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Psychological Terms — Amorphognosia
Amorphognosia is a neurological deficit characterized by an impaired ability to recognize or distinguish the shape, form, or size of objects through tactile sensation alone. Individuals with this condition can feel an object in their hand but are unable to mentally represent its form.
This condition is categorized under the broader group of tactile agnosias, in which somatosensory information is not properly interpreted despite intact basic sensory functioning. Amorphognosia is typically contrasted with ahylognosia, a related disorder in which people can detect shapes but cannot identify material qualities such as weight or texture.
The deficit may arise from lesions within the parietal lobes, particularly brain regions processing somatosensory input and object integration. Depending on lesion location, patients may retain partial tactile recognition abilities while losing others. Clinically, amorphognosia is often evaluated through bedside tactile discrimination tasks, such as asking patients to identify common objects without vision. The inability to do so affects activities of daily living, including tool use and object manipulation.
Although rare, the disorder provides insight into how the brain constructs multisensory representations of objects. It also highlights dissociations between sensory reception and cognitive interpretation.
Amorphognosia is a neurological deficit characterized by an impaired ability to recognize or distinguish the shape, form, or size of objects through tactile sensation alone. Individuals with this condition can feel an object in their hand but are unable to mentally represent its form.
This condition is categorized under the broader group of tactile agnosias, in which somatosensory information is not properly interpreted despite intact basic sensory functioning. Amorphognosia is typically contrasted with ahylognosia, a related disorder in which people can detect shapes but cannot identify material qualities such as weight or texture.
The deficit may arise from lesions within the parietal lobes, particularly brain regions processing somatosensory input and object integration. Depending on lesion location, patients may retain partial tactile recognition abilities while losing others. Clinically, amorphognosia is often evaluated through bedside tactile discrimination tasks, such as asking patients to identify common objects without vision. The inability to do so affects activities of daily living, including tool use and object manipulation.
Although rare, the disorder provides insight into how the brain constructs multisensory representations of objects. It also highlights dissociations between sensory reception and cognitive interpretation.
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Psychological Terms – Amok
Amok (also spelled amuck) is a culture-bound syndrome first documented in Malaysia and subsequently found in several other regions. It involves a period of withdrawn, agitated brooding, often triggered by perceived insult or humiliation, followed by a sudden episode of uncontrolled violent assault directed at nearby people or objects.
During the episode, the person may display paranoid thinking or automatism, and afterward often experiences amnesia for the events. Western psychiatry frequently interprets amok as a manifestation of dissociative disorder.
Amok (also spelled amuck) is a culture-bound syndrome first documented in Malaysia and subsequently found in several other regions. It involves a period of withdrawn, agitated brooding, often triggered by perceived insult or humiliation, followed by a sudden episode of uncontrolled violent assault directed at nearby people or objects.
During the episode, the person may display paranoid thinking or automatism, and afterward often experiences amnesia for the events. Western psychiatry frequently interprets amok as a manifestation of dissociative disorder.
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Psychological Terms – Amodal Completion
Amodal completion is the perceptual process by which the mind fills in missing or hidden parts of an object or image, allowing us to see it as complete even when parts are obscured. For example, when we see a dog partly behind a fence, we still perceive a whole dog.
This illustrates how perception relies on inference and structural expectations rather than raw sensory input. It contrasts with modal completion, where visible cues create the perception of contours or edges.
Amodal completion is the perceptual process by which the mind fills in missing or hidden parts of an object or image, allowing us to see it as complete even when parts are obscured. For example, when we see a dog partly behind a fence, we still perceive a whole dog.
This illustrates how perception relies on inference and structural expectations rather than raw sensory input. It contrasts with modal completion, where visible cues create the perception of contours or edges.
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Psychological Terms – Amobarbital
Amobarbital (also called amylobarbitone) is a short-acting barbiturate that functions as a central nervous system depressant. It is used as a sedative or hypnotic, though sometimes misused recreationally. Historically, it has been administered in interviews to reduce inhibition, popularly associated with so-called “truth serum” effects.
Its chemical formula is C₁₁H₁₈N₂O₃Na.
Amobarbital (also called amylobarbitone) is a short-acting barbiturate that functions as a central nervous system depressant. It is used as a sedative or hypnotic, though sometimes misused recreationally. Historically, it has been administered in interviews to reduce inhibition, popularly associated with so-called “truth serum” effects.
Its chemical formula is C₁₁H₁₈N₂O₃Na.
