Brain Structures, Stages of Sleep, and the Circadian Rhythms

Physiological Psychology
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1 Discuss the significant brain structures involved in hearing analysis/comprehension. Explain for each central structure what problems in hearing and analysis/comprehension would arise if they were damaged.
The two primary structures in hearing analysis or comprehension involve the primary and secondary auditory cortex. The pathway starts from the outer ear, which transmits the auditory frequencies to the auditory canal. Here, the sound wave causes the tympanic membrane to vibrate. The vibration depends on the loudness of the sound, where the vibration is directly proportional to the pitch. The vibrations will then be conducted to the ossicles, which include the malleus, incus, and stapes. These three structures conduct the vibrations to the inner ear. Damage in the structures in this pathway may lead to conductive hearing loss (Shahid, 2023; Sooriyamoorthy & De Jesus, 2022).
The sound waves will then be transmitted to the scala vestibuli and scala tympani, which will conduct the vibrations to the Organ of Corti. Consequently, the Organ of Corti is responsible for converting the vibrations into electrochemical signals transmitted to the brainstem nuclei via the cochlear division of the vestibulocochlear nerve. Damage to the cochlear nerve may lead to auditory neuropathy that may lead to difficulty perceiving sounds, particularly in noisy environments (Shahid, 2023).
The signals or synapses will ultimately be transmitted to the primary auditory cortex located in the temporal lobe, and this Area is responsible for the conscious perception of sounds. Damage in this Area will result in cortical deafness or the non-perception of sounds (Shahid, 2023). Javed et al. (2022) stated that the synapses would be transmitted from this Area to Wernicke's or Brodmann's Area 22, which is responsible for speech comprehension. Damage to this Area results in receptive aphasia, which is the inability to understand written or spoken language.
2 Discuss the significant brain structures involved in the movement: their role, and what problems might arise if there were damage to each.
Five brain structures are involved in the movement. First, the primary motor cortex, found in the frontal lobe, is responsible for voluntary movement. Damage to this region can result in weakness, paralysis, or difficulty initiating movements on the opposite side of the body. This condition is known as contralateral hemiparesis or hemiplegia, depending on the severity (Javed et al., 2022).
Second, the basal ganglia comprise the putamen, caudate nucleus, and globus pallidus. It has a role in the commencement, coordination, and execution of movements. Hence, damage in this Area results in tremors, bradykinesia, rigidity, and postural instability. These are seen in Parkinson's disease (Young et al., 2021).
Third, the cerebellum is responsible for fine-tuning and adjusting movements based on motor responses. Damage to this Area results in incoordination or ataxia, difficulty in fine movements, and problems with posture and balance (Solstrand et al., 2020).
Fourth, the brainstem consists of the midbrain, pons, medulla, and other significant nuclei, such as cranial nerve nuclei and red nuclei. Damage in this Area generally results in abnormal reflexes and problems with coordination and balance. Damage in cranial nerve nuclei can lead to muscle weakness in the particular areas each cranial nerve supplies (Sciacca et al., 2019).
Fifth is the primary sensory cortex. It is responsible for the feedback mechanisms to the motor cortices required to refine movement. Damage in this Area results in impaired adjustment of movements, such as promoting balance (LeMessurier & Feldman, 2018).
3 What are the stages of sleep? Describe the pattern one observes, the activity that occurs during each stage, and what adverse effect a person might experience with significant alterations to each stage of sleep.
There are five stages of sleep. Stage 1, the transitional stage, is the time between wakefulness and sleep. This stage is characterized by slowing down brain waves with a concurrent reduction in muscle activity. Beta waves, or brain waves associated with wakefulness, are transitioned to alpha waves, or brain waves associated with relaxation. The activities in this stage involve fleeting images, vivid sensations, and fragmentation of thoughts. A hypnic jerk is experienced during this stage. Disruption of this stage results in problems with sleep initiation and feeling unrested upon waking up (Patel et al., 2022).
Stage 2 comprises the majority of sleeping time, and it is the time when the body relaxes further. The pattern observed is the presence of distinctive sleep spindles and K-complexes, which are essential in sleep stability and suppressing external stimuli. Disruption of this stage results in decreased sleep quality and difficulty with memory consolidation and learning (Patel et al., 2022).
Stage 3 is the beginning of the deep sleep or slow-wave sleep. The presence of slow and high-amplitude delta waves characterizes this. During this time, the blood pressure decreases, breathing slows down, and the body enters a deep relaxation pattern. Adverse effects of disrupting this stage include a higher risk for sleep disorders and impaired immune function (Patel et al., 2022).
Stage 4 is the deepest sleep stage and is also a part of slow-wave sleep. Hence, the brain waves are similar to stage 3. It is characterized by growth and repair, immune system strengthening, and hormone regulation. Adverse effects of disrupting this stage include daytime sleepiness, fatigue, disruption in the sleep cycle, and disrupted release of growth hormones (Abad & Guilleminault, 2022).
The last stage is the rapid eye movement (REM) stage. It is the stage with REMs, increased brain activities, and temporary paralysis of voluntary muscles. It is characterized by faster and more irregular brain waves and increased blood pressure and heart rate. Dreams occur at this time. Hence, disruption in this stage results in false awakenings (Peters, 2022).
4 Discuss circadian rhythms, the pineal gland, and melatonin. What implications do circadian rhythms have for people requiring continually rotating work shifts?
