Parcellation Guide

Functional areas of the Sensorimotor Network

 

The sensorimotor network includes functional areas in the primary motor cortex, cingulate cortex, premotor cortex, and the supplementary motor area. It also includes the primary and secondary sensory cortices in the parietal lobe.

While neuroscience has known the locations of motor planning regions since the late 19th century, using recent connectomic data from the Human Connectome Project has led to a more anatomically specific understanding of the brain’s motor and somatic functional areas.

SENSORIMOTOR_COR

ᐅ  Summary

Area 1: part of primary sensory area. Along with area 3b, is involved in processing tactile stimuli. Specifically, area 1 represents the secondary point of activation following the reception of a tactile sensation activating area 3b. Area 1 also functions along with area 2 in receiving information related to bilateral tactile stimulation of the hands.

ᐅ  Where is it?

Area 1 is found on the visible surface of the postcentral gyrus. It forms the largest bulk of the postcentral operculum. It continues up to the midline, but does not fold onto the medial face.

ᐅ  What are its borders?

Area 1 borders area 3b along its anterior convexity border, and area 2 along its posterior border. Its inferior end borders OP4 and PFop. Its superior end is surrounded by areas 3b and 2.

ᐅ What are its borders?

Area 1 demonstrates functional connectivity to areas 2, 3a in the sensory strip, area 4 in the motor strip, areas SCEF, 6mp, 6d, and 6v in the premotor regions, areas 24dd, 24dv, 5m, and 5L in the middle cingulate regions, areas 43, OP1, OP2-3, OP4, IG, PFcm, and FOP2 in the superior insula opercular regions, areas A4, A5, RI, 52, MBelt, LBelt, PBelt, TA2, and STV in the lower opercula and Heschl's gyrus regions, areas LIPv, VIP, IPS1, 7AL and 7PC, in the parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, areas V6, V6a, and V7 in the dorsal visual stream areas, area FFC of the ventral visual stream, and areas PH, TPOJ1, FST, V4t, MST, MT, and LO3 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 1 is structurally connected to the pyramidal tracts, thalamocortical projections, and the parietal lobe. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Thalamocortical tracts run medial to pyramidal projections to enter the thalamus. Parietal projections are portions of the SLF and connect to PFm. Local short association fibers are connected with 1, 2, 3a, 3b, 4 and 6. White matter tracts of area 1 in the right hemisphere have less consistent projections to surrounding parcellations.

ᐅ What are its white matter connections?

Area 1, along with area 3b, is involved in processing tactile stimuli. Specifically, area 1 represents the secondary point of activation following the reception of a tactile sensation activating area 3b. Area 1 also functions along with area 2 in receiving information related to bilateral tactile stimulation of the hands.

 

1_a

A: lateral-medial

 

1_b

B: anterior-posterior

 

1_c

C: superior-inferior

 

1_dti

DTI image

ᐅ  Summary

Area 2: part of primary sensory area. Known to be involved in the processing of deep tissue sensations. Additionally, area 2 is activated in bilateral tactile stimulation of the hands.

ᐅ  Where is it?

Area 2 is makes up most of the anterior bank of the post-central sulcus. It neither folds onto the midline nor reaches the Sylvian fissure.

ᐅ  What are its borders?

Area 2 borders area 1 as its main anterior border. It makes a small anterior contact with area 3b superiorly. Inferiorly, it has a small border with PFop. Its superior border is mainly made up of area 5l. It borders area 7AL posterosuperiorly. Its long posterior border contacts (from superior to inferior): area 7PC, AIP, and PFt.

ᐅ What are its borders?

Area 2 demonstrates functional connectivity to areas 1, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas SCEF, FEF, 6a, 6mp, 6d, and 6v in the premotor regions, areas 24dd, 24dv p32prime, 5mv, 5m, and 5L in the middle cingulate regions, areas 43, OP1, OP2-3, OP4, IG, PFcm, FOP1, and FOP2 in the superior insula opercular regions, areas PoI1, PoI2, A4, A5, RI, 52, A1, MBelt, LBelt, PBelt, TA2, and STV in the lower opercula and Heschl's gyrus regions, areas AIP, VIP, LIPv, PFop, PFt, IPS1, 7AL, and 7PC, in the parietal lobe, areas V2 and V3 in the medial occipital lobe, areas V6 in the dorsal visual stream areas, area FFC of the ventral visual stream, and areas PH TPOJ1, TPOJ2, FST, V4t, MST, MT, and LO3 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 2 is structurally connected to the pyramidal tracts, thalamocortical projections, contralateral hemisphere and the parietal lobe. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Thalamocortical tracts run medial to pyramidal projections to enter the thalamus. Contralateral connections course through the body of the corpus callosum to parcellation 7am. Parietal projections are portions of the SLF and connect to PFm, IP1 and IP2. Local short association fibers are connected with 6r, 7Pc, AIP, 1, 3a, 3b and 4.

ᐅ What are its white matter connections?

Area 2 is known to be involved in the processing of deep tissue sensations. Additionally, area 2 is activated in bilateral tactile stimulation of the hands.

 

2_a

A: lateral-medial

 

2_b

B: anterior-posterior

 

2_c

C: superior-inferior

 

2_dti

DTI image

ᐅ  Summary

Area 3a: Part of primary sensory area. along with area 2, is known to receive sensory information from deep body tissues. This area is also involved in the burning, chronic pain sensations that originate from deep somatic tissue. This suggests area 3a has relevance in many of the chronic pain ailments observed in the clinical setting. Area 3a is also involved in proprioception.

ᐅ  Where is it?

Area 3a is found in the depth of the central sulcus. It follows this sulcus up to the midline but does not fold onto the medial face of the hemisphere.

ᐅ  What are its borders?

Area 3a borders area 2 along its long anterior border and area 3b along its posterior border. Inferiorly, it borders area 23 and superiorly it borders area 5m. It has a small area of posterior contact with area 2 near the Sylvian fissure.

ᐅ What are its borders?

