Microsoft PowerPoint - Accessible_Lecture_Presentation_49ed32625.pptm

[Virtual Presenter] Nervous systems have been present in animals since the Cambrian explosion, over 500 million years ago. They allow animals to sense their environment and respond quickly. To understand how billions of neurons work together, scientists have engineered mice to produce different colors in each brain cell. This helps us see how neurons are connected and how they process information..

[Audio] Nervous systems consist of circuits of neurons and supporting cells, which are organized in different ways depending on the complexity of the animal's lifestyle. In bilaterally symmetrical animals, there is a tendency towards cephalization, where sensory organs cluster at the front end of the body. The central nervous system (CNS) is composed of the brain and spinal cord, while the peripheral nervous system (PNS) consists of nerves and ganglia. The CNS processes information, while the PNS transmits it. The organization of the nervous system often reflects the animal's lifestyle, with simpler animals having less complex systems and more complex animals having more sophisticated ones..

[Audio] The central nervous system develops from the hollow dorsal nerve cord. This cavity gives rise to the narrow central canal of the spinal cord and the ventricles of the brain. The canal and ventricles fill with cerebrospinal fluid, which supplies the CNS with nutrients and hormones and carries away wastes. The spinal cord conveys information to and from the brain and generates basic patterns of locomotion. It also produces reflexes independently of the brain. A reflex is the body's automatic response to a stimulus. The vertebrate nervous system is organized into gray matter, which consists of neuron cell bodies, dendrites, and unmyelinated axons, and white matter, which consists of bundles of myelinated axons. The brain and spinal cord contain these components..

[Audio] The peripheral nervous system has two main components: the motor system and the autonomic nervous system. The motor system sends signals to skeletal muscles, which can be either voluntary or involuntary. The autonomic nervous system controls smooth and cardiac muscles, typically involuntarily. Additionally, the enteric nervous system governs the digestive tract, pancreas, and gallbladder. Both sympathetic and parasympathetic systems involve a preganglionic and postganglionic neuron pathway, where preganglionic neurons release acetylcholine and postganglionic neurons release either acetylcholine or norepinephrine. The autonomic nervous system comprises sympathetic and parasympathetic divisions, with the former regulating arousal and energy generation, while the latter promotes relaxation and a return to normal functioning. The peripheral nervous system transmits information between the central nervous system and external environment, controlling movement and internal processes. Afferent neurons send information to the central nervous system, whereas efferent neurons transmit information away from it..

[Audio] Radial glial cells and astrocytes play a crucial role in the development and maintenance of the vertebrate brain. As stem cells, they can divide indefinitely to self-renew and produce more specialized cells. This process allows them to form tracks along which newly formed neurons migrate. Moreover, astrocytes participate in the formation of the blood-brain barrier, restricting the entry of most substances into the brain. Furthermore, glial cells provide nutrients and support to neurons, regulating their activity and ensuring proper functioning..

[Audio] The vertebrate brain is regionally specialized, with different parts responsible for various functions. The forebrain divides into the diencephalon and telencephalon, which form endocrine tissues and the cerebrum respectively. The midbrain and hindbrain give rise to the brainstem and cerebellum. The hypothalamus acts as a control center, regulating the body's temperature and biological clock. The cerebellum coordinates movement and balance, while the diencephalon produces the thalamus, hypothalamus, and epithalamus. The human brain contains 100 billion neurons, making 100 trillion connections. During embryonic development, the anterior neural tube gives rise to the forebrain, midbrain, and hindbrain. The cerebrum controls skeletal muscle contraction and is the center for learning, emotion, memory, and perception. The cerebral cortex, located on the surface of the cerebrum, plays a crucial role in perception, voluntary movement, and learning. Finally, the corpus callosum connects the right and left cerebral cortices, enabling communication between them..

[Audio] Dolphins can be asleep and awake at the same time because the brainstem and cerebrum control arousal and sleep. Arousal is a state of awareness of the external world, while sleep is a state in which external stimuli are received but not consciously perceived. Sleep is an active state for the brain, and some animals have adaptations that allow for substantial activity during sleep. The neurons of the reticular formation control the timing of sleep periods characterized by rapid eye movements and vivid dreams. Sleep is also regulated by the biological clock and regions of the forebrain that regulate intensity and duration. Sleep is essential for survival and may play a role in the consolidation of learning and memory. Arousal and sleep are controlled in part by the reticular formation, a network formed mainly of neurons in the midbrain and pons..

[Audio] The storage and recall of emotional memories depend on the amygdala, a brain structure located near the base of the cerebrum. The generation and experience of emotions often require interactions between different parts of the brain. In mammals, circadian rhythms are coordinated by the suprachiasmatic nucleus, a cluster of neurons in the hypothalamus that acts as a pacemaker, synchronizing the biological clock. The limbic system, comprising the amygdala, hippocampus, and thalamus, maintains a roughly 24-hour cycle, even in the absence of environmental cues. Cycles of sleep and wakefulness are examples of circadian rhythms, relying on a biological clock that directs periodic gene expression and cellular activity..

