Sensory Perception: Light, Sound, and Chemoreception, Assignments of Psychology

Download Sensory Perception: Light, Sound, and Chemoreception and more Assignments Psychology in PDF only on Docsity! 1/25/23 Basic vertebrate brain is conserved Rostral Caudal ‘Telencephalon @ Forebrain Comparative vertebrate anatomy teary taf) y ania} \ \ ‘Corebrum. Optic abo oreo ran th vertile edule ote ~ Spinal core Pimtive sh Bony en Ahlan (ostehshay—“toout) (roa) ape atten Sra mar Large momen (rabon) (horse) Human Brain Anatomy (Sagittal or Median Section) Anirior FRONT : sai FRONTALLOBE (Glanning) . occiprraL (raion) TEMPORAL ‘factory Bub toue {arguene) appropriate scall aoe / ~ ceReBeLLuM ceomotonal responce) / X eeu ewetmaes / SS SEs fi Entorinal Cotes’ — MBPOEAMUS ~~ praiy STEM (memory) aay (ody basics) LIMBIC SYSTEM 1/30/24 5 SENSES SOUND SENSITIVITY 1.) Differences in Sensory Range: - Intensity Across All Senses: This covers how different animals perceive the strength or weakness of stimuli across various senses (such as sight, hearing, touch, etc.). - Frequency of Light: This pertains to the ability of different species to perceive various frequencies of light, determining the range of visible colors. - Frequency of Sound (Audiogram): This relates to the range of sound frequencies that different animals can hear. - Flicker-Fusion and Flutter-Fusion Rates: This section examines the rates at which animals perceive rapid changes in visual and auditory stimuli, respectively. 2.) Differences in Higher-Level Perception: - Feature Selectivity: This part discusses how different animals are attuned to specific features in their environment, affecting their perception. - Object Recognition/Speech Recognition (Learned): This focuses on the ability of animals to recognize objects and, in some cases, understand speech, which is often a learned skill. 3.) Differences in Sensory Modalities (Including the 'Sixth Sense'): - Electro-reception: This involves the ability of some animals to perceive electric fields, which is crucial for navigation, hunting, and communication. - Magneto-reception: This is the capability to detect magnetic fields, often used by animals for orientation and navigation. - Echolocation: A method used by certain animals to navigate and locate objects by emitting sound waves and interpreting the echoes. Concept of Sound Intensity and how it's measured: 1.) Sound Intensity: is basically how loud or soft a sound is. 2.) Sound Pressure Level (SPL): is a way to measure that loudness. It's like using a ruler to measure how long something is, but in this case, we're measuring how loud a sound is. 3.) The term **SPL (0 is approx threshold of hearing in humans)** means that the SPL scale starts at 0, which is the quietest sound a typical human ear can hear. Just like the zero on a ruler is the starting point for measuring length. 4. The formula 𝐿 ! = 20 log "# 𝑝 𝑝# is a mathematical way of calculating SPL. Here's a simple way to understand it: - **L**: This represents the SPL, the loudness level we want to find out. - **20 log**: This is a math operation that helps us turn the sound pressure (how strong the sound waves are) into a number that's easier to understand. - **𝑝**: This is the pressure of the sound we're measuring. - **𝑝#**: This is a reference sound pressure, which is the quietest sound that the average human can hear. In simple terms, this formula helps us figure out how loud a sound is compared to the quietest sound a person can typically hear. The higher the SPL number, the louder the sound. So, if a sound has an SPL of 30, it's louder than a sound with an SPL of 10. 3.) Birds: Many bird species have more than three types of cones. In addition to red, green, and blue, they often have an extra type (or more) that can detect ultraviolet (UV) light. This means they can see colors in the UV spectrum, which are invisible to humans. So, birds have "tetrachromatic" vision or even more complex color vision systems. 4.) Example: Imagine a flower. To us, it might just look yellow. But to a bird, that same flower might have patterns in UV that we can't see. These patterns could guide the bird to nectar or show where the pollen is. It's like birds can see a whole world of colors that are completely invisible to us. - In summary, while humans see the world through a mix of red, green, and blue light, many birds have an extra layer of color perception, allowing them to see ultraviolet light and additional colors that we can't even imagine. This image is about the evolution of color vision in primates. It compares two types of color vision: dichromatic and trichromatic: 1.) Dichromatic Vision: This is a simpler form of color vision. "Di-" means two, so dichromatic vision is based on two types of color receptors in the eyes, often sensitive to blue and green colors. Primates with dichromatic vision (like the female shown on the left side of the image) may see the world in a limited range of colors. They might have difficulty distinguishing between reds and greens, making some colors look similar or duller. 