This is part two of the Physiological Psychology and Psychopharmacology lecture. In part one, I stated that this lecture has two parts, but since recording part one, I decided to expand this lecture to three parts. Therefore, in part two, I cover the subcortical and cortical structures of the forebrain and neuroimaging techniques, and in part three, I cover the causes and symptoms of several neurological disorders and the uses and side effects of some of the major psychoactive drugs. The forebrain consists of subcortical structures and the cerebral cortex. I'll start with the subcortical structures which include the hypothalamus, thalamus, basal ganglia, amygdala, and hippocampus.
Through its effects on the autonomic nervous system and endocrine glands, the hypothalamus helps maintain many aspects of the body's homeostasis, including body temperature, blood pressure, appetite, and thirst. It also influences the development of secondary sex characteristics and sexual and reproductive behaviors by stimulating the pituitary gland to release sex hormones, and it regulates the body's response to stress by stimulating the pituitary gland to release ACTH. The suprachiasmatic nucleus is located in the hypothalamus.
It serves as the body's biological clock and controls its circadian rhythms, which are physiological changes that occur during each 24-hour period. These include the sleep-wake cycle and daily fluctuations in body temperature and the release of hormones. One way the suprachiasmatic nucleus does this is by controlling the pineal gland's release of melatonin, which is a hormone that facilitates sleep. The suprachiasmatic nucleus is sensitive to light, and during daylight hours, it signals the pineal gland to reduce the release of melatonin, while during the night, it signals the pineal gland to increase the release of melatonin.
Finally, the mammillary bodies are attached to the hypothalamus. They play an important role in memory and damage interferes with the ability to form new declarative memories, which consists of semantic and episodic memories. The thalamus is referred to as a relay station because it receives and then transmits sensory information to appropriate areas of the cortex for all of the senses except olfaction.
which is transmitted from receptors in the nose to the olfactory bulb and then to the cortex. The thalamus also coordinates incoming sensory information with motor functions regulated by the basal ganglia, cerebellum, and motor cortex and plays an important role in memory. Korsakoff syndrome is caused by a thiamine deficiency that's often the result of chronic alcoholism and that damages the thalamus and mammillary bodies. Its primary symptoms are anterograde amnesia, retrograde amnesia, and confabulation, which involves filling in memory gaps with false information that the person seems to believe is true.
The basal ganglia include the caudate nucleus, putamen, and globus pallidus, with the caudate nucleus and putamen often being collectively referred to as the striatum. The basal ganglia play an important role in the initiation and coordination of voluntary movement and are also involved in emotional processing and responses, procedural memory and habit formation, and attention, insight planning, prioritizing information, and other cognitive functions. These structures are also sensitive to rewards and are involved in reward-based associative learning.
Damage to the basal ganglia has been linked to a number of conditions including Huntington's disease, Parkinson's disease, Tourette's disorder, obsessive-compulsive disorder, schizophrenia, and ADHD. The limbic system consists of several structures that are involved in emotion, motivation, and memory and includes the amygdala and hippocampus. The amygdala plays a role in emotional reactions, especially fear and anger.
It also attaches emotions to memories and is responsible for recognizing fear and other emotions in facial expressions. Bilateral damage to the amygdala and temporal lobes in monkeys causes Kluver-Bucey syndrome, which is characterized by hyperphagia, hyperorality, reduced fear and aggression, hypersexuality, and psychic blindness, which is also known as visual agnosia and is an inability to visually recognize familiar objects. Abnormal functioning of the amygdala has been linked to PTSD, anxiety disorders, and depression. The hippocampus is involved more in learning and memory and less in emotions than other limbic system structures. It's responsible for consolidating declarative memories, which means transferring declarative information from short to long-term memory.
People with damage to the hippocampus have trouble storing new memories, but can recall memories that were formed before the damage occurred. The hippocampus also plays a role in spatial memory, MRI scans of London taxi drivers who are required to have extensive knowledge of the city streets found that the posterior hippocampus was larger in the taxi drivers than in control subjects. The role of the hippocampus in memory has also been confirmed by studies linking degeneration of cells in the hippocampus and entorhinal cortex, which is adjacent to the hippocampus, to the impairments in episodic memory, spatial navigation associated with Alzheimer's disease.
Next is the cerebral cortex which is divided into right and left hemispheres and each hemisphere contains a frontal, parietal, temporal, and occipital lobe. The corpus callosum is the major bundle of nerve fibers that connects the left and right hemispheres and allows the two hemispheres to continuously communicate with each other. The frontal lobe contains the prefrontal cortex, primary motor cortex, and Broca's area.
