Lecture 04 Part 2 Prey Capture PDF

Lecture 4.2 - Prey capture Continued Sign stimuli and release mechanisms Remember PollEverywhere: eyalgruntman960 Image taken from Fabulous Frogs, Nature series  Showing behavioural relevance in naturalistic conditions r/...

Lecture 4.2 - Prey capture Continued Sign stimuli and release mechanisms Remember PollEverywhere: eyalgruntman960 Image taken from Fabulous Frogs, Nature series  Showing behavioural relevance in naturalistic conditions r/v TOC Time of contact GF- Kir2.1 expressed in GF neuron  Showing behavioural relevance in naturalistic conditions r/v TOC Time of contact GF- Kir2.1 expressed in GF neuron How does the toad’s brain define ‘prey’? And where does it happen? Jörg-Peter Ewert Leader in neuroethological studies of toad releasing mechanisms Neuroethology of Toads (Part 1 of 3; English): Behavioral Responses to Prey Features Neuroethology of Toads (Part 1 of 3; English): Behavioral Responses to Prey Features  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Adapted from Nerve cells and animal behaviour Direction of motion  How does the toad’s brain define ‘prey’? Worm Anti-worm Adapted from Nerve cells and animal behaviour Direction of motion  Two basic processes are required for orienting responses: the identi cation of the stimulus the identi cation of its location in space. Identi cation determines what behaviour will be produced Detection localises the stimulus Together determine the motor response Ewart Scr. American 1974 fi fi fi  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Which stimulus will excite this receptive field the most? - - - - + + - - + + + - - + + - - - - Input from a single photoreceptor + Excitatory - Inhibitory A B C D  Neuronal recordings Ewert Animal Behaviour 1985  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Nerve cells and animal behaviour  Recordings from RGCs in toads Does not match behaviour Nerve cells and animal behaviour  Where is the “worm” feature detected? The Toad’s visual circuit Optic tectum: midbrain region that contains ~7 retinoreceipent nuclei. Thalamus: kind of like the hub of information in the vertebrate brain. Retinotopy Mapping of visual space in the Retina Thalamus Tectum Neuronal response in the visual circuit Neuronal response in the visual circuit Approach Avoidance Electrical stimulation Electrical stimulation Tectal  Electrical stimulation Thalamic/Pretectal Tectal  Evidence for optic tectum - thalamic connections  Evidence for optic tectum - thalamic connections Thalamic neurons (sensitive to motion) respond to point stimulation in Tectum  Evidence for optic tectum - thalamic connections Thalamic neurons (sensitive to motion) respond to point stimulation in Tectum Responses of Type II neurons in Tectum are inhibited by Thalamus stimulation  Evidence for optic tectum - thalamic connections Thalamic neurons (sensitive to motion) respond to point stimulation in Tectum Responses of Type II neurons in Tectum are inhibited by Thalamus stimulation Optic tectum surgically removed - no orienting or avoidance  Evidence for optic tectum - thalamic connections Thalamic neurons (sensitive to motion) respond to point stimulation in Tectum Responses of Type II neurons in Tectum are inhibited by Thalamus stimulation Optic tectum surgically removed - no orienting or avoidance Thalamus removed - more stimuli elicit orienting responses Consequences of Thalamic removal Consequences of Thalamic removal Behavioural Consequences of Thalamic removal Behavioural Consequences of Thalamic removal Electrophysiological Consequences of Thalamic removal Electrophysiological Neuroethology of Toads (Part 2 of 3; English) Feature Detecting Nerve Cells in the Brain Neuroethology of Toads (Part 2 of 3; English) Feature Detecting Nerve Cells in the Brain  Behavioural response as a result of a series of filters Simplified view Inhibitory synapse Ewert, Sci. American, 1974  Behavioural response as a result of a series of filters Simplified view Inhibitory synapse Orient towards Ewert, Sci. American, 1974  Behavioural response as a result of a series of filters Simplified view Inhibitory synapse Do not orient Orient towards Ewert, Sci. American, 1974  Response modulation Bright on dark background evokes stronger orienting response than dark on bright In the winter this preference is reversed Found RGCs that show this reversal In winter, overall prey catching behaviour is reduced Internal models direct dragonfly interception steering Mischiati et al, Nature 2015 Internal models direct dragonfly interception steering Mischiati et al, Nature 2015 Internal models direct dragonfly interception steering Mischiati et al, Nature 2015 Dragonfly Body Dragonfly Head Fly Dragonfly Body Dragonfly Head Fly  Prey-Capture Behaviour in Zebrafish Portugues, Curr. Op. Neuobio, 2009  Prey-Capture Behaviour in Zebrafish Portugues, Curr. Op. Neuobio, 2009 Prey-Capture Behaviour in Zebrafish Introduction What is known What is the question What was found What is the significance Fovea-like Photoreceptor Specializations Underlie Single UV Cone Driven Prey-Capture Behavior in Zebrafish Yoshimatsu, et al., Neuron, 2020 In vision, photoreceptors drive the retinal network through continuous modulations in synaptic release. However, how changes in incoming photon flux lead to changes in the rate of vesicle fusion at the synapse varies dramatically between photoreceptor designs. For example, in the vertebrate retina, the slow rod photoreceptors typically have large outer segments and high-gain intracellular signaling cascades to deliver single-photon sensitivity critical for vision at low light. In contrast, cone photoreceptors are faster and have smaller outer segments and lower-gain cascades to take over where rods saturate. Fovea-like Photoreceptor Specializations Underlie Single UV Cone Driven Prey-Capture Behavior in Zebrafish Yoshimatsu, et al., Neuron, 2020 Clearly, matching the properties of a given photoreceptor type to a specific set of sensory tasks critically underpins vision. However, these visual requirements can differ dramatically across the retinal