2.) Trichromatic Vision: This is a more complex form of color vision. "Tri-" means three, indicating that trichromatic vision involves three types of color receptors, usually for blue, green, and red. Primates with trichromatic vision (like the female shown on the right side of the image) can see a full range of colors, including rich reds and greens. This type of vision is more similar to what most humans have and allows for the perception of a wider spectrum of colors. - The pictures in the image likely show how the world might look to primates with these two different types of color vision. The dichromatic view is less vivid, especially in the red and green areas, while the trichromatic view is richer and more varied. This evolution in color vision is significant because it can affect a primate's ability to find food, recognize mates, and identify threats. Things that absorb UV appear black and thing that ref;ect UV appear white (snow) FREQUENCY OF SOUND: This graph is an audiogram that shows how sensitive human hearing is across a range of frequencies. Here's what it's telling us in simpler terms: - Horizontal Axis (Frequency in kHz): This line shows different pitches of sound, from very low on the left (bass sounds) to very high on the right (treble sounds). "Hz" stands for Hertz and "kHz" stands for kilohertz, which are units used to measure frequency. - Vertical Axis (Threshold in dB SPL): This line shows how loud a sound needs to be for the average person to hear it. "dB SPL" stands for decibels of Sound Pressure Level. The lower the number, the quieter the sound can be for us to still hear it. - Curve Shape: The shape of the curve shows that humans are best at hearing sounds in the middle frequency range (around 0.5 to 4 kHz). These are the frequencies where the line dips the lowest, meaning we can hear these sounds even when they're very quiet. - Infrasounds (<30 Hz): These are very low-pitched sounds that are generally below our hearing range. That's why the graph starts above the hearing threshold in this area. - Ultrasounds (>20 kHz): These are very high-pitched sounds that are also generally above our hearing range. The graph shoots up on the right side because we can't hear these sounds unless they're very loud. - 60-dB Low-Frequency Limit: This indicates that sounds below a certain pitch need to be at least 60 decibels for us to hear them. - 60-dB High-Frequency Limit: This indicates that sounds above a certain high pitch also need to be at least 60 decibels for us to hear them. - In summary, this audiogram is a chart that tells us what pitches of sound humans can hear and how loud those sounds need to be for us to notice them. We're really good at hearing sounds like normal conversations and telephone rings, which fall in the middle range of frequencies, but not so great at hearing very low or very high pitches. The image shows two graphs that are comparative audiograms, comparing the hearing capabilities of various animals, including humans: 1.) Left Graph: This graph plots the threshold of hearing (in decibels SPL) for different marine and land mammals across a range of frequencies (in kHz). The threshold of hearing is the softest sound that an animal can detect at each frequency. Each line represents a different animal, and the lower the line, the better that animal can hear at that frequency. For example, if one line is below another, it means that the animal can hear softer sounds at that frequency compared to the other animal. 2.) Right Graph: Similar to the left, this graph shows the hearing thresholds for different animals, including a mouse, dog, human, and Indian elephant, but displayed on a logarithmic scale for frequency. This scale makes it easier to compare a wide range of frequencies on one graph. Again, lower lines indicate better hearing at certain frequencies. - In both graphs, you can see that different animals have different hearing capabilities. Some animals, like dogs, can hear much higher frequencies than humans, which is why they can hear dog whistles that are silent to us. Meanwhile, animals like elephants can hear lower frequencies than humans, which they use for communication over long distances. - The variety in hearing thresholds across animals is related to their different environments and survival needs. For example, animals that rely on hearing for hunting or avoiding predators tend to have more sensitive hearing. can lead the brain to hear a completely different sound, highlighting the brain's tendency to categorize sounds into distinct groups rather than perceiving them as a continuum DIFFERENCES IN MODALITY (6TH SENSE EXISTS!): three types of specialized sensory systems that some animals possess, known as "Other Senses." Explanation for each one: ● Electro-reception: The first illustration shows a shark with dotted lines around its head. These dots represent the ampullae of Lorenzini, which are special sensing organs that allow sharks to detect electrical fields in the water. This sense helps sharks find prey because all living things produce small electrical signals. ● Magneto-reception: The second image appears to show a bird, a pigeon perhaps, and a fish, which might be some species of trout. Both of these animals are known to have a sense of magneto-reception, which allows them to detect the Earth's magnetic field. The illustrations indicate the parts of the animals that might be involved in this sense. Birds and fish use this sense to navigate over long distances, like when birds migrate or fish return to their spawning grounds. ● Echo-location (Active Sensing): The third picture shows a bat in