The prefrontal cortex plays an important role in executive functions which are also known as higher-order cognitive functions and include planning, insight, problem solving, decision making, behavioral inhibition, and social judgment. It also contributes to motivation, emotion regulation, working memory, and prospective memory, which is memory for future events. The effects of damage depend on its location.
Damage to the dorsolateral area of the frontal lobe produces a dis-executive syndrome. that's characterized by impaired attention, working memory, judgment, and abstract thinking, depression and a decreased range of emotion, and perseveration, which is inappropriate repetition of a response. A person is exhibiting perseveration when he or she continues to use the same problem solving strategy even when it's clear the strategy is not working.
Damage to the orbital frontal area produces a disinhibited syndrome that involves behavioral disinhibition, distractibility, emotional lability, inappropriate euphoria, and acquired sociopathy, which involves risk-taking behavior, a lack of empathy and insight, and a persistent need for immediate gratification. And finally, damage to the medial frontal area produces an apathetic akinetic syndrome that involves decreased motor behavior and verbal output. a lack of motivation in goal-directed activities, and apathy and indifference.
Based on information it receives from other areas of the cortex, the primary motor cortex executes voluntary movements by sending signals to the muscles. The effects of damage depend on its extent and location, and can cause weakness or paralysis in one or more muscles in the opposite side of the body. For example, if neurons controlling leg muscles in the left hemisphere are damaged, the person will experience weakness or paralysis in his or her right leg.
Broca's area is a major language area and is located in the dominant, which is usually the left frontal lobe. Damage to Broca's area produces Broca's aphasia, which is also known as expressive aphasia. People with this disorder have slow labored speech that consists primarily of nouns and verbs, and they also exhibit impaired repetition and anomia, which is an inability to recall the names of familiar objects. However, their comprehension of written and spoken language is relatively intact. Next is the parietal lobe, which contains the somatosensory cortex, which processes sensory information related to touch, pressure, temperature, pain, and body temperature.
Excuse me, that should have been body position. Damage can cause one or more somatosensory agnosias. These include tactile agnosia, which is an inability to recognize objects by touch, a somatognosia, which is a lack of interest in or recognition of one or more parts of one's own body, and a nocignosia. which is denial of one's own illness or disability.
Damage can also cause contralateral neglect and Gerstmann syndrome. Contralateral neglect is usually caused by damage to the non-dominant, which is usually the right parietal lobe, and involves inattention to one side of the body and visual field. A person with this disorder may groom only the left side of his face and eat food only on the left side of his plate. Gerstmann syndrome is usually caused by damage to the dominant, usually the left parietal lobe, and involves finger agnosia, right-left disorientation, agraphia, which is a loss of writing skills, and acalculia, which is a loss of math skills. The temporal lobe contains the auditory cortex and Wernicke's area.
The auditory cortex is involved in processing sound, and damage can produce auditory agnosia, auditory hallucinations, or cortical deafness. Wernicke's area is a major language area and is located in the dominant, that is usually the left, hemisphere. Damage produces Wernicke's aphasia, which is also known as receptive aphasia. People with this disorder have impaired comprehension of written and spoken language, impaired repetition, and anomia.
They also have fluent but incoherent or meaningless speech because it contains many word substitutions, made-up words, and other errors. Note that the arcuate fasciculus is a bundle of axons that connects Wernicke's area to Broca's area, and damage to this structure produces conduction aphasia. which is characterized by relatively intact comprehension with fluent speech that contains many errors, impaired repetition, and anomia.
And finally, the occipital lobe contains the visual cortex, which processes visual information. Damage to this area can cause visual agnosia, visual hallucinations, achromatopsia, which is a loss of color vision, or cortical blindness. Prasopagnosia is usually caused by bilateral lesions in the occipital temporal junction and involves an inability to recognize the faces of familiar people. Okay, next are the neuroimaging techniques. Two types of neuroimaging techniques are used to diagnose neurological disorders, structural and functional.
Structural neuroimaging techniques are used to identify structural changes that are due, for example, to strokes, tumors, blood clots, degenerative diseases, and infections, and include computerized axial tomography and magnetic resonance imaging. Computerized axial tomography is also known as computed. axial tomography or just computed tomography.
It uses x-rays to obtain images of horizontal slices of the brain. Magnetic resonance imaging uses strong magnetic fields and radio waves to obtain cross-sectional images of the brain. Advantages of CAT are that it costs less than an MRI, provides images more rapidly, and unlike MRI, doesn't require the patient to be motionless for a long period of time. Also, unlike MRI, computerized axial tomography can be used with patients who have pacemakers, metal plates, or other metal in their bodies.
