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Repetition suppression in macaque superior temporal sulcus (STS) for dynamic visual stimuli depicting hand actions.

Pradeep V. Kuravi1*, Vittorio Caggiano2, Martin Giese3 and Rufin Vogels1*
  • 1 K U Leuven, Laboratorium Neuro-en Psychofysiologie, Belgium
  • 2 Massachusetts Institute of Technology, United States
  • 3 Hertie Institute for Clinical Brain Research, Germany

An attenuated neuronal response to the repeated presentations of static stimuli (repetition suppression) is a well-known characteristic of many neurons in macaque inferior temporal cortex. Recently, Caggiano et al (2013) showed that the spiking activity of mirror neurons in area F5 did not show repetition suppression when movies of hand actions were repeated. To determine whether the absence of repetition suppression in mirror neurons was due to the brain area (F5 versus temporal cortex) or stimulus characteristics (dynamic stimuli of actions versus static stimuli), we measured the responses of macaque superior temporal sulcus (STS) neurons to repetitions of the same movies as previously used in F5. We measured local field potentials (LFP), multi-unit (MUA) and single unit (SUA) activity in 2 monkeys in the dorsal bank of the rostral STS. Monkey fMRI studies showed that this region is activated by hand actions (Nelissen et al., 2011). Throughout the recordings, the monkeys were performing a fixation task during which either the same action (duration = 1360 msec) was repeated (interstimulus interval: 640 msec) or two different actions were presented sequentially. The actions consisted of grasping an object, touching an object, and mimicking of the grasping action without an object present. All actions were presented under two mirror symmetric viewpoints with the hand starting either in the contra- or ipsilateral lower visual field. Static presentations of the hand or object were also presented in interleaved trials. In each monkey, the SUA to the reaching phase of the action showed repetition suppression when the hand action was initiated in the contra-lateral visual field. The median reduction in raw peak firing rate with repetition was 9% for those conditions and neurons for which the response peaked during reaching (N= 80; p <0.05). No repetition suppression was observed at the later phase of the action for which neurons responded less. The repetition suppression for the contralateral reaching phase was also observed for the MUA, with 93 / 121 condition-neuron combinations showing a smaller peak firing rate to the repeated action (p = 3.6 * 10-10). Time-frequency analysis of the LFPs showed a marked reduction in power when repeating the action. This repetition suppression was prominent during the reaching phase and significant in each animal for spectral frequencies above 50 Hz. Adaptation effects at lower frequencies were inconsistent across the monkeys. In conclusion, contrary to F5, repetition suppression is present for dynamic hand actions in rostral STS, suggesting differences between visual and premotor cortex in the adaptation to dynamic hand actions.

References

- Caggiano V, Pomper JK, Fleischer F, Fogassi L, Giese M, Their P (2013). Mirror neurons in monkey area F5 do not adapt to the observation of repeated actions. Nature communication 10.1038/ncomms2419.

- Nelissen K, Borra E, Gerbella M, Rozzi S, Luppino G, Vanduffel W (2011). Action observation circuits in the macaque monkey cortex. Journal of neuroscience. 31(10):3743-3756.

Keywords: repetition suppression, Neuronal firing rate, inferior temporal cortex, Rhesus Monkey, hand motion stimuli

Conference: Belgian Brain Council 2014 MODULATING THE BRAIN: FACTS, FICTION, FUTURE, Ghent, Belgium, 4 Oct - 4 Oct, 2014.

Presentation Type: Poster Presentation

Topic: Basic Neuroscience

Citation: Kuravi PV, Caggiano V, Giese M and Vogels R (2014). Repetition suppression in macaque superior temporal sulcus (STS) for dynamic visual stimuli depicting hand actions.. Conference Abstract: Belgian Brain Council 2014 MODULATING THE BRAIN: FACTS, FICTION, FUTURE. doi: 10.3389/conf.fnhum.2014.214.00025

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Received: 26 Jun 2014; Published Online: 30 Jun 2014.

* Correspondence:
Mr. Pradeep V Kuravi, K U Leuven, Laboratorium Neuro-en Psychofysiologie, Leuven, Belgium, pradeep.kuravi@med.kuleuven.be
Prof. Rufin Vogels, K U Leuven, Laboratorium Neuro-en Psychofysiologie, Leuven, Belgium, rufin.vogels@kuleuven.be