The cortex is composed of neurons, with the majority being pyramidal neurons that are excitatory and contain glutamate. Grey matter is where neural cell bodies are located, while white matter mainly consists of myelinated axon tracts. The color contrast between the two is due to the white appearance of myelin.

The Cerebral Cortex and Neocortex

The cerebral cortex is the outermost layer of the cerebral hemispheres and is composed of three parts: the archicortex, paleocortex, and neocortex. The neocortex accounts for 90% of the cortex and is involved in higher functions such as thought and language. It is divided into 6-7 layers, with two main cell types: pyramidal cells and nonpyramidal cells. The surface of the neocortex is divided into separate areas, each given a number by Brodmann (e.g. Brodmann’s area 17 is the primary visual cortex). The surface is folded to increase surface area, with grooves called sulci and ridges called gyri. The neocortex is responsible for higher cognitive functions and is essential for human consciousness.

Cytochrome P450 is an important enzyme system involved in drug metabolism. Certain substances can either increase or decrease the activity of this system. Smoking, alcohol, barbiturates, carbamazepine, Phenytoin, and St John’s Wort are known to induce the activity of cytochrome P450. On the other hand, chlorpromazine, selective serotonin reuptake inhibitors (SSRIs), and grapefruit juice are known to inhibit the activity of cytochrome P450.

The Cytochrome P450 system is a group of enzymes that metabolize drugs by altering their functional groups. The system is located in the liver and small intestine and is involved in drug interactions through enzyme induction of inhibition. Notable inducers include smoking, alcohol, and St John’s Wort, while notable inhibitors include grapefruit juice and some SSRIs. CYP2D6 is important due to genetic polymorphism, and CYP3A4 is the most abundant subfamily and is commonly involved in interactions. Grapefruit juice inhibits both CYP1A2 and CYP3A4, while tobacco smoking induces CYP1A2. The table summarizes the main substrates, inhibitors, and inducers for each CYP enzyme.

Frégoli syndrome is a type of delusional misidentification syndrome where a person believes that a familiar person is taking on the appearance of other people. It is named after Leopold Frégoli, a famous impersonator known for his quick changes. In contrast, Capgras syndrome involves the belief that a familiar person has been replaced by an imposter, while Cotard’s syndrome is characterized by nihilistic delusions such as the belief that one is dead. Intermetamorphosis is another delusional misidentification syndrome where a person thinks they can see others physically and physiologically transform into someone else. Finally, the syndrome of subjective doubles involves the belief that another person has become a copy of oneself.

Broca’s and Wernicke’s are two types of expressive dysphasia, which is characterized by difficulty producing speech despite intact comprehension. Dysarthria is a type of expressive dysphasia caused by damage to the speech production apparatus, while Broca’s aphasia is caused by damage to the area of the brain responsible for speech production, specifically Broca’s area located in Brodmann areas 44 and 45. On the other hand, Wernicke’s aphasia is a type of receptive of fluent aphasia caused by damage to the comprehension of speech, while the actual production of speech remains normal. Wernicke’s area is located in the posterior part of the superior temporal gyrus in the dominant hemisphere, within Brodmann area 22.

The Willowbrook School Study was conducted in a state-supported institution for children with learning difficulties in New York during the 1960s. The study involved inoculating healthy children with hepatitis and administering gamma globulin to assess its potential to treat the disorder.

The Tuskegee syphilis experiment was a controversial follow-up study of people with syphilis. Many participants were not informed of their illness and did not receive available treatment, even though it became available halfway through the study. The Belmont report introduced changes to US law on research ethics as a result of this study.

The Stanford prison experiment involved creating a simulated prison environment at Stanford University. Participants were assigned as either a prison of a guard and were given no guidelines for how to behave. Within two days, the participants began to act out their assigned roles, with guards becoming harsh and sometimes cruel to the prisoners. The study was terminated after only six days due to extreme emotional reactions from some of the prisoners.

The Tearooms Study involved Humphreys hanging around public toilets where men meet to have sex in order to study the population and learn more about the types of men that did it. The method was controversial as he never disclosed his motives when he interviewed the men and instead pretended to be a ‘watch queen’, raising issues of informed consent in research.

