Ch. 2 - Biology of the Mind - SE PDF

PSYC 102 The Biology of Mind Chapter 2  Presentation Outline Learning Objectives Neural and Hormonal Systems Tools of Discovery: Having Our Heads Examined Brain Regions and Structures Damage Resonses and Brain Hemispheres  Chapter Learning Obj...

PSYC 102 The Biology of Mind Chapter 2  Presentation Outline Learning Objectives Neural and Hormonal Systems Tools of Discovery: Having Our Heads Examined Brain Regions and Structures Damage Resonses and Brain Hemispheres  Chapter Learning Objectives By the end of today, you will be able to... Understand how the Be familiar with human brain changes Understand the neural different methods used and develops through and hormonal systems. to study the human the lifespan. brain. Understand the split Be able to identify brain and how damage brain structures and to the brain affects their functions. humans. Neural and Hormonal Systems  Biology, Behavior, and Mind Phrenology is an early form of biological psychology that involved determining character traits and mental abilities via the texture of their skulls. Phrenology was established by Franz Gall, a German physician. While we now know that phrenology is not an accurate way to study character traits or mental abilities, we do know that it got one thing right: Various brain regions have particular functions (aka localization of function).  Biology, Behavior, and Mind Biological psychology is the scientific study of the links between biological and psychological processes. These biological processes can be genetic, neural, or hormonal in Those who study biological nature. psychology go by many names: Biological Psychologists Biopsychologists Neuroscientists Neuropsychologists Behavior Geneticists Physiological Psychologists Image from Simply Psychology  Biology, Behavior, and Mind As humans, we are comprised of systems, which are divided into subsystems, which are further divided into more subsystems. On the other end, we exist as singular units within families, which exist within communities, and so on. In Conclusion: We are biopsychosocial beings.  The Power of Neuroplasticity “The brain you were born with is not the brain you will die with.”  The Power of Neuroplasticity Neuroplasticity is the brain’s ability to change. Creating new neural pathways based Reorganizing after damage on experiences Neuroplasticity is particularly Neuroplasticity is a big reason why we high in childhood. are able to adapt to our world. Neuroplasticity is also why parts of the brain develop differently for different people.  The Power of Neuroplasticity Cultural neuroscientists discuss how experiencing different cultural traditions, beliefs, and rituals can create distinct behaviors and brain activation patterns.  Neural Communication It may not be surprising that human and monkey brains are similar in structure and function. What may be surprising is that the human brain also shares certain basic structures and functions with animals such as squids and sea slugs!  Neural Communication Neurons are nerve cells. Like other cells, neurons die through the lifespan and new neurons form. While there are different types of neurons, they all have the same basic structure, including: Axons Dendrites Cell Body Neural Communication  Neural Communication Remember: Dendrites Listen, Axons Speak  Neural Communication The synapse is a gap between neurons.  Neural Communication Most neurons are also accompanied by glial cells, which serve numerous functions, such as: Nourishing Protecting Cleaning  Neural Communication Neurons send messages by firing signals, called action potentials. Action potentials can travel as slow as 2 miles per hour and as fast as 200 miles per hour!  Neural Communication The action potential occurs in a number of Threshold stages.  Neural Communication A cell starts at its resting potential. The resting potential involves a negatively charged axon channel Threshold with closed “ion gates” (aka closed Resting Potential membranes).  Neural Communication Neurotransmitters from another neuron’s axon terminals bind to the neuron’s dendrite receptors. When the neurotransmitters Threshold cause so much energy that the threshold is 1 Resting Potential reached, the sodium ion gates open.  Neural Communication Sodium ions (+) rush into 2 the axon channel, changing the channel’s charge from negative to Threshold positive. This process is called depolarization. 1 Resting Potential  Neural Communication The change in charge 2 causes a domino-like effect, which allows the action potential to Threshold continue through the neuron. 1 Resting Potential  Neural Communication These changes lead to 2 3 potassium ion channels opening, allowing potassium ions (+) to Threshold rush out of the axon channel. 1 Resting Potential  Neural Communication 2 3 This causes the channel’s charge to return back to negative Threshold in a process called repolarization. 1 Resting Potential  Neural Communication There is often an 2 3 overshoot, which leads to hyperpolarization. During this time (the Threshold refractory period), another action potential 1 4 cannot fire. Resting Potential  Neural Communication 2 3 The completed process leads to a continuation of the signal to other Threshold neurons, where other action potentials fire. 1 4 Resting Potential  Neural Communication Action potentials are all-or-nothing responses, meaning they either fire or they don’t. Action potentials can be either excitatory or inhibitory.  