4.4 Resolving Ambiguities

Outline 4.4 Resolving Ambiguities

• Core Argument dieses Kapitels definieren

To-Do’s

• check wording
• check sources

4.4 Resolving Ambiguities

During the analysis, some areas as A4 or PSL seem to have an ambiguous connectivity pattern. This chapter will dissolve ambiguities found in the literature and results of the RSFC analysis.

4.4.1 A4 and A5

Areas A4 and A5 exhibit connectivity profiles that position them as early gateways for the auditory pathways targeting robustly IFJa (A4: left z = 8.25, right z = 8.76; A5: left z = 11.63, right z = 6.96). Partial Correlation shows only in left hemisphere low coupling from A4 with FEF ($z=4.06$, $mean=0.01$). This connectivity pattern aligns with the Glasser parcellation

As noted in the ROI selection (Section 3.2.5), A4 and A5 were

  provisionally placed in the dorsal pathway pending empirical resolution.

   The present data provides that resolution…

According to Rolls et al. (2023) - Cerebral Cortex A4 and A5 could form a dorsal language-relates stream with PBelt and Broca’s area 44. A4 and A5 both exhibit effective connectivity to MT and MST (Rolls et al. (2023) - Cerebral Cortex), which connect further to parietal regions, therefore, according to Rolls, A4 and A5 might form a language related dorsal stream.
Glasser

A4

In Glasser et al. (2016) - Nature A4 is defined as functionally different from its neighbors:

• in contrast to STV, A4 shows a weaker connectivity to visual area PCV
• • RSFC between A4, PBelt, 7AL, 8Am, 7PC (Rolls et al. (2023) - Cerebral Cortex)
• • to BA44, 44 (Rolls et al. (2023) - Cerebral Cortex)
• We identified auditory association cortex as a region mainly on the superior temporal gyrus and within the superior temporal sulcus that is activated in the LANGUAGE STORY, MATH, and STORY-MATH contrasts. It is strongly functionally connected with the inferior frontal gyrus, including areas 44, 45, and 47l. This auditory region likely becomes progressively less purely auditory and more multi-modal as one progresses inferiorly, anteriorly, and posteriorly (away from early auditory cortex, e.g. Main Text Figure 3). Indeed, functional connectivity with early auditory cortex progressively decreases along those directions. This region includes eight areas that we identify as A4, A5, STSdp, STSda, STSvp, STSva, STGa, and TA2.

A5
Rolls (2023) treats A5 as an ambiguous
Rolls 2022 puts A5 in group 3 with STGa, STS, da, STSdp, PSL, STV and TPOJ1. Those regions show connectivity to Brocas areas 44 and 45, to TGv and TGd
also EC to MT/MST

• laut rolls ambiguous

• bei mir klar IFJa

• aber vielleicht language und deshalb kein FEF

• A5 vs STGa

  • more myelin (Glasser et al. (2016) - Nature)
  • differs in RSFC (Glasser et al. (2016) - Nature)
  • differs in RSFC (Glasser et al. (2016) - Nature)

Connectivity

• effective connectivity to MT and MST (Rolls et al. (2023) - Cerebral Cortex)
  • which connect to superior parietal regions forming a Auditory Where-Stream (Dorsal) involved in actions in space. (Rolls et al. (2023) - Cerebral Cortex)
• unscertain whether where or what pathway. (Rolls et al. (2023) - Cerebral Cortex)
  • but connectivity to MT/MST might indicate rather a being part of Auditory Where-Stream (Dorsal) (Rolls et al. (2023) - Cerebral Cortex)

Projections

• to BA44, 44 (Rolls et al. (2023) - Cerebral Cortex)

PFC targets

• connectivity with IFJa IFJa and IFSp
  • implicates short-term working memory for the Auditory What-Stream (Ventral) (Rolls et al. (2023) - Cerebral Cortex)

4.4.2 PSL the division

PSL presents a fundamental paradox within the auditory dual-stream framework. On one hand, Rolls et al. (2023) - Cerebral Cortex classify PSL as part of the auditory ventral what-stream, based on its effective connectivity along with TPOJ1, STV, TGv, TGd and PGi, as language-related semantic regions connecting to Broca’s area 45. On the other hand, Dureux (2024) demonstrates that PSL remained entirely unresponsive to all tested auditory stimuli - including vocallizations, non-vocal sounds and white noise.
In our analysis, PSL presents a complex, asymmetric connectivity profile. It is integrated into the left ventral “what” stream (L_IFJa: $z=9.65$, $mean=0.01$, single seed), but simultaneously forms a strong right-lateralized connection with the right spatial “where” stream (R_FEF: $z=21.37$, $mean=0.03$, single seed).
Our partial correlation data resolves this apparent contradiction. The massive prefrontal connectivity, combined with Rolls et al. (2023) - Cerebral Cortex’s language-related integration and acoustic silence (Dureux (2024)), suggests that PSL does not process low-level auditory input. Instead, it might function as a high-level convergence zone similar to TPOJ, which calls Rolls (2022) - NeuroImage a multimodal convergence region. PSL might link semantic identity (via left IFJa) with spatial attention (via right FEF) at an abstract, modality-independent level.

4.4.3 STV

[DRAFT — bitte prüfen und in eigene Stimme übersetzen]

The Superior Temporal Visual Area (STV) presents a nominative paradox: despite its name implying visual processing, it is consistently recruited in both auditory streams and classified by Rolls et al. (2023) - Cerebral Cortex as part of the language-related ventral network alongside PSL and TPOJ1 — with strong effective connectivity directed towards Broca’s areas 44 and 45.

Our partial correlation data reveals significant bilateral coupling of STV with both prefrontal seeds — assessed in separate single-seed analyses. In the IFJa single-seed analysis (section 4.3), STV couples directly with IFJa (left $z=18.90$, $\text{mean}=0.02$; right $z=18.55$, $\text{mean}=0.02$), after partialling out FEF and all other ROIs. Conversely, in the FEF single-seed analysis (section 4.2.4), STV couples directly with FEF (left $z=19.50$, $\text{mean}=0.02$; right $z=17.82$, $\text{mean}=0.02$), after partialling out IFJa and all other ROIs. In both cases, the coupling is direct — not mediated through the other seed — indicating that STV maintains independent functional connections with each controller.

This dual connectivity resolves the apparent paradox. STV does not process unimodal visual input in isolation; rather, it functions as a supramodal integration zone at the temporal–parietal boundary, binding auditory identity signals from the ventral stream with spatial and cross-modal information from the dorsal stream. This interpretation aligns with its anatomical position at the posterior superior temporal sulcus, a region consistently implicated in audiovisual and multimodal convergence (Rolls et al. (2023) - Cerebral Cortex, Rolls (2022) - NeuroImage). Its strong IFJa coupling suggests a primary affiliation with the “what” stream, while its weaker FEF connection positions it as a candidate gateway through which semantic identity representations gain access to spatial attentional modulation.

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Notes & Scrapbook

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

see also

4.0 Results
4.1 Global Connectivity Patterns
4.2 Testing the “Where” Stream (FEF Connectivity)
4.3 Testing the “What” Stream (IFJa Connectivity)