Description
Individual neurons in the primary visual cortex (V1) respond strongly to visual stimuli. The evoked responses of these neurons can be modulated by the behavioural state of the animal, such as increases in arousal and locomotion. This behavioural state-dependent cortical activity is regulated by neuromodulators, including the well-studied cholinergic and noradrenergic systems. Recent work examining the activity of serotonergic neurons in the dorsal raphe nucleus (DRN) during differing behavioural states, has shown an inverse relationship between serotonin (5HT) activity and locomotion. Furthermore, serotonin modulation of V1 neurons reduces the gain of evoked and spontaneous responses, whereas locomotion enhances visually evoked responses in V1 neurons. However, the relationship between serotonergic and locomotive modulation on V1 neurons remains unexamined.
Moreover, serotonergic neurons in the DRN are the main source of forebrain innervation, yet majority of research investigating serotonin activity has been performed in the DRN. Whether the activity of DRN-5HT neurons seen in relation to behavioural states is also reflected in their projection fibres, requires further investigation. Therefore, using a combination of two-photon imaging and calcium indicators, I can acquire activity of 5HT projection fibres in the V1, with high spatial and temporal resolution. Thus, allowing to examine the relationship of serotonergic activity in the V1 during different behavioural states.
Lay Abstract
Neurons in the region of the brain that respond to vision, can be affected by different behaviours of the individual, with examples being alertness and movement. These behaviours can also be affected by chemicals in the brain known as neuromodulators, such as serotonin. Research looking into the relationship between serotonin and behaviour has shown that increases in movement decreases serotonin activity, whilst increasing the activity of neurons that respond to vision. Whether the serotonin and movement systems in the brain interact with each other to achieve this, remains unresearched.
Serotonin releasing neurons are mainly found in a specific region deep in the brain, and project to the entire brain. Therefore, I aim to investigate whether the activity of these neurons, and their projections, respond similarly to movement and vision. To do this, I will use a powerful microscope that will allow me to see these projections in the brain and measure their activity using a molecule that fluoresces when the neuron is activated. This will help me further understand the relationship between the activity of serotonin in certain brain regions during different behaviours.
| Lay Title | Serotonin and movement affect how we perceive the world |
|---|---|
| Role | PhD Student |