Perception: Difference between revisions
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== Neuroscientific Foundations of Perception == | == Neuroscientific Foundations of Perception == | ||
=== Visual | === Visual Perception === | ||
Visual perception can be understood as a diverse process that begins with the transformation of light stimuli into meaningful cognitive interpretations involving retinal sensing through photoreceptors and cortical processing in multiple brain areas.<ref name=":0">Donato, R., Pavan, A., & Campana, G. (2020). Investigating the Interaction Between Form and Motion Processing: A Review of Basic Research and Clinical Evidence. ''Frontiers in Psychology'', ''11''. <nowiki>https://doi.org/10.3389/fpsyg.2020.566848</nowiki></ref> The photoreceptors receive light signals through the retina, converting them into electrical signals. Those signals are then transmitted along the optic nerve in the eye, in order to reach the lateral geniculate nucleus before arriving at the striate cortex. This cortex, known as the visual cortex serves on fundamental basis for the conscious perception of static form and local brightness differences, establishing the base for more complex visual processing.<ref>Pollen, D. A. (1999). On the Neural Correlates of Visual Perception. ''Cerebral Cortex'', ''9''(1), 4–19. <nowiki>https://doi.org/10.1093/cercor/9.1.4</nowiki></ref> Following that, after leaving the visual cortex, signals travel along the dorsal stream to the parietal cortex, serving for spatial orientation and motor actions such as reaching or eye movements. Further, focusing on forms, colours and object identity, signals must flow through the ventral stream into the inferior temporal cortex.<ref name=":0" /> For perceptual experience to be created, the visual cortex engages in recursive feedback loops with higher brain regions, for instance temporal and parietal. Those feedbacks enter into loops between each other to continuously compare new sensory data with prior knowledge or expectations, leading to our visual recognition of the outer world.<ref name=":0 | Visual perception can be understood as a diverse process that begins with the transformation of light stimuli into meaningful cognitive interpretations involving retinal sensing through photoreceptors and cortical processing in multiple brain areas.<ref name=":0">Donato, R., Pavan, A., & Campana, G. (2020). Investigating the Interaction Between Form and Motion Processing: A Review of Basic Research and Clinical Evidence. ''Frontiers in Psychology'', ''11''. <nowiki>https://doi.org/10.3389/fpsyg.2020.566848</nowiki></ref> The photoreceptors receive light signals through the retina, converting them into electrical signals. Those signals are then transmitted along the optic nerve in the eye, in order to reach the lateral geniculate nucleus before arriving at the striate cortex. This cortex, known as the visual cortex serves on fundamental basis for the conscious perception of static form and local brightness differences, establishing the base for more complex visual processing.<ref>Pollen, D. A. (1999). On the Neural Correlates of Visual Perception. ''Cerebral Cortex'', ''9''(1), 4–19. <nowiki>https://doi.org/10.1093/cercor/9.1.4</nowiki></ref> Following that, after leaving the visual cortex, signals travel along the dorsal stream to the parietal cortex, serving for spatial orientation and motor actions such as reaching or eye movements. Further, focusing on forms, colours and object identity, signals must flow through the ventral stream into the inferior temporal cortex.<ref name=":0" /> For perceptual experience to be created, the visual cortex engages in recursive feedback loops with higher brain regions, for instance temporal and parietal. Those feedbacks enter into loops between each other to continuously compare new sensory data with prior knowledge or expectations, leading to our visual recognition of the outer world.<ref name=":0" /> | ||
=== Haptic | Visual perception involves actively searching for relevant stimuli, influenced by external factors such as color salience and movement, as well as internal states in order to recognise objects. For instance, conspicuous features can capture human attention instantly, leading to unusual preferences when distractions occur. At this state, the ventral stream captures specific details from it. In addition, the temporal cortex stores those representations, helping humans to categorise and label familiar objects in fractions of a second. <ref name=":1">Jansson-Boyd, C. V., & Bright, P. (2024). Visual neuroscience. ''Elsevier EBooks'', 51–69. <nowiki>https://doi.org/10.1016/b978-0-443-13581-1.00004-2</nowiki></ref> Furthermore, visual search engages emotional and reward circuits, when identifying form and motion. The ventral tegmental area and nucleus accumbens interact with cortical regions to process rewarding stimuli, reinforcing behaviour patterns triggered by appealing elements. Likewise research shows, that emotional associations are carried firmly throughout visual perception, that bias us towards or against objects before consciously registering the object. This phenomenon, known as microvalence, refers to subconscious evaluation of an object's aversiveness during visual processing.<ref name=":1" /> | ||
=== Haptic Perception === | |||
Touch helps us to navigate through the physical space, by integrating information from the skin, muscles and joints to foster a cohesive perception of objects, surfaces and spatial relationships. While joints and muscles enables feedback about cup's orientation and weight, the skin contains a complex system of specialised nerve endings designed to detect mechanical stimuli such as pressure, vibration, and texture. <ref name=":02">Reed, Catherine L., and Mounia Ziat. “Haptic Perception: From the Skin to the Brain ☆.” ''Reference Module in Neuroscience and Biobehavioral Psychology'', 2018, <nowiki>https://doi.org/10.1016/b978-0-12-809324-5.03182-5</nowiki>.</ref> The majority of receptors, which are distributed throughout the layers of the skin, are represented by: | Touch helps us to navigate through the physical space, by integrating information from the skin, muscles and joints to foster a cohesive perception of objects, surfaces and spatial relationships. While joints and muscles enables feedback about cup's orientation and weight, the skin contains a complex system of specialised nerve endings designed to detect mechanical stimuli such as pressure, vibration, and texture. <ref name=":02">Reed, Catherine L., and Mounia Ziat. “Haptic Perception: From the Skin to the Brain ☆.” ''Reference Module in Neuroscience and Biobehavioral Psychology'', 2018, <nowiki>https://doi.org/10.1016/b978-0-12-809324-5.03182-5</nowiki>.</ref> The majority of receptors, which are distributed throughout the layers of the skin, are represented by: | ||
