PSYC100: The Biological Psychology Fall 20224 PDF

PSYC100: PSYCHOLOGY The Biological Psychology Fall 20224 @ Koç University Gözde Şentürk  BUILDING UP THE NERVOUS SYSTEM WE WILL START STRUCTURES OF HOW THOSE THE CHEMICALS THE DIVISIONS OF WITH THE CELLS THE CELLS CELLS IN THE NERVOUS THE NERVOUS...

PSYC100: PSYCHOLOGY The Biological Psychology Fall 20224 @ Koç University Gözde Şentürk  BUILDING UP THE NERVOUS SYSTEM WE WILL START STRUCTURES OF HOW THOSE THE CHEMICALS THE DIVISIONS OF WITH THE CELLS THE CELLS CELLS IN THE NERVOUS THE NERVOUS COMMUNICATE SYSTEM SYSTEM The cells in the nervous system Human body consists of cells. Cells are the smallest units. There are different types of cells: e.g. blood cells, skin cells.. Neurons and glial cells are the cells in the nervous system. We will mostly talk about neurons. Neurons are special cells that have branches to communicate with other neurons. Neurons do a lot of information transmission/modification. Glial cells support the functions of the neurons. (see Carlson, 2014) Functions of neurons ❖ Estimated number of neurons in human nervous system: around 100 billion. ❖Sensory neurons: Collect information from environment. Light, chemicals (odors and flavors), sounds.. ❖ Motor neurons: They control the contraction of muscles. ❖ Interneurons: In the central nervous system, all the neurons that are not sensory or motor neurons. ❖Local interneurons: Analyzing small piece of information by forming local circuits ❖ Relay interneurons: Connect the small circuits to other brain regions (see Carlson, 2014)  (image from Betts et al., 2022, p. 459) Soma (cell body): Housekeeping activities, keeping the cell alive. Neurons have special branches for information processing. Dendrites are the branches on a neuron that receive signals from other neurons. An axon is the branch on a neuron that send information to other neurons (or muscles). The tips of an axon are called terminal button. The terminal buttons contain vesicles (special bags) filled with neurotransmitters (chemicals that have inhibitory/excitatory effects when released) Neurons  How do neurons communicate? A presynaptic sends information by releasing neurotransmitter. A postsynaptic cell receives the information by detecting the presence of the neurotransmitters. If a presynaptic cells becomes sufficiently excited (e.g. acquiring positive electric charge), the neuron generates (fires) an action potential. Action potential: A bust of positive electric signal The action potentials travels along the axon of the presynaptic cell towards its terminal button. When the action potential reaches to the terminal button, neurotransmitters are released to the synaptic gap. The postsynaptic cell has receptors that recognize neurotransmitters. When neurotransmitters bind with the receptors on the postsynaptic cell, certain channels open on the postsynaptic cell. Depending on what kind of channels open on the postsynaptic cell, electrically charged particles (ions) flow through channels. If the postsynaptic cell acquires sufficient positive charge (sufficiently excited), it will generate action potential. If the postsynaptic cell acquires negative charge (inhibited): then it will remain silent.  (image from Betts et al., 2022, p. 459) Conduction of action potential o Most of the axon is covered by the myelin sheath. Only small segments are exposed to the extracellular fluid. Those small segments are called nodes of Ranvier. o There are channels at the nodes of Ranvier. Action potentials occur at nodes of Ranvier. Once it occurs, it travels down the axon. o While passing through the sheathed part, the electricity is conducted passively. There is no action potential happening underneath the myelin sheath. Then, an action potential occurs on the next node. This is called saltatory conduction. (see Carlson, 2014) Conduction of action potential o All-or-none law: Once an action potential is generated, you cannot take it back. It is ought to travel to the tip of the axon. Like