Anderson Emotion

Question 1

What did early work in flies by Martin Heisenberg provided evidence of?

Answer 1

Early work in flies by Martin Heisenberg provided evidence that
the neurotransmitter dopamine (DA) was involved in aversive conditioning, while octopamine (the insect equivalent of the neurotransmitter norepinephrine found in vertebrate animals) was involved in reward
learning. By contrast, in mammalian studies, DA was thought to be
involved exclusively in reward learning. This finding was interpreted
by some to mean that the DA neurotransmitter system might encode
opposite valences, in vertebrates versus invertebrates. More recent
studies, however, have shown that DA neurons control both appetitive
and aversive conditioning in flies (although octopamine is also involved
in the former). This is possible because genetically and anatomically
distinct subpopulations of DA neurons are required for the two different
forms of learning.

Question 2

What does the fly DA (dopamine) system teach us?

Answer 2

First, and most important, the emotional
valence of a given US is not encoded merely by the identity of a particular neurotransmitter; DA does not intrinsically encode reward or
pleasure, as commonly believed. Rather, the intrinsic valence of a given
US (shock or sucrose) is determined by which DA neurons it activates,
and whether these DA neurons influence synapses with neurons that
mediate approach or avoidance (Aso et al. 2014); this connectivity is
likely genetically specified and emerges during development as the brain
is wired together. That is, it is not the identity of a chemical in the brain
(for example, dopamine), but the connectivity of the neurons that release
that chemical, which determines behavior. It is, ultimately, the function of
neural circuits that specify what is being contributed to an emotion state.
2) Second, in contrast to a prevailing view, DA does not act as a “sprinkler system” in the brain, acting via so-called volume transmission that
simply douses a swath of neurons in a diffuse manner. Rather, it acts
in a highly spatially compartmentalized manner at specific synapses,
which are determined by the genetic identity and wiring of a particular
class of DA neurons—a mechanism of action more often associated with
classical neurotransmitters such as glutamate, than with neuromodulators like dopamine.
3)Third, the brain’s ability to associate a given odor (CS) with a US of
either a positive or negative valence depends upon (a) the sparse representation of the odor by Kenyon cells (that is, the activity of a relatively
small number of highly odor-specific neurons), and (b) the innervation
by a given CS-responsive Kenyon cell of multiple compartments, where
they make synapses with mushroom body output neurons (MBONs)
that promote either approach or avoidance, in a compartment-specific
manner (figure 7.1, γ2, γ3, γ4, γ5). As shown by elegant work from
Vanessa Ruta and colleagues, these Kenyon cell–MBON synapses can
be either selectively strengthened or weakened, according to which DA
neurons are activated by the US and in which compartment(s) the DA
is released (figure 7.1, A2 versus B2). Interestingly, evidence in mice
indicates that different subpopulations of DA neurons within the ventral tegmental area, traditionally implicated exclusively in reward, can
control either reward or punishment (but not both) (Lammel et al.
2012). So, one general principle that emerges from Drosophila is that
molecules (such as DA) do not encode valence; rather, it is neuronal
connectivity that determines whether a particular stimulus is rewarding
or punishing.

Question 3

Why does the adaptive function of associating valence to a previously neutral stimulus required hardwired brain at least to some degree?

Answer 3

However, in order for such a system to function, the brain has to be “hardwired,” at least to some degree, with innate representations of positive
and negative valence—in this case the different classes of DA neurons that mediate reward versus punishment—which can then be linked to
stimuli whose valence must be learned by experience (Aso et al. 2014).
Without some such innate basis, there would be nothing to ground
valence, nothing upon which learned associations could build. Those innate representations of valence, in turn, would not have been selected in
evolution if they did not afford the species a survival advantage. Natural
selection acted to link sensory circuits that detect specific, ecologically
relevant stimuli, to motor circuits that trigger appropriate responses
(approach or avoidance) through the activation of such valence representations. Whether those same valence systems are involved in learned
avoidance or approach remains to be investigated.

Question 4

What are, according to Anderson the building block of an emotion state?

Answer 4

1) Scalability
2) Valence
3) Persistance
4) Generalization
5) Global coordination
6) Automaticity
7) Social communication

Question 5

Describe scalability as a building block of emotional state:

Answer 5

An emotion state can scale in intensity. Importantly, parametric scaling
can result in discontinuous behaviors, such as the transition from hiding to fleeing
during the approach of a predator (cf. Box 2.3). Intensity is often conceptualized as
arousal, although these two are not the same thing.

Question 6

Describe valence as a building block of emotional stat:

Answer 6

Valence is thought by many psychological theories to be a necessary
feature of emotion experience (or “affect”). It corresponds to the psychological
dimension of pleasantness/unpleasantness, or the stimulus-response dimension
of appetitive vs. aversive. (But, again, these two are not the same thing.)

Question 7

Desribe persistence as a building block of emotional state:

Answer 7

An emotion state outlasts its eliciting stimulus, unlike reflexes, and so
can integrate information over time, and can influence cognition and behavior for
some time. Different emotions have different persistence. Emotions typically persist
for seconds to minutes.