surface and the corresponding position in visual space.For efficient sampling, even cones of a single type must therefore be functionally tuned depending on their retinal location. Indeed, photoreceptor tuning, even within type, is a fundamental property of vision in both invertebrates and vertebrates. Even primates make use of this trick; foveal cones have longer integration times than their peripheral counterparts, likely to boost their signal to noise ratio, as in the foveal center, retinal ganglion cells (RGCs) do not spatially pool their inputs. Understanding the mechanisms that underlie such functional tuning will be important for understanding how sensory systems can operate in the natural sensory world and how they might have evolved to suit new sensory-ecological niches. Fovea-like Photoreceptor Specializations Underlie Single UV Cone Driven Prey-Capture Behavior in Zebrafish Yoshimatsu, et al., Neuron, 2020 Here, we show that UV cones in the area temporalis (‘‘strike zone’’ [SZ]) of larval zebrafish are selectively tuned to detect microorganisms that these animals feed on (e.g., paramecia) Larval Zebrafish Prey Capture Must Use UV Vision Show prey more prominent in UV channel Larval Zebrafish Prey Capture Must Use UV Vision Test behavioural responses What will be the expected response when we ablate UV cones?  Single UV Cones May Signal the Presence of Prey Use known UV receptor distribution combined with behavioural results UV Cone-Outer Segment Size Varies More Than 10-fold across the Eye To increase photon absorption efficiency where needed most SZ UV Cones Are Light Biased and Have a High Gain and Long Integration Times SyGCaMP6f synaptically tagged fluorescent calcium biosensor mCherry expressed under same promoter non-synaptically localised fluorescent protein SZ UV Cones Are Light Biased and Have a High Gain and Long Integration Times SyGCaMP6f synaptically tagged fluorescent calcium biosensor mCherry expressed under same promoter non-synaptically localised fluorescent protein syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool syGCaMP6f Chasing down a tool Wikipedia  Methods ROI detection - maximise SNR Pre-processing Regions of interest (ROIs), corresponding to individual presynaptic terminals of UV- cones were defined automatically based on local thresholding of the recording stack’s s.d. projection over time (s.d. typically > 25), followed by filtering for size and shape using custom written software on IGOR Pro 6.3 (Wavemetrics). Specifically, only round ROIs (< 150% elongation) of size 2-5 µm2 were further analyzed.  Methods ROI detection - maximise SNR Pre-processing Regions of interest (ROIs), corresponding to individual presynaptic terminals of UV- cones were defined automatically based on local thresholding of the recording stack’s s.d. projection over time (s.d. typically > 25), followed by filtering for size and shape using custom written software on IGOR Pro 6.3 (Wavemetrics). Specifically, only round ROIs (< 150% elongation) of size 2-5 µm2 were further analyzed.  Methods ROI detection - maximise SNR Pre-processing Regions of interest (ROIs), corresponding to individual presynaptic terminals of UV- cones were defined automatically based on local thresholding of the recording stack’s s.d. projection over time (s.d. typically > 25), followed by filtering for size and shape using custom written software on IGOR Pro 6.3 (Wavemetrics). Specifically, only round ROIs (< 150% elongation) of size 2-5 µm2 were further analyzed.  Methods ROI detection - maximise SNR Pre-processing Regions of interest (ROIs), corresponding to individual presynaptic terminals of UV- cones were defined automatically based on local thresholding of the recording stack’s s.d. projection over time (s.d. typically > 25), followed by filtering for size and shape using custom written software on IGOR Pro 6.3 (Wavemetrics). Specifically, only round ROIs (< 150% elongation) of size 2-5 µm2 were further analyzed.  Methods Z-normalization - correct intensity differences Pre-processing Calcium traces for each ROI were extracted and z- normalized based on the time interval 1-6 s at the beginning of recordings prior to presentation of systematic light stimulation. x−μ μ = mean z= σ σ = S.D SZ UV Cones Are Light Biased Increased light sensitivity SZ UV Cones Are Light Biased Increased light sensitivity Exponential decay time constant −t/τ N(t) = N0e N0 = 10 τ=1 τ=2 τ=5 Exponential decay Initial quantity −t/τ N(t) = N0e τ=1 N0 = 10 N0 = 5 N0 = 1 SZ UV Cones are slow to recover from a light flash Larger integration window Slow recovery from light flash Fast recovery from dark flash  Discussion Summary and open questions  Discussion Summary and open questions Behaviourally, zebrafish only respond if the prey moves  Discussion Summary and open questions Behaviourally, zebrafish only respond if the prey moves How can motion be detected by a single receptor?  Discussion Summary and open questions Behaviourally, zebrafish only respond if the prey moves How can motion be detected by a single receptor? Raise the problem of studying zebrafish behaviour in the lab under UV deficient conditions  Discussion Summary and open questions Behaviourally, zebrafish only respond if the prey moves How can motion be detected by a single receptor? Raise the problem of studying zebrafish behaviour in the lab under UV deficient conditions Connection between UV cones activation and the prey-capture circuit  Discussion Summary and open questions Behaviourally, zebrafish only respond if the prey moves How can motion be detected by a single receptor? Raise the problem of studying zebrafish behaviour in the lab under UV deficient conditions Connection between UV cones activation and the prey-capture circuit The region-specific differences in UV cone function present the first pre- processing steps to detect prey and predators already at the visual system’s first synapse  Assigned reading Fovea-like Photoreceptor Specializations Underlie Single UV Cone Driven Prey-Capture Behavior in Zebrafish Yoshimatsu, et al., Neuron, 2020 Will require some web searches