a domino effect.. oA neuron produces identical action potentials. The shape, size, and duration of the action potentials do not change. o However, the temporal profile of the action potential depends on the intensity of the stimulus. o For example, as the intensity of the touch increases, the sensory neurons on the skin will fire more often (increased temporal frequency). o There is a limit, though.. When a neuron fires an action potential, it cannot fire another one for a few msecs. This period is called a refractory period. (see Carlson, 2014)  ACTION POTENTIALS: WITHOUT VS. WITH MYELIN SHEATH Dr. Jana, CC BY 4.0 , via Wikimedia Commons. Retrieved from: https://upload.wikimedia.org/wikipedi a/commons/4/48/Saltatory_Conducti on.gif  Terminal button o The action potential generated by the presynaptic cell reaches to the axon terminal. o This event moves the vesicles (small bags filled with special chemicals called neurotransmitters). o The vesicles fuse with the membrane. The content of the vesicles are released into the synaptic cleft. o What happens to the postsynaptic neuron? (see Carlson, 2014) (image from Betts et al., 2022, p 479)  Postsynaptic neuron 1. There are receptors on the membrane of the postsynaptic neuron. The receptors are like locks, and the neurotransmitters are like keys. 2. The neurotransmitters released to the synaptic cleft bind with the binding sites on the postsynaptic receptors. 3. This binding events leads to opening of neurotransmitter-dependent ion channels that are located on the membrane of the postsynaptic neuron. 4. Hence, certain ion channels open. This leads certain ions to come in/out of the postsynaptic neuron. 5. Opening of those channels let certain ions in/out. The postsynaptic neuron can be depolarized or polarized. (see Carlson, 2014) (image from Betts et al., 2022, p 479) SYNAPTIC COMMUNICATION: WHAT DOES IT LOOK LIKE? Marcelo Guerra, CC BY-SA 3.0, via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/8/89/Sinapsi.gif Ion channels on the the postsynaptic cells are open. Now what? ❖Depending on what type of ions these channels are permeable to, opening of the channels can make the neuron more positive (excitatory, depolarizing event) or more negative (inhibitory, polarizing event). ❖“A postsynaptic potential (PSP) is the graded potential in the dendrites of a neuron that is receiving synapses from other cells. Postsynaptic potentials can be depolarizing or hyperpolarizing. Depolarization in a postsynaptic potential is called an excitatory postsynaptic potential (EPSP) because it causes the membrane potential to move toward threshold. Hyperpolarization in a postsynaptic potential is an inhibitory postsynaptic potential (IPSP) because it causes the membrane potential to move away from threshold.” (Betts et al., 2022, p. 477) Excitation and Inhibition of neurons Excitation Inhibition  The dendrites of a post-  The dendrites of a post- synaptic neuron receives synaptic neuron receives neurotransmitter from the neurotransmitter from the presynaptic neuron. presynaptic neuron.  An excitatory signal makes the  An inhibitory signal makes the post-synaptic neuron less post-synaptic neuron more negative, or more positive. negative, or less positive.  An excitatory signal makes  An inhibitory signal makes neuron more ready to fire an neuron less ready to fire an action potential. Gregory Maxwell, Public domain, via Wikimedia Commons action potential. Retrieved from: https://commons.wikimedia.org/wiki/File:Yin_yang.svg (see Carlson, 2014) Neural integration ❖ We talked about what happens at one synapse. But a postsynaptic neuron has many dendrites, receive input from many other presynaptic neurons. ❖ Some of those inputs can be inhibitory, some of them can be excitatory. ❖ Those input are summed up. ❖ If the summation of the excitatory input is large enough, it can initiate an action potential at the stalk of the axon (axon hillock). (see Carlson, 2014) A lot of neurotransmitters are released to the synaptic gap. How