4.3 Testing the "What" Stream (IFJa Connectivity)

Outline 4.3 Testing the “What” Stream (IFJa Connectivity)

• Overall connectivity

To-Do’s

• check wording
• check sorures

4.3 Testing the “What” Stream (IFJa Connectivity)

To map the precise anatomical pathways of the top-down auditory identity network, the functional connectivity pattern of IFJa was evaluated using single-seed partial correlation. The approach filters out shared variance, showing direct functional coupling of the ventral what-stream to the IFJa.

4.3.1 Temporal-Semantic connections

The partial correlation analysis confirms that the IFJa robustly couples areas in the superior temporal sulcus (e.g. STSdp: left $z=13.94$, $\text{mean}=0.02$; right $z=14.64$, $\text{mean}=0.02$ and STSda: left $z=10.30$, $\text{mean}=0.01$; right $z=16.53$, $\text{mean}=0.02$). Additionally, the left hemisphere integrates STGa and STSva. This direct prefrontal-temporal pathway validates the IFJa as a top-down controller for decoding auditory object identity.

partial correlation:

4.3.2. Prefrontal Language Connections

Within the prefrontal cortex, the IFJa serves as a master hub for the semantic language network. IFJa bilaterally couples with the Broca’s areas 45 (left $z=18.61$, $\text{mean}=0.03$; right $z=17.61$, $\text{mean}=0.03$) and Area 44 (left $z=24.08$, $\text{mean}=0.04$; right $z=23.89$, $\text{mean}=0.04$), along with connections to 47l. Additionally, IFJa couples strongly with the dorsal language hub 55b (left $z=19.18$, $\text{mean}=0.03$; right $z=20.14$, $\text{mean}=0.03$) and FEF (left $z=18.21$, $\text{mean}=0.02$; right $z=18.06$, $\text{mean}=0.02$). This positions IFJa as a main connector and attention hub for the language network.

4.3.3. Gateways and Convergence

Partial correlation reveals bilateral coupling with auditory areas A4 (left $z=8.25$; right $z=8.76$) and A5 (left $z=11.63$; right $z=6.96$), along with right lateralized PBelt connections ($z=4.79$). Additionally, robust multimodal convergence areas like STV (left $z=18.90$; right $z=18.55$) and TPOJ1 are deeply integrated into the IFJa network, functioning as a combination of auditory identity with other sensory modalities. Additionally, PSL couples bilaterally with IFJa in both hemispheres ($mean=0.01$, right: $z=13.06$, left: 9.65)

4.3.4 The Spatial Dissociation

A fundamental topographical dissociation emerges when contrasting IFJa’s full and partial correlation patterns, especially in the parietal lobe. The results show a strong correlation pattern across the motor and spatial areas (55b, OP4, MT/MST), but dissecting the connectivity pattern with partial correlation reveals instead sparse, language-driven coupling. This confirms the IFJ’s role as a prefrontal hub for semantic, temporal pathways, segregating it from the spatial “where”-stream.

full correlation:

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Notes & Scrapbook

Hier Dinge abladen, die noch keinen Platz im Text haben, damit der Schreibfluss nicht stoppt.

Data IFJa (single seed) part correlation

Data IFJa (single seed) full correlation

see also

4.0 Results
4.1 Global Connectivity Patterns
4.2 Testing the “Where” Stream (FEF Connectivity)
4.4 Resolving Ambiguities