons, which can be identified as a “short” in electrical terms (Lodish et al., 2000). As such, the neurotransmitter is charged with overcoming the electrical short by connecting the action potential of one neuron with the synaptic potential of the other neuron. A neuron (presynaptic) fires an action potential when intending to transmit information to another neuron (postsynaptic) (Lodish et al., 2000). When the action potential arrives at the terminal, it activates calcium channels in the cell membrane that is highly concentrated on the outside of the neuron than the inside. As such, diffusion of the calcium channels into the cell facilitates fusion of the channels with the terminal membrane, thus releasing the synaptic cleft (Lodish et al., 2000).

A synapse can only function effectively if there is a method of switching off the signal after sending the required message since the termination of the signal enables the postsynaptic cell to return to its normal resting potential while awaiting new signals. The synaptic cleft must be cleared of any neurotransmitter for a successful end of the signal (Lodish et al., 2000). In most cases, the neurotransmitter is broken down by an enzyme, or it is reabsorbed back into the presynaptic neuron to await the next instructions. Similarly, the cleft may also be absorbed by glial cells around the cell (Lodish et al., 2000).

Trace in detail the structure and function of the visual system from the physical stimuli (light waves), to the structure of the eye and through the corresponding brain structures until it is processed as visual information. You will need to compare photoreceptors in darkness to photoreceptors receiving light and describe how light energy is transduced into neural signals. Describe how the trichromatic and opponent-process theory explains how light of different wavelengths is converted into color information.

The eye is a significant organ that is involved in vision. The light waves are transmitted across the cornea part of the eye as it serves as the barrier between the inner part of the eye and the outside world. Furthermore, the cornea focuses light waves into the eye that enter through the pupil. The pupil is a smaller opening in the eye where light passes (Dragoi, 2000). Moreover, the pupil adjusts by increasing or reducing in size to increase or reduce the level of light or during emotional arousal. For instance, when the light levels are low, the pupil will become dilated to allow more light to enter the eye and contract when light levels are high to reduce the amount of light that enters the eye. The size of the pupil is controlled by muscles that are linked to the iris, which is a colored portion of the eye (Dragoi, 2000).

The light then crosses the lens, which can change shape to provide extra focus on the reflected from near or far objects. The lens will then focus a picture clearly on the fovea, which is a light-sensitive indentation at the back of the eye that contains photoreceptor cells called cones. The cones perform best in bright light conditions as they are sensitive to acute detail and facilitate great spatial resolution and are involved in the provision of color (Dragoi et al., 2000). Other types of photoreceptors include the rods that perform well under low light conditions are located in the rest of the retina. The rods are involved in the perception of movement in the visual field (Dragoi, 2000).

Three types of cones are responsible for color in the eye. These types are susceptible to various wavelengths of light as per the trichromatic theory of color vision (Dragoi, 2000). The theory also states that all colors in the spectrum can be created by combining green, blue, and red and that each type of cone is receptive to one of the colors. On the contrary, the opponent-process theory claims that color is coded in opposing pairs such as yellow-blue, black-white, and green-red such that some cells in the eye are excited by one component of the opposing color. At the same time, the other cells are activated by the opposing color.

Discuss some of the methodological approaches that can be used to examine the influence of multiple genes on behavior. Then discuss what transgenic animals are and how they are produced.

The methodological approaches that are used to analyze how genetics influence or contribute to the behavior include the twin/adoption studies, genetic engineering as well as selective breeding. The twin/adoption studies are used to test whether nature (genes) or nurture (environment) affect the behavior of a person (Lodish et al., 2000). This comprehension is vital as it helps in understanding why people behave in a specific manner and predict specific behavior from future generations. As such, concordance can be used to measure the relevance of nature and nurture. Moreover, twins were considered as concordant if both illustrated a specific trait and discordant if the specific trait was present in only one of them (Lodish et al., 2000). The studies were performed on twins who were raised either together or apart, and the results indicated that both aspects of nurture and nature contributed to how a person behaved.

The concept of selective breeding was developed to study the heritability of behavioral qualities in animals such that characteristics that were identified as desirable were bred intentionally with another organism with a similar desirable trait to create offspring that had improved or similar qualities (Lodish et al., 2000). Genetic engineering is identified as the process where a gene is removed from an organism, duplicated, and then implanted into other organisms.

The process of genetic engineering has resulted in the creation of transgenic animals that have been genetically modified to possess a foreign DNA that was intentionally inserted into its genome from another organism (Lodish et al., 2000). However, this technique may be disadvantageous due to the inability to delete a gene from an organism. Furthermore, transgenic animals can be created from retrovirus-mediated gene transfer, as well as stem cell-mediated gene transfer. The retrovirus-mediated gene transfer creates transgenic animals using viruses to transfer genetic material into the embryonic cells. Consequently, the virus affects the DNA of the cells as they merge with the genetic composition of the host (Lodish et al., 2000). Stem cell-mediated gene transfer is a process where DNA is inserted into an embryo during the initial development stages of the animal.

What is the medial forebrain bundle? Discuss the evidence for and against its involvement in reward. In addition, review the evidence showing that the brain’s dopamine pathways are critically involved in pleasure and reward.

Several areas of the brain can be activated to produce rewarding effects. However, the stimulation of the medial forebrain bundle (MFB) produces intense pleasure. The MFB is located between the tegmental area (VTA) and the lateral hypothalamus. The fibers of the reward circuit are found inside this bundle, which is comprised of the axons of the dopaminergic neurons that are responsible for projecting the VTA to the nucleus accumbens. The neurons of the VTA also link to those of the septum, amygdala, as well as prefrontal cortex to indicate that even the most primitive parts of the brain can have a preponderant influence on behavior. There is no clear origin or termination system of the MFB reward sites even though it lies between the lateral hypothalamus and ventral tegmental (Wise, 2005).

The attempts to create a distinct link between the reward circuit of the MFB and the rewarding simulation in the rest of the brain have been limited, such that the most significant effort involves highlighting the potential relationship of prefrontal cortex reward sites with the MFB reward circuit...