Table 1.
Examples of behavioral flexibility described in this review.
| Behavior | Modulator | Direction/type of change | Neuronal target of modulation | Modulators involved |
|---|---|---|---|---|
| Gain changes | ||||
| Vinegar attraction | Hunger | ↑ | Or42b- and Or85b-expressing OSNs | Insulin, sNPF, tachykinin |
| Food-seeking (yeast) | Hunger | ↑ | MB circuits | Dopamine, NPF, sNPF, serotonin, insulin, allatostatin A |
| Sugar attraction | Hunger | ↑ | Sugar-sensing neurons | Dopamine, NPF |
| Bitter aversion | Hunger | ↓ | Bitter-sensing neurons | AKH, sNPF, octopamine |
| Locomotor activity | Hunger | ↑ | Octopaminergic neurons | AKH, insulin |
| Aversion to high salt concentrations | Salt deprivation | ↓ | Downstream of ppk23glut taste neurons | |
| Yeast consumption | Protein deprivation | ↑ | DA-WED cells; widespread changes in SEZ | Dopamine |
| Sugar consumption | Protein deprivation | ↓ | DA-WED cells | Dopamine |
| Yeast consumption (by females) | Mating | ↑ | Putative motor areas of SEZ | Sex peptide, octopamine |
| Salt consumption (by females) | Mating | ↑ | Sex peptide | |
| Courtship of female (by males) | Long-term sexual arousal | ↑ | DANs, P1 neurons | NPF, dopamine |
| Visual pursuit of female (by males) | Short-term sexual arousal | ↑ | LC10a neurons | |
| Sexual receptivity (by females) | Mating | ↓ | pC1 neurons, vpoDNs | Sex peptide |
| Egg-laying (by females) | Mating | ↑ | pC1 neurons, oviDNs | Sex peptide |
| Sugar consumption (by starved flies) | Water deprivation | ↓ | ISNs | AKH |
| Motion sensing* | Walking, flying | ↑ | HS and VS cells | Octopamine |
| Feeding initiation | Walking | ↓ | Mechanosensory interneurons | |
| Walking | Extended proboscis state | ↓ | ||
| Carbon dioxide avoidance | Vinegar | ↓ | DANs, glutamatergic MBONs | Dopamine |
| Sugar attraction | Yeast odor | ↑ | Downstream of Or35a-expressing OSNs | |
| Sugar attraction | Mechanosensation | ↑ | Downstream of hair plate mechanosensory neurons | |
| Sugar attraction | Cool temperatures | ↓ | Downstream of bitter-sensing and mechanosensing neurons | |
| Learned odor response | Reconsolidation (re-exposure to CS-) | ↓ if not properly reconsolidated | Recurrent MB circuits | Dopamine |
| Learned odor response | Extinction (re-exposure to CS+ alone) | ↓ | Recurrent MB circuits | Dopamine |
| Expression of memory for odor-sugar association | Latent inhibition (pre-exposure to CS+) | ↓ | MB circuit | Dopamine |
| Expression of memory for odor-sugar association | Hunger | ↑ | DANs innervating MB | Dopamine, NPF |
| Learned odor association with sugar (in flies starved after training) | Sleep | ↑ | MB circuit | Dopamine, NPF |
| Tuning changes | ||||
| Temperature preference | Hunger | Shift to lower temperatures | AC cells | |
| Salt preference | Mating (in females) | Shift to higher concentrations | ||
| Horizontal motion-sensing* | Walking | Shift to higher frequencies | HS cells | |
| Vertical motion-sensing* | Flying | Tuning broadened toward higher frequencies | VS cells | |
| Switch in behavior | ||||
| Acetic acid taste response | Hunger | Switch from aversion to attraction | Downstream of sugar- and bitter-sensing neurons | |
| Choice between feeding and mating (in males) | Hunger | Choice switches from courtship to feeding | TyrRPLP neurons, P1 neurons | Tyramine |
| Preference for light | Wing clipping or gluing | Switch from attraction to aversion | Dopamine, Octopamine | |
| Response to looming stimulus | Fast walking | More likely to flee than freeze | Downstream of DNp09 neurons | |
| Response to looming stimulus | Flying | Switch from escape to landing | Upstream of DNp07 and DNp10 | Octopamine |
| Carbon dioxide | Fast walking, flying | Switch from avoidance to approach | Octopamine | |
| Takeoff response to looming stimulus | Context (looming speed) | Switch from long to short takeoff mode | LC4 and LPLC2 visual neurons, giant fiber neurons | |
| Steering response toward aversive wind and attractive visual cue | Context (presence of both cues together) | Switch from either aversion/ attraction to turning sequence | ||
| Small visual object | Attractive odor | Switch from avoidance to attraction | Motion-sensitive visual pathway | Octopamine |
| Odor approach or avoidance | Associative learning | Induce approach or avoidance | KC-MBON synapses in MB | Dopamine |
| Learned odor response | Reversal learning | Switch response to CS+ vs. CS- | Recurrent MB circuits | Dopamine |
*These are not technically examples of behavioral modulation, but modulations of sensory processing that may relate to perception. OSNs, olfactory sensory neurons; sNPF, short neuropeptide F; NPF, neuropeptide F; AKH, adipokinetic hormone; MB, mushroom body; DANs, dopaminergic neurons; MBONs, MB output neurons; AC, anterior cells. Up or down arrows represent an increase or decrease in the behavior, respectively.