Brain Mapping and the Nervous System PDF
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This document provides a detailed overview of the brain's structure and function, outlining different brain regions and their roles in various processes. It also explores concepts like neuroplasticity and associated functions like language, thought, problem-solving, and memory.
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rain Mapping and the Nervous System B Terminology: The Compass of the Brain Brain Structure CEREBRAL CORTEX ○ Frontal lobe ○ Parietal lobe ○ Temporal lobe Occipital lobe (Insular lobe) SUBCORTI...
rain Mapping and the Nervous System B Terminology: The Compass of the Brain Brain Structure CEREBRAL CORTEX ○ Frontal lobe ○ Parietal lobe ○ Temporal lobe Occipital lobe (Insular lobe) SUBCORTICAL STRUCTURES ○ Basal ganglia ○ Hippocampus ○ Amygdala ○ Thalamus and hypothalamus ○ Corpus callosum OTHER ○ Brainstem ○ Midbrain ○ Pons ○ Medulla oblongata ○ Reticular formation ○ Cerebellum Brain Mapping Caveats Certain parts of the brain are responsible for certain functions, but… ○ Individual differences ○ Most behaviors require multiple areas ○ Brain can reorganize through early experience or reaction to trauma “plasticity” Major Brain Divisions The brain is organized into three major structures during development: ○ Forebrain ○ Midbrain ○ Hindbrain The Cerebral Cortex T he cerebral cortex is the largest and outermost portion of the human brain, supporting complex mental activity. Neocortex The majority of the cerebral cortex is neocortex, which: ○ Is evolutionarily the youngest part of the brain ○ Develops through late adolescence and young adulthood ○ Supports complex functions like language, thought, problem-solving, and imagination Is extensively folded to accommodate a large number of neurons ○ Cerebral Hemispheres and Lobes The cerebral cortex is divided into two hemispheres, each with subdivisions called lobes: 1. Occipital Lobe Located at the back of the head Primarily devoted to vision Contains the primary visual cortex 2. Temporal Lobe Runs alongside the ears Contains the primary auditory cortex Responsible for hearing, language understanding, and object/people recognition 3. Parietal Lobe Located above and behind the ears Contains the primary somatosensory cortex Supports body mapping, sense of touch, and attention to visual world 4. Frontal Lobe Located in the front of the head Contains the primary motor cortex Includes the prefrontal cortex, responsible for thought, planning, decision-making, and self-control 5. Insular Lobe Hidden under the temporal, frontal, and parietal lobes Allows perception of internal body states Includes the primary taste cortex Sensory and Motor Areas Each lobe contains specific sensory and motor areas: Primary sensory areas for each of the five senses Primary motor cortex for voluntary movements Association Cortex The association cortex: Integrates sensory information with existing knowledge Helps interpret and recognize sensory patterns Supports connections between sensory regions and pleasure Is present in every lobe Is responsible for the brain's most sophisticated abilities Comparative Brain Anatomy The cerebral cortex varies among species: Primates have a higher proportion of association cortex compared to other mammals The size of the frontal cortex and number of convolutions differ among species Dogs have a densely packed cerebral cortex, potentially supporting a rich mental life The Subcortical Brain: Emotion, Motivation, and Memory Subcortical Structures Some of these subcortical structures are older forms of cortex, but most are clusters of cells, called nuclei, that are very distinct from the cortex. The Limbic System ○ The limbic system bridges the newer, higher brain structures that are more related to complex mental functions with the older, lower, brain regions that regulate your body and its movements (MacLean, 1990). The limbic system consists of multiple interconnected yet distinct structures, including the hippocampus, amygdala, basal ganglia, thalamus, and hypothalamus (FIGURE 3.14). The limbic system is often described as the "emotional brain," but that description is not entirely accurate because the limbic system also plays important and diverse roles in smell, learning and memory, and motivation (Nishijo et al., 2018). Hippocampus ○ One of the best-understood limbic structures, the hippocampus, is crucial for certain aspects of memory and your ability to navigate the environment (Maguire et al., 2006). The hippocampus is an older region in the depths of the temporal lobe that creates memories of an event's time and place, supporting mental time-travel into the past (Moscovitch et al., 2016). The hippocampus is related to emotions insofar as it helps you remember emotionally prominent events from your life and think about your hopes and desires for your future (K. L. Campbell et al., 2018). Amygdala ○ An essential component of the limbic system that is dedicated to emotion is the almond-shaped amygdala (Latin for "almond"), which is cradled in the outstretched arms of the hippocampus. It plays an essential role in how you register the emotional significance of events. In lab animals, the removal of the amygdala can dramatically change emotional behavior. A once-ferocious animal may become tame, and fearful animals may become fearless. As FIGURE 3.15 shows, a rat without an amygdala will snuggle up to a predator, a cat -at least a partially sedated one (C. I. Li et al., 