title: A pair of motion-sensitive neurons in the locust encode approaches of a looming object.
abstract: Neurons in the locust visual system encode approaches of looming stimuli and are implicated in production of escape behaviours. The lobula giant movement detector (LGMD) and its postsynaptic partner, the descending contralateral movement detector (DCMD) compute characteristics of expanding edges across the locust eye during a loom and DCMD synapses onto motor elements associated with behaviour. We identified another descending interneuron within the locust ventral nerve cord. We named this neuron the late DCMD (LDCMD) as it responds later during an approach, with the firing rate peaking at about the time of collision. LDCMD produced lower amplitude, broader action potentials that were associated with an afterhyperpolarization, whereas DCMD action potentials showed a brief afterhyperpolarization often followed by an afterdepolarization. Within the mesothoracic ganglion, the primary LDCMD axon located adjacent to the DCMD axon, was thinner and lacked collateral projections to the lateral region of the neuropil. When compared with DCMD, LDCMD fired with fewer spikes during a loom and showed weaker habituation to repeated approaches. Coincidence of LDCMD and DCMD firing increased during object approach. Our findings indicate the presence of an additional motion-sensitive descending neuron in the locust that encodes temporally distinct properties of an approaching object.
authors.affiliation: Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada. jack.gray@usask.ca
authors.forename: John R
authors.initials: JR
authors.lastname: Gray
authors.forename: Eric
authors.initials: E
authors.lastname: Blincow
authors.forename: R Meldrum
authors.initials: RM
authors.lastname: Robertson
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000502:physiology*; D004594:Electrophysiology; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000502:physiology*; D048188:Locusta migratoria / Q000166:cytology / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012680:Sensitivity and Specificity; D011984:Sensory Receptor Cells / Q000166:cytology / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
references.citation: Nature. 2002 Nov 21;420(6913):320-4
references.pmid: 12447440
references.citation: J Comp Physiol A. 1986 Jun;158(6):775-94
references.pmid: 3735165
references.citation: J Neurophysiol. 1996 Mar;75(3):967-85
references.pmid: 8867110
references.citation: J Neurosci. 2007 Sep 12;27(37):10047-59
references.pmid: 17855619
references.citation: J Neurophysiol. 2006 Jun;95(6):3391-400
references.pmid: 16452263
references.citation: Nat Neurosci. 1998 Aug;1(4):296-303
references.pmid: 10195163
references.citation: J Neurosci. 2006 Mar 29;26(13):3454-64
references.pmid: 16571752
references.citation: Behav Brain Res. 2004 Feb 4;149(1):41-8
references.pmid: 14739008
references.citation: J Neurophysiol. 2005 Apr;93(4):2240-53
references.pmid: 15548622
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2009 Mar;195(3):253-64
references.pmid: 19093123
references.citation: Brain Behav Evol. 2001;58(4):218-40
references.pmid: 11964498
references.citation: J Comp Physiol A. 1986 Jun;158(6):765-74
references.pmid: 3735164
references.citation: J Neurophysiol. 2004 Jan;91(1):1-12
references.pmid: 13679397
references.citation: Vision Res. 2006 Jul;46(15):2388-402
references.pmid: 16542703
references.citation: J Comp Physiol A. 2001 Mar;187(2):115-29
references.pmid: 15524000
references.citation: Exp Brain Res. 2006 May;171(1):35-46
references.pmid: 16328256
references.citation: Philos Trans R Soc Lond B Biol Sci. 1978 Dec 5;285(1003):1-59
references.pmid: 34179
references.citation: J Neurosci. 2009 Aug 19;29(33):10234-53
references.pmid: 19692598
references.citation: J Exp Biol. 1984 May;110:143-67
references.pmid: 6086803
references.citation: J Neurosci. 1999 Feb 1;19(3):1122-41
references.pmid: 9920674
references.citation: Brain Behav Evol. 2003;62(4):201-11
references.pmid: 14573994
references.citation: Science. 1995 Nov 10;270(5238):1000-3
references.pmid: 15290817
references.citation: Neuron. 2004 Jul 22;43(2):177-81
references.pmid: 15260954
references.citation: J Comp Neurol. 1983 Mar 20;215(1):33-50
references.pmid: 6853764
references.citation: J Neurosci. 2004 Sep 1;24(35):7690-8
references.pmid: 15342736
references.citation: J Neurophysiol. 2005 Sep;94(3):2150-61
references.pmid: 15928055
references.citation: J Neurosci. 2008 Nov 26;28(48):12591-603
references.pmid: 19036953
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2006 Sep;192(9):915-25
references.pmid: 16676188
references.citation: J Exp Biol. 2005 Jul;208(Pt 13):2515-32
references.pmid: 15961738
references.citation: Exp Brain Res. 2005 Nov;167(1):119-27
references.pmid: 16177831
references.citation: J Neurosci. 2007 Apr 25;27(17):4621-33
references.pmid: 17460075
references.citation: J Neurophysiol. 1997 Feb;77(2):1029-33
references.pmid: 9065867
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2005 Jan;191(1):61-73
references.pmid: 15558287
references.citation: J Neurophysiol. 2006 Mar;95(3):1428-41
references.pmid: 16319198
references.citation: Vis Neurosci. 2006 Mar-Apr;23(2):209-19
references.pmid: 16638173
references.citation: J Exp Biol. 2009 Oct;212(Pt 20):3272-82
references.pmid: 19801432
references.citation: J Exp Biol. 2007 Mar;210(Pt 5):865-80
references.pmid: 17297146
references.citation: J Neurophysiol. 1989 May;61(5):900-17
references.pmid: 2723733
references.citation: Exp Brain Res. 2003 Oct;152(3):409-14
references.pmid: 12904936