to clean? ❖ The neurotransmitters cannot stay at the synaptic gap forever. ❖ Reuptake: The presynaptic cells takes back the neurotransmitters it has released. ❖ Enzymatic deactivation: Releasing enzymes that break down the neurotransmitters at the synaptic gap. ❖Autoreceptors are located on the terminal button of the presynaptic cell. They detect how much neurotransmitter it released, and help to regulate the amount of release. Basically, they signal “It is time to stop releasing neurotransmitters” to itself. (see Carlson, 2014) Neurotransmitters and hormones Both are chemicals that can effect our mood and behavior Neurotransmitters are released by neurons to the synaptic gap. Hence, they have effect only on the postsynaptic cell. Hormones are released by endocrine glands to the bloodstream. Hence, they can potentially reach anywhere in the body (including the brain) and they can have a global impact on many cell types. The nervous system compass ❖ Neuroaxis: An imaginary line from forebrain to the tip of the spinal cord. ❖ Front: anterior, rostral ❖ Back: posterior, caudal ❖ Top: dorsal, superior ❖ Down: ventral, inferior ❖ Central: medial ❖ Peripheral: lateral ❖ Ipsilateral: On the same side. ❖E.g. the right olfactory bulb send information to the right side of the brain (image from Betts et al., 2022, p. 497) ❖Contralateral: On the opposite side ❖E.g. The left side of the visual field is perceived by the right visual cortex (see Carlson, 2014)  An overview The nervous system: Central Nervous System (CNS)+Peripheral Nervous System (PNS) The CNS The PNS ❖ Brain (covered by skull) ❖ Cranial Nerves ❖ Spinal Cord (covered ❖ Spinal Nerves by the vertebral column) ❖ Peripheral Ganglia (image from Betts et al., 2022, p. 452) (see Carlson, 2014) An overview The nervous system: Central Nervous System (CNS)+Peripheral Nervous System (PNS) (image from Betts et al., 2022, p. 457) Crash course on the nervous system..  PERIPHERAL NERVOUS SYSTEM Skeletal nervous system Control striated (striped) muscles Voluntary control Autonomic nervous system Sympathetic nervous system (fight-or-flight mode) Parasympathetic nervous system (relax mode) Enteric nervous system (digestion)  THE BRAIN Forebrain Cerebral cortex (aka grey matter): the surface of the forebrain. Folded. (Sulci: folded in; Gyrus: folded out) Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe Subcortical structures Some important ones: thalamus, hypothalamus, amygdala, limbic system, basal ganglia Brainstem Midbrain Hindbrain  THE BRAINSTEM ❖ The brainstem has two major divisions: midbrain and hindbrain Images are generated by Life Science Databases(LSDB)., CC BY-SA 2.1 JP , via Wikimedia Commons (image from Betts et al., 2022, p. 507) https://upload.wikimedia.org/wikipedia/commons/0/08/Brainstem.gif  MIDBRAIN ❖Some structures contribute to eye movements and auditory perception ❖Reticular formation: Long: from the tegmentum to the medulla. Involved in arousal, sleeping, wakefulness, attention, muscle tone, and some reflexes. ❖ Major dopamine producing structures Gray's illustrations, CC BY-SA 4.0, via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/e/ ec/Midbrain-axial-showing-tectum-and- tegmentum.jpg (see Carlson, 2014) STRUCTURES IN THE HINDBRAIN ❖Medulla: control of the cardiovascular system, skeletal muscle tone, breathing. ❖Pons: Effects sleep, dreaming, and arousal. ❖Reticular formation: A long structure extending through the brainstem. Arousal, wakefulness, eye movements. ❖ Cerebellum: Coordinated skeletal muscle movement (image from Betts et al., 2022, p. 508)  The forebrain ❖The surface of the forebrain is folded. The surface is called the cerebral cortex. Cerebrum By following those folds, we divide Polygon data were generated by Database Center for Life Science(DBCLS)., CC BY- cerebral cortex into 4 lobes. SA 2.1 JP, via Wikimedia Commons https://upload.wikimedia.org/wi kipedia/commons/f/fa/Cerebru m_animation_small.gif ❖Other structures: thalamus, hypothalamus, hippocampus, amygdala, cingulate