Area 3a demonstrates functional connectivity areas 1, 2, 4, 3b in the motor and sensory strips, areas SCEF, 55b, 6d, 6v, and 6mp in the premotor regions, areas 24dd, 24dv, 5m, and 5L in the middle cingulate regions, areas 43, OP1, OP2-3, OP4, IG, and FOP2 in the superior insula opercular regions, areas PoI2, 52, A4, A5, RI, A1, MBelt, PBelt, LBelt, TA2, and STV in the lower opercula and Heschl's gyrus regions, areas PFcm, 7AL, and 7PC, in the parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, areas V6, V6a, V3a, and V7 in the dorsal visual stream areas, area FFC of the ventral visual stream, and areas PH, TPOJ1, FST, V4t, MST, MT, and LO3 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 3a is structurally connected to the pyramidal tracts, thalamocortical projections, contralateral hemisphere and the parietal lobe. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Thalamocortical tracts run medial to pyramidal projections to enter the thalamus. Contralateral connections course through the body of the corpus callosum to parcellations 3b and 4. Parietal projections are portions of the SLF and connect to PFm. Local short association fibers are connected with 4, 3b, 2, 1, and 6v.

ᐅ What are its white matter connections?

Area 3a, along with area 2, is known to receive sensory information from deep body tissues. This area is also involved in the burning, chronic pain sensations that originate from deep somatic tissue. This suggests area 3a has relevance in many of the chronic pain ailments observed in the clinical setting. Area 3a is also involved in proprioception.

 

3a_a

A: lateral-medial

 

3a_b

B: anterior-posterior

 

3a_c

C: superior-inferior

 

3a_dti

DTI image

ᐅ  Summary

Area 3b: Part of primary sensory area. involved in the sensation of tactile stimuli. Specifically, this area represents the initial regions of activation in tactile stimulation, followed by the activation of area 1. Area 3b also functions in the localization of sensation on the skin and distinguishing the features of that sensation. For example, activation of area 3b offers finger-specific information with respect to a tactile stimulus as opposed to areas 1 and 2 which cover a larger, more generalized receptive field. Additionally, area 3b receives exclusive activation in the reception of nociceptive stimuli.

ᐅ  Where is it?

Area 3b is makes up the entire anterior bank of the postcentral gyrus. It does not reach the Sylvian fissure or fold onto the medial hemispheric face.

ᐅ  What are its borders?

Area 3b borders area 3a along its anterior convexity border, and area 2 along its long posterior convexity border. Its inferior end ends superior to the Sylvian fissure and areas 3a and 2 contact each other inferior to this, forming area 3b's inferior border. Superomedially, it contacts areas 5m and 5l. It also makes a small border with area 2 posterosuperiorly.

ᐅ What are its borders?

Area 3b demonstrates functional connectivity to areas 1, 2, 3a in the sensory strip, area 4 in the motor strip, areas SCEF, 6d, and 6v in the premotor regions, areas 24dd, 24dv, 5m, and 5L in the middle cingulate regions, areas 43, OP1, OP2-3, OP4, IG, PFcm, and FOP2 in the superior insula opercular regions, areas A4, A5, RI, 52, A1, MBelt, LBelt, PBelt, TA2, and STV in the lower opercula and Heschl's gyrus regions, areas 7AL and 7PC, in the parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, areas V6, V6a, V3a, and V7 in the dorsal visual stream areas, area FFC of the ventral visual stream, and areas TPOJ1, FST, V4t, MST, MT, and LO3 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 3b is structurally connected to the pyramidal tracts, thalamocortical projections, contralateral hemisphere and the parietal lobe. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Thalamocortical tracts run medial to pyramidal projections to enter the thalamus. Contralateral connections course through the body of the corpus callosum to parcellations 3a, 3b and 4. Parietal projections are portions of the SLF and connect with IP1 and IP2. Local short association fibers are connected with 1, 2, 3a and 4.

ᐅ What are its white matter connections?

Area 3b is involved in the sensation of tactile stimuli. Specifically, this area represents the initial region of activation in tactile stimulation, followed by the activation of area 1. Area 3b also functions in the localization of sensation on the skin and distinguishing the features of that sensation. For example, activation of area 3b offers finger-specific information with respect to a tactile stimulus as opposed to areas 1 and 2 which cover a larger, more generalized receptive field. Additionally, area 3b receives exclusive activation in the reception of nociceptive stimuli.

 

3b_a

A: lateral-medial

 

3b_b

B: anterior-posterior

 

3b_c

C: superior-inferior

 

3b_dti

DTI image

ᐅ  Summary

Area 4: part of primary motor cortex. Known to produce fine motor movements of the distal forearm and fingers. Additionally, it functions in giving a muscle its tone and producing forceful muscle contractions. It is also thought to play a role in visual learning of motor-based skills in the early stages of life.

ᐅ  Where is it?

Area 4 is found in the precentral gyrus. It is predominantly located on the posterior half of the gyrus, making up the anterior bank of the central sulcus. It widens medially to fill a larger proportion of the paracentral lobule, which is the leg motor region. The somatotopic organization of this area is well known, however it is worth noting that there is an area dedicated to the eye which is adjacent to the frontal eye fields.

ᐅ  What are its borders?

Area 4 borders area 3a along its posterior convexity border. Its inferior end contains area 43. At its superior end, on the medial surface (i.e. the paracentral lobule), it borders area 5m posteriorly, area 44dd inferiorly, and area 6mp anteriorly. Its long anterior border contacts several areas, including (from superior to inferior): area 6d, FEF, area 55b, PEF, and area 6v, most of which contact it on the anterior half of the precentral gyrus.

ᐅ What are its borders?

Area 4 demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, areas SCEF, 55b, 6d, 6v, and 6mp in the premotor regions, areas 24dd, 24dv, 5m, and 5L in the middle cingulate regions, areas 43, OP1, OP2-3, OP4, IG, and FOP2 in the superior insula opercular regions, areas A4, A5, RI, PBelt, LBelt, TA2, and STV in the lower opercula and Heschl's gyrus regions, areas VIP, IPS1, LIPv and 7PC, in the parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, areas V6, V6a, V3a, and V7 in the dorsal visual stream areas, area FFC of the ventral visual stream, and areas PH, TPOJ1, FST, V4t, MT, and LO3 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 4 is structurally connected to pyramidal tracts, the contralateral hemisphere and the parietal lobule. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Contralateral connections course through the body of the corpus callosum to parcellations 4, 6ma and 6mp. Parietal projections are portions of the SLF and connect to PFm. Local short association fibers are connected with 3a, 3b, 2, 1, and 6v.

ᐅ What are its white matter connections?