Advantages of MRI are that it produces three-dimensional and more detailed images and doesn't require the use of radiation. MRI is frequently used not only to obtain structural information about the brain and spinal cord, but also other internal structures of the body. Functional neuroimaging techniques provide information about brain structure and indirect information on neuronal activity by assessing regional cerebral blood flow, oxygen consumption, or glucose metabolism.
These techniques include the three that are listed in the slide. When using positron emission tomography, the person is injected with a radioactive tracer. that's taken up by active brain cells.
Single photon emission computed tomography is similar to positron emission tomography, but is easier and less expensive to use, but produces less detailed images. And functional magnetic resonance imaging is similar to an MRI, but provides information on changes in blood, oxygenation, and flow. Okay, let's go ahead and take a look at some questions now. Here's the first question.
Research suggests that the blank is responsible for attaching fear and other strong emotions to neutral stimuli associated with the traumatic event that caused the development of PTSD. A, amygdala. B, medulla. C, substantia nigra. D, caudate nucleus.
Like some questions you'll encounter on the APPP, this question refers to research you might be unfamiliar with and therefore feel you don't have the information you need to identify the correct answer. However, as long as you recall that the amygdala is responsible for attaching emotions to memories, you would have been able to identify answer A as the correct answer. If you didn't immediately recall this information when you read the question, the best strategy would have been to use the process of elimination by recalling what you know about each structure listed in the answers. The amygdala is involved with emotions, including attaching emotions to memories.
The medulla is responsible for breathing, heart rate, and other vital functions. The substantia nigra is involved in reward-seeking behaviors and motor control, and the caudate nucleus is part of the basal ganglia, which are involved in the initiation and coordination of voluntary movement. Therefore, answer A, the amygdala, is the correct answer. Okay, here's the next question.
A person with Wernicke's aphasia will have A, slow labored speech and relatively intact comprehension. B, effortless but incoherent speech and relatively intact comprehension. C, slow labored speech and impaired comprehension. Or D, effortless but incoherent speech and impaired comprehension. For the exam, you want to be familiar with the characteristics of Broca's, Wernicke's, and conduction aphasia so you can answer questions like this one.
Recalling that Wernicke's aphasia involves impaired comprehension and speech that sounds fluent but is incoherent or meaningless because it contains word substitutions and other errors would have enabled you to identify answer D as the correct answer. Even though the word fluent is not used in any of the answers, you'd be able to eliminate answers A and C because Wernicke's aphasia does not involve slow, labored speech. That leaves answers B and D, and effortless can be considered a synonym for fluent.
By the way, answer A describes Broca's aphasia, and answer B describes conduction aphasia. Okay, here is the next question. Some research suggests that the risky, impulsive choices and behaviors of adolescents and difficulty making certain kinds of rational decisions are due to the fact that the blank does not fully develop until the early to mid-20s.
A, amygdala, B, striatum, C, prefrontal cortex, or D, somatosensory cortex? This is another question that may seem to be asking about research you're unfamiliar with and therefore don't have the information you need to identify the correct answer. However, by considering the functions of the four areas of the brain listed in the answers, you would have been able to identify answer C, the prefrontal cortex, as the correct answer, as long as you know that, of the areas of the brain listed in the answers, the prefrontal cortex is the only one that's involved in higher-order cognitive functions, such as planning, decision-making, behavioral inhibition, and social judgment.
Therefore, the late development of the prefrontal cortex helps explain why adolescents tend to engage in risky, impulsive choices and behaviors, and have difficulty making certain kinds of rational decisions. Okay, there's one more question. Severing which of the following to prevent severe seizures from spreading from one cerebral hemisphere to the other produces the split brain syndrome?
A postcentral gyrus, B precentral gyrus, C arcuate fasciculus, or D, corpus callosum. For the exam, you want to be familiar with research on split-brain patients whose corpus callosums were severed to keep severe seizures from spreading from one hemisphere to the other. I didn't mention this research in this lecture, but it is covered in the Physiological Psychology Content Summary on the Cerebral Cortex.
However, you may have been able to identify the corpus callosum answer D as the correct answer, even if you aren't familiar with that research, since I mentioned that the corpus callosum is the major bundle of fibers that connects the right and left hemispheres. I also mentioned that the arcuate fasciculus answer C connects Broca's area and Wernicke's area, but I haven't mentioned the postcentral gyrus and precentral gyrus, which are answers A and B. It's not likely you'll be asked about them on the EPPP, but just in case you are or you're interested in what they are, a gyrus is a ridge in the cerebral cortex, and the primary somatosensory cortex is located on the postcentral gyrus in the parietal lobe, while the primary motor cortex is located on the precentral gyrus in the frontal lobe. That brings me to the end of Part 2.