Question 8

Describe generalization as a building block of emotion state:

Answer 8

Emotions can generalize over stimuli and behavior, much of which
depends on learning. This creates something like a “fan-in”/“fan-out” architecture:
many different stimuli link to one emotion state, which in turn causes many different
behaviors, depending on context. Persistence and generalization underlie the
flexibility of emotion states.

Question 9

Describe global coordination as a building block of emotion states:

Answer 9

Related to the property of generalization is the broader feature
that emotion states orchestrate a very dense causal web of effects in the body and
the brain: they engage the whole organism. In this respect, they are once again
differentiated from reflexes.

Question 10

Describe automaticity as a building block of emotions:

Answer 10

Emotions have greater priority over behavioral control than does
volitional deliberation, and it requires effort to regulate them (a property that appears
disproportionate, or even unique, in humans.)

Question 11

Describe social communication as a building block of emotional states:

Answer 11

In good part as a consequence of their priority over
behavioral control, emotion states are pre-adapted to serve as social communicative
signals. They can function as honest signals that predict another animal’s behavior,
a property taken advantage of not only by conspecifics, but also predators and prey.

Question 12

What do experiments showing the looming passing stimulus over flies show about internal states?

Answer 12

Strikingly, flies became progressively more “agitated” (active), measured as an increase in their locomotor activity, as the number of exposures to the threatening visual stimulus (that is, paddle sweeps) was
increased. Moreover, the nature of the behavioral response changed
qualitatively with the number of stimulus exposures: a few passes of
the overhead shadow caused the flies to freeze or increase their walking
speed, but with further successive exposures the flies switched to hopping. Furthermore, after the last of a series of stimuli were delivered,
the flies’ response persisted for tens of seconds to minutes; the insects
continued to hop and walk at high velocity, and then gradually “calmed
down” over a period of many tens of seconds. These observations provide evidence of scalability and persistence in the flies’ response to the
threat stimulus.

Question 13

Explain what is a leaky neural integrator:

Answer 13

An analogy is to a leaky bucket
that is periodically partially filled with water from some intermittent
source; if the amount of water added each time, and/or the frequency of
fills, exceed the leak rate, then the bucket will gradually fill even though
it is leaky (figure 7.2B). Once the filling has stopped, the bucket will
slowly drain. A mathematical model based on this concept produces
similar scalability and persistence as observed in living flies exposed to
repetitive visual threats (figure 7.2C). It is similar to the drift-diffusion
models of decision-making that we introduced in chapter 3 (figure 3.4).

Question 14

What are the differences and similarity between the mammalian and the fly brain:

Answer 14

What do we know about the neural circuitry that underlies the behavioral responses of the flies under these conditions? Do flies have the
equivalent of an amygdala or a hypothalamus in their tiny brain that
integrates the influences of diverse types of aversive stimuli? We do not
yet know. The fly brain (with some notable exceptions) is organized
very differently from the mammalian brain, and generally does not have
central structures that correspond directly with (that is, are homologous
to, in the evolutionary sense) those in our brains. Nevertheless, there
are analogous areas; for example, the mushroom body may be analogous to the hippocampus and/or olfactory cortex, the antennal lobe is
similar to the mammalian olfactory bulb, and the retinae of flies and
mammals display remarkable organizational similarities even though
they evolved independently. Furthermore, the fly brain is made up of
neurons that are, from the molecular standpoint, very similar to those in
our brain. So, while the fly brain may not look superficially like a mammalian brain, it has analogous functional areas, uses the same chemicals
(dopamine, serotonin, acetylcholine, GABA), and its neurons are made
of the same molecules as mammalian neurons. Therefore, the question
is not “does the fly have an amygdala?” The question is whether there
is a common circuit node that processes defensive responses to many
different kinds of threatening stimuli, or whether each type of stimulus
activates its own “private” response pathway

Question 15

What is the pathway that Drosophila has to excape from a looming visual stimulus:

Answer 15

Drosophila have a welldescribed circuit that mediates a rapid, reflexive jump away from a looming visual threat, consisting of a large “descending interneuron,” called the
“giant fiber,” that extends from the central brain to the thoracic ganglia
(the fly’s functional equivalent of the spinal cord). Information travels quickly through electrical synapses (gap junctions) along this pathway
from the fly’s visual system to the motor neurons that activate the jump
muscles, allowing an escape response to occur within a few tens of milliseconds of detection of the threat (this is what makes flies so hard to
swat). As far as we know, this pathway is specific for threatening visual
stimuli and is not, for example, activated by aversive odors. However
there is now evidence of multiple circuits that mediate escape responses
to visual threats in flies (Reyn et al. 2014). Perhaps some of those circuits
also process escape responses to stimuli of different sensory modalities.
This question is likely to be answered in the near term. Another important
question for the future will be to understand how the circuits that mediate
reflexive defense responses are related to those mediating integrative,
emotion-like responses: are these independent, parallel pathways, or do
they reflect state-dependent modification of the same circuit?