Milgram’s Study investigated authority and obedience. Participants were assigned the role of teacher and administered fake shocks to a confederate playing the learner. Despite expressing concern, 30% of participants continued to administer shocks until 450 volts was reached. The study raised concerns for the wellbeing of participants, but Milgram decided not to terminate it as prior participants seemed to recover relatively well.

Beecher’s Study

Beecher’s study revealed more than 20 instances where individuals were subjected to experimentation without being fully informed of their participation in research and the potential risks involved. One of the cases cited was the Willowbrook State School study, where children with mental disabilities were intentionally infected with hepatitis under the guise of a vaccination program.

Antipsychotic drugs are known to cause weight gain, but some more than others. The reason for this is not due to a direct metabolic effect, but rather an increase in appetite and a decrease in activity levels. The risk of weight gain appears to be linked to clinical response. There are several suggested mechanisms for this, including antagonism of certain receptors and hormones that stimulate appetite. The risk of weight gain varies among different antipsychotics, with clozapine and olanzapine having the highest risk. Management strategies for antipsychotic-induced weight gain include calorie restriction, low glycemic index diet, exercise, and switching to an alternative antipsychotic. Aripiprazole, ziprasidone, and lurasidone are recommended as alternative options. Other options include aripiprazole augmentation, metformin, orlistat, liraglutide, and topiramate.

In 1793, Philippe Pinel was entrusted with the care of inmates at the Bicêtre Hospital in Paris, where he is renowned for his efforts in liberating patients from their chains and introducing a new approach to treatment known as ‘moral treatment’. This progressive method had already been adopted by a handful of other reformers in Britain and other countries. Bleuler, a Swiss psychiatrist, is credited with coining the term ‘schizophrenia’, while de Clérambault’s name is associated with a syndrome characterized by delusions of love (erotomania). Esquirol, on the other hand, was a student of Pinel, and Mesmer was a German physician who gained notoriety for his belief in ‘animal magnetism’ of ‘mesmerism’.

The term phatic communication is used to describe casual conversation. The ‘cocktail party effect’ is the ability to concentrate on one person’s voice in any setting, such as a classroom, sports game, of coffee shop, even if there is a lot of background noise.

The Cocktail Party Effect: Selective Attention in Noisy Environments

The cocktail party effect is a phenomenon that allows individuals to selectively focus on a single conversation in a noisy environment, while ignoring other competing conversations. This feature of selective attention is particularly useful in social situations, such as parties, where multiple conversations are taking place simultaneously. For instance, if you are conversing with a friend at a noisy party, you can effectively tune out the surrounding noise and concentrate on your friend’s conversation. This ability to filter out irrelevant information and focus on relevant information is a crucial aspect of human cognition. It enables us to navigate complex social environments and engage in meaningful interactions with others.

Mitmachen involves manipulating a patient’s body into a specific posture, even if they resist. Mitgehen is a more severe form of mitmachen, where even slight pressure can cause the patient to move in any direction, similar to an anglepoise effect. Hypnagogic hallucinations are a common occurrence when falling asleep, while chorea is characterized by sudden and jerky movements that resemble purposeful actions. Echopraxia refers to the imitation of another person’s movements.

Antidepressants can cause discontinuation symptoms when patients stop taking them, regardless of the type of antidepressant. These symptoms usually occur within 5 days of stopping the medication and can last up to 3 weeks. Symptoms include flu-like symptoms, dizziness, insomnia, vivid dreams, irritability, crying spells, and sensory symptoms. SSRIs and related drugs with short half-lives, such as paroxetine and venlafaxine, are particularly associated with discontinuation symptoms. Tapering antidepressants at the end of treatment is recommended to prevent these symptoms. TCAs and MAOIs are also associated with discontinuation symptoms, with amitriptyline and imipramine being the most common TCAs and all MAOIs being associated with prominent discontinuation symptoms. Patients at highest risk for discontinuation symptoms include those on antidepressants with shorter half-lives, those who have been taking antidepressants for 8 weeks of longer, those using higher doses, younger people, and those who have experienced discontinuation symptoms before. Agomelatine is not associated with any discontinuation syndrome. If a discontinuation reaction occurs, restarting the antidepressant of switching to an alternative with a longer half-life and tapering more slowly may be necessary. Explanation and reassurance are often sufficient for mild symptoms. These guidelines are based on the Maudsley Guidelines 14th Edition and a study by Tint (2008).