2004). Abnormalities in the amygdala can result in what was once called psychic blindness: Animals could still see, but the psychological importance of what they saw appeared to be absent. Because the amygdala is one of the most interconnected regions of the brain, it touches on many aspects of what the brain does, including how you see, think, and remember (Pessoa, 008; Todd et al., 2013). Your most vivid memories are likely to be emotionally 2 significant, and the amygdala enhances these memories by influencing the hippocampus (Cahill & McGaugh, 1998; LaBar & Cabeza, 2006; Roozendaal et al., 2009). Basal Ganglia ○ The basal ganglia are a group of interconnected structures that are an evolutionarily older subcortical motor system that is necessary for planning and executing movement. They bridge the motor regions of the cerebral cortex with nuclei that communicate with the spinal cord, sending signals to your muscles to act. Degeneration of the basal ganglia results in slow, rigid, tremor-filled movements or involuntary writhing, suggesting that the basal ganglia are critical for both starting and stopping (or inhibiting) movement. Parkinson's disease, which affects the basal ganglia, compromises the ability to plan, initiate, execute, and control movement (A. B. Nelson & Kreitzer, 2014; Zhuang et al., 2017), leading to a substantial difficulty in initiating actions that results in slow movements and tremors. As we will discuss, certain components of the basal ganglia are also involved in learning and motivation, the psychological forces that will us to move. Thalamus ○ Located between the basal ganglia and resembling two large symmetrical eggs, the thalamus serves as a central subcortical hub for the signals it receives from all of the sensory systems except the olfactory (smell) system. There is two-way communication between the thalamus, which sits deep in the middle of the brain, and the brain regions that receive its messages. This communication is critical to how your brain determines what is out there in the world (Rauss et al., 2011) ○ As you sleep, the thalamus helps you shut out the outside world by turning down its relaying of sensory inputs. In dreams, your world becomes one with the possibilities your brain can imagine. Because the thalamus plays a central role in relaying sensory information to and from the cerebral cortex, damage to it can result in a wide variety of impairments, from loss of touch, to blindness, to memory loss. Hypothalamus ○ Despite its small size, the hypothalamus, which sits below the thalamus, is the major interface between the brain and the body, integrating internal bodily signals with their associated feelings and behaviors. Like the thalamus, the hypothalamus is composed of many specialized nuclei that regulate specific functions, including hunger, biorhythms, reward seeking, and aggression. The Brainstem and Cerebellum: Key Components of the Central Nervous System The Brainstem ○ Overview Located at the base of the skull Regulates vital functions like breathing and heart rate Connects most sensory nerves to the brain Evolutionarily oldest and most primitive brain region Structure From top to bottom ○ Midbrain ○ Pons ○ Medulla oblongata ○ Reticular formation (runs through the brainstem) Functions of Brainstem Components Midbrain ○ Includes the tegmentum for reflexive head and eye movements ○ Contains the ventral tegmental area, part of the motivation and reward system ○ Houses the substantia nigra, involved in movement regulation Pons ○ Controls breathing rate ○ Relays sensations like hearing, taste, and balance Medulla Oblongata ○ Controls autonomic functions (heart rate, blood pressure) ○ Manages critical reflexes (coughing, swallowing) Reticular Formation ○ Central to arousal and attention ○ Regulates sleep and wakefulness ○ Plays a role in ADHD ○ Important for maintaining cognitive abilities with age The Cerebellum Overview ○ Located behind the pons and medulla in the hindbrain ○ Shaped like a small brain at the back of the brainstem Functions ○ Contributes to coordination, precision, balance, and accurate timing ○ Adjusts head and eye movements for balance ○ Critical for learning precision movements ○ Plays a role in thought and planning Importance in Movement and Cognition ○ Enables complex and detailed movements (e.g., sports activities) ○ Involved in mental practice for learning movements ○ Increasingly recognized for its role in overall cognition Neural Plasticity: Key Concepts and Implications Neural plasticity refers to the brain's ability to physiologically modify, regenerate, and reinvent itself throughout a lifetime. Key Concepts Critical Periods ○ Early life stages where specific experiences are crucial for normal development Example: Cataract removal in infants for normal face recognition ability ○ Damage Plasticity ○ Neural modification following injury ○ Involves brain reorganization in response to altered inputs Adult Plasticity ○ Shaping and reshaping of neural circuits in adulthood ○ Examples: Learning to navigate complex city streets, practicing musical instruments Mechanisms of Neural Plasticity Synaptogenesis ○ Generation of new synapses between neurons ○ Supports learning and memory Neurogenesis ○ Birth of entirely new neurons throughout the lifespan ○ Potentially involved in new memory formation ○ May be related to stress and depression Conclusion Understanding and harnessing neuroplasticity offers promising avenues for improving human lives and treating various neurological conditions.