Question 16

Explain how long the optogenetic stimulation of P1 neurons in Drosophila can trigger in terms of aggression and courtship:

Answer 16

Importantly, optogenetic stimulation of P1 neurons can trigger a persistent internal state in solitary flies, which promotes aggression once
the fly encounters a conspecific male. This internal state can endure for
tens of minutes in the absence of social contact and may represent a
type of persistent memory of a mating encounter with a female, which
can trigger aggression when a competing male is encountered. These
data suggest that courtship and aggression in Drosophila are not simply
reflexes, but are associated with persistent, internal states

Question 17

When and who established C. elegans as a model organism:

Answer 17

This
animal, which was introduced as a model organism by Nobel laureate
Sydney Brenner in the 1960s and ’70s, has the advantage that it is very
small (~1 mm long), transparent, has a short generation time (three days)
and only 302 neurons composing its entire nervous system. Moreover,
the complete “connectome” (neuronal wiring diagram) of the worm has
been determined by reconstruction of serial electron micrographs; it is
thus far the only adult organism for which a complete connectome has
been established.

Question 18

What is contruct validity?

Answer 18

The ability of a set of measures to yield good evidence about a certain construct is called construct validity. It is a bundle of criteria.

Question 19

What is face validity?

Answer 19

Plausibility of any specific measure to provide evidence for a particular construct. If I have a detailed questionnaire
about your feelings of fear and anxiety, this has a reasonable face
validity as a measure of fear. If I measure fMRI signal in your amygdala, this has questionable face validity as a measure of fear without
a lot more information. If I only measure your blood pressure, this
has poor face validity for fear (by itself, since we can easily think of
cases where blood pressure has no relation to fear).

Question 20

Explain convergent validity:

Answer 20

If we want to have vonvincing evidence for fear, only measuring blood pressure or facial
expression is not a very reliable indicator. However, if we measure blood pressure change, heart rate change, ratings on a fear
questionnaire, facial expression, and f MRI signal, we might be
able to use all of these together to get quite convincing evidence
for fear. If these measures all turn out to be correlated during a
fear state, this would provide convergent validity; whatever they
are measuring, they seem to be measuring the same thing, and if
at least one of them has face validity for measuring fear, then so
do the others when taken together.

Question 21

Describe descriminative validity:

Answer 21

On the other hand, we would
also want these measures to take different values for a different
emotion—the blood pressure, f MRI signal, heart rate, facial expression, and self-report should look different if the person is
feeling, say, happiness rather than fear. Many of these measures,
in isolation, may have very poor discriminative validity. For instance, the typical autonomic measures collected in the lab (heart
rate, skin conductance, etc.) do not clearly distinguish between
different emotions (cf. box 2.1), although there is active research
on whether they might provide discriminative validity if we look
at patterns across multiple measures.

Question 22

Explain how the function of the prefrontal cortex related to emotions has been conceptualized as content-specific appraisal:

Answer 22

each of the different sectors have been associated with emotion appraisals of different sorts: appraisals of exteroceptive sensations, of memories and
imagined future events, of visceral interoceptive signals, and so forth
(see Dixon et al. 2017, for review). This is thought to be achieved by
the widespread connectivity of the prefrontal cortex; each of the
different sectors implements its emotion function by serving as a hub
for inputs from a network of other brain regions. For instance, ventral and anterior parts of the cingulate cortex are thought to be most
closely related to connections with visceral and autonomic components of emotion, whereas lateral prefrontal cortex is thought to be
most closely related to emotion regulation (see box 3.4). While still
quite preliminary, such a scheme will help us eventually to understand the very complex and indirect ways in which emotion states
can be induced and coordinated in humans.

Question 23

Describe the insual both structurally and functionally:

Answer 23

The insula accounts for about 2 percent of our
cortex but cannot be seen at all from looking at a brain from the outside.
It is buried deep within the brain and consists of several distinct regions.
Its functions are still very much under investigation and range from processing of gustatory and visceral signals and pain to processing complex
social emotions (see Nieuwenhuys 2012, for review). The insula accounts for about 2 percent of our
cortex but cannot be seen at all from looking at a brain from the outside.
It is buried deep within the brain and consists of several distinct regions.
Its functions are still very much under investigation and range from processing of gustatory and visceral signals and pain to processing complex
social emotions (see Nieuwenhuys 2012, for review).

Question 24

Sanford_Dickens (2012) Summary Gustatory receptor neuron responds to DEET
and other insect repellents in the yellow-fever mosquito,
Aedes aegypti:

Answer 24

• 3 gustatory receptorneurons were characterized for contact chemoreceptivesensilla on the labella.
• The neuron with the smallest amplitude spike responded to the feeding deterrent quinine as well as DEET.
• Two other neurons with different spikes responded to salt
• The GRN for quinine responded to the broad spectrum of insect repellents DEET, IR3535, picaridin and citronellal.