Area 4 is known to produce fine motor movements of the distal forearm and fingers. Additionally, it functions in giving a muscle its tone and producing forceful muscle contractions. It is also thought to play a role in visual learning of motor-based skills in the early stages of life.

 

4_a

A: lateral-medial

 

4_b

B: anterior-posterior

 

4_c

C: superior-inferior

 

4_dti

DTI image

ᐅ  Summary

Area 5l (5 lateral): part of paracentral lobule areas. Functions in goal-oriented hand movement, specifically movement that is not based on visual cues. Recent studies suggest that area 5l, along with area 5m, is also activated in tasks that require complex coordination between the right and left hand.

ᐅ  Where is it?

Area 5l (5 lateral) is located on posterior superior most portion of the postcentral gyrus. It is located at the angle where the gyrus folds onto the interhemispheric surface.

ᐅ  What are its borders?

Area 5l borders area 2 inferiorly, and area 3b anteroinferiorly. It borders area 7AM posteriorly and area 7AL posteroinferiorly. Area 5mv is its inferior neighbor and area 5m is its anterior neighbor.

ᐅ What are its borders?

Area 5l demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas 6mp and 6d, in the premotor regions, areas 5m, and 5mv in the middle cingulate regions, areas OP1 in the superior insula opercular regions, area A4 in the lower opercula and Heschl's gyrus regions, and areas 7AL and 7PC, in the parietal lobe.

ᐅ What are its functional connections?

Area 5l is structurally connected to pyramidal tracts and the contralateral hemisphere. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Contralateral connections course through the body of the corpus callosum to parcellations 5m, 5l and 5mv. Local short association fibers connect with 5m and 5mv.

ᐅ What are its white matter connections?

Area 5l functions in goal-oriented hand movement, specifically movement that is not based on visual cues. Recent studies suggest that area 5l, along with area 5m, is also activated in tasks that require complex coordination between the right and left hand.

 

5l_a

A: lateral-medial

 

5l_b

B: anterior-posterior

 

5l_c

C: superior-inferior

 

5l_dti

DTI image

ᐅ  Summary

Area 5m (5 medial): part of paracentral lobule areas. Integrates somatosensory and visuomotor information. It participates in activities such as reaching or pointing, especially when these movements are based on somatosensory information, as opposed to visual stimuli. Recent studies also suggest that area 5m, along with area 5l, is activated when performing tasks that require complex coordination between the right and left hand.

ᐅ  Where is it?

Area 5m (5 medial) is located in the posterior superior portion of the medial face of the paracentral lobule.

ᐅ  What are its borders?

Area 5m borders area 4 anteriorly and area 5l posteriorly. It also has a small anterior border with area 24dd. Its inferior border is area 5mv. It borders areas 3a and 3b on its lateral/superior surface.

ᐅ What are its borders?

Area 5m demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas 6mp and 6d, in the premotor regions, area 5L in the middle cingulate regions, and area A4 in the lower opercula and Heschl's gyrus regions.

ᐅ What are its functional connections?

Area 5m is structurally connected to the contralateral hemisphere. Contralateral connections course through the body of the corpus callosum to parcellations 4 and 5l. No local short association fibers can be visualized.

ᐅ What are its white matter connections?

Area 5m integrates somatosensory and visuomotor information. It participates in activities such as reaching or pointing, especially when these movements are based on somatosensory information, as opposed to visual stimuli. Recent studies also suggest that area 5m, along with area 5l, is activated when performing tasks that require complex coordination between the right and left hand.

 

5m_a

A: lateral-medial

 

5m_b

B: anterior-posterior

 

5m_c

C: superior-inferior

 

5m_dti

DTI image

ᐅ  Summary

Area 6d (6 dorsal): part of the premotor areas. Shows less activation compared to area FEF during gambling tasks, in social interaction settings, and during object feature comparison. Compared to area 6a, area 6d shows less activation in solving math problems and in social interaction settings.

ᐅ  Where is it?

Area 6d (6 dorsal) is located on the anterosuperior portion of the precentral gyrus, just inferior to its junction with the SFG. It makes up the posterior bank of the adjacent precentral sulcus.

ᐅ  What are its borders?

Area 6d borders area 6mp superiorly and FEF inferiorly. Area 4 is its posterior border and area 6a forms its anterior border across the precentral sulcus.

ᐅ What are its borders?

Area 6d demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas 6a, 6mp and 6v in the premotor regions, areas 5L and 24dd in the middle cingulate regions, areas FOP2, OP4, OP1, A4 and PBelt in the insula opercula regions, areas 7PC, 7AL, and PFt in the parietal lobe, and area FST in the lateral occipital lobe.

ᐅ What are its functional connections?

Area 6d is structurally connected to the pyramidal tracts and contralateral hemisphere. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Contralateral connections course through the body of the corpus callosum to end at 6mp, FEF and 55b. Local short association fibers connect with 4, 3a, 3b, 6a, FEF, i6-8, 8Av, 3a, 3b, 6ma and 6d.

ᐅ What are its white matter connections?

Area 6d was distinguished from adjacent areas of the cortex based on differences in myelin thickness and functional connectivity. Area 6d shows less activation compared to area FEF during gambling tasks, in social interaction settings, and during object feature comparison. Compared to area 6a, area 6d shows less activation in solving math problems and in social interaction settings.

 

6d_a

A: lateral-medial

 

6d_b

B: anterior-posterior

 

6d_c

C: superior-inferior

 

6d_dti

DTI image

ᐅ  Summary

Area 6mp (6 medial posterior): part of the supplementary motor regions areas. shows less activation compared to 6ma when an individual was given a visual instruction cue and when moving their feet. Compared to 6d, 6mp shows greater deactivation when listening to a story or solving a math problem. Lastly, compared to area 6a, area 6mp shows less activation in social interaction settings.

ᐅ  Where is it?

Area 6mp (6 medial posterior) makes up the area where the SFG joins with the precentral gyrus. It makes up the medial bank of the SFG at this junction, as well as spilling onto the superior surface of the posterior most SFG and the anterosuperior portion of the precentral gyrus. It also makes up the most posterior superior portion of the superior bank of the superior frontal sulcus.

ᐅ  What are its borders?

Area 6mp borders area 4 posteriorly, area 6d laterally, area 6a anterolaterally, areas 6ma and SCEF anteriorly, and area 24dd inferiorly on the medial surface.

ᐅ What are its borders?