Neural Communication After the action potential occurs, extra neurotransmitters either drift away, are turned into enzymes, or are reabsorbed in a process called reuptake. Neurotransmitter Some Roles It Plays Acetylcholine Muscle action, learning, & memory Dopamine Movement, learning, attention, & emotion Serotonin Mood, hunger, sleep, & arousal Norepinephrine Arousal & alertness Glutamine Excitation, learning, & memory Endorphins Influence perceptions of pain & pleasure  Neural Communication If our body naturally produces opioids (and those opioids have good effects), why is excessive use of artificial opioids bad? Some drugs are agonists, Some drugs act as meaning they increase antagonists, meaning they neurotransmitter effects. decrease neurotransmitter effects. -Increasing production or release -Occupying neurotransmitter -Blocking reuptake receptors to block effects -Imitate neurotransmitter  The Nervous System The nervous system is the body’s electrochemical communication network. It is made up of: The Central The Peripheral Nervous System Nervous System (CNS) (PNS)  The Nervous System The central nervous system is The peripheral nervous made up of the brain and system receives information spinal cord. from the central nervous system and distributes it to the rest of the body. Nerves, a key part of the PNS, are bundles of axons that form neural cables. These cables connect the CNS with muscles, glands, and sensory organs.  The Nervous System Peripheral Nervous System Three types of neurons make up the nerves in the PNS. Sensory neurons carry messages from the body’s tissues and sensory receptors to the brain and spinal cord for processing. Motor neurons carry instructions from the central nervous system outwards to the body’s muscles and glands. Interneurons process information between the sensory neurons and motor neurons.  The Nervous System Peripheral Nervous System The peripheral nervous system is composed of the autonomic nervous system and the somatic nervous system. The autonomic nervous The somatic nervous system system controls our glands controls our skeletal muscles. and our internal organ muscles; it is in charge of In other words, it is in charge involuntary processes like of voluntary movement. our heartbeat, digestion, and glandular activity.  The Nervous System Peripheral Nervous System The autonomic nervous system is further composed of two subsystems: the sympathetic nervous system and the parasympathetic nervous system. The parasympathetic nervous The sympathetic nervous system produces the system arouses and expends opposite effects to the energy. sympathetic nervous system; it calms us down. The sympathetic and parasympathetic nervous system work together to maintain homeostasis, or the body’s stable state of being. The Nervous System Peripheral Nervous System  The Nervous System Image from faculty.washington.edu Reflexes are simple, automatic responses to sensory stimuli. The central and peripheral nervous systems work together, and we engage in these reflexes without even being consciously aware of it! The Nervous System  The Endocrine System The endocrine system contains glands and fat tissue that secrete hormones into the blood stream. Hormones are chemical messengers that travel through the blood stream and affect other tissues.  The Endocrine System The pituitary gland (controlled The adrenal glands activate in by the hypothalamus) is time of stress. considered the “master gland” because it influences many They release epinephrine and other glands in the body. norepinephrine, which increase heart rate, blood pressure and The pituitary gland releases blood sugar in order to fuel our hormones such as growth fight-or-flight response. hormones, oxytocin, and cortisol. Tools of Discovery: Having Our Head Examined Tools of Discovery: Having Our Heads Examined Early studies of the brain were difficult and time consuming. Another way that the One way that early brain was studied was researchers studied the by creating lesions brain was seeing how an (destroying clumps of individual was different cells) and determining before and after injury. how they affected functioning. Modern neuroscientists use stimulation of the brain (electrically, chemically, or magnetically) to see which parts of the brain react. This way, they can determine what parts of the brain play roles in which functions! Tools of Discovery: Having Our Heads Examined Electroencephalogram Image from TebMedTourism Electroencephalograms (EEG) study the brain’s chatter – i.e. the emission of electrical, metabolic, and magnetic signals by amplifying these signals with a cap covered in electrodes and conducive gel. Tools of Discovery: Having Our Heads Examined Magnetoencephalographies Image from Wikipedia Magnetoencephalographies (MEG) use a head coil similar to hair dryers at the beauty salon to measure magnetic fields generated from the brain’s natural electrical activity. Tools of Discovery: Having Our Heads Examined Position Emission Tomogrpahy Image from petscaninmumbai.com Position emission tomography (PET) uses a radioactive form of glucose (consumed by the individual being studied) to display brain activity. Tools of Discovery: Having Our Heads Examined Magnetic Resonance Imaging Image from the National Cancer Institute Magnetic resonance imaging (MRI) uses a strong magnetic field to disrupt the typical spinning of brain molecules; when these molecules return to their normal activity, they emit signals that provide detailed pictures of soft tissues. Tools of Discovery: Having Our Heads Examined Functional Magnetic Resonance Imaging Image from Psych Central Functional MRIs (fMRI) expand upon the traditional MRI to detect blood flow in the brain to determine brain functions (in addition to structure). Brain Regions and Structures  Brain Regions and structures Vertebrate brains, such as the human brain, have three main