Question 25

In Sanford_Dickens what electrophysiological responses were recorded from neurons housed within labellar sensilla?

Answer 25

Electrophysiological responses recorded from neurons
housed within labellar sensilla revealed action potentials
from three cells based on amplitude and shape of the spikes
(Fig. 1a–c). A large-amplitude spike responded to increasing
concentrations of sodium chloride, a second large-amplitude
spike with a different shape was reliably activated by sucrose (a feeding stimulant), and a small-amplitude spike was
activated by quinine (a feeding deterrent). Another feeding
deterrent, caffeine, and a feeding stimulant, ATP, did not
elicit neuronal activity at the concentration tested (1 mM)
(data not shown). Responses of the neuron activated by
sodium chloride may have been suppressed by solutions of
experimental chemicals. The small-amplitude spike activated by quinine responded
to the insect repellents DEET, picaridin, citronellal, and
IR3535.

Question 26

Where is the location of uniporous hair sensilla that are gustatory on the mouthparts?

Answer 26

On the labella (paired lobes at the tip of the labium)

Question 27

Explain the reflex opening response of the labella and the labrum in Cs. inornata (Culiseta inornata):

Answer 27

Whem chemosensilla on the outer surface of the labella of female Cs inornata were touched with sugar solution, the labella lobes parted, giving the solution access to the adoral surface of the labella and to the tip of the labrum. While 0.05-1M NaCl triggered the same behavior, higher concentration of salt tended to inhibit the response, the median inhibitory threshold being 0.28M.

Question 28

What is the reaction time of the reflex opening response:

Answer 28

From stimulation of the aboral labellar hairs with sucrose solution contraction of the labellar extension muscles was approximately 40ms.

Question 29

What do olfactory sensilla in mosquito comprise:

Answer 29

Multiporous hair and peg sensilla on the antennal flagella and multiporous peg sensilla on the maxillary palp.

Question 30

Describe short blunt single-walled multiporous hair sensilla (A2):

Answer 30

-Sensitive the esther vapors of short-chain acids, including lactic and butanoic acids.
-Believed to be used to find oviposition sites
-More sensitive to methyl butanoate and other esters 48-72 h after a blood meal than they had been earlier.
-Short chain carboxylic acids tend to be inhibitory to the short hair sensilla of both sexes.

Question 31

Describe short-pointed single-walled multiporous hair sensilla (A2):

Answer 31

• Stimulated by saturated C3 to C7 fatty acids.

Question 32

Describe the response to carbon dioxide in single-walled multiporous peg sensilla:

Answer 32

Possibly, the large phasic responses serve to heighten awareness of sudden concentration changes.When the concentration changes was prolonged e.g. for 5 minutes, a brief phasic responses was followed for the duration of the stimulus by a tonic firing rate.
1) They have an apparent threshold of 0.015-0.03 which is similar to the normal concentration of CO2 in the air (0.02, 0.04).
2)They function like absolute CO2 detectors. They are not desensitized by continuous exposure to ambient concentrations of CO2, and their response is independent of the concentration to which they were previously exposed.
3) Their concentration-response function is steep.
4)They produce phasic changes in firing rate, which in sign and amplitude of the change in CO2 concentration.
5) They are responsive over the range of CO2 concentration expected in the host odour plume near a vertebrate host.

Question 33

Describe the physiology of double-walled mulitporous peg sensilla: (A3 or grooved peg)

Answer 33

-Contains neurons sensitive to short-chain carboxylic acids, the greatest sensitivity shown to lactic acid.

Question 34

Describe the change in sensitivity to lactic acid following a blood meal:

Answer 34

The neuronal sensitivity to lactic acid of gonoactive females is reduced between at least 24 and 96 hours post-blood meal, but recovers so that by 24-48 hours after oviposition is equal to that of unfed females.

Question 35

Mappin_DeGennaro (2023)Summary:

Answer 35

• Modulation in response to 1-octen-3-ol odor exposure occurs in a time and concentration dependent manner in Aedes aegypti.
  -Transcriptomic data revealed that ORs and
  OBPs were transcriptionally responsive whereas other chemosensory gene families
  showed little to no differential expression
  -Alongside chemosensory gene expression
  changes, transcriptomic analysis found that prolonged exposure to 1-octen-3-ol
  modulated xenobiotic response genes, primarily members of the cytochrome P450,
  insect cuticle proteins, and glucuronosyltransferases families.

Question 36

Why are most of OR largely uncharacterized?