Area 6mp demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas SCEF, 6a, 6ma, and 6d in the premotor regions, areas 24dd, 24dv, p32prime, 5mv, and 5L in the middle cingulate regions, areas 43, OP1, OP4, PFcm, FOP1, and FOP2 in the superior insula opercular regions, areas A4, RI, and PBelt in the lower opercula and Heschl’s gyrus regions, areas PFop, PFt, IPS1, 7AL, and 7PC, in the parietal lobe, areas, and area FST in the lateral occipital lobe.

ᐅ What are its functional connections?

Area 6mp is structurally connected to the pyramidal tracts and contralateral hemisphere. Connections to pyramidal tracts descend through the posterior limb of the internal capsule and cerebral peduncle to the brainstem. Contralateral connections course through the body of the corpus callosum to 6ma, 6mp and FEF. Local short association fibers connect with 24dd, 6a and 6d.

ᐅ What are its white matter connections?

Area 6mp was subdivided from adjacent parcellations due to differences in myelin thickness and functional activity. Specifically, area 6mp shows less activation compared to 6ma when an individual was given a visual instruction cue and when moving their feet. Compared to 6d, 6mp shows greater deactivation when listening to a story or solving a math problem. Lastly, compared to area 6a, area 6mp shows less activation in social interaction settings.

 

6mp_a

A: lateral-medial

 

6mp_b

B: anterior-posterior

 

6mp_c

C: superior-inferior

 

6mp_dti

DTI image

ᐅ  Summary

Area 6v (6 ventral): part of the premotor areas. Comprises what is classically known as the premotor cortex. It has many different functions. The ventral premotor area is known to be active in the control of hand movements that occur while manipulating objects (eg grasping and lifting objects), and the dorsal premotor area is involved in performing specific motor tasks based on visual cues.

ᐅ  Where is it?

Area 6v (6 ventral) makes up the antero-inferior one-third of the precentral gyrus. It only minimally forms the posterior bank of the precentral sulcus, which is primarily formed by area 6r.

ᐅ  What are its borders?

Area 6v borders area 55b superiorly and area 43 inferiorly. Area 4 is its posterior border and areas 6r and PEF form its anterior border.

ᐅ What are its borders?

Area 6v is connected to areas 1, 2, 3a, 3b in the sensory strip, area 4 in the motor strip areas SCEF, FEF PEF, 6ma, 6mp, 6r, 6d, and 6v in the premotor regions, areas 24dd and p32prime in the middle cingulate regions, areas 43, OP4, OP2-3, OP1, PFcm, FOP1 FOP2, FOP3, and FOP4 in the superior insula opercular regions, areas A4, PBelt, RI, and PoI2 in the lower opercula and Heschl's gyrus regions, areas AIP, MIP, VIP, LIPv, PFop, PFt, 7AL, and 7PC, in the lateral parietal lobe, areas V3a, V3b, V6, V6a, and V7 of the dorsal visual stream, areas FFC of the ventral visual stream, and areas PH, TPOJ2, MST, and FST of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 6v is structurally connected to the contralateral hemisphere and the superior longitudinal fasciculus. Contralateral connections course through the body of the corpus callosum to FEF. Connections with the superior longitudinal fasciculus connect 6v to inferior parietal lobe parcellations PHT, FST, PH and PF. Local short association fibers connect with 4, 6r, PEF, 43, 3a and 3b.

ᐅ What are its white matter connections?

Area 6v comprises what is classically known as the premotor cortex. It has many different functions. The ventral premotor area is known to be active in the control of hand movements that occur while manipulating objects (e.g. grasping and lifting objects), and the dorsal premotor area is involved in performing specific motor tasks based on visual cues.

 

6v_a

A: lateral-medial

 

6v_b

B: anterior-posterior

 

6v_c

C: superior-inferior

 

6v_dti

DTI image

ᐅ  Summary

Area 24dd (24 dorsal-dorsal): part of anterior cingulate regions. Has been implicated in complex motor planning and regulation of muscles in the lower limb and lower trunk through coordination with the supplemental motor area and connections to the spinal cord.

ᐅ  Where is it?

Area 24dd (24 dorsal-dorsal) is located in the anterior inferior paracentral lobule straddling into the upper bank of the cingulate sulcus.

ᐅ  What are its borders?

Area 24dd has as its superior boundaries, from anterior to posterior, SCEF, area 6mp, area 4, and area 5m. It continues into the marginal ramus of the cingulate sulcus, bordering area 5mv posteriorly and inferiorly. Its inferior border includes area 24dv and area 23c.

ᐅ What are its borders?

Area 24dd demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, areas 6mp, 6v, and 6d, in the premotor regions, areas 5mv, SCEF, and 24dv in the middle cingulate regions, areas OP4, OP1, and 43 in the superior opercular areas, areas PBelt and A4 in the lower opercula and Heschl's gyrus regions, area 7PC in the parietal lobe, area V2 in the primary visual areas, and areas FST and MST in the lateral occipital lobe.

ᐅ What are its functional connections?

Area 24dd is structurally connected to the contralateral hemisphere. Fibers from 24dd project through the body of the corpus callosum to end at 24dd, 4, 5mv, 23c, SCEF, 6mp and 24dv. Local short association bundles connect with 4, 5mv, 23c, SCEF and 6mp.

ᐅ What are its white matter connections?

Area 24dd has been implicated in complex motor planning and regulation of muscles in the lower limb and lower trunk through coordination with the supplemental motor area and connections to the spinal cord.

 

24dd_a

A: lateral-medial

 

24dd_b

B: anterior-posterior

 

24dd_c

C: superior-inferior

 

24dd_dti

DTI image

ᐅ  Summary

Area 24dv (24 dorsal-ventral): part of anterior cingulate regions. Has been implicated in complex motor planning and regulation of muscles in the upper limb and upper trunk muscles through coordination with the supplemental motor area and connections to the spinal cord.

ᐅ  Where is it?

Area 24dv (24 dorsal-ventral) is located in the anterior inferior paracentral lobule and straddles into the upper bank of the cingulate sulcus.

ᐅ  What are its borders?

Area 24dv has 24dd as its superior border, p32pr and a small portion of SCEF as its anterior border, p24pr as its inferior border, and 24dd as its posterior border. Note that this area causes the 24 areas and the 32 areas to be slightly out of sync in their anterior to posterior alignment.

ᐅ What are its borders?