flight with lines and a butterfly, representing how bats use echolocation to navigate and hunt. Bats emit sound waves that bounce off objects and return to them as echoes. By listening to the echoes, bats can determine where objects are, their size, and even their texture, which is crucial for catching prey like insects in the dark. - In summary, the image is showing us different ways animals perceive their environment beyond the five senses humans typically use. These "other senses" are specialized and allow animals to interact with their world in unique ways that humans cannot. TRANSDUCTION- FROM PHYSICAL ENERGY TO NEURAL SIGNAL: The image describes the process of transduction, which is how sensory information from the environment is converted into electrical signals in the nervous system. Here's what the image explains, broken down into simpler terms: ● Transduction Pathway: It starts with some form of energy, like light, sound, or chemical energy from a smell. This energy activates a special protein called a G-protein, which then causes a graded voltage change inside the cell. This voltage change can eventually trigger an action potential (AP), which is an electrical signal that travels along neurons to the brain, allowing us to perceive the sensory information. ● Types of Receptors: ● Mechanoreceptors: These are sensory receptors that respond to mechanical pressure or distortion. For example, they're in your skin and help you feel touch or pressure. ● Hair Cells (audition, balance): These are specific types of mechanoreceptors found in the ears. They respond to vibrations caused by sound for hearing (audition) and to fluid movements for balance. ● Chemoreceptors: These receptors detect chemicals in the environment, such as the ones found in your nose and tongue to smell and taste. ● Photoreceptors: These are cells in your eyes that respond to light. ● Mechanisms of Sensory Transduction (Illustrated in Figure 2.1): ● Ionotropic Transduction (A): This occurs when a sensory stimulus directly causes ion channels in the cell membrane to open. These channels are part of the receptor molecule itself. For example, when sound waves hit hair cells in the ear, this leads to ions flowing into the cells, creating an electrical signal. ● Metabotropic Transduction (B): This is a bit more complex. The sensory stimulus activates a receptor, which is not an ion channel itself. Instead, it activates a G-protein, which then starts a series of events inside the cell. This can lead to the opening of ion channels indirectly and create a graded voltage change. This process is common in smell and vision. In essence, the image explains how different receptors in the body convert various forms of physical energy from our environment into signals that the brain can understand, allowing us to perceive the world around us 2/1/24 ● Transduction: This is like translating one language to another. Sensory cells in our body translate different forms of energy (like light for seeing, sound for hearing, or chemicals for tasting and smelling) into electrical signals that our brain can understand. ● Different Types of Sensory Cells: ● Mechanoreceptors: These cells feel physical touch or pressure. ● Hair Cells: Found in your ears, they help you hear by picking up sound vibrations and help you keep your balance by sensing the position of your head. ● Chemoreceptors: These cells taste flavors in food or smell odors in the air. ● Photoreceptors: In your eyes, these cells detect light and allow you to see. ● How Transduction Works (Based on your description): ● Energy to G-protein: When the right kind of energy (like a sound wave or a light photon) hits these sensory cells, it activates a protein inside the cell (the G-protein). ● G-protein to Graded Voltage: The G-protein starts a reaction that changes the electrical charge inside the cell. This is not an all-or-nothing signal but varies in strength depending on the stimulus. ● Graded Voltage to Action Potential (AP): If the change in electrical charge is strong enough, it will lead to an action potential, which is like an electrical message that travels down nerve cells to the brain. - In short, the image is talking about how our bodies take in information from the world (like sights, sounds, tastes, and smells) and turn it into a language that the brain can understand, which allows us to experience our senses. MECHANORECEPTORS: The image seems to describe two aspects of olfactory perception, which is the sense of smell. ● Left Side: It shows a diagram of the olfactory system, where receptor cells in the nose detect odors. The top part of the image illustrates the structure of olfactory receptor neurons with olfactory cilia, which are hair-like structures that contain receptors for odorants (smelly molecules). These neurons send signals to the brain when they detect odorants. The bottom part is likely an electron microscope image showing the actual olfactory cilia, which look like a bundle of fibers. ● Right Side: This is a diagram of the molecular process that occurs when an odorant binds to its receptor on an olfactory neuron. Here's a step-by-step breakdown of what's happening: ● An odorant molecule (1) binds to a receptor on the surface of an olfactory neuron. ● This activates a G protein inside the cell (G_olf) (2), which then binds to GTP (a molecule