Answer 36

This in large part
is due to the highly divergent nature of olfactory receptors which makes sequencebased characterization largely ineffective

Question 37

Explain the transcriptional changes observed by Mappin_DeGennaro (2023)

Answer 37

After 3 hours of exposure, the Or8 levels began to significantly downregulate and
remained suppressed at 6,12, and 24 hours of exposure time relative to their respective
controls. It was also concentration dependent. Taken together,
these assays show that modulation of Or8 occurs in a temporal and concentrationdependent manner in Ae. aegypti when exposed to 1-octen-3-ol and indicates a similar
transcriptional response profile for a given odor exposure as previously reported in Mus
musculus and Drosophila melanogaster

Question 38

What OR were differentially expressed following exposure to 1-octen-3ol in Mappin (2023):

Answer 38

In our global survey of the 97 olfactory receptors expressed at detectable abundance,
24 were downregulated at p >.01 with an average log2 fold-change of -1.75 (Fig 4A). Of
the differentially expressed receptors, Or4, Or8, and Or10 are the best characterized,
with strong responses to sulcatone, 1-octen-3-ol, and indole, respectively. These
compounds have been implicated as major components in oviposition site selection as
well as host-seeking behavior. The remaining receptors are currently orphaned with
unknown response repertoires, however earlier work has shown that Or88, Or107,
Or114, and Or115 are differentially expressed between male and female mosquitoes
and have therefore have been proposed to play important roles in regulating hostseeking behavior.

Question 39

What IR were differentially downreagulated following prolonged exposure to 1-octen-3ol?

Answer 39

Within the Ionotropic Receptors (IRs), a small number of genes were significantly
downregulated, most notably the Ir25a, and IR76b co-receptors (Fig 4C). While Ir25a
and Ir75b have functional roles in acid and amine reception, it is unknown whether any
of the ligand-specific tuning receptors associated with them respond to 1-octen-3-ol45,46

Question 40

Describe the finding of Pulido_Duque (2022) Differentiation of action mechanisms between natural and synthetic repellents through neuronal electroantennogram and proteomic in Aedes aegypti (Diptera: Culicidae)

Answer 40

-Adult females of Ae. aegypti of Rockefeller strain were exposed to specific concentrations of repellent compounds like geranyl acetate, α-bisabolol, nerolidol, and DEET.
-The neuronal effect was measured by electroantennography technique, and the effect of exposure to either DEET or a mixture of natural molecules on protein expression was determined with 2D-PAGE followed by MALDI-TOF-mass spectrometry (MS). Their finding support a masking-like mechanism whereby either simultaneous or sequential exposure to repellents decrease the EAG response to ammonia.
-This approach revealed that DEET affected proteins related to synapses and ATP production, whereas natural-based repellents increased transport, signaling, and detoxification proteins.
-The proteomic and electrophysiology experiments demonstrated that repellent exposure disrupts ionic channel activity and modifies neuronal synapse and energy production processes.

Question 41

What was the EAG recording obtained in responsetovarious repellents in Pulido_Doque?

Answer 41

They look at the electroantennography signals patterns and percentage changes in the post-treatment ammonia signals after applying the molecules. In the first set of experiments, α-bisabolol, DEET, and nerolidol changed in a greater ratio the post-treatment ammonia signal registered in comparison with the pre-treatment EAG signal. The same was true when they used distinct mixtures of the repellents. This treatment indicates that olfactory mosquito capability decreases since the mosquito is exposed to repellent compounds for a more extended period. Therefore, it hinders the electrical signals and ion flux through the neuronal membrane.
This response implies that applying the repellent molecules individually or in mixtures creates an olfactory system inhibition in the mosquito.

Question 42

Why apply DEET at the end of the recording is a good idea?

Answer 42

DEET is generally recognized to be a sticky molecule and contaminate assays. In addition, administration to DEEThas been shown to alter the response to subsequent administration of ammonia compared to the normal signal in Pulido_Doque.

Question 43

What is MALDI-TOF MS:

Answer 43

MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry) is a type of mass spectrometry that is commonly used for the analysis of biological molecules such as proteins, peptides, and lipids.

In this technique, a laser is used to vaporize and ionize a sample that has been mixed with a matrix material, which absorbs the laser energy and transfers it to the sample. The ions produced are accelerated by an electric field and separated according to their mass-to-charge ratio (m/z) in a time-of-flight mass analyzer. The time taken for the ions to reach the detector is measured, and this information is used to determine the mass of the ions.

MALDI-TOF MS is a powerful analytical tool that allows for rapid and accurate identification of proteins and other biomolecules, and it has found applications in various fields such as clinical microbiology, proteomics, and drug discovery. It is also a sensitive technique that requires minimal sample preparation, making it ideal for high-throughput analysis.

Question 44

What does the DEET interactome done by Pulido (2022) reveal?

Answer 44

On the other hand, the DEET interactome displayed interactions between proteins related to signaling, synapse, ATP production, and nitric oxide synthesis processes.

Question 45

What is the result of mixing natural and synthetic repellents?

Answer 45

Pulido (2022): In addition to the above, it could be suggested that by implementing the mixtures with 2–3 metabolites, a synergic effect is obtained and confirmed by the in vivo repellence assays. Similarly, DEET repellent applied at 25% v/v in commercial repellents could exhibit synergic effects using the metabolites used in this research, which might be replaced partially by DEET at 0.5–2% using natural-based repellents with synergic effect. Thereby, suggesting an enhanced effect with natural-based and synthetic repellents simultaneous usage. At the same time, mixing DEET with natural repellents allows reducing in a greater proportion the health threats for humans that implies using DEET. Nonetheless, it is highlighted that EAG experiments are not able to predict inhibition, or receptor activity blockage, and more experiments are needed. However, the repellency time of these molecules, previously tested, might show a clue for ion channels performing over a period.