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Psychological Terms — Amytal
Amytal is the proprietary name for amobarbital (also known as amylobarbitone), a short-acting barbiturate that functions as a central nervous system depressant. Primarily used in the mid-20th century, it was administered to induce sedation, reduce anxiety, and facilitate sleep. The drug enhances the inhibitory neurotransmitter GABA by increasing the duration of chloride channel opening, thereby decreasing neuronal firing rates across the brain.
Historically, Amytal was of interest not only in clinical sedation but also in forensic and psychiatric settings. At times, it was controversially used for so-called narcoanalytic interviews, in which lowered inhibitions were thought to promote truth-telling. These uses were later rejected due to ethical concerns and lack of scientific validity.
Medically, its sedative effects made it useful for short-term management of anxiety and preoperative calm, but because barbiturates have a narrow therapeutic index — meaning the difference between an effective dose and a dangerous one is small — their routine use declined with the advent of safer alternatives such as benzodiazepines.
In recreational contexts, Amytal has been used illicitly for its euphoria and relaxation, although misuse may lead to physical dependence, impaired cognition, and life-threatening overdose, especially when combined with alcohol or opioids. Today, Amytal holds limited clinical application, largely confined to tightly controlled circumstances.
Amytal is the proprietary name for amobarbital (also known as amylobarbitone), a short-acting barbiturate that functions as a central nervous system depressant. Primarily used in the mid-20th century, it was administered to induce sedation, reduce anxiety, and facilitate sleep. The drug enhances the inhibitory neurotransmitter GABA by increasing the duration of chloride channel opening, thereby decreasing neuronal firing rates across the brain.
Historically, Amytal was of interest not only in clinical sedation but also in forensic and psychiatric settings. At times, it was controversially used for so-called narcoanalytic interviews, in which lowered inhibitions were thought to promote truth-telling. These uses were later rejected due to ethical concerns and lack of scientific validity.
Medically, its sedative effects made it useful for short-term management of anxiety and preoperative calm, but because barbiturates have a narrow therapeutic index — meaning the difference between an effective dose and a dangerous one is small — their routine use declined with the advent of safer alternatives such as benzodiazepines.
In recreational contexts, Amytal has been used illicitly for its euphoria and relaxation, although misuse may lead to physical dependence, impaired cognition, and life-threatening overdose, especially when combined with alcohol or opioids. Today, Amytal holds limited clinical application, largely confined to tightly controlled circumstances.
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Psychological Terms — Amyotrophic Lateral Sclerosis (ALS)
Amyotrophic lateral sclerosis (ALS) is a severe, progressive motor neuron disease that typically begins in middle adulthood and is marked by rapid degeneration of neurons controlling voluntary muscle movement. Early symptoms often include weakness, twitching, and muscle atrophy in the hands, arms, or legs, gradually progressing to nearly all skeletal muscles. Over time, affected individuals develop difficulties with speech (dysarthria), swallowing (dysphagia), and eventually respiration, which is the primary cause of fatality. Average survival after diagnosis is approximately five years, though progression may vary.
The disease involves deterioration of both upper and lower motor neurons, leading to the loss of neural input to muscles and subsequent wasting. Cognitive functioning is usually preserved, though a subset of patients develop related frontotemporal dementia. ALS shares features with other neurodegenerative conditions but is distinguished by its primary impact on motor pathways.
Known colloquially as Lou Gehrig’s disease in North America, ALS has been the focus of extensive research into genetic and environmental causes. Although no cure exists, supportive care—including ventilation assistance, speech therapy, and medications to slow symptom progression—can improve quality of life.
Notably, the etymology derives from Greek: a- (“without”), myo- (“muscle”), trophic (“nourishment”), reflecting the disease’s hallmark of muscle wasting.
Amyotrophic lateral sclerosis (ALS) is a severe, progressive motor neuron disease that typically begins in middle adulthood and is marked by rapid degeneration of neurons controlling voluntary muscle movement. Early symptoms often include weakness, twitching, and muscle atrophy in the hands, arms, or legs, gradually progressing to nearly all skeletal muscles. Over time, affected individuals develop difficulties with speech (dysarthria), swallowing (dysphagia), and eventually respiration, which is the primary cause of fatality. Average survival after diagnosis is approximately five years, though progression may vary.
The disease involves deterioration of both upper and lower motor neurons, leading to the loss of neural input to muscles and subsequent wasting. Cognitive functioning is usually preserved, though a subset of patients develop related frontotemporal dementia. ALS shares features with other neurodegenerative conditions but is distinguished by its primary impact on motor pathways.