similar to ATP), activating it. ● The activated G protein then activates adenylate cyclase (3), an enzyme that converts ATP to cyclic AMP (cAMP) (4). ● The increase in cAMP opens ion channels (5) that allow sodium (Na+) and calcium (Ca2+) ions to flow into the cell. ● This influx of ions causes a change in the electrical charge inside the cell (depolarization), leading to the generation of a nerve impulse that travels to the brain, where it is interpreted as a particular smell. - In simple terms, the image is showing how smelling works, from detecting odor molecules with special cells in the nose to sending a message to the brain telling it what you're smelling CHEMORECEPTION: ● Immense Surface Provided by the Cilia: Cilia are tiny hair-like structures in the nose that have receptors for detecting odors. Humans have about 20 square centimeters of this olfactory surface in their noses, while dogs have a much larger area, between 5 to 10 square meters, which helps explain their much more sensitive sense of smell. ● Many Receptor Variants: Both humans and mice have a number of different genes that code for olfactory receptors, which are proteins that respond to odor molecules. Humans have between 300 to 350 types of these genes, while mice have around 1000, giving them the ability to detect a wider variety of smells. ● Constant Regeneration of Receptors: Olfactory receptors are regularly replaced with new ones. This is unique among sensory cells, as not many other types of sensory cells regenerate in this way. ● Nobel Prize in 2004: Richard Axel and Linda Buck won the Nobel Prize for their discoveries of how the olfactory system works, including the fact that each receptor is specialized to recognize a few odors, and how the brain interprets this information to perceive a wide variety of smells. ● Taste: The sense of taste is similar to smell in that it uses specialized receptors, but these are located in "taste bud" cells on the tongue and other parts of the mouth. Humans have fewer types of taste receptors, which are specifically sensitive to five basic tastes: bitter, sweet, umami (savory), salty, and sour PHOTORECEPTORS: The image depicts the structure of the human retina and the details of rod and cone photoreceptors, which are the cells responsible for vision: ● Part A: This shows a cross-section of the retina, highlighting the various types of cells and layers: ● RPE: Retinal Pigment Epithelium, a layer that absorbs excess light and supports the photoreceptors. ● Rods and Cones: Photoreceptor cells that detect light. Rods are more numerous and are sensitive to low light levels, while cones are responsible for color vision and function best in bright light. ● Horizontal Cells: Interneurons that help integrate and regulate input from multiple photoreceptor cells. ● Bipolar Cells: They receive information from photoreceptors and pass it on to ganglion cells. ● Muller Cells: Glial cells that provide structural support. ● Amacrine Cells: These cells process the signal further and can modulate the signal from bipolar to ganglion cells. ● Ganglion Cells: These neurons send the visual information to the brain through their axons, which form the optic nerve. ● Nerve Fiber Layer: The layer that contains the axons of the ganglion cells. ● Part B: This is a detailed illustration of a rod and a cone cell, showing the differences in their structure: ● OS (Outer Segment): This is the part of the photoreceptor that contains stacks of membranes where light is detected. ● Calycal Processes: Structures that extend from the inner segment of the photoreceptors. ● IS (Inner Segment): The part of the photoreceptor that contains the cell's organelles and connects to the synaptic terminal. ● N (Nucleus): The cell's nucleus, which contains its genetic material. ● Ribbons: Specialized structures in the synaptic terminal where neurotransmitters are released to communicate with the next cells in the visual pathway. - The image is essentially showing you how light information is processed in the retina from the moment it hits the photoreceptors (rods and cones) until it's converted into electrical signals that are sent to the brain. This complex interplay of cells and layers is how we are able to see. PHOTORECEPTORS AND VISUAL TRANSDUCTION: Coding Schemes: ● Labeled Line: This concept suggests that specific neurons in the brain are dedicated to processing certain types of sensory information. For instance, specific neurons might only respond to light touch, while others might respond to temperature. ● Spike-rates: This refers to the rate at which neurons fire action potentials (spikes) in response to stimuli. The spike-rate can change depending on the intensity of the stimulus. ● Stimulus-response curves describe how the firing rate of a neuron changes with increasing stimulus intensity. ● Tuning curves represent the range of stimuli to which a neuron is most responsive, indicating how selective a neuron is for particular features of a stimulus, like the pitch of a sound or the angle of a light. Temporal Code: This coding scheme refers to the timing of neuronal spikes. It suggests that the pattern and frequency of spikes, not just the rate, can convey information to the brain. Computations: ● Adaptation: This is the process by which neurons adjust their sensitivity to a constant stimulus over time. When