Giacomo Benvenuti

• PhD
• PostDoc Position at University of Texas at Austin

I want to claim in an article that our Self is a simple and unstable mental representation and not something transcending the neural computation (e.g. a Soul) as it can appear to us.

What are the best arguments and scientific proofs in support to this claim?

For example: what are the best studies showing that:

- The self is not unique and a single brain can produce multiple Selfs?

> schizophrenic patients experience multiple Selfs (we all have multiple Selfs but in these patients this appears more clearly).

> split brain patients can develop the perception of different Selfs in the two hemispheres (Graziano)

- The agency of the self is an illusion?

> For example, we may be induced to make a decision based on subliminal cues but then we would believe that the decision was made independently by the Self. Anything showing that what appear as a deliberated decision of the Self is not.

- Buddhist monks can eliminate the internal narrative of the Self through meditation and experience it as a flow of mental representations (more direct perception of the Mind).

- Anything similar to the Rubber hand illusion.

Many thanks for your help! :)

I want to train a CNN to segment Ground Glass Opacities (GGO) in Lungs CT-scans.

I would need a dataset with CT scans and corresponding masks indicating for every voxel if it is GGO or not (i.e. the ground truth for the segmentation).

Do you know any dataset like that?

Many thanks for your help!!

Are functional maps in the cortex used by the brain to carry out computations or are they just a byproduct of wiring minimization?

A key element to answer this question is to know if, when neurons from a cortical map project their axons to the dendrite of a downstream neuron, they retain any spatial order proportional to their location in the map.

For example, in the cartoon below, the four neurons from a cortical map (in black) project their axons to a downstream neuron's dendrite (in green). The relative spatial position of the synapses (black circles) is proportional to the relative position of the neuron in the map.

I would be very grateful if you could point me to any relevant paper addressing this question, in particular in the cortex of the primate (e.g. axon tracing experiments).

Thanks!

I am looking for visual stimuli that produce a similar effect than the well know “Dalmatian dog illusion” (see Figure attached).

If you look briefly  at the Dalmatian dog illusion  for the first time, it looks like a pattern of meaningless black and white stains (left panel). However, once a priming cue is briefly presented (the red contour in the right panel) the representation of a Dalmatian dog in a field becomes apparent. Once “seen” this representation will remain apparent even after the priming cue is removed and can't be unseen (look at the left panel again without the red contour).

Do you know other types of visual stimuli containing a hidden object shape that never pops-out before and always pops-out after the transient presentation of a priming stimulus? 

Thank you!

Hi,

I am interested in how subject performance are affected by the spatial frequency of the stimulus in a 2-alternative forced choice orientation discrimination task.

So far, I have found this old paper that is quite relevant in answering to this question <Burr, D. C. & Wijesundra, S.-A. Orientation discrimination depends on spatial frequency. Vision Res. 31, 1449–1452 (1991).> (I have attached one of the main figures). Interestingly, increasing the spatial frequency of the stimulus with respect to an ""optimal"" one, rapidly decreases subjects performance, while they make a pretty good job in discriminating low spatial frequencies..

I would be very grateful if you could suggest me any other relevant paper concerning this issue.

Thanks

Ganglion cells in the retina have relatively small receptive fields (RF) (~1deg or less). If we assume that these neurons work as spatial filters for local contrast, we should expect that spatial frequencies (SF) stimuli lower than ~0.5cyc/deg would be hardly detected by these neurons because the local contrast within their RF is very small. However, signals with SF lower than 0.5cyc/deg are encoded by the retinal output and made accessible to higher level visual areas with wider RF (the neurons in these areas could therefore detect these kind of stimuli).

How are low spatial frequency signals transmitted then?

The simplest way would be that ganglion cells would respond not only to local contrast but also to local luminance. In this way low SF signals would be encoded in the ganglion cells output as a "place code". In other words every ganglion cell output could represent a "pixel" of the un-filtered luminance pattern projected on the retina preserving the low SF information.

Could you please suggest any sort of material addressing this question?

Thank you!

Hi, 

I am looking for a paper/book chapter showing the ganglion cells receptive fields average size as a function of eccentricity in macaque retina

Thanks a lot for your help!

Giac

Hi,

I have a budget of ~20.000$ and I would like to buy a system to record and stimulate (electrical micro-stimulation) from laminar electrode (i.e. Plexon U-probe http://www.plexon.com/products/plexon-u-probe). I am working with behaving macaques. At the moment I am not interested in a perfect single-neuron spike-shape isolation. 

I would be very grateful if you could suggest me any item/company.

Thank you!