Circadian Rhythm
It refers to the 24-hour cycle that regulates the body's physiological processes, including body temperature, metabolism, hormone production, and cognitive performance. This is controlled by the body's internal biological clock, located at the hypothalamus's suprachiasmatic nucleus. This depends on the light-dark cycle and is highly regulated by light exposure (Walker et al., 2020).
Pineal Gland
This gland secretes melatonin in response to darkness. It receives synapses from the suprachiasmatic nucleus, which helps regulate melatonin (Aulinas, 2019).
Melatonin
This hormone is responsible for regulating the sleep-wake cycle. It receives impulses from the suprachiasmatic nucleus, which depends on the retina's photoperiodic cues. It is synthesized during dark times and is blocked by the presence of light even during nighttime (Cipolla-Neto & Amaral, 2018; Pévet, 2022).
Implications to Workers with Work Shifts
Shift workers, especially those who continually rotate work shifts, face significant challenges in maintaining healthy circadian rhythms. Here are some implications:
1 Disrupted Sleep-Wake Cycle: Frequent changes in work shifts can disrupt the body's natural sleep-wake cycle. Shift workers often struggle to adjust their sleep patterns according to their shifting schedules, leading to irregular and insufficient sleep (d’Ettorre et al., 2020).
2 Increased Risk of Sleep Disorders: Shift work is associated with an increased risk of sleep disorders, such as shift work disorder. This condition involves difficulties with sleep initiation, maintenance, and excessive sleepiness due to the misalignment between work schedules and the body's circadian rhythms (d’Ettorre et al., 2020).
3 Fatigue and Reduced Performance: Continual rotation of work shifts can lead to chronic sleep deprivation and fatigue. Fatigue impairs cognitive function, attention, and decision-making, increasing the risk of accidents and errors in demanding work environments (Min et al., 2019).
5 Discuss the mechanisms and structures of visual learning and the mechanisms and structures of auditory learning.
Visual Learning
Visual learning involves three mechanisms: visual perception, visual processing, and object recognition.
1 Visual perception is the initiation of visual learning. It starts by perceiving visual stimuli through the eyes. The retina captures the light and converts it to electrical signals, which are transmitted to the central nervous system for interpretation via the optic nerve (Dijkstra et al., 2019).
2 Visual processing is the process by which the brain processes and interprets light. The primary visual cortex at the occipital lobe receives synapses and analyzes basic visual features such as shape, color, and motion. The visual association cortex, a higher-order brain structure, interprets and integrates these synapses (Baek & Chong, 2020).
3 Object recognition is recognizing and categorizing objects, visual patterns, and faces. This recognition process occurs within specialized visual association areas, such as the fusiform face area (FFA) and the parahippocampal place area (PPA), which are dedicated to face and scene recognition, respectively (McGugin et al., 2020; Smithson et al., 2023).
Structures for Visual Learning
1 The retina is the light-sensitive tissue located at the rear of the eye. It consists of specialized photoreceptor cells called rods and cones, which capture visual stimuli (Gupta & Bordoni, 2020).
2 The optic nerve carries visual information from the retina to the brain. It transmits photoreceptors' electrical signals (Gupta & Bordoni, 2020).
3 The primary visual cortex in the occipital lobe is responsible for the initial processing and analysis of visual stimuli (Gupta & Bordoni, 2020).
4 Higher-level visual processing and object recognition occur in various association areas (Gupta & Bordoni, 2020).
Auditory Learning
Auditory learning begins with the perception of sound waves through the ears. The ear collects sound vibrations, which are then converted into electrical signals by the cochlea. The auditory information is processed in the auditory cortex in the temporal lobes. The auditory cortex analyzes sound features such as pitch, timbre, and duration. Auditory learning also involves recognizing and comprehending spoken language, which occurs in specialized regions like Wernicke's Area, which is responsible for language comprehension (Peterson et al., 2018).
Structures for Auditory Learning
1 The cochlea, a spiral-shaped structure in the inner ear, transforms sound vibrations into electrical signals that can be processed by the brain (Shahid, 2023).
2 The auditory nerve carries these electrical signals from the cochlea to the brain, transmitting auditory information (Shahid, 2023).
3 In the temporal lobes, the auditory cortex receives and processes auditory information, analyzing different aspects of sound and interpreting it for perception and understanding (Shahid, 2023).
4 Language processing areas, such as Wernicke's and Broca's, play essential roles in language comprehension and speech production, respectively (Shahid, 2023).
6 Discuss the signs and symptoms of amnesia and its possible causes/mechanisms.
1 Anterograde Amnesia: This type of amnesia refers to the inability to form new memories after the onset of amnesia. The individual may have difficulty remembering recent events, conversations, or new information. They may repeatedly ask the same questions or forget recent conversations (Legg, 2018).
2 Retrograde Amnesia: Retrograde amnesia involves the inability to recall memories from a certain period before the onset of amnesia. The extent of memory loss can vary, ranging from a few minutes or hours to years. Typically, recent memories are more affected than remote memories (Legg, 2018).
3 Fragmented Memories: Some individuals with amnesia may have fragmented memories or "islands" of intact memory mixed with significant memory gaps. They may recall specific events or pieces of information while unable to remember other crucial aspects (Charlwood, 2018).
4 Impaired Learning and Memory Consolidation: Amnesic individuals may have difficulty learning new skills or retaining information over time. They may struggle with memory recall tasks, such as remembering appointments, following directions, or recalling recent conversations (Bertoncello et al., 2019).
The causes and mechanisms of amnes...