Question 46

What are the two possible fixative effect that could explain a masking-like mechanism in the liquid and vapor phase?

Answer 46

Pulido (2022): Previous researches36,39 carried out suggest that the repellent effect is evidenced due to changes in physical-chemistry properties such as vapor pressure producing a masking effect. In other words, the liquid phase interactions decrease the attractant compounds’ volatilization. This prevents attractant molecules from approaching the mosquito at the same ratio or in greater amounts (Fig. 10). Other research suggests that repellent and attractant molecules interact in the vapor phase, notwithstanding, it is unlikely since gas molecules evidence weaker interactions due to molecule–molecule distances45. With this statement, it is deduced that changes in attractant molecule properties like volatilization, as well as ion channel activity disturbance, are due to interactions caused by repellent substances.

Question 47

What explanation does Pulido offer for the delayed reduction in ammonia response in EAG experiments following exposure to repellents?

Answer 47

The ionotropic pathway is associated with direct receptor activation once the volatiles are transported from sensilla lymph to neuron membranes30,47. This effect is swift, and the electrical response recorded is immediate. This was evidenced by recording the ammonia signals, in which a high millivolt amplitude value was recorded after ammonia stimulation. In the current research, the repellent molecules showed electrical signals with no more than a few millivolts of amplitude or even null, in the case of α-bisabolol. However, recording the ammonia signal after repellent treatment displayed a decrease in the signal values, likely due to metabotropic pathway participation. The mentioned pathway is slow and dependent on volatile concentration as a wide type of signaling proteins takes part in this process.

Question 48

Could exposure to DEET induce apoptosis?

Answer 48

Pulido: the DEET exposure might produce apoptosis and neurotoxicity due to protein inhibition and upregulation of apoptosis factors like cytochrome c in endothelial, neurons, and hepatocyte cells

Question 49

Explain the link between DEET and higher nitric oxideproduction and neurotransmitter:

Answer 49

Another function in respect of nitric oxide is related to retrograde neurotransmitters56,65. This description is attributed to neurotransmitters synthesized in the postsynaptic neuron and transported towards presynaptic neurons, producing a cyclic effect in signaling transmission. As a result, the information flux towards postsynaptic neurons is delayed. Therefore, this indicates that DEET synthetic repellent’s long-lasting effect is due to the previous process explained. Once the DEET molecule is inside the olfactory system, the neurons start to produce a high amount of nitric oxide. In consequence, other metabolic processes like energy production, signaling, and detoxification slower their activity. This was evidenced since proteins related to signaling and regulation were found as downregulated.

Question 50

Explain the possible effect of DEET on ATP production found in the interactome:

Answer 50

Pulido (2022) Thereby, in contrast with the obtained results in electroantennography and in vivo experiments, a possible reception or action mechanism for synthetic repellents is the ATP and secondary messengers production disturbance and inhibition of proteins involved in information transmission during neuronal synapses. In consequence, the neuron-neuron signal transmission occurs more slowly until DEET is eliminated or degraded by the organism.

Question 51

Following exposure to natural repellents mixture, was oxidative stress exhibited and was the detoxification exhibit similar to that observed following DEET exposure?

Answer 51

Although oxidative stress was not exhibited, the cell eliminates the repellent mixture molecules using detoxification proteins, a more effective pathway due to the chemical bonds present in the natural-based repellents. This indicates that the low repellent effectiveness of natural-based repellents is highly related to elimination pathways such as detoxification proteins, an event not displayed for DEET synthetic repellent. Similarly, with DEET treatment, energy production proteins like ATP synthase β-subunit, malate dehydrogenase, and ubiquinone synthase showed downregulation. In this case, the energy production alteration reduces the activity of other ATP-dependent processes. This might be related to neurotransmitter transport proteins’ down-regulation since a high demand for ATP is needed for proper performance.

Question 52

Do natural and synthetic repellents exhibit the same mechanisms of reception

Answer 52

Afify: No
Pulido: Concerning the reception of repellent compounds, it is likely that either synthetic or natural-based based molecules exhibit almost the same reception mechanism through odorant-binding proteins. However, the mosquito response is different for both repellents. In the case of DEET, synapse efficacy and energy production (ATP) processes showed alterations, reducing the electroantennographic signal due to neuronal activity decrease. Besides, the DEET treatment showed no upregulation of detoxification proteins. Therefore, it is suggested that DEET displays enhanced and prolonged interaction with ion channels and receptors compared to natural-based repellents.
Thus, Protein–protein interaction diagrams demonstrated that DEET and natural-based repellents exhibit different reception/action mechanisms. In the case of DEET, synaptic processes, energy production, and neurotransmitter biosynthesis like nitric oxide were disrupted. On the other hand, vesicle transport, signaling processes important for synapse, and energy production were disrupted when the mosquitoes were exposed to mixture 1 (natural) repellent.