Area 24dv demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, area 6mp in the premotor regions, areas 5mv, SCEF, a24prime, p24prime, p32prime, 23c, and 24dd in the middle cingulate regions, areas FOP1, FOP3, FOP4, PFcm, OP4, OP1, and 43 in the superior opercular areas, areas PoI1 and 52 in the lower opercula and Heschl's gyrus regions, areas 7AL, 7PC, and PFop in the parietal lobe, and area V2 in the primary visual areas.

ᐅ What are its functional connections?

Area 24dv is structurally connected to the contralateral hemisphere, marginal branch of the cingulate sulcus and precuneus. Contralateral connections course through the body of the corpus callosum to 24dv, SCEF and p32pr. Fibers from 24dv project posterior to the marginal branch of the cingulate sulcus and precuneus areas to 23c and 31a. Local short association fibers connect with SCEF, p32pr and 24dv.

ᐅ What are its white matter connections?

Area 24dv has been implicated in complex motor planning and regulation of muscles in the upper limb and upper trunk muscles through coordination with the supplemental motor area and connections to the spinal cord.

 

24dv_a

A: lateral-medial

 

24dv_b

B: anterior-posterior

 

24dv_c

C: superior-inferior

 

24dv_dti

DTI image

ᐅ  Summary

Area 52: part of parietal apex regions. An understudied region on the insular opercular cortex. No specific functional capabilities have been discussed in the literature for this regions.

ᐅ  Where is it?

Area 52 is located in the posterior edge of the lower limb of the circular sulcus of the insula. It lies between Heschl's gyrus and the long gyri of the insula.

ᐅ  What are its borders?

Area 52 borders MBelt laterally, and PoI1 and IG medially. Its posterosuperior limit ends in OP2-3, and its anteroinferior limit ends in PI.

ᐅ What are its borders?

Area 52 demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, areas 24dv, p32prime, a24prime, 23c and 5mv in the middle cingulate areas, areas SCEF and FEF in the premotor regions, area 46 in the lateral frontal lobe, areas 43, IG, FOP1, FOP3, FOP4, OP4, OP1, PFcm in the superior insula opercular regions, areas MI, PoI1, PoI2, LBelt, PBelt, MBelt, A1, TA2, PI, A4, and STV in the lower opercula area and Heschl's gyrus regions, area PHT in the temporal lobe, areas DVT, PF, and PFop in the parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, area V6 and V3a of the dorsal visual stream, and area TPOJ2 of the lateral occipital lobe.

ᐅ What are its functional connections?

Area 52 is structurally connected to local parcellations. In some individuals fibers connect to parietal and occipital lobes, however, these tracts are inconsistent. Local short association bundles connect anteriorly to PoI1 and PoI2, and to surrounding parcellations A1, Ig, MBelt, OP1, OP2-3, PoI1, PoI2 and TA2.

ᐅ What are its white matter connections?

Area 52 is an understudied region on the insular-opercular cortex. No specific functional capabilities have been discussed in the literature for this region. However, area 52 was parcellated from MBelt in the Human Connectome Project study based on differences in activity on fMRI during arithmetic and auditory story tasks.

 

52_a

A: lateral-medial

 

52_b

B: anterior-posterior

 

52_c

C: superior-inferior

 

52_dti

DTI image

ᐅ  Summary

Area A1 (primary auditory cortex): part of parietal apex regions. Receives input from the ventral division of the medial geniculate complex and contains a tonotopic map which then interprets input received from the cochlea.

ᐅ  Where is it?

Area A1 (Primary auditory cortex) is located in superior central portion of Heschl's gyrus.

ᐅ  What are its borders?

Area A1 is largely surrounded by the MBelt and Lbelt. Its deep surface borders the RI area.

ᐅ What are its borders?

Area A1 demonstrates functional connectivity to areas 2, 3a, and 3b in the sensory strip, areas 43, PFcm, and OP4 in the superior opercular region, areas A4, MBelt, PBelt, LBelt, RI, and 52 in the inferior insula opercular region, and areas V1, V2, V3, and V4 in the medial occipital lobe.

ᐅ What are its functional connections?

Area A1 is structurally connected to the parietal lobe, occipital lobe, inferior frontal gyrus and local parcellations. Parietal connections are likely portions of the middle longitudinal fasciculus. Fibers from A1 project posterior to parital parcellations LIPv and 7PC, and to occipital parcellations V3B, V3CD and V4. Fibers that project anteriorly to the inferior frontal gyrus connect to 44. Local short association bundles connect with 52, LBelt, MBelt, PBelt and MI.

ᐅ What are its white matter connections?

Area A1, also known as the primary auditory cortex, receives input from the ventral division of the medial geniculate complex and contains a tonotopic map which then interprets input received from the cochlea.

 

A1_a

A: lateral-medial

 

A1_b

B: anterior-posterior

 

A1_c

C: superior-inferior

 

A1_dti

DTI image

ᐅ  Summary

Area A4 (auditory area 4): part of temporal hypotenuse regions. Parcellated from the auditory association cortex. There is evidence that this regions of the brain processes perceptual and conceptual acoustic sounds.

ᐅ  Where is it?

Area A4 (auditory area 4) is on the superior face of the posterior half of the STG. It occupies this portion of the gyrus posterior to its junction with Heschl's gyrus.

ᐅ  What are its borders?

Area A4 borders A5 laterally and PBelt medially. Its posterior borders are with PSL and STV. Its anterior border is with MBelt and TA2.

ᐅ What are its borders?

Area A4 demonstrates functional connectivity to areas 1, 2,3a and 3b in the sensory strip, area 4 in the motor strip, areas SCEF, FEF, 6mp, and 6v in the premotor regions, areas 5m, 5l, and 24dd in the medial frontal lobe, areas 43, PFcm, OP4, OP2-3 and OP1 in the superior insula opercular regions, areas STV, 52, RI, TA2, PI, MI, PBelt, MBelt, LBelt, A1, A5, PoI1, and PoI2 in the lower opercula and Heschl's gyrus regions, areas 7PC and PFop, in the lateral parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, areas V6, V6a, V7, and V3a in the dorsal visual stream area, areas V8, FFC, VVC, and PIT in the ventral visual stream regions, and areas TPOJ1, TPOJ2, LO1, LO3, MT, MST, PH, and FST in the lateral occipital lobe

ᐅ What are its functional connections?