a stimulus is constant and unchanging, neurons may fire less frequently, which prevents the nervous system from being overwhelmed by unimportant information. ● Spatial Derivative – Lateral Inhibitory Circuit: This computation involves neurons inhibiting their neighbors in the nervous system, enhancing the contrast and sharpness of sensory information. It's like how edge detection works in visual processing, where cells that detect the edges of objects inhibit the response of adjacent cells, making the edges stand out more. ● Temporal Derivative – Inhibition + Delay: This involves the time-based processing of sensory information. Neurons can delay their responses to a stimulus and also inhibit other neurons over time. This can help the nervous system detect changes in a stimulus over time, like the beginning and end of a sound. - In summary, these terms describe various ways that neurons encode and process sensory information to allow us to perceive and interact with the world around us. It includes where information is processed, how often neurons fire in response to stimuli, how they adjust to continuous stimuli, and how they emphasize important sensory details. LABELED LINE: the identity of the neuron carries information 3 different models for how taste information might be encoded and transmitted from taste receptor cells to the brain: ● Labeled Line: This model suggests that each taste receptor cell is specific to a single taste quality (like umami, sour, salty, bitter, or sweet). Each cell sends its signal to the brain via a dedicated axon. So, there is a direct line (hence "labeled") from the receptor for each taste to the brain. In this way, each taste quality is represented by a different "line" of communication. ● Across Fiber Model 1: This model shows that each axon can transmit signals for more than one taste quality. Instead of one taste per axon, multiple tastes can activate the same axon but with different patterns of activity. For example, Axon 1 responds to salty and bitter, Axon 2 to umami and sour, and so on. ● Across Fiber Model 2: Similar to the first across fiber model, this one also shows that a single axon can respond to multiple tastes, but it simplifies the pattern even further. In this model, Axon 1 responds to both bitter and sour tastes. This suggests that the brain distinguishes different tastes not by which line is active (as in the labeled line model) but by the pattern of activity across multiple lines. These models are ways to explain how we can perceive a variety of tastes and how this complex information might be communicated to the brain. The true mechanism of taste coding likely involves a combination of these models. RATE CODE: the number of spikes carries information Concept of a "Rate Code" in the context of neural responses to sensory information: Rate Code: This refers to the idea that the frequency of action potentials (or "spikes") fired by a neuron carries information about the intensity of a stimulus. More spikes per unit of time generally mean a stronger or more intense stimulus: Left Side - Response of a single cortical cell to bars presented at various orientations: ● This shows a series of bar stimuli at different angles being presented to a neuron. ● The response (spike rate) of the neuron is shown below each bar. ● The neuron fires action potentials at a rate that depends on the orientation of the bar. Some orientations cause the neuron to fire more frequently, indicating that the neuron is selectively sensitive to that particular orientation. Middle - Tuning Curve: ● This graph demonstrates how the neuron's firing rate changes with the orientation of the bar. ● The peak of the curve indicates the preferred orientation of the neuron—the angle at which it fires the most action potentials. Right Side - Graphs A, B, C, D: ● These graphs show the response of neurons to different frequencies of sound (5kHz and 10kHz) at various sound intensities (measured in decibels, dB SPL). ● Graph A: At low sound intensities, there's a gradual increase in spikes as intensity increases. ● Graph B: Shows a neuron's response peaking at a particular intensity and then declining, suggesting that the neuron is most responsive at that specific intensity. ● Graph C and D: Show similar responses for two different frequencies, indicating that each neuron has a specific sound intensity and frequency at which it is most responsive. In summary, the image illustrates how neurons encode the properties of stimuli (like orientation of a visual stimulus or the frequency and intensity of sound) into the rate at which they fire. This neural code is fundamental to how the brain interprets sensory information. TEMPORAL CODE: the timing of spikes carries information The image seems to describe the concept of adaptation in sensory systems and how it affects sensory processing. Left Graph: ● It shows the response of cone cells in the retina to different levels of light intensity (measured in log retinal illuminance, which is a scale for measuring light). ● The curves represent the response of the cones to a flash of light after adapting to different background illuminance levels. ● The "flash response" line indicates the response of the cones to a brief flash of light without prior adaptation. ● The "adaptation response" line shows that after adaptation to