Question 53

Lee_Kim_Montell (2010) Summary: Avoiding DEET through insect gustatory receptors

Answer 53

• DEET suppressed feeding behavior in Drosophila, and this effect was mediated by gustatory receptor neurons (GRNs).
• DEET was potent in suppressing feeding as <0.1% DEET elicited aversive behavior.
• Inhibition of feeding required multiple gustatory receptors (GRs) expressed in inhibitory GRNs. DEET stimulated action potentials in GRNs that respond to aversive compounds, and this response was lost in the Gr32a, Gr33a, and Gr66a mutants.

Question 54

What is the potency of DEET?

Answer 54

the potency of DEET is low as it is used most commonly at levels ranging from 25% to 100% (Lee, Kim, Montell)

Question 55

Is there a gene that is expressed in virtually all GRNs that respond to aversive chemicals via contact chemosensation?

Answer 55

Yes, Gr33a is expressed in virtually all GRNs that respond to aversive chemicals via contact chemosensation (Lee, Kim, Montell) in Drosophila

Question 56

Does DEET interfere with the sensing of sucrose?

Answer 56

In Drosophila, it has been observed that DEET reduced the frequency of sucrose-induced action potential I-type sensilla. Kim, Lee, Montell.

Question 57

Did all the GRs normally recognized to respond to aversive compounds respond to DEET in Drosophila?

Answer 57

No, Kim, Lee and Montell tested various GRs normally known to respond to aversive compounds such as caffeine but not all of them seem to be implicated in DEET sensing when mutant were produced. Gr6a mutant animals, which are also compromised in caffeine avoidance were impaired in DEET repulsion. Even more surprising, the
DGr32a mutant, which displays increased male-to-male courtship behavior (Miyamoto and Amrein, 2008), was also required
for avoiding DEET.

Question 58

What receptors are responsible for contact-mediated repulsion by DEET in Drosophila?

Answer 58

Given the expression of Gr32a in aversive taste GRNs situated
on leg tarsi (Miyamoto and Amrein, 2008), we tested whether the
gustatory sensilla on the forelegs were responsive to DEET using
an alternative assay, the proboscis extension response (PER).
Application of sucrose only to wild-type forelegs resulted in
extension of the proboscis in most animals tested (Figure S2E).
Addition of DEET to the sucrose resulted in a significant
reduction in the PER (Figure S2E). In contrast, application of
sucrose plus DEET to the leg tarsi of DGr32a flies did not reduce
the PER produced by presentation of sucrose alone (Figure S2E).
These results indicate that the leg tarsi and Gr32a contribute to
DEET avoidance.

Question 59

All the GR responding to DEET in Drosophila co-expressed in the same Gustatory Sensory Neurons?

Answer 59

Gr32a RNA was
expressed in more GRNs than the Gr32a-GAL4 and suggests
that it may be coexpressed in all of the same s-type sensilla
that express Gr66a. Our data indicate that at least three GRs are required for
sensing minute concentrations of DEET in GRNs. However, the
minimum number may exceed three since misexpression of
UAS-Gr66a, UAS-Gr33a, and UAS-Gr32a in either water- or
sugar-activated GRNs, using the NP1017-GAL4 or the Gr5aGAL4 respectively did not produce DEET-induced action potentials in these cells (data not shown).

Question 60

Do the GRs repsonding to DEET in Drosophila also respond to other aversive compounds?

Answer 60

Yes, e GR33a is required for producing action potentials induced by a wide array of aversive compounds (Moon
et al., 2009), these results demonstrate that all three GRs that
are necessary for responding to DEET, function broadly in the
detection of noxious compounds.

Question 61

Does DEET cause lethality in Drosophila (is it toxic?)

Answer 61

0.1% DEET did not
cause lethality over the time course examined. However, 0.2%
DEET caused lethality among 50% of the animals after 48 hr
(LT50). The LT50 decreased to 38.4 hr in the presence of 0.4%
DEET.

Question 62

Describe thermosensilla:

Answer 62

Sunken single-walled peg sensilla at the tip of the antennal flagella of female Ae. aegypti contain three sensory neurons. The distal dendrite of one of these neurons is lamellated, which is a characteristic of insect sensory neurons that are temperature sensitive. Of the three neurons that are temperature sensitive, commonly one is cold-sensitive and the other is warm-sensitive, but some sensilla contained only warm-sensitive or cold-sensitive neurons.

Question 63

Might it be that mosquitoes are sensitive to infrared radiation emanated by the host?

Answer 63

No, the result of most behavioral experiments suggest that they do not detect infrared radiation. (Clements, p.47)

Question 64

How is the brain of mosquitoes formed during embryogenesis?