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At different rates of stimulation each of the receptor types adapts continuously.<ref>Andrade, Maria, et al. “The Senses 4: Touch – Physiology of the Sensation and Perception of Touch | Nursing Times.” ''Nursing Times'', 13 Dec. 2022, www.nursingtimes.net/neurology/the-senses-4-touch-physiology-of-the-sensation-and-perception-of-touch-13-12-2022/.</ref> Likewise it converts physical energy (pressure, vibration, temperature) into electrical impulses, which are send along nerve fibers towards the spinal cord ensuring instantaneous awareness of haptic changes.<ref>Blumenrath, Sandra . “The Neuroscience of Touch and Pain.” ''Www.brainfacts.org'', 3 Feb. 2020, www.brainfacts.org/thinking-sensing-and-behaving/touch/2020/the-neuroscience-of-touch-and-pain-013020.</ref> The electrical impulses are either transmitted through slowly adapting fibers, firing with persistent pressure, or rapidly adapting fibers. Once triggered, these signal travel to the somatosensory cortex, containing topographic maps of the skin, which represents different body parts.<ref name=":02" /> | At different rates of stimulation each of the receptor types adapts continuously.<ref>Andrade, Maria, et al. “The Senses 4: Touch – Physiology of the Sensation and Perception of Touch | Nursing Times.” ''Nursing Times'', 13 Dec. 2022, www.nursingtimes.net/neurology/the-senses-4-touch-physiology-of-the-sensation-and-perception-of-touch-13-12-2022/.</ref> Likewise it converts physical energy (pressure, vibration, temperature) into electrical impulses, which are send along nerve fibers towards the spinal cord ensuring instantaneous awareness of haptic changes.<ref>Blumenrath, Sandra . “The Neuroscience of Touch and Pain.” ''Www.brainfacts.org'', 3 Feb. 2020, www.brainfacts.org/thinking-sensing-and-behaving/touch/2020/the-neuroscience-of-touch-and-pain-013020.</ref> The electrical impulses are either transmitted through slowly adapting fibers, firing with persistent pressure, or rapidly adapting fibers. Once triggered, these signal travel to the somatosensory cortex, containing topographic maps of the skin, which represents different body parts.<ref name=":02" /> | ||
Furthermore, heating or cooling are detected by skin thermoreceptors influencing our recognition of objects (e.g metal feels colder than plastic at room temperature). If an object begins to warm up or cool down in the hand, through feedback humans can then indicate material properties such as moisture. | Furthermore, heating or cooling are detected by skin thermoreceptors influencing our recognition of objects (e.g metal feels colder than plastic at room temperature). If an object begins to warm up or cool down in the hand, through feedback humans can then indicate material properties such as moisture. This overall process from touching to interpretation follows multiple pathways. First of all the skin collects input with receptors (touch and vibration). Further, it lead's to an awareness of the object's movement in order to judge its weight and orientation, which is defined as kinaesthetic feedback. This refers to the sense of limb movement, where muscles, tendons, and joints work together with inputs to inform the brain. Those informations are then processed at the cortex and other parietal regions. Consequently, the multiple lines of sensory information offer a detailed and adaptive representation of the physical world.<ref name=":02" /> | ||
=== 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" /> | |||
=== Smell Perception === | |||
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. | |||
=== | === Taste Perception === | ||
The idea of taste starts with taste visual buds found in across the tongue's surface - called papillae, where each bud contains receptor cells, supporting cells, and basal cells. <ref>Henley, Casey. “Taste.” ''Openbooks.lib.msu.edu'', Michigan State University Libraries, 1 Jan. 2021, openbooks.lib.msu.edu/neuroscience/chapter/taste/.</ref> Flavour such as sugars or bitter alkaloids are detected by those cells and converted into electrical signals. The signals are then transmitted via the cranial nerves to the brainstem and thalamus before reaching the primary gustatory cortex, where flavour information is perceived and processed.<ref>team, NeuroLaunch editorial. “Brain’s Taste Control Center: Mapping the Neural Pathways of Flavor Perception.” ''NeuroLaunch.com'', 30 Sept. 2024, neurolaunch.com/what-part-of-the-brain-controls-taste/. Accessed 29 Dec. 2024.</ref> | |||
Besides the gustatory cortex, taste, smell, and texture are as well processed by the orbitofrontal cortex, influencing decisions about consume behaviour. In comparison, certain tastes evoke memories being attributable to the amygdala, while the hypothalamus contributes by regulating appetite and taste preferences. However, flavour depends, as a research depicts, further from genetics, aging, and neurological conditions. This underlies that the function of taste involves numerous neural circuits ensuring that each bite resonates beyond the tongue.<ref>Trivedi, Bijal P. “Neuroscience: Hardwired for Taste.” ''Nature'', vol. 486, no. 7403, June 2012, pp. S7–S9, <nowiki>https://doi.org/10.1038/486s7a</nowiki>.</ref> | |||
== Philosophical Dimensions of Perception == | == Philosophical Dimensions of Perception == | ||