different background illuminance levels, the cones require a stronger flash to reach the same response level. ● The "95% discrimination range" indicates the range of light intensity over which the cones can distinguish between different levels of brightness after adaptation. ● The "threshold" indicates the minimum intensity of light required for the cones to respond after adaptation. Right Side (A, B, C, D): ● A: Shows control of stimuli and adapting stimuli over time. Adapting stimuli are patterns that the visual system becomes used to after prolonged exposure. ● B: Illustrates a simplified neural circuit with presynaptic neurons responding to a stimulus and generating a combined response. ● C: Depicts a graph of "gain" (which is a measure of the amplification of the response) over time, with the 'near' and 'far' likely referring to the distance of the stimulus or the time since adaptation began. ● D: Shows how the response of neurons to a stimulus (like the orientation of a line) changes over time. The different curves might represent responses at different times after adaptation, showing that the peak response shifts or diminishes after adaptation. In summary, the image is demonstrating how sensory systems, specifically visual and possibly auditory systems, adapt to constant stimuli. This adaptation changes the sensitivity of the sensory system, often reducing its response to a constant or repeated stimulus, which allows the system to be more responsive to changes or new stimuli in the environment. SPATIAL DERIVATIVE- LATERAL INHIBITORY CIRCUIT: LATERAL INHIBITION: removing spatial redundancy- enhancing edges The image provided explains the concept of lateral inhibition and how it contributes to sensory processing, particularly in vision. Lateral Inhibition: This is a process by which neurons suppress the activity of neighboring neurons, resulting in enhanced contrast at edges within the field of perception. This makes edges appear more defined. Left Side: ● The diagrams A1 and B1 show a uniform stimulus applied to the skin or a sensory surface, leading to a uniform response across the sensory receptors. ● Diagrams A2 and B2 introduce the concept of lateral inhibition. When a stimulus is applied, the receptors directly under the stimulus activate strongly, but they also inhibit their neighbors. This inhibition is shown by the downward-pointing arrows. The result is a more peaked frequency response at the center with inhibition on the sides, as shown in the frequency plots. This sharpens the perception of the stimulus. Right Side - Receptive Fields: ● This part of the image illustrates two types of receptive fields for retina ganglion cells: "On-center, Off-surround" and "Off-center, On-surround." ● "On-center, Off-surround" cells respond most strongly when light hits the center of their receptive field and less strongly (or not at all) when light hits the surrounding area. ● "Off-center, On-surround" cells have the opposite response: they are inhibited by light in the center and activated by light in the surrounding area. ● These receptive fields help to process visual information by emphasizing the contrast at edges, which is crucial for recognizing objects and understanding scenes visually. In summary, the image is demonstrating how lateral inhibition in the nervous system sharpens sensory information by reducing redundancy (when too many neurons respond in the same way), thus enhancing the perception of edges and contrasts. This mechanism is key to our ability to detect where one object ends and another begins, both in touch and vision. TEMPORAL DERIVATIVE- INHIBITION + DELAY: DELAY + INHIBITION: removing temporal redundancy- enhancing motion The image describes the concept of how motion is processed in the nervous system, using delay and inhibition to enhance the detection and perception of movement. Delay + Inhibition: ● This is a neural mechanism that processes motion by combining delayed responses with inhibitory signals. It helps the brain to detect the direction of motion and to enhance the perception of moving objects. PD (Preferred Direction) and ND (Null Direction): ● PD refers to the direction in which a neuron is most responsive to motion. When movement occurs in this direction, the neuron's response is the strongest. ● ND is the opposite direction to the PD, where the neuron's response is weakest or inhibited. Left Side (a, c): ● a: This diagram shows two neurons with an inhibitory connection (the flat-ended line with the circle). When motion is detected in the preferred direction (PD), it enhances the signal in one neuron and suppresses the response in the other (ND suppression). ● c: This diagram adds a delay (represented by the "T4" symbol) to the response of one neuron. The combination of delayed response and inhibition can sharpen the perception of motion, making it easier for the brain to distinguish the direction of movement. Right Side (d): ● The graphs show the neuronal responses over time, with the blue line representing the response to the preferred direction of motion and the red line representing the response to the null direction. ● The top graph might represent a basic response without delay and inhibition, showing some differentiation between PD and ND. conceptual framework combining ideas from both neuroethology and computational