Area A4 is structurally connected to the arcuate/SLF and middle longitudinal fasciculus. Arcuate/SLF fibers wrap around the termination of the sylvian fissure from A4 to inferior frontal gyrus parcellations 45 and FOP5. The middle longitudinal fasciculus projects posterior from A4 to run just lateral to the lateral ventricle ending at occipital and parietal lobe parcellations V2, V3, V6, V7, MIP, LIPd, LIPv and IP1. Local short association bundles connect with A5, PFop, RI, STV, LBelt, MBelt, PBelt and PFcm

ᐅ What are its white matter connections?

Area A4 is a newly described area of the brain parcellated from the auditory association cortex. There is evidence that this region of the brain processes perceptual and conceptual acoustic sounds. Area A4 was differentiated from area TA2 based on differences in fMRI activity during arithmetic and auditory story tasks.

 

A4_a

A: lateral-medial

 

A4_b

B: anterior-posterior

 

A4_c

C: superior-inferior

 

A4_dti

DTI image

ᐅ  Summary

Area Ig (insula granular cortex): part of parietal apex regions. has been shown to be activated in response to cutaneous stimuli. This area has also been shown to respond to different stimuli related to taste and is thought to be the gustatory center of the brain.

ᐅ  Where is it?

Area Ig (insula granular cortex) is at the superior portion of the long insular gyri. It is the posterior superior most part of the insula proper.

ᐅ  What are its borders?

Area Ig borders PoI1 and PoI2 inferiorly, FOP2 anteriorly, OP2-3 and a bit of OP4 superiorly and RI and area 52 posteriorly.

ᐅ What are its borders?

Area Ig demonstrates functional connectivity to areas 1, 3a, 3b of the sensory strip, area 4 of the motor strip, and areas FOP2, OP2-3, OP4, 42, 52 and PoI2 in the insula opercular region.

ᐅ What are its functional connections?

Area Ig is structurally connected to local parcellations and MI. From Ig there are anterior fibers that project to MI. Local short association bundles are connected with A1, MBelt, FOP2, OP1, OP2-3, OP4, PoI2 and PoI1.

ᐅ What are its white matter connections?

Area Ig has been shown to be activated in response to cutaneous stimuli. This area has also been shown to respond to different stimuli related to taste and is thought to be the gustatory center of the brain.

 

Ig_a

A: lateral-medial

 

Ig_b

B: anterior-posterior

 

Ig_c

C: superior-inferior

 

Ig_dti

DTI image

ᐅ  Summary

Area LBelt (lateral belt): part of parietal apex regions. Parcellated from the auditory cortex.

ᐅ  Where is it?

Area LBelt (Lateral belt) is located on the lateral surface of Heschl's Gyrus.

ᐅ  What are its borders?

Area LBelt borders A1 and part of Mbelt medially and Pbelt laterally. Its deep surface abuts RI.

ᐅ What are its borders?

Area LBelt demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, areas 43, PFcm, OP1, and OP4 in the superior opercular region, areas PoI1, PoI2, A1, A4, A5, Mbelt,, MBelt, STV, Ta2, PI, RI, and 52 in the inferior insula opercular region, and areas V1, V2, V3, and V4 in the medial occipital lobe.

ᐅ What are its functional connections?

Area LBelt is structurally connected to the arcuate/SLF. Arcuate/SLF fibers wrap around the termination of the sylvain fissure ending at inferior frontal gyrus and insula parcellations 44 and MI. Local short association bundles, include the temporal terminations of the arcuate/SLF to parcellations MBelt, PBelt, A4 and A5. White matter tracts from LBelt in the right hemisphere have more insula projections from the arcuate/SLF.

ᐅ What are its white matter connections?

Area LBelt is a newly described area of the brain parcellated from the auditory cortex. Area LBelt was differentiated from area PBelt and RI based on differences in activity on fMRI during arithmetic, auditory story, and social interaction tasks.

 

LBelt_a

A: lateral-medial

 

LBelt_b

B: anterior-posterior

 

LBelt_c

C: superior-inferior

 

LBelt_dti

DTI image

ᐅ  Summary

Area MBelt (medial belt): part of parietal apex regions. Parcellated from the auditory cortex.

ᐅ  Where is it?

Area MBelt (Medial belt) runs on the medial surfaces of Heschl's gyrus.

ᐅ  What are its borders?

Area MBelt borders A1 on its lateral surface and IG and area 52 on its medial surface. Its superior edge borders RI and its inferior edge borders TA2.

ᐅ What are its borders?

Area MBelt demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, areas 43, PFcm, and OP4 in the superior opercular region, areas PoI1, A1, A4, Pbelt, LBelt, Ta2, PI, RI, and 52 in the inferior insula opercular region, and areas V1, V2, V3, and V4 in the medial occipital lobe.

ᐅ What are its functional connections?

Area MBelt is structurally connected with the middle longitudinal fasciculus. Fibers from the middle longitudinal fasciculus project posterior just lateral to the lateral ventricle to occipital and parietal lobes to end at parcellations V3, V3A, V6, V6A, IPS1 and DVT. The majority of short association bundles connect anterior to A4, TA2, STGa, and locally to PBelt and LBelt.

ᐅ What are its white matter connections?

Area MBelt is a newly described area of the brain parcellated from the auditory cortex. Area MBelt was differentiated from area 52 based on differences in activity on fMRI during arithmetic and auditory story tasks. In addition, MBelt was differentiated from PBelt based on differences in activity on fMRI during arithmetic, auditory story, and object recognition tasks.

 

MBelt_a

A: lateral-medial

 

MBelt_b

B: anterior-posterior

 

MBelt_c

C: superior-inferior

 

MBelt_dti

DTI image

ᐅ  Summary

Area OP1 (operculum 1): part of parietal apex regions and posterior opercular cortex. This area likely contributes to somatosensory processing tasks such as recognition of pain, tactile attention, and working memory. It has also been suggested that area OP1 plays an important role in bimanual task activities.

ᐅ  Where is it?

Area OP1 (Operculum 1) is located on the undersurface of the anterior portion of the superior supramarginal gyrus.

ᐅ  What are its borders?

Area OP1 is small and diamond shaped. Its anterior superior border is OP4. Its anterior inferior border is OP2-3. Its posterior superior border is PFcm. Its posterior inferior border is RI.

