Perception: Difference between revisions

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Smell perception

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Haris Omerhodzic

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 Therefore, the multiple lines of sensory information offer a detailed and adaptive representation of the physical world.<ref name=":02" />
-====Auditory Perception====
+====Auditory perception====
 The interpretation of sound, begins with sound waves defined as vibration through a medium, for instance air pressure, which travales through the outer ear channels towards the eardrum. The eardrums begin to vibrate and convey them through the middle ear bones into the fluid-filled cochlea of the inner ear. Further, the frequency being established in the basilar membrane of the cochlea disperse it to specific locations, forming a tonotopic map. Hair cells convert these mechanical vibrations into neural signals transmitted onwards the auditory nerve to the brain. However, due to fine arranged cochlear filters a vast range of sound frequencies can be detected and separated into distinct pitches.<ref name=":2">Oxenham, Andrew J. “How We Hear: The Perception and Neural Coding of Sound.” ''Annual Review of Psychology'', vol. 69, no. 1, 4 Jan. 2018, pp. 27–50, www.ncbi.nlm.nih.gov/pmc/articles/PMC5819010/, <nowiki>https://doi.org/10.1146/annurev-psych-122216-011635</nowiki>.</ref> Once the signals travel through the central auditory nerve, main sound properties such as amplitude and frequency are processed by the midbrain's inferior colliculus, while high frequency is received by the inferior colliculus, overlapping with pure auditory processing. However, before tactile high frequencies reach the inferior colliculus, they must pass through the pacinian corpuscles of the skin. Pacinian corpuscles are primarily touch receptors contributing to a better sound experience. This overall convergence suggests, that touch and sound information being shared thereby interchangeable neuronal circuits, being the reason therefore why we feel and hear music. This underlines the human capacity to distinguish numerous pitches due to the cochlea's ability to segregate frequencies precisely.<ref name=":2" />
-====Perception of smell====
+====Smell perception====
-"The origins of the sense of smell lie in the perception of environmental molecules and go back to unicellular organisms such as bacteria. Odors transmit a multitude of information about the chemical composition of our environment. The sense of smell helps people and animals with orientation in space, warns of potential threats, influences the choice of sexual partners, regulates food intake and influences feelings and social behavior in general."<ref name="ref7"/>.On both sides of the nasal septum there are olfactory mucous membranes that are equipped with olfactory sensory cells. These have receptors for around 350 different fragrances. Scent stimuli are conducted via nerve tracts into the olfactory brain, from where they go directly to the hypothalamus and the limbic system.<ref name="ref8"/>
+Generally speaking, perceiving smell begins in the nose, where specialised olfactory receptors bind molecules. Correspondingly, humans posses approximately 396 functional receptor genes and many pseudogenes. These genes encode a large family of proteins found on the surface of cells. As a result of encoding these G protein-coupled receptors, cells can respond to thousands of potential molecules entering our nasal cavity. This binding creates an electrical signal to the transmitted to the olfactory bulb, where subtle scent differences are distinguished.<ref>Sharma, Anju, et al. “Sense of Smell: Structural, Functional, Mechanistic Advancements and Challenges in Human Olfactory Research.” ''Current Neuropharmacology'', vol. 17, no. 9, 22 Aug. 2019, pp. 891–911, www.ncbi.nlm.nih.gov/pmc/articles/PMC7052838/, <nowiki>https://doi.org/10.2174/1570159x17666181206095626</nowiki>.</ref> After initial processing in the olfactory bulb, those information are passed to the piriform cortex region, where odor identification occurs, while on the other hand the amygdala and hippocampus receive likewise signals. The amygdala and hippocampus link smells to emotions and memories, contributing additional to an experience of recollections.<ref>NeuroLaunch editorial team. “Brain and Smell: Exploring the Olfactory System’s Neural Pathways.” ''NeuroLaunch.com'', 30 Sept. 2024, neurolaunch.com/what-part-of-the-brain-controls-smell/.</ref> Moreover, research suggest that the right orbitofrontal cortex (OFC) is essential for consicous olfactory awareness. As depicted in a case, individuals with damage to the right OFC can partially response to smell, while being unaware of it. Even though, odor processing occurs at the piriform cortex or left OFC, a full smell perception requires the connectivity of all involved brain regions.<ref>Li, Wen, et al. “Right Orbitofrontal Cortex Mediates Conscious Olfactory Perception.” ''Psychological Science'', vol. 21, no. 10, 3 Sept. 2010, pp. 1454–1463, <nowiki>https://doi.org/10.1177/0956797610382121</nowiki>.</ref> Nevertheless, the interplay between smell, memory and emotion is profound, hence it can evoke memories and shape our affective mood.
 ====Perception of taste====