Answer 64

An anterior group of three or four neuromeres fuses to form the supraesophageal ganglion or brain, and to an extent they remain distinguishable as three brain regions (protocrebrum, deutocerebrym and tritrocerebrum). A posterior group of neuromeres associated with the gnathal segments form the subesophageal ganglion.

Question 65

What connects the supra and subesophageal ganglia in the mosquito brain?

Answer 65

By a paired tractsof fibres called the circumesophageal connectives.

Question 66

Describe the development of the optic lobes?

Answer 66

The optic lobes, which contain ganglion centres of the compound eyes, arise separately from the cephalic neuromeres but later fuse with the protocerebrum.

Question 67

Explain the basic structure of the sub and supraesophageal ganglia:

Answer 67

A neural lamella and glial cells form an outer sheath, inside the neural lamella are distributed cell bodies of neurones, forming a layer called the cortex.
Within the cortex is a highlyordered mass of fibre tracts and interweaving dendritic and axonal arborization called the neuropile.

Question 68

Describe the protocerebrum:

Answer 68

Consists of several neuropile masses. It receives and integrates inputs form many sources and it is the region in which the most complex behaviors are initiated.

Question 69

Describe the deutocerebrum:

Answer 69

Contains two paired association centres for the antenna. One pair, the antennal lobes, receive axons from the sensilla of the antenna and max palps. Within the neuropile of each antennal lobe can be distinguished the glomeruli. The other pair, the antennal mechanosensory and motor centers receive axons from the mechanosensory sensilla of the flagella and pedicels and contains efferent fibres serving the antennal muscles.

Question 70

Describe the tritocerebrum:

Answer 70

Smalles part of the brain, has connections with the anterior alimentary canal and labrum.

Question 71

Describe the subesophageal zone:

Answer 71

It receives afferent axons from sensilla on the mouthpart, and it contains motor neurons which innervate the muscles of the mouthparts. It also collaborates with the brain in the initiation and coordination of behaviors such as walking and flight.

Question 72

How is the mosquito head called morphologically?

Answer 72

It is hypognathus: the head is oriented vertically and the mouthparts are directed downwards.

Question 73

Describe the bilobed protocerebrum of Aedes aegypti:

Answer 73

Contains several major masses of neuroil within a peripheral cortex Some of thee masses are paired others are unpaired.

The protocebral lobes are divided into two pairs of lobes: the primary and accessory lobes. They have an unstructured neuropil which surrounds more distinct neuropila masses.

The paired mushroom bodies extend through most of the protocerebrym. Each consists of a large, cup-shaped calyx and a columnar stalk which has two elongate projections, the alpha and beta lobes.

The central complex is the only unpaired neuropil mass in the brain and it is located in the centre of the brain.

The optic tubercles are located anterodorsally in the protocerebrum. During the larval stage the opticlobes which arose separately fuse with protocerebrum.

Question 74

Describe the central complex in mosquitoes:

Answer 74

The central complex is the only unpaired neuropil mass in the brain and it is located in the centre of the brain. It consists of five clearly delineated but interconnected neuropiles.

Question 75

Describe the nervous connection of the antennae of mosquitoes:

Answer 75

In the adult mosquitoe, the turnk of each antennal nerve is composed of two flagellar nerves, which eventually fuse and a large bundle of axons from Johnston organ.

Question 76

How many neurons do flagellar nerves contain in Aedes?

Answer 76

Female: 2060 axons (of each antenna). 5% are from mechanosensory neurons.
Male: 780 38% is mechanosensory neurons.

Question 77

Where do axons from gustatory chemosensilla in the tarsi travel to?

Answer 77

Travel in nerves that enter the fused thoracic ganglia.

Question 78

Describe the findings of Shim et al. (Moon), 2015: The full repertoire of Drosophila gustatory receptors for detecting an aversive compound

Answer 78

• Report that three gustatory receptors, GR8a, GR66a and GR98b function together in the detection of L-canavanine, a plant derived insecticide in Drosophila.
  -Ectopic co-expression of these receptors confers responsiveness to L-canavanine.
  -Misexpression of all three Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound.
  -Co-expression in S2 tissue culture cells induces L-canavanine activated nonselective cation conductance.

Question 79

Why it is likely that a grand theory of cognition (or behavior) that covers everything may not be useful?

Answer 79

brains are the product of millions of years of complex and often idiosyncratic
evolution, not a single grand design. It might be most prudent to
investigate how they function more locally, in specific systems and for
specific topics, and to then abstract fundamental principles that are more
descriptive than full- fledged “theories” of how the brain works.

Question 80

What does the conscious experience of an emotion requires?

Answer 80

First, you need to be conscious (not in a coma); this applies
to humans and animals. Second, you need to have some somatic
content to your conscious experience (how the emotion feels in your
body); this also applies to humans and animals. Third, you need to have
some cognitive content to your conscious experience (for example, a
motivational component, like the feeling that you need to run away
from a threat); this also applies to humans and animals. Note that humans
additionally have the metacognitive knowledge of all these components
(if they reflect on them); we know we are not in a coma, that we
are feeling our body, and that certain things are going on in our minds.