Known colloquially as Lou Gehrig’s disease in North America, ALS has been the focus of extensive research into genetic and environmental causes. Although no cure exists, supportive care—including ventilation assistance, speech therapy, and medications to slow symptom progression—can improve quality of life.
Notably, the etymology derives from Greek: a- (“without”), myo- (“muscle”), trophic (“nourishment”), reflecting the disease’s hallmark of muscle wasting.
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Psychological Terms — Amyloid Plaque
An amyloid plaque is a dense extracellular deposit of beta-amyloid protein (BAP) found within the brain, especially common in aging populations and prominently associated with Alzheimer’s disease. These insoluble deposits accumulate in regions such as the cerebral cortex, hippocampus, amygdala, and the entorhinal cortex, disrupting neural communication and contributing to neuronal degeneration.
They are believed to interfere with synaptic functioning, ultimately impairing cognition, memory, and executive processes.
Beta-amyloid consists of roughly 40 amino acids and is derived from the abnormal breakdown of a larger precursor protein encoded on chromosome 21 — a fact that helps explain the elevated incidence of Alzheimer-like pathology in individuals with Down syndrome. As plaques accumulate, they are often accompanied by neurofibrillary tangles composed of tau protein, which further destabilize neuronal structure.
Amyloid plaques are so central to Alzheimer’s research that they form a major diagnostic feature in neuropathological examination. Their presence has spurred pharmacological efforts to prevent or remove beta-amyloid buildup, although therapeutic results have been mixed. Historically, the term amyloid derives from the mistaken belief that plaques resembled starch; later studies disproved this characterization, identifying them as proteinaceous formations.
An amyloid plaque is a dense extracellular deposit of beta-amyloid protein (BAP) found within the brain, especially common in aging populations and prominently associated with Alzheimer’s disease. These insoluble deposits accumulate in regions such as the cerebral cortex, hippocampus, amygdala, and the entorhinal cortex, disrupting neural communication and contributing to neuronal degeneration.
They are believed to interfere with synaptic functioning, ultimately impairing cognition, memory, and executive processes.
Beta-amyloid consists of roughly 40 amino acids and is derived from the abnormal breakdown of a larger precursor protein encoded on chromosome 21 — a fact that helps explain the elevated incidence of Alzheimer-like pathology in individuals with Down syndrome. As plaques accumulate, they are often accompanied by neurofibrillary tangles composed of tau protein, which further destabilize neuronal structure.
Amyloid plaques are so central to Alzheimer’s research that they form a major diagnostic feature in neuropathological examination. Their presence has spurred pharmacological efforts to prevent or remove beta-amyloid buildup, although therapeutic results have been mixed. Historically, the term amyloid derives from the mistaken belief that plaques resembled starch; later studies disproved this characterization, identifying them as proteinaceous formations.
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Psychological Terms — Amylobarbitone
Amylobarbitone is a short-acting barbiturate classified as a central nervous system depressant. Chemically known as amylobarbital, it was formerly widely prescribed as a sedative and hypnotic agent to assist with sleep initiation and anxiety reduction. Like other barbiturates, it works by enhancing inhibitory GABAergic transmission, thereby producing a calming effect and decreasing overall neural excitability.
In clinical settings, amylobarbitone was historically used for insomnia, pre-operative sedation, and occasionally for managing agitation. Its rapid onset and moderate duration made it appealing for short-term therapeutic use. However, barbiturates carry a high risk of dependence, tolerance, and overdose, especially when combined with other depressants such as alcohol. Because of these dangers, their medical use has dramatically declined and been largely replaced by benzodiazepines, which generally have safer therapeutic windows.
Outside legitimate medical contexts, amylobarbitone has occasionally been taken as a street drug, valued for its sedating and euphoric effects. It has also appeared in legal literature concerning forensic contexts, including its rare historical association with “narcoanalysis,” in which sedatives were administered to lower inhibitions during interrogation—an approach now considered unethical and scientifically unsupported.
Amylobarbitone may also be referred to by the proprietary name Amytal.
Amylobarbitone is a short-acting barbiturate classified as a central nervous system depressant. Chemically known as amylobarbital, it was formerly widely prescribed as a sedative and hypnotic agent to assist with sleep initiation and anxiety reduction. Like other barbiturates, it works by enhancing inhibitory GABAergic transmission, thereby producing a calming effect and decreasing overall neural excitability.
In clinical settings, amylobarbitone was historically used for insomnia, pre-operative sedation, and occasionally for managing agitation. Its rapid onset and moderate duration made it appealing for short-term therapeutic use. However, barbiturates carry a high risk of dependence, tolerance, and overdose, especially when combined with other depressants such as alcohol. Because of these dangers, their medical use has dramatically declined and been largely replaced by benzodiazepines, which generally have safer therapeutic windows.
