A multidimensional neurobiological analysis of the state of play
We assume that the power and effortlessness of playful learning is related to a particular internal state of the subject. We speculate that this “state of play” is the decisive variable that accounts for beneficial effects of playing on cognition and that understanding it will be a fundamental advance in understanding biological learning. In order to investigate the state of play the Brecht group has pioneered neural analysis of heterospecific play (Fig. 4).
Fig. 4: Heterospecific play and neuronal recordings during playful activity
(A) A Human-Rat heterospecific tickling interaction. (B) A Human-Rat chasing hand game. (C) Neuronal recording from a single neuron in the deep layer of the trunk region of rat somatosensory cortex. (A-C) are adapted from Ishiyama & Brecht (2016). This cell responds intensely to tickling and touch, but also is active during the play (chasing hand), when the animal is not touched. The origin of such non-sensory play-evoked activity in sensory cortex is a riddle that BrainPlay will explore.
Mood, social factors and sensory cues shaping play
Playfulness is strongly affected by mental variables such as mood. We do not play, when we are in a bad mood or when we are afraid. The Bavelier and the Brecht groups will manipulate mood in animals and humans and quantify the effects on playfulness and neural activity. Playfulness is strongly affected by social variables both in human and animal behavior. Playing by yourself is less fun than playing together. The gaming industry is spending billions on arranging games, suggesting that fine sensory cues play a decisive role in engaging the playing brain.
Determining neuromodulator regimes and brain activity during play
The analysis neuromodulator regimes associated with the state of play will be a core part of our research. Neuromodulator action is a prime candidate mechanism, which might initiate a “state of play brain state” and initiate the enhanced synaptic plasticity that goes along with it. To quantify neuromodulator action we will measure axonal activity in neuromodulator systems, in which neuromodulator fibres have been transfected with genetically encoded calcium indicators. Alternatively, we will visualize neuromodulators directly with genetically encoded cnipher molecules. We will measure patterns of neural activity during play in humans (the Bavelier group using FMRI) and in animals (the Brecht group using tetrodes).
Understanding the difference between play and reality
A profound behavioral distinction is the differentiation between play and reality. The play context is associated with positive emotional signals such as laughter and in this context play-attacks evoke laughter and non-violent defenses. Shooting somebody is fun in gaming, whereas the same action in reality can cause trauma-disorders. We confront play and reality with different mindsets / brain states. Hence, we need to understand the differences in brain activity associated with play and reality.
The consequences of state of play for synaptic plasticity
We will induce neuromodulator regimes and neural activity patterns as measured in vivo and then prepare brain slices of brain structures involved in play, i.e. the somatosensory cortex. We will then measure synaptic plasticity. We will also explore the pharmacology of the state of play and the effect of drugs such as Ritalin, which is widely applied in hyperactive children, on play-related neural activity.
Power in Numbers