ᐅ What are its borders?

Area OP1 demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, area 4 in the motor strip, areas 6d, 6v, and 6mp in the premotor areas, areas 5L, 24dd, 24dv, and SCEF in the medial cingulate areas, areas 43, OP4, OP2-3, FOP2, and PFcm, in the superior insula opercular regions, areas PBelt, A4, 52, and RI in the lower opercula and Heschl's gyrus regions, areas 7AL and PFop in the lateral parietal lobe, and areas MST and FST in the lateral occipital lobe.

ᐅ What are its functional connections?

Area OP1 is structurally connected to local parcellations, the anterior insula and the temporal pole. Fibers from OP1 project anteriorly to the anterior insula ending at parcellation MI and continue to the temporal pole at parcellation TGd. Local short association bundles connect with PFcm, RI, OP2-3, OP4 and 43. There are less consistent connections from OP1 to the temporal pole.

ᐅ What are its white matter connections?

Area OP1 is also part of the posterior opercular cortex. This area likely contributes to somatosensory processing tasks such as recognition of pain, tactile attention and working memory. It has also been suggested that area OP1 plays an important role in bimanual task activities. Area OP1 was differentiated from OP2-3 based on decreased levels of fMRI activity during working memory tasks.

 

OP1_a

A: lateral-medial

 

OP1_b

B: anterior-posterior

 

OP1_c

C: superior-inferior

 

OP1_dti

DTI image

ᐅ  Summary

Area OP2-3 (operculum part 2 and 3): part of parietal apex regions. Originating in the posterior operculum. There is evidence that the posterior operculum plays a role in receiving input from somatosensory stimuli.

ᐅ  Where is it?

Area OP2-3 (Operculum part 2 and 3) is a small area located in the posterior superior most part of the circular sulcus of the insula.

ᐅ  What are its borders?

Area OP2-3 borders OP 4 and OP1 superiorly, RI posteriorly and IG anterosuperiorly.

ᐅ What are its borders?

Area OP2-3 demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, area 4 in the motor strip, areas IG, 43, OP4, OP1, and PFcm, in the superior insula opercular regions, areas PBelt, A4, and RI in the lower opercula and Heschl’s gyrus regions, area PFop in the lateral parietal lobe, areas V2 and V3 in the medial occipital lobe, and areas V6, andV3a of the dorsal visual stream.

ᐅ What are its functional connections?

Area OP2-3 is structurally connected to anterior insula areas and local parcellations. Anterior projections from OP2-3 end at anterior insula parcellations MI, AAIC and PoI2. Local short association bundles connect with A1, Ig, LBelt, MBelt and OP4.

ᐅ What are its white matter connections?

Area OP2-3 is a newly described region originating in the posterior operculum. These two areas are located within the Sylvian fissure and are so closely intertwined that it is difficult to distinguish between them. There is evidence that the posterior operculum plays a role in receiving input from somatosensory stimuli. Area OP2-3 was separated from areas Ig and OP1 based on differences in activity on fMRI during motor and arithmetic tasks.

 

OP2-3_a

A: lateral-medial

 

OP2-3_b

B: anterior-posterior

 

OP2-3_c

C: superior-inferior

 

OP2-3_dti

DTI image

ᐅ  Summary

Area OP4 (operculum 4): part of parietal apex regions and posterior opercular cortex. This regions is involved in processes required for sensory motor functions, such as integrating sensory responses into motor actions, and is crucial in tangible object recognition and manipulation.

ᐅ  Where is it?

Area OP4 (Operculum 4) is located in the posterior portion of the subcentral gyrus, which is the opercular portion of the sensory and motor cortices. It folds onto the inferior surface to face the Sylvian Fissure. It appears slightly on the lateral surface of the operculum, but is mostly located on the undersurface

ᐅ  What are its borders?

Area OP4 borders 43 anteriorly, and the parietal areas (discussed elsewhere) PFcm, and PFop posteriorly. Its superior border is with postcentral areas 1, 3a, and 3b. Its interior (inferior) border is with OP1, OP2-3, and a small part of IG.

ᐅ What are its borders?

Area OP4 demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, area 4 in the motor strip, areas SCEF, FEF, 6mp, 6r, 6d and 6v in the premotor regions, areas a24prime, p32prime, 24dd, 24dv, 5mv, and 23c in the middle cingulate regions, area 46 in the lateral frontal lobe, areas IG, 43, OP2-3, OP1, PFcm, FOP1, FOP2, FOP3, and FOP4 in the superior insula opercular regions, areas STV, LBelt, PBelt, MBelt, A1, TA2, PI, A4, A5, TA2, MI, STV, 52, RI, PoI1 and PoI2 in the lower opercula and Heschl's gyrus regions, areas PF, PFop, PFt, AIP, 7PC, and 7AL in the lateral parietal lobe, area V3 in the medial occipital lobe, areas V6, V6a, and V7 of the dorsal visual stream, areas FFC of the ventral visual stream, and areas LO3, TPOJ2, TPOJ3, MT, MST, and FST of the lateral occipital lobe.

ᐅ What are its functional connections?

Area OP4 is structurally connected to local parcellations. Local short association bundles connect with 43, PFcm, PFop, Ig, LBelt, OP1, OP2-3, OP4, 1, 3a, 3b, RI, PoI1, and PoI2.

ᐅ What are its white matter connections?

Area OP4 is a part of the posterior opercular cortex. This region is involved in processes required for sensory motor functions, such as integrating sensory responses into motor actions, and is crucial in tangible object recognition and manipulation. Area OP4 was differentiated from areas OP1 and OP2-3 based on differences in activity on fMRI during motor and arithmetic tasks.

 

OP4_a

A: lateral-medial

 

OP4_b

B: anterior-posterior

 

OP4_c

C: superior-inferior

 

OP4_dti

DTI image

ᐅ  Summary

Area PBelt (parabelt complex): part of parietal apex regions and superior insula opercular regions. Parcellated from the auditory cortex.

ᐅ  Where is it?

Area PBelt (Parabelt complex) is located on the superior surface of the inferior portion of the supramargina gyrus. It lies in the small region between the lateral edge of Heschl's gyrus and the opercular cleft of the inferior SMG.

ᐅ  What are its borders?

Area PBelt borders Lbelt and Mbelt medially and A4 laterally. Its deep surface borders with RI

ᐅ What are its borders?