cortex, the limbic system Diencephalon Images are generated by Life Science Databases(LSDB)., CC BY-SA 2.1 JP, via Wikimedia Commons https://upload.wikimedia. org/wikipedia/commons/c /c4/Diencephalon_small.g (see Carlson, 2014) if THE FOREBRAIN ❖ The cerebral cortex is folded. A fold-up is called gyrus (plural: gyri), a small fold-in is called sulcus (plural: sulci). A large groove is a fissure. ❖ Because it is highly folded, most of the cerebral cortex is folded-in. The thickness is about 3mm. ❖ Cerebral cortex is also called gray matter because it appears gray due to many glial cells, somas and dendrites of the neuron. ❖Just below the gray matter, there are millions of axons. Hence, it looks white (white matter). ❖ The cerebral cortex has four lobes: frontal lobe, parietal lobe, temporal lobe, and occipital lobe. (see Carlson, 2014) The Forebrain: The Four Lobes of the (image from Betts et al., Cerebral Cortex 2022, p. 501) The Forebrain: The Four Lobes of the Cerebral Cortex Frontal Lobe Location: At the front part of the forebrain Major structures: Motor cortex and prefrontal cortex Motor cortex: Plan, calculate and execute skeletal muscle control Prefrontal cortex: Higher-order cognitive functions (problem solving, decision making, planning, morality..) Occipital lobe Location: At the back portion of the forebrain Major structure: visual cortex. Processes the sense of vision. Parietal Lobe Location: Behind the frontal lobe, in front of the occipital lobe, above the temporal lobe Major structures: somatosensory cortex and posterior parietal cortex Somatosensory cortex: Processes the sense of touch Temporal Lobe Location: Behind the frontal lobe, in front of the occipital lobe, below the parietal lobe Major structures: auditory cortex, medial temporal lobe (including hippocampus), and inferior temporal lobe Auditory cortex: Processes the sense of hearing. Medial temporal lobe: Memories.  Forebrain: Other structures ❖ Limbic system is involved in emotions and motivations. ❖ Major subdivisions: ❖ Cingulate Gyrus ❖ Hippocampus (Greek: sea horse) ❖ Involved in learning and memory ❖amygdala (Greek: almond- shape) ❖ emotions (image from Betts et al., 2022, p. 609) (see Carlson, 2014) Other structures in the Forebrain ❖Thalamus: A hub of the incoming sensory information to the cortex ❖Hypothalamus ❖Small in size, but does a lot! ❖ Controls the autonomic nervous system ❖ Controls the endocrine system (hormones) ❖The pituitary gland (aka the master gland) secretes hormones ❖The pituitary gland also releases many other hormones! ❖Regulates survival behaviors (image from Betts et al., 2022, p. 674) ❖4 F’s: fighting, feeding, fleeing, mating (see Carlson, 2014) Crash course on the brain.. (Spielman et al. 2020, p. 100)  Peripheral nervous system (PNS) ❖The PNS has two anatomical divisions: Cranial Nerves and Spinal Nerves ❖Cranial nerves and spinal nerves for sending signal to various parts of the body from neck above and receiving signals from various parts of the body from neck above. ❖Spinal nerve is attached to the spinal cord, traveling to muscles and sensory organs from the neck below. ❖ Peripheral Nervous System has three functional divisions: Somatic Nervous System, Autonomic Nervous System, Enteric Nervous System (see Carlson, 2014)  Cranial nerves in the PNS ❖ Twelve pairs of cranial nerves. ❖ Located within the cranium. ❖ Send signals to/receive signals from face and head ❖Mostly ipsilateral organization (image from Betts et al., 2022, p. 523) ❖ Roman numerals SOMATIC NERVOUS SYSTEM in the PNS ❖Sensing touch: The somas of the neurons that carry the incoming sensory input is located outside the CNS. ❖Somas are outside the CNS ❖Skeletal muscle command: The somas are in the gray matter of the spinal cord. Motor control of the skeletal muscles. ❖Somas are inside the CNS (see Carlson, 2014) (image from Betts et al., 2022, p. 600) AUTONOMIC NERVOUS SYSTEM in the PNS ❖ Controls the smooth muscles in the body. ❖ Regulates vegetative functions of the