Outside legitimate medical contexts, amylobarbitone has occasionally been taken as a street drug, valued for its sedating and euphoric effects. It has also appeared in legal literature concerning forensic contexts, including its rare historical association with “narcoanalysis,” in which sedatives were administered to lower inhibitions during interrogation—an approach now considered unethical and scientifically unsupported.
Amylobarbitone may also be referred to by the proprietary name Amytal.
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Psychological Terms — Amyl Nitrite
Amyl nitrite is an amber-colored, volatile liquid with a sweet, fruity odor that belongs to the class of nitrite inhalants. When inhaled, it acts primarily as a potent vasodilator — a substance that relaxes and widens blood vessels — producing a rapid decrease in blood pressure and a sensation of warmth or flushing. These physiological effects have contributed to its recreational use, particularly for its perceived aphrodisiac qualities and its ability to enhance sexual experience.
Inhaled amyl nitrite reduces the oxygen supply to the brain, potentially causing light-headedness or faintness. Although originally synthesized from starch, the compound’s modern form is chemically defined as a nitrous acid ester. Its small capsules are commonly known as “poppers,” and recreational use has been associated with episodic headache, dizziness, and in rare cases, hypoxia-related complications.
Historically, amyl nitrite has been used medically to relieve angina due to its vasodilating action. In psychological and social contexts, it has been studied primarily for its recreational use patterns and its role among specific subcultures.
Amyl nitrite is an amber-colored, volatile liquid with a sweet, fruity odor that belongs to the class of nitrite inhalants. When inhaled, it acts primarily as a potent vasodilator — a substance that relaxes and widens blood vessels — producing a rapid decrease in blood pressure and a sensation of warmth or flushing. These physiological effects have contributed to its recreational use, particularly for its perceived aphrodisiac qualities and its ability to enhance sexual experience.
Inhaled amyl nitrite reduces the oxygen supply to the brain, potentially causing light-headedness or faintness. Although originally synthesized from starch, the compound’s modern form is chemically defined as a nitrous acid ester. Its small capsules are commonly known as “poppers,” and recreational use has been associated with episodic headache, dizziness, and in rare cases, hypoxia-related complications.
Historically, amyl nitrite has been used medically to relieve angina due to its vasodilating action. In psychological and social contexts, it has been studied primarily for its recreational use patterns and its role among specific subcultures.
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Psychological Term — Amygdalohippocampectomy
Amygdalohippocampectomy is a neurosurgical procedure used primarily to treat certain forms of temporal lobe epilepsy. The surgery entails removal of most of the amygdala along with the anterior portion of the hippocampus — two structures frequently implicated in seizure generation. Because seizures often originate within this region, excision can significantly reduce or eliminate their occurrence when medication is ineffective.
The procedure is typically considered when patients experience recurrent disabling seizures that do not respond adequately to anti-epileptic drugs. Preoperative evaluation includes neuroimaging, electroencephalography, and assessments of cognitive and memory function, since the hippocampus in particular plays a crucial role in memory consolidation. While the surgery can yield substantial reductions in seizure frequency, it carries risks including memory impairment, emotional changes, and other cognitive side effects due to tissue removal from the limbic system.
The success of amygdalohippocampectomy demonstrates the hierarchical organization of seizure networks and illustrates how targeted intervention within brain circuits can produce lasting therapeutic effects. The procedure has contributed to broader understanding of the limbic system’s role in behavior, emotion, and memory.
Amygdalohippocampectomy is a neurosurgical procedure used primarily to treat certain forms of temporal lobe epilepsy. The surgery entails removal of most of the amygdala along with the anterior portion of the hippocampus — two structures frequently implicated in seizure generation. Because seizures often originate within this region, excision can significantly reduce or eliminate their occurrence when medication is ineffective.
The procedure is typically considered when patients experience recurrent disabling seizures that do not respond adequately to anti-epileptic drugs. Preoperative evaluation includes neuroimaging, electroencephalography, and assessments of cognitive and memory function, since the hippocampus in particular plays a crucial role in memory consolidation. While the surgery can yield substantial reductions in seizure frequency, it carries risks including memory impairment, emotional changes, and other cognitive side effects due to tissue removal from the limbic system.
The success of amygdalohippocampectomy demonstrates the hierarchical organization of seizure networks and illustrates how targeted intervention within brain circuits can produce lasting therapeutic effects. The procedure has contributed to broader understanding of the limbic system’s role in behavior, emotion, and memory.