Area PBelt demonstrates functional connectivity to areas 1, 2, 3a, and 3b in the sensory strip, area 4 in the motor strip, area 24dd in the paracingulate areas, areas FEF, 6d, 6v, and 6mp in the premotor areas, areas 43, PFcm, OP1, OP2-3, and OP4 in the superior opercular region, areas A1, A4, A5 Mbelt, LBelt, PoI1, PoI2, STV, Ta2, PI, RI, and 52 in the inferior insula opercular region, areas PFop and 7PC in the parietal lobe, areas V1, V2, V3, and V4 in the medial occipital lobe, areas V6, V67a, V7, V3a, and V3b in the dorsal visual stream, areas V8, FFC, Pit and VVC in the ventral visual stream, and areas LO2, LO3, V3cd, FST, MT, MST, V4t, TPOJ1, and TPOJ2 in the lateral occipital lobe.

ᐅ What are its functional connections?

Area PBelt is structurally connected to the middle longitudinal fasciculus and arcuate/SLF. Arcuate/SLF fibers wrap around the termination of the sylvian fissure to end at the inferior frontal gyrus at parcellation 45 and FOP5. Fibers from the middle longitudinal fasciculus project posterior just lateral to the lateral ventricle to occipital and parietal lobes to end at parcellations MIP, LIPv and IP1. Local short association bundles connect with A1, LBelt, MBelt, PFcm, PSL, A4, A5, TPOJ1.

ᐅ What are its white matter connections?

Area PBelt is a newly described area of the brain parcellated from the auditory cortex. Area PBelt was differentiated from areas A4 and LBelt based on differences in activity on fMRI during arithmetic, auditory story, and motor cue tasks.

 

PBelt_a

A: lateral-medial

 

PBelt_b

B: anterior-posterior

 

PBelt_c

C: superior-inferior

 

PBelt_dti

DTI image

ᐅ  Summary

Area Pir (piriform cortex): part of the opercular cortex: Found to contain axons that distribute widely and extensively branch throughout other cortical regions with functional roles attributed to cognition, behavior, emotion, and memory. Largest area of the brain to receive olfactory signals. Shows activation with all olfactory tasks and plays a pivotal role in the memory of olfaction, discrimination of odors, and distribution of this information to other regions of the brain.

ᐅ  Where is it?

Area Pir (piriform cortex) is located in the pyriform cortex, which itself is located just anterior to the anterior perforated substance, at the point where the limen insula folds onto the orbitofrontal surface.

ᐅ  What are its borders?

Area Pir borders AAIC and a small part of area 47s anteriorly, pOFC medially POI1 POI2, PI and TA2 laterally. Its posterior border is with the anterior perforated substance.

ᐅ What are its borders?

Area Pir demonstrates functional connectivity to areas AAIC, PoI1 and PoI2 in the insula.

ᐅ What are its functional connections?

Area Pir is structurally connected to local parcellations and posterior insular regions. The white matter tracts of this parcellation are difficult to delineate due to the proximity of the area to underlying white matter tracts. Connections to posterior insular regions project from Pir to PoI2, Ig and OP2-3. Local short association bundles connect with AAIC and TGd.

ᐅ What are its white matter connections?

The piriform cortex is a region of the anterior apex that has been studied previously. Area Pir has been found to contain axons that distribute widely and extensively branch throughout other cortical regions with functional roles attributed to cognition, behavior, emotion and memory. Area Pir is also the largest area of the brain to receive olfactory signals. Area Pir shows activation with all olfactory tasks and plays a pivotal role in the memory of olfaction, discrimination of odors, and distribution of this information to other regions of the brain.

 

Pir_a

A: lateral-medial

 

Pir_b

B: anterior-posterior

 

Pir_c

C: superior-inferior

 

Pir_dti

DTI image

ᐅ  Summary

Area RI (retroinsular cortex): part of parietal apex regions, and an area of the early auditory cortex. Area RI is connected to various somatosensory areas and receives somatosensory input. As a result, it is believed that this regions plays a role in receiving auditory-somatosensory communications from the auditory cortex in conjunction with the granular insula.

ᐅ  Where is it?

Area RI (Retroinsular cortex) is located in the retroinsular cortex, which itself is located anterior superior to the long gyri of the insula. It is located at the deep termination of Heschl's gyrus as its superomedially.

ᐅ  What are its borders?

Area RI is slanted from anterior-inferior to posterior superior. On its anterior inferior border, it meets IG, OP2-3 and OP1. On its exterior border, it meets PFcm and PSL. On its deep inferoposterior border, it joins with A1, Mbelt, Lbelt, and Pbelt, the Heschl's gyrus regions.

ᐅ What are its borders?

Area RI demonstrates functional connectivity to areas 1, 2, 3a, 3b in the sensory strip, area 4 in the motor strip, areas FEF, 6mp, and 6v in the premotor regions, areas 43, OP4 OP2-3, OP1, PFcm in the superior insula opercular regions, areas LBelt, PBelt, MBelt, A1, TA2, PI, A4, A5, TA2, STV, and 52 in the lower opercula area and Heschl's gyrus regions, area PFop in the lateral parietal lobe, areas V2, V3, and V4 in the medial occipital lobe, area V6, V3b, V3a, and V7 of the dorsal visual stream, areas FFC of the ventral visual stream, and areas LO3, TPOJ1, TPOJ2, TPOJ3, MT, MST V4t, and FST of the lateral occipital lobe.

ᐅ What are its functional connections?

Area RI is structurally connected to portions of the arcuate/SLF, anterior insula and local parcellations. Arcuate/SLF fibers project anterior form RI to inferior frontal gyrus parcellations 44 and 6r. Insular fibers course anterior to insular parcellations PoI2 and PoI1. Local short association bundles are connected with A1, OP1, OP4, PBelt and A4 .

ᐅ What are its white matter connections?

Area RI is an area of the early auditory cortex. Area RI is connected to various somatosensory areas and receives somatosensory input. As a result, it is believed that this region plays a role in receiving auditory-somatosensory communications from the auditory cortex in conjunction with the granular insula.

 

RI_a

A: lateral-medial

 

RI_b

B: anterior-posterior

 

RI_c

C: superior-inferior

 

RI_dti

DTI image

The information provided in this guide has been adapted from 'A Connectomic Atlas of the Human Cerebrum' (Briggs et al, 2018).
 
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