body ❖ It has two divisions ❖ Sympathetic Nervous System ❖ Parasympathetic Nervous System ❖ Enteric Nervous System (see Carlson, 2014)  Sympathetic nervous Parasympathetic system Nervous System NERVOUS SYSTEM: Activates body, spending energy! Relax mode Storing energy, Fight or flight, get increased blood ready for the action!! supply to digestive TWO MODES system AUTONOMIC When activated Increase heart rate Secrete norepinephrine Increased body flow to the muscles Piloerection (see Carlson, 2014) Left and right cerebral hemispheres Corpus Callosum is a bridge Some All those lobes between the left and right lateralization of come in left and hemisphere. It consists of the brain right pairs. axons and connects the two functions hemispheres. Left Cerebral Hemisphere Right Cerebral Hemisphere Analysis of information Synthesis of information Recognizing serial events Draw sketches, reading maps Speech perception and production Constructing objects (see Carlson, 2014) NEUROTRANSMITTERS Neurotransmitters are released by neurons to the synaptic gap. They are detected by receptors. The receptors open ion channels. Ions enter/exit the postsynaptic cell. (Spielman et al., 2020, p. 83) HORMONES Endocrine glands release hormones to the bloodstream. Hence, hormones can travel anywhere in the body via the bloodstream. However, only the cells with receptors for a hormone can respond to the hormone. The pituitary gland is the master gland. It orders other endocrine glands to release hormones. Pituitary gland is attached to the hypothalamus. Pituitary gland Releases hormones that directly control behaviors/emotions Oxytocin: Reproductive behavior and parenting. Childbirth contractions. Milk letdown reflex. Vasopressin: Antidiuretic. Water consumption. Bonding? Growth hormone Release hormones to control other glands The pineal gland: Release melatonin. Control sleep/wake cycle The thyroid gland: Release thyroxin. Control metabolism. The pancreas: Release insulin and glucagon. Control blood sugar level and satiety. The gonads: Release hormones that control reproductive behavior The adrenal glands: Releases Corticoids (cortisol). Stress response. MEASURING BRAIN ACTIVITY EEG/ERP Attaching electrodes on the scalp Recording the collective electrical activity of the neurons High temporal specificity Low spatial specificity Non-invasive  Involves radiation Computerized How X-rays passes through the tissue depends on the tissue type Tomography (CT) Usually for detecting tumors or scan significant brain atrophy. (Spielman et al., 2020, p. 95) Positron emission tomography (PET) scan Involves ration. Participants drinks/injected with a radioactive substance called tracer. Blood flow increases to the activated brain region, hence amount of tracer. Currently, usually used for diagnostic purposes. (Spielman et al., 2020, p. 96)  magnetic resonance imaging (MRI) and functional resonance imaging (fMRI) Measures the magnetic properties of the hydrogen atoms. MRI machine is a huge magnet. In the magnet, hydrogen atoms behave in a certain way. As different brain tissues have different hydrogen density, we can locate those tissues by looking at the behaviors of the hydrogen atoms. MRI scans tells different tissues apart. Functional MRI (fMRI) scans measure the blood flow and (Spielman et al., 2020, p. 95) oxygen levels. It informs about the brain activity. MRI gives more detailed brain image and accurate activation than PET scan.  References Betts, J. G, Desaix, P. , Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J. A., Womble, M., Young, K. A. (2022). Anatomy and physiology 2e. OpenStax. https://openstax.org/details/books/anatomy-and-physiology- 2e Carlson, N.R. (2014). Foundations of behavioral neuroscience (Pearson New International Edition, 9th Ed.). Pearson. Spielman, R. M., Jenkins, W. J. , & Lovett, M. D. (2020). Psychology 2e. OpenStax. https://openstax.org/details/psychology-2e Note: The Designer function powered by Office Intelligence services were used to design the slides.