[Audio] The cerebral cortex plays a crucial role in processing sensory information, controlling voluntary movements, and facilitating cognitive functions. Through functional imaging techniques such as fMRI and PET scans, researchers can study brain structures and detect changes in local oxygen concentrations or metabolic activity. This allows them to map abnormalities in conditions like migraine headaches and monitor recovery from strokes. Furthermore, brain imaging helps increase the effectiveness of brain surgery by providing valuable insights into brain function and structure..

[Audio] The two hemispheres of the brain collaborate to facilitate effective communication, facilitated by the fibers of the corpus callosum. When severed, this connection leads to a "split-brain" effect. Studies demonstrate that Broca's area is active during speech production, while Wernicke's area is active when speech is perceived. This disparity in hemisphere function is referred to as lateralization. Individuals with damage to Broca's area may comprehend language but struggle to articulate, whereas those with damage to Wernicke's area can still verbalize but fail to grasp language. The two hemispheres contribute uniquely to brain function, with the left hemisphere excelling in language, mathematics, and logical reasoning, and the right hemisphere being stronger at facial recognition, spatial relationships, and non-verbal thinking..

[Audio] Changes in synaptic connections play a crucial role in memory and learning. This process involves regulated gene expression and signal transduction, determining where neurons form. Neurons then compete for growth-supporting factors to survive. Only half of the synapses formed during embryonic development survive into adulthood, and in the final phase, synapse elimination occurs. This concept challenges previous ideas that a highly convoluted neocortex is necessary for advanced cognition. Instead, the anatomical basis for sophisticated information processing in birds, without a highly convoluted neocortex, lies in the clustering of nuclei in the top or outer portion of the brain, known as the pallium. The formation of the nervous system occurs in steps, with early mammalian evolution transforming the clustered organization of the pallium into a layered one..

[Audio] Hippocampal damage and memory loss are common in the early stages of Alzheimer's disease, where neuronal plasticity plays a crucial role. Autism spectrum disorder also involves disruptions in activity-dependent remodeling at synapses, which may contribute to its development. Furthermore, individuals with damaged hippocampi can recall past events but struggle to form new lasting memories. This highlights the importance of neuronal plasticity in memory formation..

[Audio] Schizophrenia is a complex mental illness that can be understood at the molecular level. Research shows that it affects specific neural pathways involving dopamine, and many treatments target these pathways. Despite its genetic roots, environmental factors also play a significant role. This highlights the importance of considering both genetic and environmental influences in understanding the development of neurological disorders like schizophrenia..

[Audio] Some drugs are addictive because they increase activity in the brain's reward system, which rewards motivation with pleasure. Examples of such drugs include cocaine, amphetamine, heroin, alcohol, and tobacco. The brain's reward system is also associated with Alzheimer's disease, which is a mental deterioration characterized by confusion and memory loss. The incidence of Alzheimer's disease increases with age, and it is associated with the formation of amyloid plaques and neurofibrillary tangles in the brain. Massive shrinkage of brain tissue, reflecting the death of neurons in many areas of the brain, is also a hallmark of this disease. The neurotransmitter dopamine plays a key role in the reward system, and treatments for depression often target the activity of biogenic amines in the brain. Two broad forms of depressive illness are recognized: major depressive disorder, characterized by a persistent lack of interest or pleasure in most activities, and bipolar disorder, marked by manic and depressive phases. Drug addiction is characterized by compulsive consumption and an inability to control intake. Addictive drugs enhance the activity of the dopamine pathway, leading to long-lasting changes in the reward circuitry that cause a craving for the drug. It is hoped that research in this area will lead to better prevention and treatment of drug addiction..

[Audio] Parkinson's disease is a motor disorder caused by the death of dopamine-producing neurons in the midbrain. As people age, the incidence of Parkinson's disease increases. The disease is characterized by muscle tremors, flexed posture, and a shuffling gait. While most cases lack an identifiable cause, one form of the disease has been linked to a genetic basis. There is currently no cure for Parkinson's disease, but some medications can help relieve its symptoms. Additionally, tau protein accumulation is also seen in another degenerative brain disease, known as chronic traumatic encephalopathy, which affects athletes, military veterans, and others with a history of concussions..

[Audio] In the future directions of brain research, scientists aim to map brain circuits, measure activity within those circuits, and understand how this activity is translated into thought and behavior. This involves studying the nervous system's circuits of neurons and supporting cells. Recent initiatives, such as the BRAIN project, have been launched to advance innovative neurotechnologies. These efforts seek to achieve a better understanding of the brain's functions and develop new treatments for neurological disorders..

[Audio] The presentation has come to an end. I hope you found the information presented informative and useful in your understanding of the topic. Remember that all materials used in this presentation are copyrighted and may only be used by instructors for educational purposes. Your cooperation in respecting these restrictions is appreciated. Goodbye..