neuroscience, specifically referencing the work of Nikolaas Tinbergen and David Marr. Neuroethology is the study of the neural basis of natural animal behavior. Tinbergen, one of the founders of this field, proposed that to fully understand a behavior, one must answer four kinds of questions, relating to two objects of explanation: ● Developmental/Historical (Ontogeny): How does a trait develop in an individual over time? This includes descriptions of the trait's changes through different life stages and the mechanisms controlling this development. ● Single Form (Mechanism): What is the structure of a trait and how does it work? This involves detailing the trait's anatomy, physiology, and how it functions to achieve a particular result. ● Evolutionary (Phylogeny): What is the evolutionary history of a trait? This is answered by describing the trait's progression over generations, tracing back through the species' lineage. ● Adaptive Significance: How have variations in the trait interacted with the environment to influence survival and reproduction (fitness)? This looks at how the trait has evolved to help the organism survive and reproduce. Computational Neuroscience (Comp Neuro) involves using mathematical models and theoretical analysis to understand the function and mechanisms of the nervous system. David Marr, a computational neuroscientist, proposed three levels of analysis for understanding information-processing systems: ● Computation: What is the goal of the computation, why is it appropriate, and what is the strategy by which it can be carried out? ● Algorithm: What is the algorithm for the transformation of the input to output? This involves understanding the series of computational steps that transform sensory input into a motor response. ● Mechanism: How can the algorithm be physically realized in the nervous system? This concerns the hardware or biological implementation of the algorithm in the neural structures. In summary, the image is showing how these two approaches can be integrated to provide a comprehensive understanding of how neural mechanisms are involved in behavior. It suggests that by answering Tinbergen's four questions and applying Marr's three levels of analysis, one can gain a full picture of the functioning of a biological system in both biological and computational terms. The image describes a concept in animal behavior known as a "fixed action pattern," which is a series of innate, pre-programmed behaviors that occur in response to specific stimuli. This sequence of actions is typically performed in the same way each time, virtually without variation, and can be seen across individuals of the same species. The fixed action pattern illustrated in the image seems to be for a frog and includes the following behaviors: ● Orienting: The frog adjusts its body position toward the stimulus. This could be in response to the sight or sound of potential prey or a threat. ● Snapping: Once the prey is within reach, the frog snaps or lunges to catch it with its mouth. ● Eating: After successfully capturing the prey, the frog proceeds to eat it. ● Escaping: If the stimulus is a threat rather than prey, the frog may perform an escape behavior to flee from the danger. The illustrations likely depict these stages with: ● a: The frog is in a resting state. ● b: The frog orienting toward the stimulus. ● c: The frog snapping or lunging at the prey. ● d: The frog with its mouth open to eat the prey. ● e: The frog in a state of alertness or preparing to escape. ● f: The frog in the act of escaping, possibly leaping away from a threat. Fixed action patterns are crucial for survival, aiding in foraging, predator avoidance, mating rituals, and other essential behaviors. They are triggered by a specific stimulus and will typically continue to completion once started, even if the original stimulus is removed. how animals respond to certain visual stimuli, known as "sign stimuli" or "releasing stimuli." These are external cues that can trigger a fixed action pattern, an innate behavior in animals. In the context of this slide: Estimating the releasing value of sign stimuli: ● The phrase suggests that the experiment is trying to quantify how different shapes and sizes of visual stimuli trigger responses in toads. Graphs: ● The graphs compare the responses of a "normal toad" and a "toad without thalamus" to different visual stimuli such as squares, vertical bars, horizontal bars, and double bars. The thalamus is a part of the brain that, among other things, processes sensory information. ● The x-axis of each graph represents the size or distance of the stimuli, and the y-axis represents the number of times the toad turns towards or away from the stimuli. ● This setup is designed to measure the toad's instinctual response to stimuli that may represent prey or predators. Interpretation: ● For the normal toad, as the size of the square increases, the toad is more likely to turn toward the stimulus, indicating that it may perceive it as prey. ● With the vertical bar, the toad's response rate increases as the height increases, but only up to a certain point. ● For the horizontal bar, the toad turns toward the stimulus more frequently as the length increases, also up to a point. ● The double bar's distance affects the toad's turning response, potentially mimicking the movement of prey.