divisions: The hindbrain contains brainstem structures that direct essential survival functions, such as breathing, sleeping, arousal, coordination, and balance. The midbrain connects the hindbrain with the forebrain and controls some movement and transmits information that enables our seeing and hearing. The forebrain manages complex cognitive activities, sensory and associative functions, and voluntary motor activities. Brain Regions and structures The Brainstem The brainstem is the brain’s centermost region. It contains the medulla and the pons. The brainstem serves as a crossover point, where nerves connect to the opposite side of the body. The Brainstem The medulla is the region of slight swelling in the spinal cord just after it enters the skull. It controls functions such as our heartbeat and our breathing. The Brainstem The pons sits just above the medulla. It controls sleep and helps coordinate movement. The Thalamus The thalamus sits atop the brainstem and acts as the brain’s sensory control center. It receives information about all of the senses except smell, then reroutes that information to the parts of the brain that deal with those senses. The thalamus sometimes also receives replies from these regions that deal with sensory information, which it redirects to the medulla or the cerebellum. The Reticular Formation The reticular formation is a netlike collection of nerves that extends from the spinal cord up to the thalamus. The reticular formation intercepts some sensory input, filters it, and sends it to the proper parts of the brain. The reticular formation also deals with arousal. The Cerebellum The cerebellum is located at the rear portion of the brainstem. It is often called the “little brain.” The cerebellum enables nonverbal learning and skill memory (along with the basal ganglia) and coordinates voluntary movement with help from the pons.  The Limbic System The limbic system is responsible for emotions and drives; it contains the amygdala, the hypothalamus, and the hippocampus.  The Limbic System The limbic system is responsible for emotions and drives; it contains the amygdala, the hypothalamus, and the hippocampus. The amygdala, two almond shaped structures, control fear and aggression.  The Limbic System The limbic system is responsible for emotions and drives; it contains the amygdala, the hypothalamus, and the hippocampus. The hypothalamus, located just below the thalamus, controls hunger, thirst, body temperature, and sexual behavior; it also serves as one of the brain’s reward centers.  The Limbic System The limbic system is responsible for emotions and drives; it contains the amygdala, the hypothalamus, and the hippocampus. The hippocampus (a curved brain structure) processes conscious, explicit memories.  The Cerebral Cortex When we refer to the cerebrum, we are talking about the two hemispheres of the brain - aka 85% of the brain’s weight! The cerebrum is responsible for perception, thinking, and speaking. The cerebral cortex is an interconnected layer of nerve cells that covers the cerebrum. The cerebral cortex is divided into four lobes: frontal, temporal, occipital, and parietal.  The Cerebral Cortex Functions of the Cortex Motor Functions The motor cortex is a portion of the brain located at the rear of the frontal lobes, which controls movement. The right side of the cortex controls the left side of the body and vice versa. Research has found that those parts of the body that require the most specific and precise control occupy the greatest amounts of cortical space. The Cerebral Cortex Functions of the Cortex Sensory Functions The somatosensory cortex, located at the front of the parietal loves, registers and processes body touch, temperature, and movement sensations. Similar to the motor cortex, the more sensitive a body region, the larger the portion of the somatosensory cortex dedicated to it is.  The Cerebral Cortex Functions of the Cortex Other portions of the cortex that are not involved in motor or sensory inputs have higher functions such as language, memory, and thinking. These are called association areas. One such area, the prefrontal cortex, is involved in planning, judgement, social interactions, and making memories. Image from Fllint Rehab Damage Responses and Brain Hemispheres  Responses to Damage For a while, it has been believed that when damaged, the brain cannot heal by creating new cells. Rather, it has been noted that our brains change in response to damage through neuroplasticity. The parts of our brain that are not damaged often compensate and adapt. In recent years, it has been debated whether neurogenesis (the creation of new neural cells, often through stem cells) is possible and can help heal damaged brains.  The Divided Brain Lateralization refers to the brain’s different hemispheres (left and right) serving different functions. In an intact brain, the right side of the brain controls movement on the left side and vice versa. The left and right hemispheres also serve different functions: The left is responsible for reading, writing, speaking, arithmetic reasoning, and understanding The right side deals with making inferences, modulating speech to make meaning clear, and orchestrating self-awareness.  The Divided Brain Lateralization refers to the brain’s different hemispheres (left and right) serving different functions. These hemispheres are connected via the corpus callosum, a large band of neural fibers. Sometimes, doctors may “split” a person’s brain by severing the corpus callosum. Individuals with split brains often feel as if one side of their body is unaware of what the other side is doing.  That’s All! Questions, Comments, Concerns?